Published online by Cambridge University Press: 11 July 2013
This paper, following up on the previous work, investigates the effect of the input coupler's load termination of a balanced amplifier in a beam-steering system. The noise generated in this load termination deteriorates the amplifier noise resistance, which increases the noise temperature due to a varying active reflection coefficient at the antenna ports as a function of scan angle. In reducing this effect, the balanced configuration is made more favorable for radio astronomy applications. By lowering the value of the impedance termination on the fourth port of the quadrature coupler an improvement in noise temperature sensitivity is achieved at the cost of reduced power matching.