| TOPIC: Microwave Circuits |
| Manuscript Title: Design of Input and Output Sections of a High Gain Helix TWT and Measurement of their Loss Profiles |
| Manuscript Id: IJMOT-2006-5-52 |
| Abstract: A high gain high efficiency helix TWT was designed in two sections separated by sever for gain more than 50dB and electronic efficiency more than 25%, using SUNRAY-3D large signal model. For stable performance of a TWT against the reflected signals, high tip loss profiles at sever ends for the input and the output sections were designed using the large signal model. It was proposed to use tip loss of more than 30dB over the length of more than 20mm for return loss at sever ends better than 25dB. Experimental study has been done on the input and the output section assemblies for the high gain TWT to find the return loss in the region of carbon coating of high tip loss. A good agreement has been found between the experimental and the simulated results.This was validated that the two-section TWT with small-signal gain more than 55dB can have stable operation if return loss at sever ends are better than 25dB,and better than 15dB at the input and the output coupler |
| Authors: Vikas Kumar , Vishnu Srivastava, Anil Vohra |
Category: MicrowaveTechnology Submitted On: 7/25/2006 Full Text [PDF] Pg.Nos: 275-279
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| Manuscript Title: Branch-Line 3-dB Couplers of One- and Three-Quarters Wavelength and Realization Using Lumped Element |
| Manuscript Id: IJMOT-2006-6-83 |
| Abstract: A branch-line 3-dB coupler consisting of combination of one-quarter and three-quarters wavelength transmission lines will be discussed. The input match, isolation, and equal power divisions are all to be satisfied at center frequency. Under these conditions, four kinds of branch-line couplers classified by line length and their four equivalent lumped element couplers will be presented. |
| Authors: Iwata Sakagami |
Category: MicrowaveTechnology Submitted On: 6/6/2006 Full Text [PDF] Pg.Nos: 280-283
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| Manuscript Title: An Efficient Steady-State Analysis of Microwave Circuits |
| Manuscript Id: IJMOT-2006-6-116 |
| Abstract: Two methods for determining the steady-state are compared from the point of view of their efficiency and stability. The first one is based on idea of extrapolation and uses the epsilon-algorithm as an efficient tool; the second one is based on idea of sensitivities and uses the standard sensitivity analysis built in software packages. The comparison is done using a set of typical microwave circuits, especially the nonlinear C-class amplifier. For the autonomous circuits, a reliable detection of unknown period is implemented using derivatives of circuit variables. As a demonstration of solving the autonomous circuits, the steady-state analyses of distributed and feedback oscillators are fulfilled with the results compared using measured data. |
| Authors: Josef Dobes, Dalibor Biolek, Petr Posolda |
Category: MicrowaveTechnology Submitted On: 8/3/2006 Full Text [PDF] Pg.Nos: 284-289
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| Manuscript Title: A Nonlinear Microwave Circuit Simulator for Power Amplifier Designs with QAM-base Modulation Signals |
| Manuscript Id: IJMOT-2006-6-147 |
| Abstract: This paper presents a general-purpose nonlinear microwave circuit simulator for treating quadrature amplitude modulation (QAM) signals efficiently, based on the hybrid Volterra-series method with the modified nodal analysis (MNA) scheme. The S-parameters including the large-signal cases are acquired by using the ideal directional coupler expressed in the nodal voltage and branch current formats. The brief theoretical derivation and program implementation shown in the flowchart are given. A FET load-pull characterization with the modulation signal excitation for power amplifier designs is demonstrated to show the availability and efficiency of the software package. |
| Authors: Chien-Chang Huang |
Category: MicrowaveTechnology Submitted On: 7/20/2006 Full Text [PDF] Pg.Nos: 290-294
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| Manuscript Title: Analysis and Design of Multi-bit Distributed MEMS Phase Shifter |
| Manuscript Id: IJMOT-2006-6-148 |
| Abstract:
Abstract --This paper presents analysis and design of distributed MEMS phase shifters for Ka-band communication systems. The phase shift can be obtained by changing MEMS bridge capacitors located periodically over the transmission line. Simulation results of phase shifters with various structural parameters are analyzed to develop the optimized designs. It is observed that the distributed microelectromechanical transmission-line (DMTL) phase shifter can be accurately modeled using a combination of full-wave electromagnetic and microwave circuit analysis. The full-wave electromagnetic simulation of the unit cell is done by finite element using Ansoft High Frequency Structure Simulator (HFSS). After the full wave analysis is performed, S-parameters are extracted in the frequency range going from 26 to 40 GHz for di
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| Authors: Habibollah Zolfkhani, F. Hojjat-Kashani , J. Rashed-Mohassel |
Category: MicrowaveTechnology Submitted On: 8/13/2006 Full Text [PDF] Pg.Nos: 295-300
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| Manuscript Title: Saleh Function Based RF Power Amplifiers Nonlinear Orthogonal Bandpass Model |
| Manuscript Id: IJMOT-2006-6-161 |
| Abstract: This paper presents a Saleh function based RF power amplifier’s nonlinear orthogonal bandpass model. By transform power amplifier’s AM-AM and AM-PM nonlinearity to two orthogonal channels that have only AM-AM nonlinearity, the channel’s AM-AM nonlinearity is described by Saleh function. Compared to the Taylor’s series based orthogonal model, the new one is a better choice. |
| Authors: Zeng Xingbin, He Jiaming, Gu Weikang |
Category: MicrowaveTechnology Submitted On: 6/18/2006 Full Text [PDF] Pg.Nos: 301-304
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| Manuscript Title: Inverse Tangent Function Based RF Power Amplifiers Nonlinear Model |
| Manuscript Id: IJMOT-2006-6-163 |
| Abstract: By carefully analyze measured data of power amplifier, this paper presents an inverse tangent function to model RF power amplifier’s AM-AM nonlinear behavior. Comparison among the new model, Taylor series and Saleh function show that the new model is better. |
| Authors: Zeng Xingbin, He Jiaming |
Category: MicrowaveTechnology Submitted On: 6/18/2006 Full Text [PDF] Pg.Nos: 305-308
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| Manuscript Title: A Vector Network Analyzer Based on Six-Port Technology with an Ultimate Calibration Method |
| Manuscript Id: IJMOT-2006-6-177 |
| Abstract: A vector network analyzer (VNA) based on six-port technology with an ultimate calibration method is presented and developed. The vector network analyzer is based on only one six-port junction, which is either functioning as a reflectometer or as a wave-correlator depending on the measurements expected. Then an ultimate calibration method, in which the conventional two calibration procedures, one for the six-port junction and one for the VNA, are combined and simplified to one. Only one phase shifter, one short, and one thru (PsST) are required in the calibration. The main features of the proposed method are its simplicity, least number of standards, and expected improvement in measurement accuracy. The validity and utility of the proposed method are confirmed by experiments. |
| Authors: Toshiyuki Yakabe, Hajime Kondo, Fengchao Xiao |
Category: MicrowaveTechnology Submitted On: 6/23/2006 Full Text [PDF] Pg.Nos: 309-314
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