Abstract: In a cell of a microwave cellular video distribution system, e.g a multichannel video distribution system operating at frequencies of around 29 GHz or 40 GHz, the transmitting antenna is composed of individual antenna sectors (62a,62b,62c . . . ) for transmitting the microwave signal towards different sectors (216a,216b,216c . . . ) of the cell. In accordance with the present invention, a respective monitor (D,R) is present in each of the different sectors (216a,216b,216c . . . ) of each/the cell to monitor the microwave signal transmitted in that sector. The antenna sectors (62a,62b,62c . . . ) are individually fed through controllable feed means (59,60,61) which permit individual control of the power level of the microwave signals transmitted by the individual antenna sectors (62a,62b,62c . . . ), including the switching off of that sector. A feedback coupling (40,44,49) is present between each monitor (R,D) and the controllable feed means (59,60,61) of the respective antenna sector (62a,62b,62c . . .

Abstract: A receiver comprising an antenna array having a number of antenna elements. The antenna array is fed by a feeder. Switching apparatus are arranged for switching at least a first antenna element to the feeder or at least a second antenna element to the feeder. This provides a spatial shift of the antenna array without changing its radiation pattern. This improves the signal level when poor signal reception occurs due to multipath fading.

Abstract: In multiple-channel microwave transmitters and communications systems, such as multi-point video distribution systems operating at frequencies of around 29 GHz or 40 GHz, good frequency stability for each of the channel frequencies is achieved with a feed-back loop including an error detector circuit. The error detector circuit (39,29) is coupled between a sampler and an input circuit of the source. This detector circuit detects any drift or other error in the carrier frequency of the sample from the desired microwave frequency for that channel signal and provides a corrective signal to the input circuit. The part of the feed-back loop comprising at least a part of the detector circuit is common to a group of the channels. Switch means couple the common part of the feed-back loop between the sampler and the source input circuit of each channel, and so permit this common part to be time multiplexed between the respective feed-back loops of the group of channels.

Abstract: A communications system includes a plurality of directional signal propagators, each defining a cell. The cells are arranged in a plurality of rows (R1 to R12), each row including repeating sequences of four propagators transmitting first, second, third and fourth signals (A, B, C, D), respectively, wherein the sequences in successive pairs of contiguous rows (R1, R2 etc.) are offset by one cell, and wherein diagonally arranged pairs of the propagators in pairs of contiguous rows transmit the same signal.