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Microwaves, Antennas & Propagation, IET

Popular Articles (April 2015)

Includes the top 50 most frequently downloaded documents for this publication according to the most recent monthly usage statistics.
  • 1. Review of substrate-integrated waveguide circuits and antennas

    Publication Year: 2011 , Page(s): 909 - 920
    Cited by:  Papers (87)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    Substrate-integrated waveguide (SIW) technology represents an emerging and very promising candidate for the development of circuits and components operating in the microwave and millimetre-wave region. SIW structures are generally fabricated by using two rows of conducting cylinders or slots embedded in a dielectric substrate that connects two parallel metal plates, and permit the implementation of classical rectangular waveguide components in planar form, along with printed circuitry, active devices and antennas. This study aims to provide an overview of the recent advances in the modelling, design and technological implementation of SIW structures and components. View full abstract»

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  • 2. Triple-band compact circularly polarised stacked microstrip antenna over reactive impedance meta-surface for GPS applications

    Publication Year: 2014 , Page(s): 1057 - 1065
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1161 KB)  

    In this study, a compact, triple-band, circularly polarised stacked microstrip antenna is proposed over the artificial eta-surface called reactive impedance surface (RIS) for enhancing antenna radiation efficiency for GPS applications. The proposed design utilises the concept of combining multi-stacked patches with RIS as imaginary-impedance metamaterial-ground-plane for selective frequency reduction of lower bands with improvement in antenna radiation properties for multi-band applications. The circularly polarised (CP) radiation with compact antenna size is achieved for triple-band GPS frequencies of L1 (1.575 GHz), L2 (1.227 GHz) and L5 (1.176 GHz) by placing three stacked patches with two different pairs of symmetric slits, four different sized symmetric cross-shaped slots and truncated corners over RIS. As RIS meta-surface reduces the wave penetration through the lossy substrate beneath it, the proposed stacked patch antenna over RIS demonstrates enhanced forward gain with suppressed back radiation. The measured results for antenna prototype are (1.168-1.185 GHz): L5 band, (1.2-1.245 GHz): L2 band and (1.51-1.59 GHz): L1 band for 10 dB return loss bandwidth with good CP radiation. Forward (boresight) right-handed CP gain of 2.88 dBic (L5 band), 3.25 dBic (L2 band) and 5.53 dBic (L1 band) is observed for compact antenna overall volume of 0.32λo × 0.32λo × 0.024λo at 1.2 GHz. View full abstract»

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  • 3. Design of compact reconfigurable ultra-wideband slot antenna with switchable single/dual band notch functions

    Publication Year: 2014 , Page(s): 541 - 548
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1011 KB)  

    A compact reconfigurable microstrip slot antenna with switchable single and dual band notch functions for ultra-wideband (UWB) applications is presented in this study. In the proposed structure, an additional resonance is excited by etching two symmetrical notches on the feed-line and thereby a UWB characteristic is obtained. Then, by cutting two slots on the radiating patch and embedding two positive-intrinsic-negative (PIN) diodes along these slots, switchable single and dual band notch performances are added to the antenna performance. By changing the bias states of the PIN diodes, the antenna is capable of exhibiting four different performances of UWB spectrum coverage, UWB coverage with single rejection of the wireless local area network (WLAN) band, UWB coverage with single rejection of the WiMAX and C-band spectrum, and UWB coverage with dual band notch function at the WLAN, the WiMAX and the C-band frequencies. Good agreement between the simulated and the measured results is achieved at different performances of the antenna. The designed antenna has a small size of 20 × 20 mm2 and the measured results reveal that the fabricated antenna has good radiation behaviour in the UWB frequency spectrum with switchable band notch functions at 3.15-3.85 and 5.43-6.1 GHz which can eliminate the UWB frequency band interference with the WiMAX, the C-band and the WLAN systems. View full abstract»

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  • 4. Two feeding methods based on substrate integrated waveguide for microstrip patch antennas

    Publication Year: 2015 , Page(s): 423 - 430
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1204 KB)

    Two feeding methods for microstrip patch antennas (MPAs), namely aperture coupling (AC) and probe feeding (PF), based on a substrate integrated waveguide (SIW) are presented in this study. Exploiting an SIW structure for MPA feeding combines the benefits of both structures. It results in a compact antenna structure retaining advantageous properties of MPAs and having a radiation characteristic non-effected by spurious radiation that is usually produced by a conventional feeding line. The proposed antenna structures are studied using parametric analyses and their design procedures are presented. The antenna structures are fabricated and verified by measurement at 10 GHz. At the operation frequency, the fabricated AC-MPA and PF-MPA with a coax-to-SIW transition achieved an impedance bandwidth of 9 and 13.1% and a gain of 8.6 and 9.2 dBi, respectively. View full abstract»

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  • 5. Planar antennas for compact multiband transceivers using a microstrip feedline and multiple open-ended ground slots

    Publication Year: 2015 , Page(s): 486 - 494
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1119 KB)

    Two planar antennas for compact multiband transceivers are presented, that employ an open-ended microstrip feedline that couples to multiple open-ended ground slots. The effect of separately introducing each of the slots on the antenna performance is outlined, and it is shown that the resonant frequencies of the antennas can be independently controlled by adjusting the dimensions of the ground slots. Antenna 1, consisting of an open-ended microstrip feedline that couples to three open-ended ground slots, exhibits a measured |S11| <; -6 dB in the frequency ranges of 1.64-3.50 GHz, and 5.22-6.81 GHz, covering the standards of DCS, PCS, UMTS, Wibro, Bluetooth, WiMAX, HiperLAN 2 and WLAN with a measured gain that varies between 1.85 and 3.98 dBi, and with radiation efficiencies in excess of 80%. Antenna 2, consisting of an open-ended microstrip feedline that couples to four open-ended ground slots, exhibits a measured |S11| <; -6 dB in the entire frequency range of 2.74-6.71 GHz, covering the standards of WiMAX, HiperLAN 2 and WLAN with a measured gain that varies between 4.98 and 5.28 dBi, and with radiation efficiencies in excess of 80%. Both antennas occupy a total size of only 40 × 30 × 1.6 mm3. View full abstract»

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  • 6. Design of band-notched ultra wideband antenna for indoor and wearable wireless communications

    Publication Year: 2015 , Page(s): 243 - 251
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (881 KB)

    Design of a tapered-slot ultra wideband (UWB) band-notched wearable antenna is presented in this study. The antenna operation covers the whole UWB frequency spectrum of 7.5 GHz ranging from 3.1 to 10.6 GHz, while rejecting the wireless local area network operation at 5.25 GHz band. The performance of the antenna is analysed through simulations and validated through measurements. The antenna makes use of ultra-thin liquid crystal polymer (LCP) substrate. The presented return loss and radiation pattern results show that the antenna offers excellent performance in the UWB frequency band in free space. Use of the LCP substrate makes the antenna to efficiently mitigate the bending effects. Moreover, the antenna performs well in on-body configurations and its working is little affected in adversely hot and humid weather conditions. Furthermore, it offers good on-body communication link and pulse fidelity. These features make the proposed antenna design a well-suited choice for hand-held and wearable UWB applications. View full abstract»

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  • 7. Loading metamaterial perfect absorber method for in-band radar cross section reduction based on the surface current distribution of array antennas

    Publication Year: 2015 , Page(s): 399 - 406
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1206 KB)

    A loading metamaterial perfect absorber (MPA) method is proposed to reduce the in-band radar cross section (RCS) and preserve the radiation characters for the guidewave slot array antennas in this study. The surface current distributions of the array antennas are divided into the strong current area and the weak current area. The metal surface with the strong current is retained to avoid the radiation deterioration, and the MPA is only loaded on the weak current area by the three layers MPA for RCS reduction. The RCS of a 1 × 10 guidewave slot array antennas is reduced using the method. Simulated S11, radiation patterns, gain and RCS reduction of the array antennas are compared with measured results. Experimental results indicated that the in-band RCS of the array antennas loading the MPA has dramatically reduced with only about 0.73 dB gain reduction and the RCS reduction are not significant in out-of-band while the radiation characters is unchanged. The experimental results are in good agreement with the numerical simulations. View full abstract»

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  • 8. New design of compact dual band-notch ultra-wideband bandpass filter based on coupled wave canceller inverted T-shaped stubs

    Publication Year: 2015 , Page(s): 64 - 72
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (769 KB)

    The procedure of attaining a compact bandpass filter (BPF) with dual band-notch function for ultra-wideband (UWB) applications is presented and discussed. In the proposed BPF, defected ground structure is used in order to improve the out-of-band performance of the filter. Also, four short-circuited bent stubs are employed in order to improve the selectivity of the filter at its cutoff frequencies. Dual band-notch function is added to the performance of the filter by coupling two short-circuited inverted T-shaped stubs to the filter main resonator. The fabricated filter satisfies well the demands of the Federal Communications Committee with two narrow band-notch functions at 5.5 and 8 GHz, which eliminates the interference of the UWB system with wireless local area network (WLAN) and satellite communication systems, respectively. The improved upper stop-band of the proposed filter with more than 20 dB attenuation level extends up to 20 GHz. View full abstract»

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  • 9. Compact planar ultra-wideband antenna with quintuple band-notched characteristics

    Publication Year: 2015 , Page(s): 206 - 216
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1400 KB)

    A compact ultra-wideband planar monopole antenna with a size of 22 mm by 34 mm is presented to achieve the quintuple-band-notched characteristics. The proposed antenna consists of a Mickey-mouse shaped radiating element, a truncated/smoothed ground plane and a microstrip feed-line. The quintuple-band-notched function is achieved by integrating five specially designed half/one-wavelength M-shaped resonators into the radiator, feed-line and ground plane. The simulated and measured results show that the proposed antenna is able to operate from 2.24 to 10.8 GHz for |S11| <; -10 dB with excellent band rejection performance in the frequency bands of 2.35 to 2.61 GHz, 3.16 to 3.69 GHz, 5.0 to 6.1 GHz, 7.2 to 7.7 GHz and 8.1 to 8.74 GHz for some existing communication systems such as wireless local area networks, worldwide interoperability for microwave access, downlink of X-band satellite communication and ITU 8-GHz band, respectively. In addition, both the frequency-domain and time-domain performances of the antenna are investigated by simulation and measurement. The results obtained are also in very good agreement. View full abstract»

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  • 10. Design of a compact dual-band-notch ultra-wideband bandpass filter based on wave cancellation method

    Publication Year: 2015 , Page(s): 1 - 9
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (890 KB)

    In this study, a compact ultra-wideband (UWB) bandpass filter (BPF) with sharp roll-off, improved out-of-band performance and dual-band-notch operation is presented and its design procedure is discussed. In the proposed structure, in order to reject the unwanted harmonic pass bands, a pair of modified cross-shaped coupled lines (CCLs) is implemented along the ports of the filter. Moreover, a pair of half-circle-shaped stubs and a stepped-impedance stub are loaded on the main resonator in order to obtain additional transmission zeros (TZs) which are controllable separately. Implementation of the CCLs and the stub loaded resonator (SLR) reduce the total size of the presented microstrip BPF. Besides, by extending and folding the upper coupled line of each CCLs and also through an open stub which is protruded inside a slot on the main resonator, dual-band-notch operation is added to the performance of the presented filter. The fabricated prototype has a small size and is capable to cover frequency band of 2.8-10.69 GHz with two band-notch functions at 4.9-5.4 and 7.83-8.25 GHz which suppresses the interference between UWB spectrum with wireless local area network (WLAN) and satellite communication frequency bands, respectively. The proposed filter has a compact size while showing good return loss and insertion loss characteristic in the frequency band of interest. View full abstract»

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  • 11. Reconfigurable PIFA with a parasitic strip line for a hepta-band WWAN/LTE mobile handset

    Publication Year: 2015 , Page(s): 108 - 117
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1512 KB)

    In this study, a reconfigurable planar inverted-F antenna (PIFA) with a parasitic strip line for a hepta-band wireless wide area network (WWAN)/long term evolution (LTE) mobile handset is proposed. The PIN diode is located between the end of the parasitic strip line and the protruded ground plane. Depending on the on/off-state of the PIN diode, the degree of coupling between the conventional PIFA and the parasitic line is controlled and the fundamental resonant frequency of the proposed antenna is adjusted. As a result, the fundamental resonant frequencies cover the (global system for mobile communication) GSM850 (824-894 MHz) and GSM900 (880-960 MHz) bands. By the parasitic strip line extended from the protruded ground plane, impedance matching at the higher-order modes (f2 and f3) is improved and the fourth resonant frequency f4 is remarkably decreased. The high band of the antenna is formed by combining these three higher-order modes to cover the GSM1800 (1710-1880 MHz), GSM1900 (1850-1990 MHz), universal mobile telecommunication system (UMTS) (1920-2170 MHz), LTE2300 (2305-2400 MHz) and LTE2500 (2500-2690 MHz) bands. View full abstract»

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  • 12. Unequal Wilkinson power divider with wide range of arbitrary power division based on recombinant technology

    Publication Year: 2015 , Page(s): 166 - 175
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (998 KB)

    An arbitrary ratio Wilkinson power divider with large power dividing ratio is analysed and demonstrated in this study. This kind of Wilkinson power divider is constructed by incorporating equal (or unequal) power divider cells, recombinant structures, extra low power branches and transformers for matching the circuits. The proposed structure is compatible with single-layer printed circuit board fabrication process. The structure is analysed in detail, while the formulas are given as design guidelines. Moreover, this method is extended to unequal power dividers based on three-way Wilkinson power divider with larger dividing ratio. To verify the proposed design approach, the prototypes of 5:1, 7:1 and 11:1 unequal power divider are optimised, fabricated and measured. The measured bandwidth of 20 dB return loss are about 10, 10 and 6%, respectively, while the isolations of the output ports are better than 20 dB. Good agreements can be observed between the simulated and measured results. The phase differences of output ports are within ±3° over 10% fractional bandwidth. View full abstract»

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  • 13. Stacked microstrip antenna fed by an L-probe for quadruple band operation

    Publication Year: 2015 , Page(s): 360 - 368
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1048 KB)

    A stacked patch microstrip antenna combined with a stacked ring microstrip antenna is proposed for quadruple band operation. The two antennas (a stacked patch microstrip antenna and a stacked ring microstrip antenna) are excited by an L-probe feed. The impedance bandwidth is enhanced by using double resonance at all frequency bands. With simulations, the relationships between the antenna's geometrical parameters and operational frequencies are clarified. The operational principle for quadruple band is explained by the simulated electric currents. The antenna is designed for Wi-Fi (2.45/5.25/5.6 GHz bands) and mobile WiMAX (3.5 GHz band). View full abstract»

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  • 14. U-shaped bow-tie magneto-electric dipole antenna with a modified horned reflector for ultra-wideband applications

    Publication Year: 2014 , Page(s): 990 - 998
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1160 KB)  

    A novel U-shaped bow-tie magneto-electric dipole unidirectional antenna with a dual-layer horned reflector for ultra-wideband (UWB) applications is proposed. To broaden impedance bandwidth, a U-shaped bow-tie electric dipole structure with two notch slots is presented. In addition, to reduce the size of the antenna and improve impedance matching, a new feeding structure designed with perforation and tapered line is introduced. Finally, a double-layer horned reflector, instead of a ground plane, is employed to improve radiation patterns and gains for high-rate data transmission. The prototype antenna can achieve a stable gain of 10 ± 1.2 dBi and an impedance bandwidth of 118% for standing wave ratio ≤ 2 from 2.81 to 10.92 GHz. To the best of the authors knowledge, it is the first U-shaped bow-tie magneto-electric dipole unidirectional antenna for UWB applications. The proposed antenna, which possesses the advantages of UWB antenna and magneto-electric dipole antenna simultaneously, can be easily fabricated with low cost. With these features, it is a practicable candidate for UWB communications. View full abstract»

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  • 15. Reduced and conventional size multi-band circular patch antennas loaded with metamaterials

    Publication Year: 2013 , Page(s): 768 - 776
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (783 KB)  

    In this study, a novel technique to achieve multi-band performance for both reduced and conventional size circular microstrip patch antennas loaded with metamaterial has been proposed. Incorporation of symmetric slotting concept with the concept of additional mode modification for both MNG (μ negative) and ENG (ε negative) metamaterial loaded circular patch antennas have been shown. The use of metamaterial creates an unconventional mode, whereas symmetrical slotting not only modifies another band but also improves the gain by around 1 dB of unconventional mode for MNG loaded antenna. Design algorithms for metamaterial loaded circular patch antennas have been developed to achieve size reduction and highly directive multiband property. Based on these design algorithms, at first a reduced size triple band circular patch antenna loaded with MNG metamaterial has been shown where around 35% size reduction is achievable. Later, a triple band conventional size circular patch antenna partially loaded with ENG metamaterial has been designed with high gain and directive performances for all three bands compared to previously reported such antennas. View full abstract»

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  • 16. Dual band-notched small monopole antenna with novel W-shaped conductor backed-plane and novel T-shaped slot for UWB applications

    Publication Year: 2013 , Page(s): 8 - 14
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (777 KB)  

    In this study, a novel method for designing a new monopole antenna with dual band-notched characteristic for UWB applications has been presented. The proposed antenna consists of a square radiating patch with a modified T-shaped slot, and a ground plane with two E-shaped slots and a W-shaped conductor backed-plane. By cutting two E-shaped slots in the ground plane, additional resonance is excited and hence much wider impedance bandwidth can be produced, especially at the higher band, which results in a wide usable fractional bandwidth of more than 130% (2.73%13.3 GHz). In order to generate single band-notched characteristic, the authors use a W-shaped conductor backed-plane structure on the other side of the substrate. In addition, by cutting a modified T-shaped slot in the radiating patch and microstrip feed-line, a dual band-notched function is achieved. The measured results reveal that the presented dual notch band monopole antenna offers a very wide bandwidth with two notched bands, covering all the 5.2/5.8 GHz wireless local area network, 3.5/5.5 GHz WiMAX and 4 GHz C bands. The designed antenna has a small size of 12 % 18 mm2. Good voltage standing wave ratio (VSWR) and radiation pattern characteristics are obtained in the frequency band of interest. Simulated and measured results are presented to validate the usefulness of the proposed antenna structure for ultra-wideband (UWB) applications. View full abstract»

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  • 17. Electromagnetic band gap-dipole sub-array antennas creating an enhanced tilted beams for future base station

    Publication Year: 2015 , Page(s): 319 - 327
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1405 KB)

    A novel customised electromagnetic band gap (EBG)-dipole sub-array antenna with a tilted beam for future base-station applications is presented. An enhanced tilted beam for the base-station antenna is one of the safest methods to increase radio coverage area adhering to the strict power requirements. An array of four dipole-EBG elements is designed demonstrating the enhanced down-tilt beam. Each single element consists of dipole antenna mounted on a customised EBG ground plane created by connecting several unit cells of the EBG. The proposed array radiates a tilted beam in order to achieve a high directivity at fixed down-tilt angle. The array antennas are simulated, fabricated and measured. The directivity of 11 dB is measured at the angle of 28° at 3.5 GHz. This directivity is 1.9 dB higher than the reference case that uses the broadside single element. In addition, the EBG-dipole array that can be mechanically tilted is designed. The proposed array antenna exhibits acceptable impedance matching across the operational frequency band. View full abstract»

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  • 18. Wideband 60 GHz circularly polarised stacked patch antenna array in low-temperature co-fired ceramic technology

    Publication Year: 2015 , Page(s): 436 - 445
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1102 KB)

    A wideband circularly polarised (CP) cross-aperture-coupled stacked feed antenna array with the top-metal strip via fence based on multilayer low-temperature co-fired ceramic technology is designed and measured for 60 GHz wireless communication applications. The influence of the large substrate and ground size on the radiation patterns of the proposed CP antenna array is investigated. Considering the 10 dB impedance bandwidth, 3 dB axial ratio bandwidth and 3 dB gain bandwidth, the measured results reveal that a wide operating bandwidth more than 17% at the centre frequency of 61.75 GHz from 56.5 to 67 GHz of the presented CP antenna array is achieved. View full abstract»

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  • 19. Design of an efficient ambient WiFi energy harvesting system

    Publication Year: 2012 , Page(s): 1200 - 1206
    Cited by:  Papers (13)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (629 KB)  

    This study is focused on equipping wireless devices (including sensors) with novel, high-efficiency circuitry to harvest and convert ambient radio frequency (RF) power to direct current (dc). Key components of this technology are (a) miniaturised antenna and (b) high-efficiency rectifying circuit. The first is responsible for capturing the RF waves, and the latter converts the RF energy to dc. A major challenge is the design of novel circuitry to generate a battery-like voltage from very low incoming RF energy. Under this study, the authors designed a novel RF power harvesting front-end whose conversion efficiency is significantly improved at low RF power levels (<;-20 dBm) as compared to existing technologies. Thus, the new circuitry can harvest ambient and widely available RF energy, making a game changing technology for powering mobile devices. In this study, the authors demonstrate this technology by using it to power a commercially available temperature and humidity meter with an LCD display. The latter is powered using nothing more than ambient WiFi signals in an office environment. View full abstract»

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  • 20. Design of broadband and tunable terahertz absorbers based on graphene metasurface: equivalent circuit model approach

    Publication Year: 2015 , Page(s): 307 - 312
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (427 KB)

    This study presents an effective method to model, analyse and design graphene metasurface-based terahertz (THz) absorbers using equivalent circuit model approach. Broadband and tunable absorbers consisting of graphene metasurface and metal-backed dielectric layer have been designed based on the formulas derived from this approach and verified by full-wave electromagnetic simulation. By properly constructing the graphene metasurface, broadband absorption over 70% fraction bandwidth has been achieved, showing that graphene can provide a wideband absorption in the low THz spectrum. Furthermore, tunability of the graphene metasurface has also been investigated. It is demonstrated that the absorption peak frequencies can be tuned while maintaining the peak absorption unchanged, which is highly desirable for THz sensing applications. View full abstract»

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  • 21. Controllable triple band-notched monopole antenna for ultra-wideband applications

    Publication Year: 2015 , Page(s): 336 - 342
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (962 KB)

    This study presents a new design of a triple band-notched ultra-wideband antenna. The designed structure of the antenna is based on two radiating strips, and a microstrip feed-line on the front, an inverted T-shaped element and a partial ground on the back. By etching a slot off the ground plane, another resonance is excited resulting in the extended bandwidth. The antenna with new structure occupies a small size of 20 × 14 mm2. The measured results show that the antenna has a wide bandwidth from 2.8 to 12.5 GHz for voltage standing wave ratio less than 2 apart from the rejected bands from 3.0 to 3.8 GHz, 5.1 to 6.1 GHz and 7.8 to 8.9 GHz. Meanwhile, radiation patterns and gain at various frequencies have been given. View full abstract»

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  • 22. Inkjet-printed antennas, sensors and circuits on paper substrate

    Publication Year: 2013 , Page(s): 858 - 868
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (932 KB)  

    Inkjet-printing is a very promising technology for the development of microwave circuits and components. Inkjet-printing technology of conductive silver nanoparticles on an organic flexible paper substrate is introduced in this study. The paper substrate is characterised using the T-resonator method. A variety of microwave passive and active devices, as well as complete circuits inkjet-printed on paper substrates are introduced. This work includes inkjet-printed artificial magnetic conductor structures, a substrate integrated waveguide, solar-powered beacon oscillator for wireless power transfer and localisation, energy harvesting circuits and nanocarbon-based gas-sensing materials such as carbon nanotubes and graphene. This study presents an overview of recent advances of inkjet-printed electronics on paper substrate. View full abstract»

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  • 23. Balanced substrate integrated waveguide bandpass filter with high selectivity and common-mode suppression

    Publication Year: 2015 , Page(s): 133 - 141
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1009 KB)

    A new method of designing balanced (differential) bandpass filters (BPFs) with high selectivity and common-mode suppression is proposed and implemented by taking advantage of the existence of multiple substrate integrated waveguide cavity modes. The major design concept is by properly choosing, feeding and coupling dual-mode cavities operating at TE102 and TE201 modes so as to not only provide capabilities to realise the desired differential-mode passband associated with two transmission zeros, but also generate high common-mode suppression over a wide range. Two X-band BPFs with different internal coupling mechanisms are then proposed and designed. The two design examples having the same centre frequency of 10 Hz and respective passband width of 300 and 270 Hz are fabricated for demonstration. High selectivity is observed for both filters. Meanwhile, c is ~37 dB for the first design example, whereas it is improved to 48.5 dB for the second one with multi-layered structure. Good agreement can be observed between simulated and measured performances in the authors' study. View full abstract»

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  • 24. Multiple-parameter reconfiguration in a single planar ultra-wideband antenna for advanced wireless communication systems

    Publication Year: 2014 , Page(s): 849 - 857
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (962 KB)  

    A compact frequency, pattern and polarisation reconfigurable planar ultra-wideband antenna is presented. The antenna is frequency reconfigurable to allow flexible functionality such as limiting the impact of out-of-band interferers if required in certain applications. Moreover, it provides basic pattern reconfiguration to enhance the scanning or the communication performance in future wireless applications by sensing interferers in the space domain and achieving pattern diversity to mitigate fading and increase signal-to-noise ratio. Another special feature of the proposed antenna is that its polarisation is reconfigurable at specific frequencies to generate circular polarised (CP) radiation. The antenna performance characteristics are verified through parametric simulations and measurements. The proposed antenna presents significant degrees of freedom in providing reconfigurable properties in frequency, radiation patterns and polarisation as compared to standard single-parameter reconfigurable antennas; therefore providing a flexible radio front-end for smart radio and wireless applications such as cognitive radio. View full abstract»

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  • 25. Design of fractal patch antenna for size and radar cross-section reduction

    Publication Year: 2010 , Page(s): 175 - 181
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    This research study presents a novel design of star-shaped fractal patch antenna for miniaturisation and backscattering radar cross-section (RCS) reduction. The proposed fractal antenna gives 50% size reduction compared with a conventional circular microstrip patch (CCMP) antenna. The antenna is studied experimentally for return loss behaviour using vector network analyser R&S ZVA40. It can be useful for wireless application in 0.85-4 GHz frequency band. Further, the study focuses on backscattering RCS (both monostatic and bistatic) reduction by the proposed antenna compared with the CCMP antenna. It is found that increase in number of fractal iterations included in the conventional patch to design fractal antenna geometry reduces backscattering RCS at multiband compared to the conventional patch antenna. This reduction in backscattering RCS by the antenna is observed at multiband. The antenna can be tuned for low backscattering by variation in the substrate dielectric constant and thickness and the superstrate dielectric constant and thickness. For maximum RCS reduction by the antenna, optimisation of substrate thickness becomes necessary. The study also deals with effect of frequency and aspect angle variation on backscattering RCS reduction. View full abstract»

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  • 26. Compact multiple-input–multiple-output antenna using quasi-self-complementary antenna structures for ultrawideband applications

    Publication Year: 2014 , Page(s): 1021 - 1029
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1180 KB)  

    A compact multiple-input-multiple-output (MIMO) antenna with a very small size of only 21 × 38 mm2 is proposed for ultra-wideband (UWB) applications. It consists of two quasi-self-complementary antenna (QSCA) elements with an inverted T-shaped common ground plane. The QSCA elements are the mirror images of each other, having a half-circular conductor patch on one side of the substrate and a slot with the complement of the half-circular shape on the other side. To reduce mutual coupling between the two QSCA elements, two rectangular slots are cut symmetrically on the ground plane between the two elements. Simulation and measurement are used to study the performance of the MIMO antenna in terms of reflection coefficient, isolation between the two ports, radiation pattern, realised gain, efficiency and envelope correlation coefficient. The results show that the MIMO antenna has a bandwidth from 3.1 GHz to more than 10.6 GHz with a mutual coupling of less than -15 dB and a correlation of less than 0.1, respectively, making it a good candidate for portable UWB applications. View full abstract»

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  • 27. Design of a salisbury screen absorber using frequency selective surfaces to improve bandwidth and angular stability performance

    Publication Year: 2011 , Page(s): 149 - 156
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (735 KB)  

    A new design method that greatly enhances the reflectivity bandwidth and angular stability beyond what is possible with a simple Salisbury screen is described. The performance improvement is obtained from a frequency selective surface (FSS) which is sandwiched between the outermost 377 Ω/square resistive sheet and the ground plane. This is designed to generate additional reflection nulls at two predetermined frequencies by selecting the size of the two unequal length printed dipoles in each unit cell. A multiband Salisbury screen is realised by adjusting the reflection phase of the FSS to position one null above and the other below the inherent absorption band of the structure. Alternatively by incorporating resistive elements midway on the dipoles, it is shown that the three absorption bands can be merged to create a structure with a -10 dB reflectivity bandwidth which is 52% larger and relatively insensitive to incident angle compared to a classical Salisbury screen having the same thickness. CST Microwave Studio was used to optimise the reflectivity performance and simulate the radar backscatter from the structure. The numerical results are shown to be in close agreement with bistatic measurements for incident angles up to 40° over the frequency range 5.4-18 GHz. View full abstract»

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  • 28. Design of dual-bandpass filter using zeroth-order resonance and Bragg frequency

    Publication Year: 2015 , Page(s): 431 - 435
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (274 KB)

    This study presents a novel compact dual-bandpass filter using zeroth-order resonance and Bragg frequency of the composite right/left handed transmission line (CRLH-TL) resonator. By taking advantage of the Bragg frequency, two resonance modes are obtained with only one CRLH-TL unit cell. The equivalent circuit for the novel resonator is proposed and analysed. The resonance frequencies are given by using the circuit model and the input impedance is calculated. Dimensions of the resonator can be obtained based on the values of the lumped elements in the equivalent circuit. Compared with the conventional half-wavelength resonator, the size of the presented resonator is only about one-tenth of it. Then, the zeroth-order resonance and Bragg frequency modes are demonstrated using the dispersion curve. A dual-bandpass filter is designed to verify the resonator analysis. The source-load coupling is involved to improve the frequency selectivity of the filter. The fabricated filter is compact with a size of only 0.09 λg × 0.16 λg. The two central frequencies are located at 2.4/3.3 GHz and the filter has a wide upper stopband of over 4 GHz. Moreover, the fabricated filter has five transmission zeros and good frequency selectivity is observed. View full abstract»

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  • 29. Ambient RF energy harvesting trial in domestic settings

    Publication Year: 2015 , Page(s): 454 - 462
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1263 KB)

    This study investigates the feasibility of ambient radio frequency (RF) energy harvesting for powering low-power electronic devices, in domestic environments. An RF spectrum survey was carried out in a variety of locations around the city of Bristol, UK between 500 MHz and 6 GHz. Locations are limited to indoor residential environments, and as a comparison an office. The measurement setup consists of an omnidirectional, broadband, discone antenna and a handheld spectrum analyser. On the basis of the measured power consumption of a number of low-power electronic devices and the analysed results, the required harvesting time to power each device is calculated. The results show that in order to harvest enough energy to power-up a small calculator (2 μW) for 1 s, an antenna array covering 1.7-2.5 GHz with effective area of 1 m2 requires on average about 10 min of harvesting. View full abstract»

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  • 30. Microstrip dual-mode bandpass filter design using pie-section truncated semi-circle and quarter-circle resonators

    Publication Year: 2015 , Page(s): 224 - 229
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (595 KB)

    New dual-mode microstrip bandpass filters (BPFs) using pie-section truncated semi-circle and/or quarter-circle resonators are presented. The even-mode and odd-mode frequency responses of these two resonators are investigated. Compared to the four-parameter optimisation of the conventional stub-loaded dual-mode resonator, only three parameters need to be adjusted and optimised for the proposed resonators. Based on these two novel resonators, three BPF examples are designed, fabricated and tested. In addition, the technique of source-load cross coupling to improve performance of the filters is adopted. The good agreement between simulated and measured results validates the design concept. View full abstract»

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  • 31. Antenna Q calculation using radiated modes and reflection coefficient

    Publication Year: 2015 , Page(s): 328 - 335
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (529 KB)

    Optimisation techniques are currently being used to design antennas with Q values close to theoretical limits. In order to evaluate how closely these designs approach the limits, it is necessary to calculate their Qs from measured or simulated data. Many standard techniques are accurate for large Qs, but yield values significantly below the actual Q for low Q cases. In this study, equations are derived to bracket the actual value of Q, and the issues involved in attempting to determine an exact value are discussed. Both time-averaged and time-varying energies are considered. The derivations and conclusions are different from those previously published. Data from electromagnetic simulations of design examples are used to illustrate. View full abstract»

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  • 32. Equivalent circuit model of a coaxial excited microstrip-fed quasi-lumped element resonator antenna array

    Publication Year: 2015 , Page(s): 446 - 453
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (868 KB)

    An approximate lumped-parameter equivalent circuit model of the quasi-lumped element resonator antenna array is presented. The array consists of six series resonant circuits of frequency-independent elements, each with an interdigital finger capacitor (IDC), and shorted across by a parallel narrow strip inductor. Each resonator exhibits an aperture size of 0.207λg × 0.2λg at a centre frequency of 5.8 GHz, with entire array size of 2.857λg × 1.07λg. The resulting design is fed by a microstrip line and excited by a coaxial feed probe. A simple equivalent circuit model representing the six resonant circuits as well as the coaxial feed probe circuit, using the magnetic-frill model approach but with the simplest uniform-current model is described to predict the characteristics of the proposed resonator (and by extension, the proposed array), the effects of the coaxial probe and the microstrip feed line. Simulated data obtained from a full wave analysis using finite integration technique commercial solver is compared with the Agilent advanced design system results of the equivalent circuit. The derived equivalent circuit model was validated both analytically and by numerical simulations. View full abstract»

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  • 33. A 60 GHz simple-to-fabricate single-layer planar Fabry–Pérot cavity antenna

    Publication Year: 2015 , Page(s): 313 - 318
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (780 KB)

    A planar single-layer single-feed Fabry-Pérot cavity antenna is designed and fabricated to operate at 60 GHz. The simplicity and planarity of this design is achieved by using only a laminated and commercially available dielectric slab, forming the cavity of the antenna, and by exciting the antenna through a planar feed, that is, a coplanar-waveguide-fed slot-dipole, printed directly on the ground plane of the cavity. The backward radiation because of a feeding-slot on the ground plane of the cavity is also investigated and a new closed form formula is presented. The radiation performance of the fabricated antenna is measured using an automated measurement setup built to characterise high-gain millimetre-wave antennas being probed on the opposite side of the main radiation beam. View full abstract»

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  • 34. Two-section asymmetric coupled-line impedance transforming directional couplers

    Publication Year: 2015 , Page(s): 343 - 350
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (547 KB)

    Two-section impedance transforming directional couplers have been proposed. It has been shown that such asymmetric coupled-line directional couplers can provide equal power split between the coupled and transmission ports as well as impedance transformation in the same broad frequency range, as classic two-section coupled-line couplers. The theoretical analysis has been presented and appropriate formulas allowing for calculation the required per-unit-length parameters of broadband two-section impedance transforming couplers have been derived. Moreover, it has been shown that the impedance transformation ratio of the presented coupler can be increased by the appropriate modification of the two-section coupled-line directional coupler in a way that the directly fed and coupled-line transformation ratios are different. The proposed modification allows for the design of broadband impedance transforming directional couplers with increased transformation ratio over the limit fixed by the coupling coefficient of the tightly coupled section and having at the same time acceptable impedance match and isolation between the respective ports. The presented theory has been confirmed by the measurements of a two-section 3 dB impedance transforming directional coupler having bandwidth fu/fl = 3:1 and impedance transformation ratio R = 2. View full abstract»

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  • 35. Compact arc-shaped antenna with binomial curved conductor-backed plane for multiband wireless applications

    Publication Year: 2015 , Page(s): 351 - 359
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1191 KB)

    This study proposes a novel design of compact printed multiband monopole antenna with binomial curved conductor-backed plane which generates five wide resonant frequency bands for |S11| ≤ -10 dB to cover 2.4/5.2/5.8 GHz wireless local area network, 2.5/3.5/5.5 GHz worldwide interoperability for microwave access and ultra-wideband applications simultaneously. The radiating elements of the monopole are composed of multiple arc-shaped strips. The radius of each arc-shaped strip varies proportionally to the arithmetic progression sequence. The proposed multiband antenna is studied with different shapes of conductor-backed plane through the variation in order N of binomial curve equation. The overall dimension of the proposed multiband antenna is 32 × 25 × 0.8 mm3. The prototypes of the proposed multiband antenna are fabricated and tested. The radiation mechanism of the proposed multiband antenna is explained using simulated current distributions. Simulated and experimental results obtained for these antennas show that they exhibit good radiation behaviour within the operational frequency bands. View full abstract»

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  • 36. Design of reconfigurable antennas based on an L-shaped slot and PIN diodes for compact wireless devices

    Publication Year: 2009 , Page(s): 47 - 54
    Cited by:  Papers (28)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (665 KB)  

    A basic antenna structure to design pattern and pattern/frequency reconfigurable antennas is proposed. The structure consists of an L-shaped slot, PIN diodes, lumped capacitors and bias networks. The PIN diodes and the lumped capacitors located at specific positions are used to create short circuits across the slot. By carefully controlling these diodes, the induced current distribution around the slot can be changed, resulting in different antenna radiation patterns. Thus, a pattern reconfigurable antenna can be achieved. The proposed structure is then extended to design frequency/pattern reconfigurable antennas by introducing varactor diodes. Two compact reconfigurable antennas based on the proposed structure are designed and implemented to prove the design concepts. The experiment results fully demonstrated the performances of the proposed designs. Owing to the compact size and ease on manufacture, the proposed structure can be a promising solution in compact wireless devices such as smart phones and notebook computers. View full abstract»

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  • 37. Miniature microstrip-fed ultra-wideband printed monopole antenna with a partial ground plane structure

    Publication Year: 2011 , Page(s): 1683 - 1689
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (662 KB)  

    A new microstrip-fed planar monopole antenna is presented for ultra-wideband (UWB) communication systems. The antenna structure consists of a dome-topped, bowl-shaped patch with a truncated ground plane structure. The ground plane is predominately tapered and includes a notch below the feed-line in the vicinity of the patch. The effects of dimensional parameters on the performance of the antenna have been investigated through a parametric study. Current density distribution on the antenna was also computed to gain a better insight of its behaviour. The antenna performance is validated through measurement, including its radiation patterns. The measured impedance bandwidth of the proposed antenna for |S11||| |10|dB is 10.35|GHz (2.65|13.0|GHz), constituting 132| impedance bandwidth. The fabricated antenna has a compact size of 18|20|1.6|mm3. Additional features that make the antenna a suitable candidate for UWB systems are its simple configuration, compactness and low fabrication cost. View full abstract»

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  • 38. Analytical equivalence between substrate-integrated waveguide and rectangular waveguide

    Publication Year: 2008 , Page(s): 35 - 41
    Cited by:  Papers (34)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (275 KB)  

    Rectangular waveguide (RW) with sidewalls of vertical conducting cylinders (i.e. SIW, substrate-integrated waveguide) becomes popular with the advent of low-temperature co-fired ceramic structure; its analysis is usually numerical, or modal, leading to empirical design formulas. However, its analytical equivalence to the common RW of the solidwall is identified; in other words, analytical design formulas of the SIW and the equivalent RW of solid sidewalls are the same. The equivalence is established on comparing the surface impedances along the side walls, of the SIW and of an RW through analytical continuation. The equivalence formulas, propagation and cut off frequency show very good agreement with the results from both numerical simulations and measurements of hardware experiments, and over wide frequencies. The good agreements are easily understood on the basis of the conformal maps and the variational principle. View full abstract»

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  • 39. Analysis and design of wideband widescan planar tapered slot antenna array

    Publication Year: 2010 , Page(s): 1632 - 1638
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (811 KB)  

    Phased arrays have been required to operate over wide bandwidths and wide scan angle to support multifunction operation in both telecommunication and radar. In response to that need, this study firstly analyses the performance of the connected planar tapered slot antenna array and finds that the mutual coupling is essential and has good effect in wideband antenna array design. Then the authors design a wideband widescan planar tapered slot antenna array system with novel dual-parabola tapered slot antenna elements and feed network. This array can operate from 1.6 to 9 GHz and scan angle up to 45 . Both simulation and measurement results are shown to certificate the performance of the proposed antenna array. View full abstract»

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  • 40. Four-port beam reconfigurable antenna array for pattern diversity system

    Publication Year: 2012 , Page(s): 1179 - 1186
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1044 KB)  

    This study investigates a practical design for a switched beam planar antenna that can be implemented as a compact, low-cost switchable and/or reconfigurable beam antenna array. The antenna consists of a four-port antenna array, which is based on L-shaped quarter-wavelength slot antenna elements. This type of antenna array is a planar structure and its maximum directional radiation beam pattern presents in an azimuth plane covering 3600. The antenna array operates based on the `ON' or `OFF' states of PIN diodes in each individual slot antenna element and the combined signals from the four-port output. Therefore by properly controlling the state of the PIN diodes, the antenna exposes its characteristics of switchable/ reconfigurable beam patterns in the Φ-plane. To validate the proposed design, a small smart, switched-beam antenna operating at 2.7 GHz in multiple input-multiple output applications is simulated and fabricated. View full abstract»

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  • 41. Design and implementation of low sidelobe substrate integrated waveguide longitudinal slot array antennas

    Publication Year: 2009 , Page(s): 790 - 797
    Cited by:  Papers (18)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (682 KB)  

    Low sidelobe longitudinal slot array antennas are investigated based on substrate integrated waveguide (SIW) technology. The design method consists of the characterisation of the radiating element, the synthesis of the linear array and the development of the planar array including a feeding power divider by performing full-wave electromagnetic simulations for the final accurate design. Two planar slot array antennas are fabricated with a normal printed circuit board (PCB) process. Low sidelobe features are verified by the measured results which are in agreement with the simulated results. For an 8 times 8 SIW slot array antenna, the measured sidelobe levels (SLLs) are below -36 dB in the H-plane and below -25 dB in the E-plane with the Gain of 20.3 dB at 9.9 GHz. And for a 16 times 16 antenna, the SLLs are below -30 dB both in the E-plane and H-plane with the Gain of 24.4 dB at 10 GHz. The achieved design goals on the radiation patterns therefore validate the proposed low sidelobe SIW slot array antennas to be valuable candidates for high performance communication and radar applications. View full abstract»

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  • 42. Design of miniaturised band-notch ultra-wideband monopole-slot antenna by modified half-mode substrate-integrated waveguide

    Publication Year: 2013 , Page(s): 26 - 34
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1512 KB)  

    In this study, a compact ultra-wideband (UWB) two-layer printed microstrip line monopole-slot antenna with triple band-rejection characteristics is investigated. The proposed antenna consists of a planar UWB monopole-slot antenna with a size of 40 × 47 × 1.016 mm3 and a modified half-mode substrate-integrated waveguide (M-HMSIW) cavity with folded defected ground structure slot. The antenna is fabricated using two-layer printed circuit board process. To generate band-notched characteristics, M-HMSIW cavity in the bottom layer of the antenna are utilised. By tuning the dimension of M-HMSIW, triple notched bands with sharp rejection can be achieved at WiMAX band (3.3-3.69 GHz), along with a major part of the C-band (3.7-4.2 GHz), lower wireless local area network (WLAN) band (5.15-5.35 GHz), and upper WLAN band (5.725-5.825 GHz). The simulated and measured impedance matching, radiation patterns and gain results of antenna are investigated. The results of the fabricated antenna show that this antenna is a good candidate for various UWB applications. View full abstract»

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  • 43. Compact slot antenna for ultra-wide band applications

    Publication Year: 2014 , Page(s): 200 - 205
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (689 KB)  

    A novel compact ultra-wide band antenna with L-shaped slot is presented. The printed antenna is fed by a microstrip feed line to achieve impedance matching for the SMA connector. The proposed antenna offers 118% bandwidth when printed on a substrate of dielectric constant 4.4 and has an overall dimension of 23.7 × 23.7 × 0.8 mm3. The simulated and measured reflection characteristics of the antenna with the variation of key-parameters along with radiation patterns of the final antenna are presented and discussed. In addition, by decreasing the dimension of radiating patch, band-notched properties in the lower wireless local area network (WLAN) (5.15-5.35 GHz) or higher WLAN (5.725-5.825 GHz) bands are achieved. With the compact size and broadband, this antenna is very suitable for using in a trade-off which has to be taken account for a design of miniaturisation. View full abstract»

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  • 44. Dual-band microstrip-to-coplanar stripline Wilkinson balun using composite right- and left-handed transmission lines and its application in feeding dual-band bow-tie antenna

    Publication Year: 2014 , Page(s): 532 - 540
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (828 KB)  

    Using a composite right- and left-handed transmission lines, a dual-band microstrip-to-coplanar stripline balun is proposed that presents the benefits of bandwidth enlargement, excellent isolation and equal power split between output ports in the two passbands. Also, the dual-band nature of the balun, close space between output ports and ease of integration with a printed antenna in a compact size make it well suited for feeding dual-band planar two-wire antennas. As an example of an application, the proposed balun is designed and fabricated to work at two arbitrary frequency bands, 0.9 and 1.8 GHz. There is a good agreement between the measured and predicted results, which verifies the proposed design methodology. The fabricated balun shows a measured differential output phase bandwidth (180° ± 10°) of 22.95% and 18.76% for the first and second frequency bands, respectively. Moreover, this device is shown to have enhanced bandwidth performance in both isolation and 3-dB magnitude balance. To validate the performance of the proposed balun, the balun is employed to feed a dual-band metamaterial-loaded bow-tie antenna. The experimental results show that the return losses for both the operating bands remain below 10 dB. Likewise, the dual-band bow-tie antenna provides quasi-omnidirectional radiation over the frequency bands. View full abstract»

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  • 45. Square monopole antenna for microwave imaging, design and characterisation

    Publication Year: 2015 , Page(s): 49 - 57
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (982 KB)

    A novel ultra-wideband (UWB) antenna is presented which has UWB characteristics in a medium same as breast. To optimise the antenna for its best operation, effect of variation in different parts of the antenna is analysed and presented. The antenna's characteristics are presented in simulation and experimental measurements. The results of the authors' study show that the antenna has excellent performance across 4 to more than 9 GHz. View full abstract»

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  • 46. Circularly polarised printed antenna miniaturised using complementary split-ring resonators and reactive pin loading

    Publication Year: 2015 , Page(s): 118 - 124
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (680 KB)

    A circularly polarised printed antenna, miniaturised by utilising a combination of complementary split-ring resonators (CSRR) and reactive pin loadings, is presented. This design technique is shown to reduce the electrical size of the antenna diameter by 44% at 2.4 GHz. The antenna prototype, when radiating a right-hand circularly polarised beam, displayed 4.1 dBic of broadside realised gain with 70% radiation efficiency. Specifically, it was demonstrated that the stand-alone CSRR loading resulted in a size reduction of 30%. The addition of reactive pins enhances this factor up to 44% without causing any observable degradation in antenna performance. View full abstract»

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  • 47. Pencil beam radiation pattern from a single-layer substrate-integrated waveguide leaky-wave antenna with simple feeding

    Publication Year: 2015 , Page(s): 24 - 30
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (794 KB)

    A central feeding array radiating at broadside and manufactured in substrate-integrated waveguide (SIW) technology is shown in this work. The single-layer array consists of N = 8 line-source leaky-wave antennas (LWAs), which are designed to satisfy the splitting condition (α = β) of the leaky mode. The LWAs are arranged in a radial configuration, in this manner, by properly designing the SIW width W and the spacing between SIW vias P for each SIW LWA, the leaky mode can be independently controlled to fulfil the splitting condition, and all the individual beams from each SIW LWA can merge into one at broadside direction (θ = 0°) for a given design frequency. The two-dimensional radiating surface allows obtaining a pencil beam radiation pattern, which is linearly polarised because of the radial arrangement. A prototype with a radiating length of LA = 60 mm for each SIW LWA, and a total radius of R = 73 mm has been manufactured for a design frequency of 15 GHz. Input matching, gain and radiation patterns at several planes have been measured and compared with full-wave simulations, obtaining good agreement between them. View full abstract»

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  • 48. Ultra-wideband circular slot antenna with reconfigurable notch band function

    Publication Year: 2012 , Page(s): 108 - 112
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    An ultra-wideband (UWB) antenna is presented whose frequency characteristics can be reconfigured electronically to have either a single- or dual-band notch function to block interfering signals from C-band satellite communications systems, IEEE802.11a and HIPERLAN/2 WLAN systems for example. The proposed antenna is excited using a circular ring resonator fabricated on one side of the dielectric substrate with a circular slot etched on the ground plane. To realise a single- or dual-band notch characteristic the antenna includes a semi-circular parasitic strip located above the circular ring, and a T-shaped stub is located near the inner edge of circular ring. The parasitic strip and T-shaped stub are connected to the circular ring via PIN diodes to give the antenna reconfigurable capability by configuring the PIN diodes in a prescribed combination of ON and OFF states. It is shown that there is virtually no change in the antenna's E-plane and H-plane radiation patterns for the various PIN diode switching conditions. The proposed antenna's performance has been verified by measurements. View full abstract»

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  • 49. Compact E-band planar quasi-Yagi antenna with folded dipole driver

    Publication Year: 2010 , Page(s): 1728 - 1734
    Cited by:  Papers (10)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (977 KB)  

    A broadband planar quasi-Yagi antenna using a folded dipole driver is presented. The new antenna element is realised on a low dielectric constant substrate and it is suitable for millimetre-wave applications using low-cost thick-film fabrication. The advantage of the quasi-Yagi antenna with folded dipole driver compared to the standard quasi-Yagi antenna is a reduction in the length of the driver, which allows closer spacing of the elements for array applications on low dielectric constant substrates. Use of the folded dipole driver gives a 4:1 impedance range because of its extra parameters. The element was designed for E-band applications, but operates over a much wider bandwidth of approximately 1.3:1. Mutual coupling between two antenna elements in an array environment is investigated and results obtained are similar to conventional quasi-Yagi antenna elements. Four linear arrays, each containing four elements and having a different beamforming network, were fabricated to demonstrate the scanning capabilities of the folded dipole quasi-Yagi antenna, and measured reflection coefficient, radiation patterns and gain for each array are presented. View full abstract»

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  • 50. Design of a compact ultra-wide-band monopole antenna with band rejection characteristics

    Publication Year: 2014 , Page(s): 604 - 610
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1010 KB)  

    This study presents a design of two compact monopole antennas with band-notched characteristics for ultra-wide-band application. The compact antennas are etched on an FR4 substrate with the size of 14 × 16 × 1 mm3, consists of a tree-shaped radiation patch with modified ground structure, providing a wide usable fractional bandwidth of more than 170% (2.8-19.2 GHz). To reject certain-frequency bands, two completely different approaches are proposed. First a shorted T-shaped quarter-wavelength resonator is used to omit undesired frequency band of 5.1-5.9 GHz. In the second approach, two L-shaped slots are inserted in the patch to act as a filter structure for worldwide interoperability for microwave access (3.4-3.6 GHz) and wireless local area network (5-5.6 GHz) applications. The band-notched can be controlled by adjusting the length of the rectangle slots. The effects of dimensional parameters on the antenna performance have been investigated through a parametric study. Furthermore, current density distribution on the antenna is also computed to gain a better insight of its behaviour. The antennas are investigated numerically and experimentally for their impedance matching properties, frequency notched characteristics and radiation performances. View full abstract»

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