GB1376046A - Radio receiving antenna systems - Google Patents

Abstract

1376046 R.F. Couplings SIEMENS AG 5 July 1972 [13 Aug 1971] 31371/72 Heading H4A In a radio receiving aerial system relatively weak signals from distant stations are received on directional aerials A, B at respective carrier frequencies f a , fb, and relatively strong signals from local stations are received on an omnidirectional (e.g., crossed-dipole) aerial C at respective carrier frequencies f c1 , f c2 , f c3 . Each received signal is processed in an individual channel level unit K1 to K5. These units each comprise input ports 2, 3 and output ports 4, 5 of a directional coupler, also a further port 1 which is directly coupled to the output. The signals from the aerials A, B are applied to the ports 1 of the units K1, K2, and the signal from the aerial C is applied to the port 2 of the unit K3. An output loop is formed by linking the ports 4, 5 of the adjacent channel level units K1 to K5, the port 5 of the unit K5 being earthed through a terminating resistor 7, and the port 4 of the unit K1 being coupled through an amplifier 8 to a feed line 9. The ports 2, 3 of the adjacent channel level units K3 to K5 are also looped, the port 3 of the unit K5 being earthed through a terminating resistor 6. In each of the units K1 to K5 the particular associated received signal, after selection by tuned resonant circuits and conversion to an intermediate frequency, is amplified, limited and subsequently converted back to its original or to another suitable frequency. Any signals of frequencies f a , f b which are picked up by the omni-directional aerial C and which appear at the output 4 of the channel level unit K3 are so heavily attenuated as not to constitute a disturbance.