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Microwaves, Antennas & Propagation, IET

Issue 1 • Date January 8 2014

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Displaying Results 1 - 11 of 11
  • On the selection of radiating elements for compact indoor massive-multiple input multiple output base stations

    Publication Year: 2014 , Page(s): 1 - 9
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (742 KB)  

    Massive-multiple input multiple output (MIMO) was recently proposed as a key solution for improving the performance of multi-user MIMO in future cellular generations. The main paradigm in this novel MIMO technique is to use a very large number of antenna elements at the base station (BS), which was shown to drastically increase capacity while saving transmission power. However, envisioning indoor BS with such number of antennas it is essential to assess the implementation of compact arrays based on different antenna candidates, which constitutes the main objective of this work. Antenna solutions ranging from miniaturised patches to triple-polarised radiators are proposed. Characteristics such as return loss and mutual couplings are obtained via full-wave electromagnetic simulations and as a function of elements density in a given limited BS real estate. The different antenna candidates are compared by computing the signal-to-interference plus noise ratio in both noise and interference-limited regimes and for different multi-user MIMO precoding strategies. This analysis allows reporting on optimal antenna densities above which performance degrades despite an increasing number of antennas, and identifying the main cause of this limitation for the different antenna types and scenarios. Finally, practical considerations such as antenna miniaturisation, bandwidth and cost are included in the discussion. View full abstract»

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  • Method for designing low-pass filters with a sharp cut-off

    Publication Year: 2014 , Page(s): 10 - 15
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (729 KB)  

    A novel method for designing a compact low-pass filter (LPF) with a sharp cut-off and wide stop-band is presented. In this technique, a simple open-stub microstrip line is printed on top of a substrate and the desired performance is obtained by optimising the shape of the defected ground structure using the genetic algorithm. Details of the design procedure are presented and evaluated through designing two different LPFs. The first LPF is optimised for a 3.5 GHz cut-off frequency and a stop-band up to 10 GHz, whereas the second one is optimised for a 5 GHz cut-off frequency and the stop-band is extended to 16 GHz. Both filters are fabricated and good agreement between simulation and measurement result is obtained. The designed filters have a sharp transition along with a compact size of 25 ?? 20 ?? 0.787 mm3. View full abstract»

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  • Physically-based indicator for identifying ultra-wideband indoor channel condition

    Publication Year: 2014 , Page(s): 16 - 21
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    In this study, a model based on the generalised-K (GK) distribution is proposed for identifying ultra-wideband (UWB) indoor channel profiles. In particular, an index (y-index) based on a proper combination of GK parameters is proposed to unambiguously and effectively distinguish among line-of-sight (LOS) and non-LOS propagation conditions. This clear distinction is achieved by defining two non-overlapping sets which correspond to the two well-defined profiles. The technique is user-friendly since it does not call for any complex estimation process. Comparison among the results achieved by both real measurements and IEEE.802.15.4a channel model simulations confirm the soundness of the employed method and the effectiveness of the proposed y-index. View full abstract»

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  • Integration of ultra-wideband planar baluns into the eleven feed

    Publication Year: 2014 , Page(s): 22 - 28
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1078 KB)  

    Integration of decade bandwidth baluns into the Eleven feed faces many challenges. The authors present a compact, low-loss and low-cost integration solution to the ultra-wideband balun feeding network for the dual-polarised Eleven feed in this study. The design procedures are described in detail. Evaluation of the balun integration based on the BOR1 (Body of Revolution type1) efficiency is introduced. Numerical simulations and measurements are presented for verifying the design. View full abstract»

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  • Ultra-wideband tapered slot antenna with dual band-notched characteristics

    Publication Year: 2014 , Page(s): 29 - 38
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1225 KB)  

    A novel tapered slot antenna (TSA) with 3.5/5.5 GHz dual band-notched characteristics for ultra-wideband radios is proposed in this study. To realise dual band-notched characteristics at the TSA, the author employ (a) a pair of nested C-shaped stubs beside the feed line and (b) a broadband microstrip-slotline transition with an Archimedean spiral-shaped slot. The proposed antenna has been successfully simulated, implemented and measured. Measured data for the optimised case show the bandwidth for the voltage standing wave ratio < 2 to be 9.2 GHz (from 2.4 to 11.6 GHz) with two notched bands of 3.1-4.0 GHz (world interoperability for microwave access band) and 5.1-6.2 GHz (wireless local area network band), respectively. The measured electrical parameters of the proposed antenna and its radiation patterns show excellent performance with good pulse handling capabilities. Also, the 3.5/5.5 GHz dual band-notched characteristics are achieved without increasing the size of the single band-notched TSA reported previously. View full abstract»

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  • Printed monopole antenna with tapered feed line, feed region and patch for super wideband applications

    Publication Year: 2014 , Page(s): 39 - 45
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (757 KB)  

    A novel and compact super wideband (SWB) exponentially tapered feed region and patch printed monopole antenna is proposed. This antenna is fed by a 50-ω triangular tapered feed line. The antenna operates over a bandwidth of 2.5-80 GHz with a return loss of 10 dB or more. The dimensions of the proposed antenna are 40 ?? 30 ?? 1.6 mm3. An exponential curve is employed in the feed region and a triangular tapered feed line is used. The ground plane feed gap is optimised to 1.3 mm. The proposed tapered monopole antenna has demonstrated an ultra-large bandwidth with satisfactory radiation properties. Two particular antennas are examined, one with a rectangular feed line and another with a triangular tapered feed line. The performance of the antenna in frequency domain is investigated, and a good agreement is achieved between the simulation and experimental results. In addition, the time domain characteristics of the proposed antenna are evaluated experimentally. This antenna can be used in ultra-wideband or SWB applications. View full abstract»

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  • Fast monostatic radar cross-section computation for perfectly electric conducting targets using low-rank compression and adaptive integral method

    Publication Year: 2014 , Page(s): 46 - 51
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    The adaptive integral method (AIM) in conjunction with the low-rank compression method is developed to calculate the monostatic radar cross-section (RCS) of arbitrarily shaped three-dimensional perfectly electric conducting objects. For backscattering problems, the excitation matrix is usually highly rank-deficient and can be compressed via low-rank techniques without explicitly assembling the original matrix beforehand. Therefore, only the matrix equations corresponding to the linearly independent excitation vectors need to be solved, whose number is much less than that of incident angles. As a result, fast monostatic RCS calculation over a widely angular range can be achieved. To facilitate the analysis of electrical large problems, the AIM is applied to accelerate the matrix??vector product and reduce the memory usage. Numerical examples are presented to demonstrate the validity and efficiency of the method. View full abstract»

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  • Wide frequency independently controlled dual-band inkjet-printed antenna

    Publication Year: 2014 , Page(s): 52 - 56
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (474 KB)  

    A low-cost inkjet-printed multiband monopole antenna is presented. The unique advantage of the proposed antenna is the freedom to adjust and set the dual-band of the antenna independently over a wide range (148.83%). To demonstrate the independent control feature, the 2.4 and 3.4 GHz bands for the wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications are selected as an example. The measured impedance bandwidths for the 2.4 and 3.4 GHz are 15.2 and 23.7%, respectively. These dual-bands have the ability to be controlled independently between 1.1 and 7.5 GHz without affecting the other band. In addition, the proposed antenna can be assigned for different mobile and wireless applications such as GPS, PCS, GSM 1800, 1900, UMTS, and up to 5-GHz WLAN and WiMAX applications. The mechanism of independent control of each radiator through dimensional variation is discussed in detail. The antenna has a compact size of 10 ?? 37.3 ?? 0.44 mm3, leaving enough space for the driving electronics on the paper substrate. The measured results from the prototype are in good agreement with the simulated results. Owing to inkjet printing on an ordinary paper, the design is extremely light weight and highly suitable for low cost and large volume manufacturing View full abstract»

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  • Wideband analytical extraction technique of πequivalent circuit model for Si/SiGe heterojunction bipolar transistor in BICMOS process

    Publication Year: 2014 , Page(s): 57 - 63
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (437 KB)  

    A developed analytical extraction technique of small-signal -topology equivalent circuit model for Si/SiGe heterojunction bipolar transistor is presented. The intrinsic model parameters, including base resistance (Rb) which are difficult to extract in the previous works, are analytically extracted by utilising a novel set of exact equations that do not need any numerical fitting, special polarisation of the device or any kind of post processing. Moreover, the substrate effect and the distributed base-collector junction are accurately modelled and extracted. To the authors knowledge, the extracted values using the presented methodology exhibit flattest and widest frequency independent behaviour among all those extracted with earlier published analytical techniques, especially for base resistance. Excellent agreement is noted between the S-parameters measurements and their simulated counterpart using the extracted model in the frequency range from 40 MHz-40 GHz at different bias conditions. View full abstract»

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  • Comments on 'distance from unconditional stability boundary of a two-port network'

    Publication Year: 2014 , Page(s): 64
    Save to Project icon | PDF file iconPDF (53 KB)  
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  • Reply to comments on 'distance from unconditional stability boundary of a two-port network'

    Publication Year: 2014 , Page(s): 65 - 66
    Save to Project icon | PDF file iconPDF (68 KB)  
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