Band rejection filtering arrangement
First Claim
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1. A band rejection filtering arrangement comprising:
- a quadrature hybrid circuit having a first pair of terminals and a second pair of terminals, said first pair of terminals being isolated from each other, said second pair of terminals being isolated from each other, signal transmissions between the first of said first pair of terminals and the first of said second pair of terminals being effected without phase shift, signal transmission between the first of said first pair of terminals and the second of said second pair of terminals being effected with a 90°
phase shift, signal transmission between the second of said first pair of terminals and the second of said second pair of terminals being effected without phase shift, and signal transmission between the second of said first pair of terminals and the first of said second pair of terminals being effected with a 90°
phase shift;
a first bandpass filter having its input coupled to the first of said second pair of terminals;
a second bandpass filter having its input coupled to the second of said second pair of terminals;
a first load coupled to the output of said first bandpass filter;
a second load coupled to the output of said second bandpass filter;
means for providing an input signal at the first of said first pair of terminals; and
means for receiving a signal at the second of said first pair of terminals;
wherein said first and second bandpass filters are tuned to pass the rejection band.
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Abstract
A band rejection filtering arrangement utilizing bandpass filters each terminated by a matched load. A quadrature hybrid circuit divides the input signals and applies them to the bandpass filters. Signals within the rejection band are dissipated by the filters and matched loads, whereas desired signals are reflected. The reflected signals are then combined by the quadrature hybrid circuit to provide the band rejected output. This arrangement is made switchable between an all pass mode and the band rejection mode by providing PIN diodes between the quadrature hybrid circuit and the bandpass filters.
42 Citations
10 Claims
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1. A band rejection filtering arrangement comprising:
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a quadrature hybrid circuit having a first pair of terminals and a second pair of terminals, said first pair of terminals being isolated from each other, said second pair of terminals being isolated from each other, signal transmissions between the first of said first pair of terminals and the first of said second pair of terminals being effected without phase shift, signal transmission between the first of said first pair of terminals and the second of said second pair of terminals being effected with a 90°
phase shift, signal transmission between the second of said first pair of terminals and the second of said second pair of terminals being effected without phase shift, and signal transmission between the second of said first pair of terminals and the first of said second pair of terminals being effected with a 90°
phase shift;a first bandpass filter having its input coupled to the first of said second pair of terminals; a second bandpass filter having its input coupled to the second of said second pair of terminals; a first load coupled to the output of said first bandpass filter; a second load coupled to the output of said second bandpass filter; means for providing an input signal at the first of said first pair of terminals; and means for receiving a signal at the second of said first pair of terminals; wherein said first and second bandpass filters are tuned to pass the rejection band. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification