Analogue IF beamformers

Two IF beamforming techniques are described. The first is a method of providing a fixed fan of beams where a large number is required, and the second gives a small number of adaptive beams where the weights applied in each beam can be changed to alter the beamshapes and steer them around the sky. In order to specify a particular beamset a certain amount of loss must be introduced into a beamformer in order to overcome the restrictions of orthogonality. Since this loss can be calculated and amplification can be provided to maintain the signal to noise ratio, complete freedom in the choice of beams can be had. An example of a lossy IF beamformer providing a fan of beams with specified cross-over points is a resistive matrix