Abstract: A dual polarisation waveguide probe system for use with a satellite dish (10) for receiving satellite signals orthogonally polarised in the same frequency band and for providing improved isolation between these polarised satellite signals is disclosed. The probe system has a waveguide (28) incorporated in a low-noise block receiver (12) into which two probes (34, 38) are located for receiving linearly polarised energy of both orthogonal senses. The probes (34, 38) are located in the same longitudinal plane on opposite sides of a single cylindrical bar reflector (36) which reflects one sense of polarisation and passes the orthogonal signal with minimal insertion loss, and then reflects the rotated orthogonal signal. The probes (34, 38) are spaced .lambda./4 from the reflector (36). A reflection rotator (44) is also formed using a thin plate which is orientated at 45.degree. to the incident linear polarisation with a short circuit (46) spaced approximately a quarter wavelength (.lambda.

Abstract: A switch for transmitting a signal with gain from one of a plurality of input transmission lines (10A,10B,10N) to a common output line (14) is described which achieves high isolation by omitting the transmission line between the output matching section and the junction of the input and the output. In one embodiment the output of each amplifier, a field effect transistor (38,40), is coupled directly to a common output (34) and the output matching circuitry is also omitted from the input lines, there being provided a common output matching and bias network located in the output line. In another embodiment the output matching network (26a,26b;64a,64b) is coupled directly to the common junction (16;56) and the transmission line length between the output matching network and the junction is omitted for each input line.