Electronically Variable Coupler.
Final technical rept. Jan 68-Jul 69,
WESTINGHOUSE DEFENSE AND ELECTRONIC SYSTEMS CENTER BALTIMORE MD AEROSPACE DIV
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The microwave characteristics of an electronically variable coupler EVC were investigated. The electronically variable coupler EVC is a quarter-wavelength, parallel-line, directional coupler fabricated in microstrip on a high resistivity approximately 2m000 ohm-cm silicon substrate. The variable coupling of the device is derived by varying the dc biasing of a distributed pn junction inserted between the parallel microstrip lines of the coupler. A theoretical model was developed and expressions for the elements of the scattering matrix of the device were derived. Comparison between the theoretical model and experiment was made through the measurement of the coupling, insertion loss, isolation and VSWR of the EVC. Coupling variations with applied dc bias at X-band frequency of 9.56 Hz measured 6.5 dB with a dc bias change of 20 volts under reverse bias. Measured insertion loss at X-band frequencies ranged from 3 to 8 dB depending upon the geometry of the EVC. The isolation, measured for these units, varied from 8 dB to greater than 20 dB. Units designed to operate with a C-band center frequency of 5.5 GHz displayed similar results. Author
- Electrical and Electronic Equipment