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Microwaves, Antennas & Propagation, IET

Issue 14 • Date Nov. 19 2013

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Displaying Results 1 - 10 of 10
  • Independently switchable quad-band bandpass filter

    Publication Year: 2013 , Page(s): 1113 - 1119
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (706 KB)  

    A switchable microstrip quad-band bandpass filter (BPS) is investigated in this study. Owing to the low loading effect from distributed coupling technique, many channels can be obtained without the requiring of complicated matching network. Each passband can be turned on and off independently. The switchable quad-band BPS consisting of half-wavelength/quarterwavelength resonators, loaded open stubs and p-i-n diodes features compactness and good selectivity. To validate this design concept, theory as well as experiment is presented and compared in this study. View full abstract»

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  • Realisation of new single-layer triple-mode substrateintegrated waveguide and dual-mode half-mode substrate-integrated waveguide filters using a circular shape perturbation

    Publication Year: 2013 , Page(s): 1120 - 1127
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (662 KB)  

    A method of 'mode shifting' is presented for realisation of triple-mode and dual-mode filters, in which the resonant frequency of one mode is shifted near to the resonant frequency of another mode using a perturbation. To realise a triplemode filter, a single-layer substrate-integrated waveguide (SIW) square cavity is perturbed by introducing vias at the middle of the structure. This perturbation causes mode shifting of the dominant mode (TE101) near to the next modes (TE102 and TE201). Operation of this triple-mode resonator is analysed and resonant frequencies of the perturbed cavity are obtained theoretically. A triple-mode filter is realised using this resonator and the filter is modelled by a coupling matrix based on the global eigenmodes. Moreover, by using the mode shifting technique, a novel dual-mode bandpass filter with half-mode SIW (HMSIW) structure is presented. Both the triple-mode SIW and dual-mode HMSIW filters are fabricated on a single-layer substrate using a printed circuit board process. View full abstract»

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  • Generalised method of current excitation reconstruction from near-field data of planar, cylindrical and spherical antenna arrays

    Publication Year: 2013 , Page(s): 1128 - 1136
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    Currently chemotherapy, radiation and surgery are the widely accepted treatments for cancer. A fourth modality, hyperthermia, or heat treatment, is emerging as an adjuvant cancer treatment along with radiation or chemotherapy, and works as a booster, sometimes even doubling the effects of these standard treatments. Hyperthermia essentially heats the cancer region to around 42°C by precisely controlled electromagnetic radiation in the 27, 900 or 2400 MHz frequency range. The re-emergence of hyperthermia is primarily due to advanced antenna technology, which can precisely target the tumour volume, while delivering minimal energy to neighbouring healthy tissue. The precise focusing of the electromagnetic beam is realised either by focusing plates or lenses, or by conformal antenna arrays. In order to achieve efficient array near-field control for hyperthermia applications, electronic control of the array currents is essential to control the beam over the tumour volume and achieve uniform heating. This paper reports a generalised analytical technique to reconstruct the array currents from a specific near-zone electric field profile. This reconstruction technique is applicable to conformal arrays with planar, cylindrical or spherical geometry. Several simulations have been carried out to test the validity and accuracy of the reconstruction algorithm. View full abstract»

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  • Small artificial magnetic conductor backed log-periodic microstrip patch antenna

    Publication Year: 2013 , Page(s): 1137 - 1144
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (916 KB)  

    An artificial magnetic conductor (AMC) backed reduced-size log-periodic microstrip patch antenna (LPMA) is presented. To maintain the broadband performance of the LPMA, the AMC ground plane was modified to exhibit a log-periodic structure. Specifically, an AMC ground plane configuration was realised over 0.889 mm thick εr = 10.2 Rogers 6010.2LM substrate for an LPMA printed over 1.524 mm thick εr = 2.94 Rogers 6002 substrate. The AMC-backed LPMA is measured to operate from 5.3 to 8 GHz with linearly polarised broadside radiation, performing with 21% reduced size as compared with a conventional LPMA designed over the identical substrate stack-up. View full abstract»

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  • H2-matrix-based fast volume integral equation solver for electrodynamic analysis

    Publication Year: 2013 , Page(s): 1145 - 1153
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (646 KB)  

    An H2-matrix-based mathematical framework is introduced and further developed to reduce the computational complexity of the volume integral equation (VIE)-based analysis of electrodynamic problems. Numerical experiments have demonstrated a significant reduction in CPU time and memory consumption. A linear scaling with respect to matrix size in both CPU time and memory is achieved for small and medium-sized electrodynamic problems with an interpolation-based H2-representation of the VIE operator in conjunction with a rank function for accuracy control. The proposed solver is applicable to arbitrarily shaped three-dimensional structures immersed in inhomogeneous materials. View full abstract»

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  • Design of compact multiresonator-loaded planar antenna with quad-band working properties for wireless communication

    Publication Year: 2013 , Page(s): 1154 - 1160
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (857 KB)  

    In this study, a novel design of a compact multiresonator-loaded planar antenna with quad-band working properties is proposed for wireless communication. Multiresonator-loaded structures are employed, which include a pair of symmetrical edge resonators embedded into the edges of the monopole, a T-shaped stub resonator extended from the ground and an inverted Ushaped narrow slot resonator etched on the T-shaped stub. By loading these resonators, a modified U-shaped monopole antenna can easily produce four separate working bands while achieving a very compact size of 18 ¿¿ 20 mm2. Based on this concept, a prototype of quad-band antenna is designed, fabricated and tested. The measured results demonstrate that the proposed antenna is capable of operating over the frequency ranges, 2.39-2.49, 3.37-4.06, 4.73-5.46 and 5.69-6.31 GHz, suitable for wireless local area network 2.4/5.2/5.8 GHz and worldwide interoperability for microwave access 3.5 GHz applications. View full abstract»

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  • X-parameter-based modelling of polar modulated power amplifiers

    Publication Year: 2013 , Page(s): 1161 - 1167
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    X-parameters are developed as an extension of S-parameters capable of modelling non-linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied at separate ports and the envelope port is neither an RF nor a DC port. As a result, X-parameters may fail to characterise the effect of the envelope port excitation and consequently the polar PA. This study introduces a solution to the problem for a commercial polar PA. In this solution, the RF-phase path is modelled by X-parameters and the envelope path of the polar PA is simulated by a low-pass filter. The solution can be applied to a group of polar PAs who have the similar topology and design as the one in this work. Modulated signals with different channel bandwidths were applied to the model of the polar PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2% point and 3 dB, respectively. View full abstract»

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  • Radiation characteristics improvement of aperture coupled antennas using double reflector structure

    Publication Year: 2013 , Page(s): 1168 - 1173
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (972 KB)  

    The radiation characteristics of aperture stacked patch antenna, namely, front-to-back (F/B) ratio, gain, and gain bandwidth are improved. The results show that the gain bandwidth of the proposed antenna is up to 72% (6.09-12.87 GHz) with F/B ratio better than 8 dB across the band of operation which is a considerable improvement compared to the available microstrip antennas. View full abstract»

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  • Effect of the fabrication parameters on the performance of embroidered antennas

    Publication Year: 2013 , Page(s): 1174 - 1181
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (789 KB)  

    Simulated and measured microstrip patch antennas produced using embroidery techniques have been presented. The antennas use a standard microwave substrate material. The effect of stitch direction and stitch density is described and a clear requirement to understand how the currents flow in an antenna, so that the stitch direction can be correctly chosen is shown. Two different simulation approaches for these antennas are discussed and one is linked to measurement results, pointing to a simplified model for simulating embroidered patch antennas. View full abstract»

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  • Millimetre-wave waveguide reflectometers for early detection of skin cancer

    Publication Year: 2013 , Page(s): 1182 - 1186
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (242 KB)  

    Millimetre-wave (mm-wave) reflectometry is an efficient technique for diagnosis of human tissue disease such as early stage skin cancer. Two sets of non-invasive and in-package reflectometers operating at 42 and 70 GHz are designed, fabricated and successfully tested with different kinds of samples. The tests are performed for a number of liquids, and pure water at different temperatures. Also, the proposedWR-22 device is tested over skin at different locations. The clinical trial tests are performed on a number of volunteer patients who suffered from Basal cell carcinoma. The proposed devices are easy-to-fabricate, and provide a low-cost solution for fast and accurate skin cancer detection. Furthermore, the proposed technology has the potential to be used for fast tissue inspection during a surgery View full abstract»

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