GB1390561A - Radio receiving system - Google Patents

Abstract

1390561 R.F. couplings MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 13 June 1972 [16 June 1971] 27593/72 Heading H4A A radio receiving system comprises an antenna 501, an active circuit 502, and a receiver 503. The input of the active circuit is directly connected to the aerial, without an extended cable, and the respective impedances are matched, to obtain resonance, at a frequency f 1 . The condition # 1 (f 1 )=0 is then satisfied, where # 1 is the reflection factor at the input of the active circuit 502. The output impedance of the active circuit is matched to the input impedance of the receiver 503 at a frequency f 3 , that is, # 2 (f 3 )=0, where # 2 is the reflection factor at the output of the active circuit 502. Furthermore, the reflection factors at the input and at the output of the active circuit are arranged to be equal at a frequency f 2 which is intermediate the frequencies f 1 and f 3 , that is, # 1 (f 2 )=# 2 (f 2 ). In order to maintain the signal-to-noise ratio in the output of the receiving system substantially constant throughout the operating frequency band it is arranged that, where # 1 (f 3 ) is the reflection factor at the input of the active circuit at the frequency f 3 , # 2 (f 1 ) is the reflection factor at the output of the active circuit at the frequency f 1 , and #= P R /G C .P C , G C being the power gain of the active circuit, P R , P C being the respective noise powers of the receiver and the active circuit, converted to equivalent powers at their inputs. It is also arranged that,