COMPUTER AIDED DESIGN OF MICROWAVE PLANAR SIX PORT REFLECTION ANALYZER

Abstract

The reflection analyzer is an instrument which measures the reflection parameters i.e. reflection coefficient , VSWR and S ;; scattering parameter. The six port technique for measuring reflection coefficient has steadily gained acceptance in standards laboratories and in research establishments since the mid-1970s when several major theoretical breakthroughs were made. Now most of the modern reflection analyzers are six - port systems. This is due to simplicity of hardware, which helps in making a traceability analysis based on power measurement performance. The six port reflection analyzer system consists of a six port reflectometer, a frequency synthesizer, four detectors/power meters and a computer ( or a microprocessor based system ) which controls the system and perform the calculation and the presentation of the measured data. Most of the modern six port reflection analyzers are fabricated using microstrip technology because of its advantages such as low cost, small size...etc. This thesis is involved only in computer aided design of the microstrip six port reflectometer and the synthesizer parts of the six port reflection analyzer. In this thesis description of the construction and operation of various types of microwave network analyzers and reflection analyzers where given with a detailed study of the six port reflection analyzer with emphasis on the six port reflectometer and synthesizer parts. Study of the microstrip transmission line characteristics and parameters is presented. Design algorithms and formulas for the design of the circuits constituting the microstrip six port reflectometer and the microstrip frequency synthesizer circuits are given. These algorithms are written in a suitable form to be used in special or general purpose CAD programs. A FORTRAN 77 program is made to be used as a CAD tool for microstrip circuits. A new proposed method for the design and synthesis of broad band planar microwave hybrid couplers is presented. This work was published in the (NRSC'98). CAD of a microstrip frequency synthesizer from 7.7 GHz to 9.5 GHz is presented. A new proposed CAD method for the design of broadband microstrip six-port reflectometer is presented. The design details of a broadband six-port reflectometer from 7.7 GHz to 9.5 GHz using the proposed method are presented. The measured S parameters of the reflectometerliiusiraie iigood performance in the desired bandwidth.