Integrated microwave power distribution network

The paper first discusses the general use of circulators as circuit elements in integrated microwave circuits. In particular it is pointed out that circulators greatly reduce some of the requirements on the other components, thus making possible circuits with higher overall performance than would ordinarily be possible in stripline. The cost of these circulators is low enough to allow one to use quite a profusion of them. In addition to the usual function of the circulator to provide isolation, its use as a power splitter is introduced here. Power splitting can certainly be done by conventional means, e.g., using directional couplers, but the use of a circulator in conjunction with a controlled mismatch provides an unusual degree of flexibility. The splitting ratio can be very simply adjusted over a wide range. Finally, a physical realization of an integrated microwave circuit is shown. It utilizes six circulators, one of which is a power splitter. In addition to its main function of dividing an amount of input power between two loads, the circuit contains a variable attenuator and a power sampler, and provides high isolation between the two loads. The size is a fraction of that of the waveguide circuit it replaces.