Online ISSN
1751-8733
Print ISSN
1751-8725
IET Microwaves, Antennas & Propagation
Volume 6, Issue 11, 21 August 2012
Volumes & issues:
Volume 6, Issue 11
21 August 2012
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- Author(s): E.G. Wintucky ; R.N. Simons ; J.C. Freeman ; C.T. Chevalier ; A.J. Abraham
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1195 –1199
- DOI: 10.1049/iet-map.2012.0207
- Type: Article
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This article presents the design, simulation and characterisation of a novel high-efficiency Ka-band (32.05±0.25 GHz) rectangular waveguide three-way serial combiner for monolithic microwave integrated circuit power amplifiers (PAs) with unequal output power. The combiner presented here is suited for low data rate communications from deep space using a single carrier with constant envelope (amplitude) type modulation. The three-way combiner consists internally of two branch-line hybrids connected in series by a short length of waveguide. The two branch-line hybrids were each designed to combine two input signals that are equal in phase and with an amplitude ratio of two, although in general the amplitude ratio could be arbitrary. The combiner was fabricated in an E-plane split-block arrangement and precision machined from blocks of aluminium with standard WR-28 waveguide ports. S-parameter measurements demonstrated a close achievement of the design goals. The measured return loss at the output port was greater than 16 dB and the isolation between the three input ports of the three-way combiner were greater than 22 dB. The combining of three PAs was successfully demonstrated in which the measured combining efficiency was greater than 90% at the centre frequency of 32.05 GHz. - Author(s): U. Olgun ; C.-C. Chen ; J.L. Volakis
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1200 –1206
- DOI: 10.1049/iet-map.2012.0129
- Type: Article
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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. - Author(s): C.H. See ; R.A. Abd-Alhameed ; F. Elmegri ; D. Zhou ; J.M. Noras ; N.J. McEwan ; S.M.R. Jones ; P.S. Excell
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1207 –1214
- DOI: 10.1049/iet-map.2012.0086
- Type: Article
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This study presents two multiband planar printed monopole antennas with an optimised size of 57×37.5×0.8 mm3 for mobile/wireless and low-band ultra-wide band (UWB) applications. Both these antennas are constructed as a chorded crescent-shaped radiator, a feed line and a defected ground plane. The experimental and computed results confirm that one design offers a wide usable impedance bandwidth of 114.3%, with a reflection coefficient |S11|<−10 dB, over 1.5–5.5 GHz. The other incorporates a tapered sickle-shaped slot in the radiator and demonstrates a band-suppression feature giving rejection of the worldwide interoperability for microwave access band (3.4–3.69 GHz) where this is not required. The gains and far-field patterns of the antennas are presented and their group delay over the lower band UWB frequency range is also discussed. - Author(s): S.Z. Ibrahim ; A. Abbosh ; M. Bialkowski
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1215 –1220
- DOI: 10.1049/iet-map.2011.0539
- Type: Article
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The design of a novel wideband six-port network constituted by in-phase and quadrature Wilkinson power dividers is presented. To achieve wideband operation of the quadrature divider, the device uses a 90° phase shifter in the form of a double vertical wireless interconnect that utilises microstrip to coplanar waveguide transitions. The performance of the designed in-phase and quadrature dividers and the entire six-port network is assessed via full-wave electromagnetic simulations and measurements. The obtained results show that the designed six-port network offers good performance in terms of amplitude and phase characteristics across the frequency band of 3.5–9 GHz. - Author(s): A. Miller and J. Hong
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1221 –1226
- DOI: 10.1049/iet-map.2012.0134
- Type: Article
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This study presents an electronically reconfigurable wideband bandpass filter with four distinct states. There were three filter states designed and combined to achieve a filter with four reconfigurable states. The filter obtained has reconfigurable fractional bandwidth (FBW) ranging from 89.5% to about 35.9% and tunable centre frequencies of 3.15–4.96 GHz in addition to an all-pass state. The measured insertion loss varies from 0.68 to 2.6 dB, depending on the FBW. This type of concept shows good promise for the development of future wideband wireless communication and sensor systems. - Author(s): X. Zhao ; Y. Lee ; K.Y. Jung ; J.H. Choi
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1227 –1235
- DOI: 10.1049/iet-map.2012.0006
- Type: Article
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A novel metamaterial-inspired loop antenna is proposed towards wideband operation, size reduction and frequency scanning capabilities. The high permeability characteristic of split rings resonators (SRRs) is utilised to reduce the size of a loop antenna. The SRRs also improve the impedance matching of the loop antenna, and thus significantly increase the bandwidth. Moreover, the proposed antenna has a frequency scanning capability because of the existence of SRRs. According to the measured results, the proposed antenna has a 10 dB operating band from 2.3 to 3.8 GHz with the absolute bandwidth of 1.5 GHz and the fractional bandwidth of 50%. Owing to SRRs, the first-order resonant frequency of the antenna shifts from 3.5 to 2.4 GHz, leading to an effective size reduction of 32% against the original loop antenna. The proposed antenna exhibits a continuous frequency scanning capability with the total scanning angle of 135°, sweeping from 75 to −60°. - Author(s): S. Akkar ; F. Harabi ; A. Gharsallah
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1236 –1243
- DOI: 10.1049/iet-map.2011.0492
- Type: Article
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This study proposes a new uniform concentric circular (UCCA) shape of electronically steerable parasitic array radiator (ESPAR) antennas for directions of arrival (DoAs) estimation problem. The well-known estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm is adapted to this special shape of UCCA and the authors demonstrate that the resulting algorithm yields better DoAs estimation accuracy and solves the failure of estimation problem when the signals' DoAs are in some particular sectors: notably for [0°–30°] and [160°–180°]. This approach has shown interesting performances since it can ensure good DoAs estimation over the entire azimuth plane with a low extra computational overhead. The constraints are the same imposed to the ESPRIT algorithm allowing about 66% reduction on the required computational efforts. The Cramer Rao bound on the variance of DoAs estimated by the proposed array geometry is analysed. Through simulation results, the authors demonstrate that applying ESPRIT in conjunction with the proposed antennas shape not only provides superior high-resolution localisation capabilities but also it drastically reduces computations compared with previous works. - Author(s): Y.-L. Geng
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1244 –1250
- DOI: 10.1049/iet-map.2011.0230
- Type: Article
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Electromagnetic scattering by a general gyrotropic sphere is discussed in terms of spherical vector wave functions. From the source-free Maxwell's equations and Fourier transform, the eigenvalue and eigenvectors of the electric field in a source-free gyrotropic medium can be obtained. The electromagnetic fields may then be obtained in terms of spherical vector wave functions in a source-free gyrotropic medium. Applying the continuous boundary conditions of electromagnetic fields on the surface between the free space and gyrotropic sphere, the spectral coefficients of the transmitted fields inside a gyrotropic sphere and the scattered fields in an isotropic medium (free space) can be obtained exactly by expanding spherical vector wave eigenfunctions. Numerical results are provided for some representative cases. Results from this study and those from an adaptive integral method are in agreement. - Author(s): R. Burghelea ; S. Avrillon ; B. Uguen
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1251 –1258
- DOI: 10.1049/iet-map.2011.0503
- Type: Article
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In ultra-wide band (UWB) propagation channel modelling, antenna effects – namely frequency and polarisation aspects – must be considered to provide realistic waveform characteristics and realistic signal received power. The authors propose an efficient method which enables ultra-compact parametric modelling of fully three-dimensional antenna radiation behaviour for UWB ray tracing channel simulation tools. Two complementary techniques based on a vector spherical harmonic (VSH) expansion of antenna radiation function are proposed as a solution for (i) compression of the amount of data needed for describing antenna characteristics and (ii) fast and reliable reconstruction of antenna array response for waves coming from arbitrary directions and with arbitrary frequency variations. The most significant VSH coefficients are first extracted and then compressed in the frequency domain. The method is evaluated through the study of an UWB monocone antenna. It is shown that data compression rates as high as 1:1719 are achievable in practice. - Author(s): M. Rafaei Booket ; M. Veysi ; Z. Atlasbaf ; A. Jafargholi
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1259 –1268
- DOI: 10.1049/iet-map.2011.0436
- Type: Article
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The design of ungrounded meander line inductors (UMIs) and ungrounded interdigital capacitors (UICs) employed in the practical realisation of a planar ungrounded composite right-/left-handed (UCRLH) metamaterial is presented. Accurate lumped-element circuit models are proposed based on partial element theory and conformal mapping method. New and accurate analytical design formulas, for both the UMI and the UIC at very high frequency and ultra high frequency bands are derived and successfully validated through a proper comparison with the existing measurement data and the results obtained with the full wave method of moments. Further insight is sought through the investigation of the resonance mechanism of a printed dipole antenna loaded with UCRLH metamaterial cells. A prototype of the loaded dipole is fabricated to confirm and validate the theoretical calculations. The experimental results are found to be in good agreement with the theoretical calculations. - Author(s): M.Á. Sánchez-Soriano ; G. Torregrosa-Penalva ; E. Bronchalo
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1269 –1276
- DOI: 10.1049/iet-map.2012.0248
- Type: Article
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In this work, a new method for stopband extension in both open-ended and interdigital parallel-coupled line filters is presented. This method is intended for the suppression of spurious bands which inherently appear in the stopband of this kind of filters. The multispurious suppression is achieved by means of a precise control of the coupling between resonators at unwanted resonant frequencies. The coupling section lengths between successive resonators are used as control parameters to obtain the required couplings. The dependence of the coupling coefficients on coupling section lengths at resonant frequencies is given by closed expressions, obtained following an energetic coupling approach. Several microstrip bandpass filters designed following the new method are presented as examples. These filters feature wide spurious-free bands with high rejection levels. - Author(s): J. Ouyang ; X. Luo ; J. Yang ; K. Zhi Zhang ; J. Zhang ; F. Yang
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1277 –1285
- DOI: 10.1049/iet-map.2012.0054
- Type: Article
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In this study, for the first time, volume-surface integral equation (VSIE) and improved NSGA-II (INSGA-II) algorithms analyse and synthesise a conformal conical surface linear phased array. The antenna element patterns and port characteristic with mutual coupling have been simulated with the VSIE algorithm. Then, the patterns of all the elements terminated by their characteristic impedances, which are called active element patterns, are measured in a microwave chamber for comparison. The results show a good match between the simulated and the measured results. The pattern of the conformal antenna array is a superposition of all these active patterns of the elements with various weights. However, the design objects containing the 3-dB beam width, side lobe levels, and beam direction must be taken into account simultaneously. So, the INSGA-II algorithm is used for a multi-object optimisation here. Moreover, by using this algorithm, the entire optimum solutions, that is, the optimum solutions of the main beam of the conformal-phased array directing to different angles, can be solved by one optimisation. Comparisons between the experimental and the simulated results show the effectiveness of the proposed approach for conformal-phased arrays. - Author(s): K.-C. Lin ; H.-K. Chiou ; D.-C. Chang ; Y.-Z. Juang
- Source: IET Microwaves, Antennas & Propagation, Volume 6, Issue 11, p. 1286 –1290
- DOI: 10.1049/iet-map.2011.0274
- Type: Article
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This work presents an inductor with a high quality factor (Q) that is fabricated using wafer-level integrated passive device (IPD) technology and a 5.2 GHz differential low noise amplifier (DLNA) in a Taiwan semiconductor manufacturing company (TSMC™) 0.18 µm complementary metal-oxide-semiconductor (CMOS) process. The IPD inductors were stacked on top of a CMOS DLNA. The use of IPD inductors in the input matching network (IMN) is an efficient alternative to on-chip inductors for mass production. The performance of the DLNA with and without an IPD inductor is studied. The IPD CMOS-DLNA achieves a noise figure (NF) of 2.1 dB with a power consumption of 10 mW. The measured NF of the CMOS-IPD DLNA is 0.6 dB better than that of the typical CMOS DLNA at the same power consumption. The CMOS-IPD DLNA achieves the best figure of merit of any of the recently described 5–6 GHz CMOS LNAs.
High-efficiency three-way Ka-band waveguide unequal power combiner
Design of an efficient ambient WiFi energy harvesting system
Planar monopole antennas for new generation mobile and lower band ultra-wide band applications
Design of wideband six-port network formed by in-phase and quadrature Wilkinson dividers
Electronically reconfigurable multi-channel wideband bandpass filter with bandwidth and centre frequency control
Design of a metamaterial-inspired size-reduced wideband loop antenna with frequency scanning characteristic
Concentric circular-shaped electronically steerable parasitic array radiator antennas for full-azimuth directions of arrival estimation with reduced computational load
Analytical solution of electromagnetic scattering by a general gyrotropic sphere
Ultra-compact parametric modelling of three-dimensional antenna radiation pattern for impulse radio-ultra-wide band ray tracing
Ungrounded composite right-/left-handed metamaterials: design, synthesis and applications
Multispurious suppression in parallel-coupled line filters by means of coupling control
Analysis and synthesis of conformal conical surface linear phased array with volume surface integral equation+AEP (Active Element Pattern) and INSGA-II
2.1 dB noise figure 5.2 GHz CMOS low noise amplifier using wafer-level integrated passive device technology with a DC power consumption of 10 mW
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