Generalised hybrid matrix antennas

A technique is introduced for the reduction of the complexity and cost of transmitting multiple beam antenna systems. The technique is applicable to both phased array antennas and array fed reflectors. Conventional methods of generating multiple transmit beams from a single antenna are constrained by the choice of beamforming architecture. Previously reported work indicates that if the number of amplifiers in the system is not to exceed the number of beams, then the set of beams must have the property of orthogonality. Alternatively, it is possible to generate the optimum beams for a system, but the number of amplifiers is then equal to the number of feeds, and the designer will then want to minimise the number of feeds. The objective of this paper is to offer an alternative system design which eliminates some of these constraints. It is shown that for the majority of practical transmitting antenna systems where the number of feeds is represented by J, it is possible: to generate N beams using M amplifiers where M need be no greater than N (J>N and M⩾N); that these amplifiers operate at equal and unchanging power levels regardless of how the power is distributed between beams; and that there is no constraint of orthogonality on the beam set