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2008-11-15
PIER Letters
Vol. 4, 191-203, 2008
download: 323
Design, Fabrication and Test of Parabolic Cylinder Reflector and Horn for Increasing the Gain of Vlasov Antenna
Mohammad Fazaelifar Mohammadreza Fatorehchy
This paper proposes two methods for increasing the Gain of Vlasov Antenna. The first method, using a Parabolic Cylinder Reflector, results in a 7dB increase in the Gain. The second method, constructing a Horn on the aperture, increases the Gain by about 5dB. The results were checked using a prototype antenna and there was a close agreement.
DESIGN, FABRICATION AND TEST OF PARABOLIC CYLINDER REFLECTOR AND HORN FOR INCREASING THE GAIN OF VLASOV ANTENNA
2008-11-10
PIER Letters
Vol. 4, 183-190, 2008
download: 189
Comparison of the Radiation Pattern of Fractal and Conventional Linear Array Antenna
Refa'at Talib Hussein Fawwaz Jinan Jibrael Jabri
The purpose of this paper is to introduce the concept of fractals and its use in antenna arrays for obtaining multiband property. One type of fractals namely, Cantor set is investigated. Cantor set is used in linear array antenna design. Therefore, this array know fractal Cantor linear array antenna. A comparison with conventional non-fractal linear array antenna is made regarding the beamwidth, directivity, and side lobe level. MATLAB programming language version 7.2 (R2006a) is used to simulate the fractal and conventional non-fractal linear array antenna and their radiation pattern.
COMPARISON OF THE RADIATION PATTERN OF FRACTAL AND CONVENTIONAL LINEAR ARRAY ANTENNA
2008-10-31
PIER Letters
Vol. 4, 173-181, 2008
download: 101
PSO-Based Fast Optimization Algorithm for Broadband Ayyray Antenna by Using the Cubic Spline Interpolation
Jian-Feng Li Bao-Hua Sun Qi-Zhong Liu Lan Gong
This paper describes a fast pattern synthesis method for a broadband array antenna using the particle swarm optimization (PSO) and cubic spline interpolation (CSI). Being an indispensable part of a high speed space-division communication system, the array antenna operates in a wide frequency band (200-400 MHz) and has stable patterns with 60-degree half power beam width (HPBW) in the whole frequency band. Firstly, by establishing a versatile objective function, the complex excitations of the circular array at the selected seven frequency points are determined via the PSO algorithm. Then, the complex excitations of the circular array at arbitrary frequency points in the whole working frequency band are calculated effectively using the CSI method. A uniform circular array with six broadband dipole elements is examined. The broadband patterns with 60-degree HPBW and the accuracy of the interpolation method are demonstrated.
PSO-BASED FAST OPTIMIZATION ALGORITHM FOR BROADBAND AYYRAY ANTENNA BY USING THE CUBIC SPLINE INTERPOLATION
2008-10-31
PIER Letters
Vol. 4, 167-172, 2008
download: 110
A Novel Radiation Pattern and Frequency Reconfigurable Microstrip Antenna on a Thin Substrate for Wide-Band and Wide-Angle Scanning Application
Jun Ou Yang
A novel radiation pattern and frequency reconfigurable microstrip antenna is introduced in this paper. This antenna is designed on a thin substrate for the application of conformal phased antenna future. The proposed antenna make the operating frequency range 6 times larger than that of a simple rectangular microstrip antenna, and make the beam covering from -70∼70 compared with the traditional rectangular microstrip antenna beam which only covers -50∼50. It is potential on the application of wide-band and wideangle.
A NOVEL RADIATION PATTERN AND FREQUENCY RECONFIGURABLE MICROSTRIP ANTENNA ON A THIN SUBSTRATE FOR WIDE-BAND AND WIDE-ANGLE SCANNING APPLICATION
2008-10-07
PIER Letters
Vol. 4, 159-166, 2008
download: 122
A New Method to Avoid Crowding Phenomenon in Extracting the Permittivity of Ferroelectric Thin Films
Yunqiu Wu Zong-Xi Tang Yuehang Xu Xi He
In this paper, a new method is proposed to avoid crowding phenomenon in extracting the permittivity of ferroelectric thin films. Polynomial curve fitting technique is used to determine the filling factor while the thickness of the thin film is very small. Conformal mapping (CM) combining with partial capacitance approach (PTA) is used to obtain the relationshipb etween the effective permittivity of multiplayer coplanar waveguide (CPW) and the permittivity of each layer. A CPW with a thin film layer is simulated and the permittivity of thin film is extracted, the results show that, by using the proposed method, the crowding phenomenon can be avoided successfully and the permittivity of thin films can be extracted accurately.
A NEW METHOD TO AVOID CROWDING PHENOMENON IN EXTRACTING THE PERMITTIVITY OF FERROELECTRIC THIN FILMS
2008-09-29
PIER Letters
Vol. 4, 149-158, 2008
download: 112
Simultaneous Switching Noise Mitigation Capability with Low Parasitic Effect Using Aperiodic High-Impedance Surface Structure
Chin-Sheng Chang Mau-Phon Houng Ding-Bing Lin Kuo-Chiang Hung I-Tseng Tang
A novel design with low parasitic effect for eliminating the simultaneous switching noise (SSN) in high-speed circuits is proposed by using the aperiodic high-impedance surface (A-HIS) structure. The A-HIS configuration is proposed in this work, revealing suppression of the SSN from 1.1∼1.85 GHz. It is shown that the HIS structure with aperiodic design, the SSN will be effectively suppressed. The undesired resonances of the proposed A-HIS structure are less than that of the conventional structure below 1 GHz. Less undesired peaks will ensure the electromagnetic interference (EMI) and signal integrity (SI). The measured results show very well compared with the conventional periodical HIS structures. The suppression results of the proposed A-HIS structure is checked by both measurement and simulation results. By using this proposed method, the simplicity of the structure is easier to fabricate as well as to route signal lines with a perfect power/ground planes. In addition, the proposed designs provide excellent SSN suppression and good signal integrity (SI) as the conventional structure.
SIMULTANEOUS SWITCHING NOISE MITIGATION CAPABILITY WITH LOW PARASITIC EFFECT USING APERIODIC HIGH-IMPEDANCE SURFACE STRUCTURE
2008-09-15
PIER Letters
Vol. 4, 139-148, 2008
download: 126
Measurement of RF PCB Dielectric Properties and Losses
Yun-Hsih Chou Ming-Jer Jeng Yang-Han Lee Yih-Guang Jan
This paper presents the calculations of transmission line loss factor by extracting from the Q-factor measurement of the quarterwavelength open stub resonators over the designed frequency and other resonant frequencies. A comparison of the loss factor of the design frequency with other resonant frequencies of each of the stub's quarter-wave resonances is provided in this paper. The radiation and discontinuity losses are undesirably included in the unloaded Q-factor measurement andit shows that the unloadedQ-factor is not repeatable at different designed frequency. The implementation of the loss factor measurement by quarter-wavelength open stub resonators is becoming more andmore important to be consideredwith the increase of using the electronic circuits operating at high frequencies.
MEASUREMENT OF RF PCB DIELECTRIC PROPERTIES AND LOSSES
2008-08-15
PIER Letters
Vol. 4, 131-138, 2008
download: 111
Half Mode Substrate Integrated Waveguide Broadband Bandpass Filter
Cuilin Zhong Jun Xu Zhi-Yuan Yu Mao-Yan Wang Jun-Hong Li
A planar half mode substrate integrated waveguide (HMSIW) broadband bandpass filter is proposed. It is realized by cascading a lowpass filter and a highpass filter. A transmission line with half mode substrate integrated waveguide (HMSIW) on the circuit board has the characteristic of highpass, while a periodic uniform photo band structure (PBG) array has the characteristic of bandstop. Combining these two structures, a novel compact broadband bandpass filter (BPF) is fabricated and measured. Measured results show that the proposed BPF has wide bandwidth from 11.8 GHz to 23.8 GHz, all the measured insert loss are less than 2.1 dB, return loss are less than 9 dB in the passband. The BPF achieves a wide stopband with 34 dB attenuation low to 5GHz and 27 dB attenuation up to 35GHz.
HALF MODE SUBSTRATE INTEGRATED WAVEGUIDE BROADBAND BANDPASS FILTER
2008-08-06
PIER Letters
Vol. 4, 121-129, 2008
download: 193
Influence of Time and Temperature on Resistivity and Microstructure of CuX Co1-X FE2 O4 Mixed Ferrites
Bantesh Bammannavar Lalasing Naik Rangappa Pujar Baburao Chougule
Copper-cobalt ferrites with general chemical formula CuxCo1-xFe2O4 (with x = 0.0, 0.4, 0.6 & 1.0) were prepared by ceramic method. The solid state reaction was confirmed by XRD patterns. DC conductivity was measured by two probe method. Electrical resistivity is found to increase on lowering of sintering temperature and time. At x = 1.0, the conduction is mainly due to hopping of electrons leading to n-type conductivity while at x = 0.0, conduction is due to holes leading to P-type conductivity. The lowest conduction at x = 0.4 is attributed to the electron hole compensation. SEM micrographs were obtained from JEOL scanning electron microscope. The micrographs reveal that an average grain size increases with sintering temperature and time as a result of decrease in porosity. This leads to the decrease in resistivity with sintering temperature and time. One of the factors for higher conductivity in ferrites is an increase in average grain size and decrease in pore concentration during the heat treatment.
INFLUENCE OF TIME AND TEMPERATURE ON RESISTIVITY AND MICROSTRUCTURE OF Cu<sub>x</sub> Co<sub>1-x</sub> Fe<sub>2</sub> O<sub>4</sub> MIXED FERRITES
2008-07-07
PIER Letters
Vol. 4, 113-120, 2008
download: 115
Miniaturization of Wilkinson Power Dividers by Using Defected Ground Structures
Homayoon Oraizi Mehdi Seyyedesfahlan
It is proposed that the application of defected ground structures (DGS) and electromagnetic bandgap (EBG) reduce the phase velocity, increase effective permittivity of microstrips and reduce the effective the wavelength which eventually lead to the reduction of overall length of Wilkinson power dividers. Furthermore, the adjacent strip lines may approach each other, which cause coupling problems. The undesired coupling maybe cancelled by connecting a capacitance in parallel with the isolation resistor of Wilkinson power divider. Application of DGS and EBG will not only reduce the dimensions of the divider, but also improves its scattering parameters.
MINIATURIZATION OF WILKINSON POWER DIVIDERS BY USING DEFECTED GROUND STRUCTURES
2008-06-30
PIER Letters
Vol. 4, 109-112, 2008
download: 137
The Quasi-Yagi Antenna Subarray Fed by an Orthogonal T Junction
X. C. Zhang J .G. Liang Jun Wei Xie
A 2×2 quasi-Yagi antenna array fed by a novel orthogonal T junction is presented. The orthogonal T junction is constructed with a traditional microstrip T junction, two planar microstrip to CPW transitions and two orthogonal microstrip to CPW transitions. The orthogonal T junction can be integrated with the quasi-Yagi array element directly. A 2×2 prototype operated from 7.6 GHz to 12 GHz is fabricated and measured.
THE QUASI-YAGI ANTENNA SUBARRAY FED BY AN ORTHOGONAL T JUNCTION
2008-06-30
PIER Letters
Vol. 4, 99-107, 2008
download: 105
Simulation Research on Turbo Equlization Algorithm Based on Microwave Fading Channel
S.-X. Guo Y. Gao Lin-Xi Zhang
Turbo equalization is applied to microwave channel in this paper, and we bring forward an improved Turbo equalization algorithm named Max-Log-Map. A simulation based on a given microwave fading channel has been made. The results show that performances are close to each other between improved TE-Max-Log-Map and Log-Map, and the coding gain is 1 dB at 10-4 of BER compared with Max-Log- Map. The improved Max-Log-Map method improves the reliability of microwave communication.
SIMULATION RESEARCH ON TURBO EQULIZATION ALGORITHM BASED ON MICROWAVE FADING CHANNEL
2008-06-20
PIER Letters
Vol. 4, 91-98, 2008
download: 102
Analysis of Co-Channel Interference at Waveguide Joints Using Multiple Cavity Modeling Technique
Debendra Kumar Panda Ajay Chakraborty Sankar Choudhury
A method of moment based analysis of the co-channel interference at waveguide joints has been presented using Multi Cavity Modeling Technique (MCMT). The proposed analysis has good agreement with the theoretical; CST microwave studio and HFSS simulated data.
ANALYSIS OF CO-CHANNEL INTERFERENCE AT WAVEGUIDE JOINTS USING MULTIPLE CAVITY MODELING TECHNIQUE
2008-06-18
PIER Letters
Vol. 4, 81-89, 2008
download: 202
Wideband Co-Planar Microstrip Patch Antenna
Alex Danideh Reza Sadeghi Fakhr Hamid Reza Hassani
A new antenna structure comprising a semicircular microstrip patch alongside a small rectangular shape ground proximity fed by a microstrip line is proposed. On a thin substrate this antenna achieves in the range of 5.8-12.9 GHz an impedance bandwidth of almost 75%. Details of the antenna design, simulation and measured results on the return loss and the E and H-plane radiation pattern of the proposed antenna are presented.
WIDEBAND CO-PLANAR MICROSTRIP PATCH ANTENNA
2008-06-16
PIER Letters
Vol. 4, 73-80, 2008
download: 645
Design Method of the Ring-Focus Antenna with a Variable Focal Distance for Forming an Elliptic Beam
Zhi-Yong Lu
In this paper, equations are derived for solving the important geometrical parameters of the ring-focus antenna with a variable focal distance for forming an elliptic beam, a simple and efficient method for this antenna is presented, and measured and calculated patterns are given. This antenna can form a high-efficiency elliptic beam.
DESIGN METHOD OF THE RING-FOCUS ANTENNA WITH A VARIABLE FOCAL DISTANCE FOR FORMING AN ELLIPTIC BEAM
2008-06-09
PIER Letters
Vol. 4, 63-72, 2008
download: 296
A Novel Cross-Slot Geometry to Improve Impedance Bandwidth of Microstrip Antennas
Mohammad Albooyeh N. Kamjani Mojtaba Shobeyri
Circular polarization (CP)designs of circular and rectangular microstrip patch antennas are demonstrated. Proximity coupled feed and aperture coupled feed methods are used. The proposed CP designs are achieved by implementing a suitable crossslot either on the patch (in the case of proximity coupled feed method) or on the ground plane (in the case of aperture coupled feed method), which results in excitation of two near degenerate orthogonal modes of near equal amplitudes and 90 phase difference. Attempts are made to change the geometry of slots' ends to introduce a novel structure in order to achieve a better matching performance.
A NOVEL CROSS-SLOT GEOMETRY TO IMPROVE IMPEDANCE BANDWIDTH OF MICROSTRIP ANTENNAS
2008-06-02
PIER Letters
Vol. 4, 55-61, 2008
download: 276
A Printed Volcano Smoke Antenna for UWB and WLAN Communications
Guo-Ping Gao Xuexia Yang Jin-Sheng Zhang
A novel printed version of the classic volcano smoke antenna is presented and investigated in this article. The effects of some important parameters on the VSWRof the proposed antenna have been investigated in the design. The measured bandwidth of VSWR<2 is from 1.80 to 14.35 GHz, which covers all UWB (3.1- 10.6 GHz) and 2.4 GHz WLAN (2.4-2.4835 GHz) bands. Moreover, the antenna features near omnidirectional characteristics in the operation range and good radiation efficiency. A gain variation from 2.04 to 7.02 dBi (2-13 GHz) is obtained.
A PRINTED VOLCANO SMOKE ANTENNA FOR UWB AND WLAN COMMUNICATIONS
2008-05-30
PIER Letters
Vol. 4, 43-53, 2008
download: 183
Scattering of Dipole Field by a Perfect Electromagnetic Conductor Cylinder
Ahsan Illahi M. Afzaal Qaisar Naqvi
Scattering of dipole field by a perfect electromagnetic conductor (PEMC) cylinder is studied theoretically. Electric dipole and magnetic dipole are considered separately as source of excitation. Plots are given for different values of admittance parameter of the PEMC cylinder.
SCATTERING OF DIPOLE FIELD BY A PERFECT ELECTROMAGNETIC CONDUCTOR CYLINDER
2008-05-28
PIER Letters
Vol. 4, 33-41, 2008
download: 99
An Elaborate Frequency Offset Estimation for OFDM Systems
Seung-Hyun Nam Jae-Seon Yoon Hyoung-Kyu Song
In this paper, a carrier frequency offset estimation scheme in orthogonal frequency division multiplexing is proposed. We focus on increasing the correlation of each PN sequence code repeated in one preamble. We aim at getting an efficiency like using many preambles. The proposed method can improve the performance of the system by estimating fine frequency offset. Also, the proposed method enhances reliability by maximizing the number of correlations compared with the established method in time domain.
AN ELABORATE FREQUENCY OFFSET ESTIMATION FOR OFDM SYSTEMS
2008-05-28
PIER Letters
Vol. 4, 25-31, 2008
download: 169
Compact Ultra-Wideband Bandpass Filter with Defected Ground Structure
Mojtaba Shobeyri Mohammad Vadjed-Samiei
Acompact planar microstrip ultra-wideband (UWB) bandpass filter is presented in this paper. The proposed UWB filter is realized by cascading a high pass filter (HPF) and a lowpass filter (LPF). HPF with short-circuited stubs is used to realize the lower stopband and a lowpass filter based on a defected ground array in the ground plane employed to attenuate the upper stopband. One such a bandpass filter is designed and simulated.
COMPACT ULTRA-WIDEBAND BANDPASS FILTER WITH DEFECTED GROUND STRUCTURE