Synthesis of multiple output coupled resonator circuits using coupling matrix optimisation

Abstract

Coupled resonator circuits are the basis for the design of many bandpass microwave filters. Design techniques used for two-port coupled resonator circuits are extended here to multiple output circuits such as power dividers and diplexers. The design approach is based on synthesis of coupling matrix for multiple coupled resonators with multiple outputs using gradient-based optimisation. It allows the synthesis of power dividers with arbitrary power division, as well as diplexers and multiplexers with novel topologies. Since there is no need to use separate energy distribution networks such as circulators, manifolds or other junctions, the components can be miniaturised. An X-band unequal power divider and diplexer have been designed and realised using waveguide cavity resonators to confirm the new design methodology.