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Microwaves, Antennas & Propagation, IET

Issue 6 • Date April 23 2013

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Displaying Results 1 - 10 of 10
  • Multiphysics design and experimental verification of a quad-band dichroic mirror for deep space ground stations

    Publication Year: 2013 , Page(s): 391 - 398
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (828 KB)  

    This study presents the multi-disciplinary approach used to study a quad-band dichroic mirror to be installed in the European Space Agency deep space antennas. Traditional electromagnetic (EM) analyses based on a uniform plane wave incidence were augmented by advanced numerical techniques to investigate the impact of the dichroic mirror on the overall antenna performance. In addition, along with the EM design, a parallel study considering mechanical, thermal and power-handling aspects allowed their impact on the EM behaviour of the dichroic mirror to be evaluated. This comprehensive study permitted an optimum design to be achieved for the dichroic mirror, which accounts for the actual operational conditions of the mirror itself when installed in the antenna. The device was manufactured and measured, verifying also the mechanical and thermal theoretical predictions, obtaining an excellent agreement between simulations and experimental results. View full abstract»

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  • Small-size printed coupled-fed antenna for eight-band LTE/GSM/UMTS wireless wide area network operation in an internal mobile handset

    Publication Year: 2013 , Page(s): 399 - 407
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1332 KB)  

    A simple small-size printed antenna for eight-band long-term evolution (LTE)/GSM/UMTS wireless wide area network operation in an internal mobile handset application is proposed. Occupying a compact size of 15 × 40 mm2 on the ungrounded region of the system circuit board and a low profile of 4 mm, the presented antenna is a coupled-fed configuration. With the longer branch of the feeding strip, a λ/4 resonant mode at around 2.7 GHz can be obtained to cover the desired LTE2500 operation. A fundamental λ/4 resonant mode over the desired lower band of LTE700/GSM850/900 can also be generated at 750 MHz by the long meandered coupling strip (length of about 113 mm). Moreover, two additional higher-order resonant modes at around 1.75 and 2.25 GHz can also be obtained by the coupling strip. By including a chip inductor L at the feeding point, the impedance matching over the lower and upper bands can be improved in order to achieve the two wide operating bands of 698-960 and 1710-2690 MHz. With the following properties of small size, ease of fabrication and good radiation characteristics, the proposed antenna is a good candidate for the fourth LTE mobile phone applications. View full abstract»

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  • Tunable dual-mode microstrip patch resonators and filters

    Publication Year: 2013 , Page(s): 408 - 414
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (691 KB)  

    In this study, tunable dual-mode microstrip patch resonators are presented and utilised to design microstrip bandpass filters (BPFs). The novelty of the designs lies in that the performance of frequency agility can be realised by using either the signal line or the return path (the ground) of microwave transmission line. For the proposed resonators, the resonant frequencies of two coupled degenerate modes can be tuned using a square-loop slot with loaded tunable capacitors on the ground plane or on the patch. The locations of the capacitors are determined according to the electric field distributions of the two orthogonal modes. The variations of the modes in spectrum are studied. Finally, two types of demonstration compact tunable BPFs are designed and fabricated, and the simulated and measured results show good agreement. View full abstract»

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  • Full duplex reflection amplifier tag

    Publication Year: 2013 , Page(s): 415 - 420
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (638 KB)  

    The authors describe a reflection amplifier adapted to have both a reflection and a transmission port. The amplifier uses a single silicon bipolar transistor and demonstrates a reflection gain of 13 dB, transmission gain of 10 dB and 3.4 dB noise figure at 5.25 GHz. The added feature of transmission gain in the reflection amplifier permits practical implementation of full duplex microwave radiofrequency indentification (RFID) tag operation. By using a simple subcarrier modulation scheme full duplex RFID operation utilising this amplifier is demonstrated. These results indicate that for 27 dBm (0.5 W) effective isotropic radiated power (EIRP) transmit power it should be possible to obtain approximately 8 m downlink range and 25 m uplink range. View full abstract»

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  • Compact split-ring resonator-loaded multiple-input–multiple-output antenna with electrically small elements and reduced mutual coupling

    Publication Year: 2013 , Page(s): 421 - 429
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1031 KB)  

    The authors present a compact four-element multiple-input-multiple-output antenna with the potential to operate in WiMAX frequency bands, with its elements being not only closely spaced but also electrically small. Split-ring resonators or metal stipes are utilised to achieve both goals, that is element miniaturisation and reduction of mutual coupling. The design process is systematic, as it deals with both issues quite separately. Very low values of the envelope correlation coefficient and overall good performance are obtained, without compromising planarity and simplicity. View full abstract»

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  • Frequency reconfigurable planar inverted-F antenna using switchable radiator and capacitive load

    Publication Year: 2013 , Page(s): 430 - 435
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    A frequency reconfigurable planar inverted-F antenna (PIFA) using real PIN-diodes is presented for mobile worldwide interoperability for microwave access (m-WiMAX) applications. This antenna not only alters the frequency band of the m-WiMAX using PIN-diode switching, but it also has a small profile using capacitive load within an FR4 dielectric constant substrate. The PIFA consists of the following: a main radiator, an additional radiator, a band-switchable capacitive load, two PIN-diodes and control circuits. One diode is placed between the main and additional radiator on the top side, and the other is vertically attached between the capacitive load and ground. Depending upon whether the diodes are on or off, the antenna operates over 2.3-2.4, 2.5-2.7 and 3.4-3.6 GHz for worldwide m-WiMAX bands. To investigate the effect of load capacitance, a parametric analysis is performed by sweeping the length and width of the capacitive load. All simulated and measured results for the proposed antenna are presented, and they show excellent agreement. View full abstract»

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  • Technique for inversion of an inhomogeneous bianisotropic slab through an optimisation approach

    Publication Year: 2013 , Page(s): 436 - 443
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (613 KB)  

    An electromagnetic inversion method is presented to reconstruct the constitutive parameters of an inhomogeneous bianisotropic slab. The measured co- and cross-reflection and transmission coefficients are used to extract the electromagnetic parameters profiles of the inhomogeneous bianisotropic media from the proposed method, using truncated Fourier series expansion and Gravitational Search Algorithm (GSA). GSA is used to improve the speed and accuracy of the optimisation process because of the complexity of inhomogeneous bianisotropic media, highly non-linearity of optimisation problem, and extremely large search space. Finally, the accuracy and robustness of the proposed reconstruction method are validated using some typical examples. View full abstract»

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  • Compact multiple input and multiple output/diversity antenna for portable and mobile ultra-wideband applications

    Publication Year: 2013 , Page(s): 444 - 451
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (895 KB)  

    This study presents a miniaturised multiple input and multiple output /diversity antenna which is suitable for high data-rate communication systems such as mobile ultra-wideband (UWB). This antenna assembly comprises two identical planar inverted-F antennas, a T-shaped structure connecting them and a finite ground plane. The T-shaped structure improves the impedance matching and suppresses the mutual coupling between the antenna elements over a wider bandwidth than previously reported. The compact envelope dimension of this antenna is 50 × 90 × 7.5 mm3. Theoretical and experimental S-parameters are illustrated for this antenna that fully cover the UWB operating frequency band of 3.1-10.6 GHz, with a reflection coefficient and mutual coupling better than -10 and -20 dB, respectively. Acceptable agreement is obtained between computed and measured radiation patterns, gains, envelope correlation coefficient and channel capacity loss. The proposed antenna is an attractive candidate to provide pattern diversity and enhance channel capacity in a rich scattering environment. View full abstract»

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  • Position-only side lobe reduction of a uniformly excited elliptical antenna array using evolutionary algorithms

    Publication Year: 2013 , Page(s): 452 - 457
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (339 KB)  

    This study deals with the design of elliptical antenna arrays for specific radiation property using three different evolutionary algorithms; namely, self-adaptive differential evolution method, biogeography based optimisation method and firefly algorithm. These methods are used to determine an optimum set of positions for uniformly excited elliptical antenna array (EAA) that provides a radiation pattern with optimum side lobe level reduction with the constraint of a fixed major lobe beamwidth. Three examples are investigated; 8, 12 and 20 elements EAAs using these evolutionary algorithms. The comparison shows that the design of non-uniform EAAs using evolutionary algorithms presents a good side lobe reduction in the radiation pattern for the optimised design. Furthermore, the BBO method shows somewhat better performance compared with the other two methods. View full abstract»

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  • Optimisation of antenna arrays using the cuckoo search algorithm

    Publication Year: 2013 , Page(s): 458 - 464
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    The goal of this article is to introduce and use the cuckoo search (CS) as an optimisation algorithm for the electromagnetics and antenna community. The CS is a new nature-inspired evolutionary algorithm (EA) for solving N-dimensional optimisation problems. Compared with other nature-inspired algorithms, the CS algorithm is easy to understand and implement and has minimum number of parameters to tune. Different examples are presented that illustrate the use of the CS algorithm, and the results are compared with results obtained using other optimisation methods. Preliminary results suggest that the CS algorithm can in some cases outperform other EAs, at least for the examples studied in this article. View full abstract»

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