Abstract: A multi-port microwave coupler has six input ports In 1, In 2, In 3, In 4, In 5 and In 6 and six output ports Out 1, Out 2, Out 3, Out 4, Out 5 and Out 6 and is synthesized from nine 2.times.2 90.degree. hybrid couplers which are arranged as three sets, that is a first set A, B and C, a second set D, E and F and a third set G, H and I. A first group of transmission lines interconnect the first and second sets of hybrid couplers, and a second group of transmission lines interconnect the second and third sets of hybrid couplers The first and third sets of couplers each give a 3 dB power reduction, but the second set give a 1:2 power split between their outputs. Three 90.degree. phase shift, devices X, Y and Z correct the phase of the signals in three of the transmission lines of the second group. When equal amplitude signals are applied to all of the input ports, the combined signal can be directed to any one of the output ports by appropriately selecting the respective phases of the input signals.

Abstract: A microwave power amplifier having application in multiple beam phased antenna array systems including a biasing means connection to the base of a microwave transistor being responsive to radio frequency signals applied to the amplifier to automatically adjust the transistor bias level to maintain constant amplifier gain. The biasing means includes two voltage regulators with their outputs capacitively coupled via a fixed resistor having a value determined by the characteristics of the transistor, the base of the transistor being connected to the biasing means at the junction of the resistor and the capacitive coupling of one of the regulators. The mode of operation of the power amplifier gives rise to a highly efficient linear system while under effective Class B (non-linear) bias.