Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Patent
1985-07-17
1987-04-28
Nussbaum, Marvin L.
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
330103, 330260, 330286, 333166, H03H 1112, H01P 120
Patent
active
046617892
ABSTRACT:
A broadband microwave recursive filter that provides sharp transitions in the frequency domain between adjacent stop and passbands comprising a signal input node; a signal output node; a filter circuit connected between the signal input node and the signal output node for providing a signal flow therebetween which has a predetermined frequency bandwidth characteristic; a microwave transistor circuit, with the microwave transistor circuit being band-limited to provide gain in only a restricted window of frequencies within the predetermined frequency bandwidth and connected for providing amplification to signals flowing in the filter circuit between the signal input node and the signal output node while suppressing out-of-window signals resulting from design approximations. The filter circuit includes a plurality of distributed feedback loop circuits, with each of the feedback loop circuits including the microwave transistor circuit therein, and wherein each of the feedback loop circuits has a different electrical length in relation to the other of the plurality of feedback loop circuits. Finally, the present filter design includes a passive filter connected in common to all of the plurality of distributed feedback loop circuits in the filter circuit for circuit for providing filter zeros on both sides of the restricted window of frequencies. In a preferred embodiment, the microwave transistor circuit includes an FET which is impedance-matched to obtain an approximately flat gain response across the window. It is preferred that the plurality of feedback loops all have amplitude weighting factors of the same sign.
REFERENCES:
patent: 2210503 (1940-08-01), Shaw
patent: 3356962 (1967-12-01), Morgan
patent: 4243943 (1981-01-01), Cherry
"Analysis and Design of a Microwave Transistor Active Filter," Richard V. yder, Jr. and David L. Bozarch, IEEE Transactions on Microwave Theory and Techniques, vol. MTT-18, No. 1, Jan. 1970.
"Active Filters for UHF and Microwave Frequencies," David K. Adams and Raymond Y. C. Ho, IEEE Transactions on Microwave Theory and Techniques, vol. MTT, No. 9, Sep. 1969.
"Microwave Bandwidth Active Transversal Filter Concept with MESFETs" Wilhelm Jutzi, IEEE Transactions on Microwave Theory and Techniques, vol. MTT-19, Sep. 1971.
Ellis William T.
Forrest John L.
Nussbaum Marvin L.
The United States of America as represented by the Secretary of
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