Electroacoustic Wave Tunable Filter.
Final rept. Dec 67-Dec 68,
SPERRY RAND RESEARCH CENTER SUDBURY MA
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The performance of an electronically tunable filter, operating through the excitation of electroacoustic resonances in a plasma, was optimized in the VHF band. The plasma was generated from an annular inverse brush cathode discharge requiring a 400 V, 2.5 mA power supply. The filter was tuned to frequencies from 150 to 250 MHz by varying the voltage applied to the discharge at rates up to 1 kHz. Over this frequency range the passband insertion loss varied from 15.2 to 4.5 db and the Q varied from 14.2 to 7.7. The power handling capability was 0.1 mW, and 6 intermodulation between two signals transmitted through the filter was observed. The noise temperature of the device was estimated to be 2,500K. Numerous attempts were made to improve the performance of the filter by empirical variation of various critical dimensions. Some detailed theoretical calculations relating to the insertion loss of the filter were carried out. Author
- Electrical and Electronic Equipment
- Plasma Physics and Magnetohydrodynamics