Vol. 106
Latest Volume
All Volumes
PIER 176 [2023] PIER 175 [2022] PIER 174 [2022] PIER 173 [2022] PIER 172 [2021] PIER 171 [2021] PIER 170 [2021] PIER 169 [2020] PIER 168 [2020] PIER 167 [2020] PIER 166 [2019] PIER 165 [2019] PIER 164 [2019] PIER 163 [2018] PIER 162 [2018] PIER 161 [2018] PIER 160 [2017] PIER 159 [2017] PIER 158 [2017] PIER 157 [2016] PIER 156 [2016] PIER 155 [2016] PIER 154 [2015] PIER 153 [2015] PIER 152 [2015] PIER 151 [2015] PIER 150 [2015] PIER 149 [2014] PIER 148 [2014] PIER 147 [2014] PIER 146 [2014] PIER 145 [2014] PIER 144 [2014] PIER 143 [2013] PIER 142 [2013] PIER 141 [2013] PIER 140 [2013] PIER 139 [2013] PIER 138 [2013] PIER 137 [2013] PIER 136 [2013] PIER 135 [2013] PIER 134 [2013] PIER 133 [2013] PIER 132 [2012] PIER 131 [2012] PIER 130 [2012] PIER 129 [2012] PIER 128 [2012] PIER 127 [2012] PIER 126 [2012] PIER 125 [2012] PIER 124 [2012] PIER 123 [2012] PIER 122 [2012] PIER 121 [2011] PIER 120 [2011] PIER 119 [2011] PIER 118 [2011] PIER 117 [2011] PIER 116 [2011] PIER 115 [2011] PIER 114 [2011] PIER 113 [2011] PIER 112 [2011] PIER 111 [2011] PIER 110 [2010] PIER 109 [2010] PIER 108 [2010] PIER 107 [2010] PIER 106 [2010] PIER 105 [2010] PIER 104 [2010] PIER 103 [2010] PIER 102 [2010] PIER 101 [2010] PIER 100 [2010] PIER 99 [2009] PIER 98 [2009] PIER 97 [2009] PIER 96 [2009] PIER 95 [2009] PIER 94 [2009] PIER 93 [2009] PIER 92 [2009] PIER 91 [2009] PIER 90 [2009] PIER 89 [2009] PIER 88 [2008] PIER 87 [2008] PIER 86 [2008] PIER 85 [2008] PIER 84 [2008] PIER 83 [2008] PIER 82 [2008] PIER 81 [2008] PIER 80 [2008] PIER 79 [2008] PIER 78 [2008] PIER 77 [2007] PIER 76 [2007] PIER 75 [2007] PIER 74 [2007] PIER 73 [2007] PIER 72 [2007] PIER 71 [2007] PIER 70 [2007] PIER 69 [2007] PIER 68 [2007] PIER 67 [2007] PIER 66 [2006] PIER 65 [2006] PIER 64 [2006] PIER 63 [2006] PIER 62 [2006] PIER 61 [2006] PIER 60 [2006] PIER 59 [2006] PIER 58 [2006] PIER 57 [2006] PIER 56 [2006] PIER 55 [2005] PIER 54 [2005] PIER 53 [2005] PIER 52 [2005] PIER 51 [2005] PIER 50 [2005] PIER 49 [2004] PIER 48 [2004] PIER 47 [2004] PIER 46 [2004] PIER 45 [2004] PIER 44 [2004] PIER 43 [2003] PIER 42 [2003] PIER 41 [2003] PIER 40 [2003] PIER 39 [2003] PIER 38 [2002] PIER 37 [2002] PIER 36 [2002] PIER 35 [2002] PIER 34 [2001] PIER 33 [2001] PIER 32 [2001] PIER 31 [2001] PIER 30 [2001] PIER 29 [2000] PIER 28 [2000] PIER 27 [2000] PIER 26 [2000] PIER 25 [2000] PIER 24 [1999] PIER 23 [1999] PIER 22 [1999] PIER 21 [1999] PIER 20 [1998] PIER 19 [1998] PIER 18 [1998] PIER 17 [1997] PIER 16 [1997] PIER 15 [1997] PIER 14 [1996] PIER 13 [1996] PIER 12 [1996] PIER 11 [1995] PIER 10 [1995] PIER 09 [1994] PIER 08 [1994] PIER 07 [1993] PIER 06 [1992] PIER 05 [1991] PIER 04 [1991] PIER 03 [1990] PIER 02 [1990] PIER 01 [1989]
2010-07-28
PIER
Vol. 106, 395-417, 2010
download: 144
Estimation for Small-Scale Fading Characteristics of RF Wireless Link Under Railway Communication Environment Using Integrative Modeling Technique.
Shi Pu Jun-Hong Wang Zhan Zhang
The small-scale fading behavior in common wireless communication systems can be predicted by a series of propagation models. Although these types of models are feasible and effective for the situations of transmitting/receiving (Tx/Rx) antennas in relatively open surrounding environments, they are unable to address the coupling between the antenna and environment. In order to overcome this difficulty, a full-wave numerical method is applied in terms of the advantage in considering the interaction between complicated environments and the Tx/Rx antennas, and it can take into account the effect of the interaction on signals. In this paper, an integrative modeling technique involving FDTD method, two-path propagation model and multi-path statistical distribution model is presented, which combines the deterministic and statistical methods. For achieving reliable communication especially in high-speed railway environment, high sampling rate and adequate sampling points are needed for analyzing the propagation properties of the radio frequency (RF) link. This can be easily achieved by the integrative modeling technique, and the output voltage and current of train antenna under the illumination of base-station (BS) antenna along the railway can be given in detail. Results obtained from the integrative simulation for three different multi-path statistical distribution models are presented and analyzed.
ESTIMATION FOR SMALL-SCALE FADING CHARACTERISTICS OF RF WIRELESS LINK UNDER RAILWAY COMMUNICATION ENVIRONMENT USING INTEGRATIVE MODELING TECHNIQUE.
2010-07-28
PIER
Vol. 106, 377-394, 2010
download: 184
Inverse Equivalent Surface Current Method with Hierarchical Higher Order Basis Functions, Full Probe Correction and Multilevel Fast Multipole Acceleration (Invited Paper)
Thomas F. Eibert Ismatullah E. Kaliyaperumal Carsten H. Schmidt
An inverse equivalent surface current method working with equivalent electric and/or magnetic surface current densities on appropriately chosen Huygens surfaces is investigated. The considered model with triangular surface meshes is compatible with the models known from method of moments (MoM) solutions of surface integral equations. Divergence conforming current basis functions of order 0.5 and of order 1.5 are considered, where the order 0.5 functions are the well-known Rao-Wilton-Glisson basis functions. Known near-field samples typically obtained from measurements are mapped on the unknown equivalent surface current densities utilizing the radiation integrals of the currents as forward operator, where the measurement probe influence is formulated in a MoM like weighting integral. The evaluation of the forward operator is accelerated by adaptation of the multilevel fast multipole method (MLFMM) to the inverse formulation, where the MLFMM representation is the key to full probe correction by employing only the far-field patterns of the measurement probe antennas. The resulting fully probe corrected algorithm is very flexible and efficient, where it is found that the computation speed is mostly dependent on the MLFMM configuration of the problem and not that much on the particular equivalent current expansion as long as the expansion is able to represent the currents sufficiently well. Inverse current and far-field pattern results are shown for a variety of problems, where near-field samples obtained from simulations as well as from realistic measurements are considered.
INVERSE EQUIVALENT SURFACE CURRENT METHOD WITH HIERARCHICAL HIGHER ORDER BASIS FUNCTIONS, FULL PROBE CORRECTION AND MULTILEVEL FAST MULTIPOLE ACCELERATION (Invited Paper)
2010-07-28
PIER
Vol. 106, 363-376, 2010
download: 282
A Dual-Band Omni-Directional Microstrip Antenna
Ooi Tze-Meng Kim Geok Tan Ahmed Wasif Reza
Omni-directional antennas are useful for variety of wireless communication devices as well as capable of handling the additional different frequency bands since the radiation pattern allows good transmission and reception from a mobile unit. However, to implement the two frequencies on a single antenna with wide bandwidth can be significant because of the presence of mutual coupling and interference effects between the two radiating elements. In this paper, a novel method of combining dual-band frequencies onto a single layer board with wide bandwidth is described. A dual-band printed dipole antenna is designed in this study by combining a rectangular and two "L" shaped radiating elements and are embedded on a single layer structure with relatively small size. The obtained results show that the proposed dual-band omni-directional microstrip antenna achieves high antenna efficiency and provides better bandwidth while maintaining the structural compact size.
A DUAL-BAND OMNI-DIRECTIONAL MICROSTRIP ANTENNA
2010-07-26
PIER
Vol. 106, 349-362, 2010
download: 167
Flexible Uniplanar Artificial Magnetic Conductor
María Elena de Cos Yuri Alvarez-Lopez Ramona Cosmina Hadarig Fernando Las Heras Andres
The design of a flexible uniplanar AMC is presented. A prototype is manufactured and characterized based on reflection coe±cient phase under flat and bent conditions. The designed prototype shows broad AMC operation bandwidth and polarization angle independency in both flat and bent situations. Its angular margin when operating under oblique incidence is also tested. FEM simulations and measurements in an anechoic chamber are presented.
FLEXIBLE UNIPLANAR ARTIFICIAL MAGNETIC CONDUCTOR
2010-07-26
PIER
Vol. 106, 335-347, 2010
download: 167
Plasmonic Resonant Light Scattering by a Cylinder with Radial Anisotropy
Yuwen Jin Dongliang Gao Lei Gao
We apply the full-wave electromagnetic theory to study electromagnetic scattering by a small cylindrical particle with radial anisotropy for normally incident light with transverse magnetic (TM) polarization. The scattering coefficients are derived, when the radial anisotropies in both the permittivity and permeability tensors are taken into account. It is shown that the surface and volume plasmon resonances can be identified by the sign of t/dq, in which εt is the permittivity element in a direction tangential to the local r-axis, and q is the size parameter. The near field distributions for surface and volume modes are illustrated by finite element method. It is found that small changes of anisotropy can affect the scattering efficiencies significantly. Moreover, the quadrupole and octupole resonant peaks may be much higher and sharper than those of dipole resonance in the scattering efficiency spectra.
PLASMONIC RESONANT LIGHT SCATTERING BY A CYLINDER WITH RADIAL ANISOTROPY
2010-07-25
PIER
Vol. 106, 321-333, 2010
download: 154
Planar UWB Antenna with 5 GHz Band Rejection Switching Function at Ground Plane
Chow-Yen-Desmond Sim Wen-Tsan Chung Ching-Her Lee
The design of an octagonal-shaped microstrip-fed planar monopole antenna for ultrawideband (UWB) operation is studied. Two inverted T-shaped slits are embedded on the ground plane to allow band rejection characteristic from 5 to 6 GHz (for VSWR < 2). To enable switching capability for this band rejection function, a PIN diode is connected to each slit via a specified chip inductor that will be further investigated. Several prototypes were constructed and the measured results show that the proposed antenna can provide an operating bandwidth from 3.07 to 10.7 GHz, except for the rejected band. Simulation analyses are also carried out to validate the experimental results.
PLANAR UWB ANTENNA WITH 5 GHz BAND REJECTION SWITCHING FUNCTION AT GROUND PLANE
2010-07-25
PIER
Vol. 106, 311-319, 2010
download: 130
Compact UWB Filter Based on Surface-Coupled Structure with Dual Notched Bands
Jian-Quan Huang Qing-Xin Chu Chuan-Yun Liu
A novel compact ultra-wideband (UWB) band-pass filter (BPF) based on surface-coupled structure is proposed. The surface-coupled structures and Y-shaped shorted stub resonator are adopted as quasi-lumped circuit elements to achieve UWB pass-band. To avoid the interference of the wireless local area network (WLAN) at 5.25 and 5.775 GHz, two different quarter-wavelength lines are arranged on the ground of UWB BPF to generate dual narrow stop bands. Being developed from the quasi-lumped elements, the proposed UWB BPFs have very compact size. The fabricated UWB BPFs have the advantages of low insertion loss, good selectivity and flat group delay. Good agreement between equivalent circuit modeled, simulated and measured responses of these filters is demonstrated.
COMPACT UWB FILTER BASED ON SURFACE-COUPLED STRUCTURE WITH DUAL NOTCHED BANDS
2010-07-25
PIER
Vol. 106, 295-309, 2010
download: 333
Azimuth Beam Pattern Synthesis for Airborne SAR System Optimization
Sangho Lim Jung-Hoon Han Se-Young Kim Noh-Hoon Myung
The limitation of the pulse repetition frequency (PRF) of an airborne synthetic aperture radar (SAR) system is not a serious problem to obtain high azimuth resolution and wide swath imaging compared with a spaceborne SAR system. Hence, continuous high azimuth resolution imagery over a wide area can be obtained using an antenna having a wide beamwidth. Since a small antenna with a large beamwidth has very low gain, which results in difficulty in detection; the azimuth beam pattern optimization of a large active phased array antenna is needed for airborne SAR system optimization. To improve the airborne SAR system performance, such as the noise-equivalent sigma zero (NEσ0), the azimuth resolution, the radiometric accuracy (RA), and the azimuth ambiguity ratio (AAR), we present an optimal azimuth beam pattern mask template and suggest an azimuth beam pattern satisfying the mask template using the particle swarm optimization (PSO). The mode having the proposed beam pattern guarantees continuous and high resolution images, simultaneously. Using a point target simulation, the advantages of the mode are shown compared to strip-map and spotlight modes.
AZIMUTH BEAM PATTERN SYNTHESIS FOR AIRBORNE SAR SYSTEM OPTIMIZATION
2010-07-25
PIER
Vol. 106, 279-293, 2010
download: 156
Improved Current Decomposition in Helical Antennas Using the ESPRIT Algorithm
Yang Li Hao Ling
We apply the ESPRIT algorithm to decompose the currents on a helical antenna into different traveling wave modes. The strengths, phase velocities and decay constants of the various modes are extracted across frequencies. Their contributions to the antenna performance including gain, polarization and time-domain radiated pulse shape are investigated. Our results show that the T0+ mode is a dominant contributor to the helix gain at the low end of the frequency band while the T1+ mode contributes significantly to the gain at higher frequencies. It is also found that the reflected current modes from the open end reduce the circular polarization purity of the helix. Lastly, it is observed that the T1+ and T0+ modes contribute constructively to a low-dispersion pulse from the antenna.
IMPROVED CURRENT DECOMPOSITION IN HELICAL ANTENNAS USING THE ESPRIT ALGORITHM
2010-07-25
PIER
Vol. 106, 263-278, 2010
download: 160
A Novel Positioning System Utilizing Zigzag Mobility Pattern
Ahmed Wasif Reza Sherene Meetha Pillai Kaharudin Dimyati Kim Geok Tan
This paper proposes a new positioning system utilizing mobile readers that are programmed to move in a zigzag pattern to locate the tags. The proposed zigzag mobility pattern is able to cover an area completely within a given period, determine optimal number of required mobile readers, and find out reader placement and movement pattern. The received signal strength (RSS) model is used to exchange the information over a short range by estimating the position of the tag by means of distance information between the reader and the tag. The results obtained from this study point out that the proposed method is able to provide near exact tag position. The proposed method can achieve average error as low as 0.6 m. With this proposed method, the scanning of large areas, such as warehouses, libraries, and storage areas can be done very quickly. Mobile reader is proposed because it is cost-effective, fast, and is able to provide relatively accurate results.
A NOVEL POSITIONING SYSTEM UTILIZING ZIGZAG MOBILITY PATTERN
2010-07-25
PIER
Vol. 106, 243-261, 2010
download: 122
Modal Method Based on Spline Expansion for the Electromagnetic Analysis of the Lamellar Grating
Ana Maria Armeanu M. Kofi Edee Gerard Granet Patrick Schiavone
This paper reports an exact and explicit representation of the differential operators from Maxwell's equations. In order to solve these equations, the spline basis functions with compact support are used. We describe the electromagnetic analysis of the lamellar grating as an eigenvalues problem. We choose the second degree spline as basis functions. The basis functions are projected onto a set of test functions. We use and compare several test functions namely: Dirac, Pulse and Spline. We show that the choice of the basis and test functions has a great influence on the convergence speed. The outcomes are compared with those obtained by implementing the Finite-Difference Modal Method which is used as a reference. In order to improve the numerical results an adaptive spatial resolution is used. Compared to the reference method, we show a significantly improved convergence when using the spline expansion projected onto spline test functions.
MODAL METHOD BASED ON SPLINE EXPANSION FOR THE ELECTROMAGNETIC ANALYSIS OF THE LAMELLAR GRATING
2010-07-25
PIER
Vol. 106, 225-241, 2010
download: 123
Non-Iterative Imaging of Thin Electromagnetic Inclusions from Multi-Frequency Response Matrix
Won-Kwang Park
Although MUSIC (MUltiple SIgnal Classification)-type algorithm has shown feasibilities as a non-iterative imaging technique of thin penetrable electromagnetic inclusion from its far-field multi-static response (MSR) matrix, it induces a poor result whenever one tries to obtain such inclusion of both dielectric and magnetic contrast with respect to the embedding homogeneous space R2 case. In this paper, we develop an improved non-iterative imaging algorithm based on the modeling of multi-frequency MSR matrix according to a rigorous asymptotic expansion of the scattering amplitude. Numerical examples exhibit that presented algorithm performs satisfactorily for single and multiple thin inclusions, even with a fair amount of random noise.
NON-ITERATIVE IMAGING OF THIN ELECTROMAGNETIC INCLUSIONS FROM MULTI-FREQUENCY RESPONSE MATRIX
2010-07-22
PIER
Vol. 106, 203-223, 2010
download: 146
Solutions of Large-Scale Electromagnetics Problems Using an Iterative Inner-Outer Scheme with Ordinary and Approximate Multilevel Fast Multipole Algorithms
Ozgur Ergul Tahir Malas Levent Gurel
We present an iterative inner-outer scheme for the efficient solution of large-scale electromagnetics problems involving perfectly-conducting objects formulated with surface integral equations. Problems are solved by employing the multilevel fast multipole algorithm (MLFMA) on parallel computer systems. In order to construct a robust preconditioner, we develop an approximate MLFMA (AMLFMA) by systematically increasing the efficiency of the ordinary MLFMA. Using a flexible outer solver, iterative MLFMA solutions are accelerated via an inner iterative solver, employing AMLFMA and serving as a preconditioner to the outer solver. The resulting implementation is tested on various electromagnetics problems involving both open and closed conductors. We show that the processing time decreases significantly using the proposed method, compared to the solutions obtained with conventional preconditioners in the literature.
SOLUTIONS OF LARGE-SCALE ELECTROMAGNETICS PROBLEMS USING AN ITERATIVE INNER-OUTER SCHEME WITH ORDINARY AND APPROXIMATE MULTILEVEL FAST MULTIPOLE ALGORITHMS
2010-07-22
PIER
Vol. 106, 177-202, 2010
download: 116
Analytical Model of Electromagnetic Waves Propagation and Location of Inclined Plasma Layers Using Occultation Data
A. G. Pavelyev Yuei-An Liou J. Wickert Keifei Zhang Chuan-Sheng Wang Yuriy Kuleshov
An analytical model for the description of the electromagnetic waves propagation in a layered medium consisting of sectors having the locally spherical symmetric distributions of refractivity is introduced. Model presents analytical expressions for the phase path and refractive attenuation of electromagnetic waves. Influence of the inclined ionospheric layers is a cause of the ionospheric interference in the trans-ionospheric communication satellite-to-satellite or satellite-to-Earth links. It follows from the analytical model that the identification of the inclined ionospheric layers contributions and measurements of their location and parameters may be fulfilled by use of comparative analysis of the amplitude variations and the eikonal acceleration of the RO signals. Model is applied to analysis of the radio occultation (RO) signals propagating through the ionosphere and atmosphere. Model explains existence of the ionospheric contributions in the RO signals at the altitudes 30-90 km of the RO ray perigee as connected with influence of a tangent point in the ionosphere where the electron density gradient is perpendicular to the RO ray trajectory. By use of the CHAMP RO amplitude data a description of different types of the ionospheric contributions to the RO signals is introduced and compared with results of measurements obtained earlier in the communication link satellite-to-Earth at frequency 1.5415 GHz of MARSAT satellite.
ANALYTICAL MODEL OF ELECTROMAGNETIC WAVES PROPAGATION AND LOCATION OF INCLINED PLASMA LAYERS USING OCCULTATION DATA
2010-07-21
PIER
Vol. 106, 163-176, 2010
download: 110
Multi-Wavelength Fiber Optical Parametric Oscillator Based on a Highly Nonlinear Fiber and a Sagnac Loop Filter
Daru Chen Bing Sun
A novel multi-wavelength fiber optical parametric oscillator (MW-FOPO) with a ring cavity structure is proposed. In the ring cavity of the MW-FOPO, a Sagnac loop filter which is formed by a 3-dB optical coupler, a polarization controller and a segment of polarization maintained fiber is used as the comb filter, and a segment of highly nonlinear fiber is used as the gain medium. Multi-wavelength lasing of the MW-FOPO with a wavelength spacing of about 0.8nm is achieved and its power stability at room temperature is demonstrated by measuring peak power fluctuation within 42 minutes for 5 lasing wavelengths. The output spectrum of the MW-FOPO covers a large wavelength region from 1500nm to 1610 nm. A comparison of the output spectra between the MW-FOPO and the multi-wavelength Erbium-doped fiber laser is also presented.
MULTI-WAVELENGTH FIBER OPTICAL PARAMETRIC OSCILLATOR BASED ON A HIGHLY NONLINEAR FIBER AND A SAGNAC LOOP FILTER
2010-07-21
PIER
Vol. 106, 147-162, 2010
download: 323
A New Calculation Method for the Characteristic Impedance of Transmission Lines with Modified Ground Structures OR Perturbation
Jongsik Lim Jun Lee Jaehoon Lee Sang-Min Han Dal Ahn Yongchae Jeong
In this paper, a new calculating method for the characteristic impedance (Zc) of transmission lines with perturbation and periodic modified ground structure (MGS), such as defected ground structure (DGS), photonic bandgap (PBG), and substrate integrated artificial dielectric (SIAD), is discussed. The proposed method is based on simple transmission line theories and proper related equations. The previous method to find Zc of transmission lines with MGS or perturbation produces the fluctuating Zc value depending on frequency, while the proposed method results in a constant value without frequency-dependence. As examples, several microstrip lines with DGS, PBG, and SIAD structure are simulated and measured, and their Zc values are calculated from S-parameters by the previous and proposed methods. It is shown that the Zc obtained by the proposed method is much more reliable than that calculated by the previous method for all examples.
A NEW CALCULATION METHOD FOR THE CHARACTERISTIC IMPEDANCE OF TRANSMISSION LINES WITH MODIFIED GROUND STRUCTURES OR PERTURBATION
2010-07-20
PIER
Vol. 106, 121-145, 2010
download: 163
Propagation Analysis and Deployment of a Wireless Sensor Network in a Forest
Jose Antonio Gay-Fernandez Manuel Garcia Sanchez Inigo Cuinas Ana Vazquez Alejos Javier Garcia Sanchez Jose Luis Miranda-Sierra
A complete study for the deployment of a wireless sensor network in a forest based on ZigBee is presented in this paper. First, due to the lack of propagation models for peer to peer networks in forests, propagation experiments were carried out to determine the propagation model. This model was then used for planning and deploying an actual wireless sensor network. The performance of the network was compared with the expected theoretical behavior to extract some conclusions that are presented in the paper. Finally, some general conclusions, as an estimation of the minimum number of routers necessary to cover a given area, are extracted from the experiments and presented in the paper.
PROPAGATION ANALYSIS AND DEPLOYMENT OF A WIRELESS SENSOR NETWORK IN A FOREST
2010-07-13
PIER
Vol. 106, 107-119, 2010
download: 191
Shaping the Radiation Pattern with MU and Epsilon-Near-Zero Metamaterials
Bo Wang Ka-Ma Huang
In this paper, mu and epsilon-near-zero (MENZ) metamaterials are used to convert the waves emitted from an embedded line source to various waveforms. The simulation results show that the converted waveforms are consistent with the exit face shape of the metamaterials. The power distributions in different beams are dependent on the length proportion of the exit faces due to its impedance matching with the surrounding media, which is different from the epsilon-near-zero (ENZ) metamaterials. A numerical verification with the finite element method (FEM) was presented, followed by physical insights into this phenomenon and theoretical analysis. We also propose some potential applications, including high directive emissions, multi-beams emissions.
SHAPING THE RADIATION PATTERN WITH MU AND EPSILON-NEAR-ZERO METAMATERIALS
2010-07-12
PIER
Vol. 106, 91-106, 2010
download: 137
Design of CMOS Quadrature VCO Using on-Chip Trans-Directional Couplers
Ching-Ian Shie Jui-Ching Cheng Sheng-Chun Chou Yi-Chyun Chiang
This work presents a quadrature voltage-controlled oscillator (QVCO) realized by on-chip trans-directional (TRD) couplers. The TRD coupler is implemented by sections of parallel-coupled lines connected by shunt capacitors periodically. The TRD couplers allow decoupling the DC path between input and output. Thus, it can make connections with active circuits easier, eliminating some off-chip biasing circuits. Since the quadrature signals are generated by 90°hybrid couplers, the oscillator core can be optimized for circuit performance without considering the generation of quadrature signals. A Ka band QVCO fabricated in CMOS 0.18 μm technology was designed to verify the effectiveness of the proposed QVCO structure. The measurement results reveal that the quadrature output signals of QVCO have about -1.52 dBm output powers with less than 1 dB amplitude imbalance and less than 6°phase difference in the frequency range of 31.9 to 32.7 GHz. The best measured phase noise of the QVCO is -110.6 dBc/Hz at 1 MHz offset from the center frequency. The figure-of-merit of the circuit is 187.5 dBc/Hz.
DESIGN OF CMOS QUADRATURE VCO USING ON-CHIP TRANS-DIRECTIONAL COUPLERS
2010-07-12
PIER
Vol. 106, 75-89, 2010
download: 180
Through -the-Wall Target Localization with Time Reversal MUSIC Method
Wenji Zhang Ahmad Hoorfar Lim Li
Time Reversal Multiple Signal Classification (TR-MUSIC) method is studied and adapted for the detection and localization of multiple targets behind the wall in this paper. TR-MUSIC does not involve the FDTD solver for the implementation of the backpropagation of the time reversed field and is very computational efficient. The Green's function vectors for the computation of the TR-MUSIC pseudo-spectrum is efficiently evaluated with the saddle point method for a homogeneous wall. By employing the null space of the multistatic response matrix, simultaneous localization of multiple targets behind the wall can be achieved by TR-MUSIC method. Numerical results are presented to show the effectiveness of through-the-wall imaging (TWI) with TR-MUSIC method.
THROUGH-THE-WALL TARGET LOCALIZATION WITH TIME REVERSAL MUSIC METHOD