Effects of microwave switch isolation on a Butler matrix beamforming network in smart antenna systems

The paper analyzes the effect of finite microwave switch isolation on the beam pattern generated by an N×N Butler matrix beamforming network. The result indicates that, as switch isolation becomes lower, the array´s sidelobe levels increase, and the angle in the main beam shifts slightly. The sidelobe level increases in proportion to the level of isolation, but was found to be non linearly related to the switch isolation, and is dependent on the selected beam.