Designs of Microstrip Four- and Five-Channel Multiplexers Using Branch-Line-Shaped Matching Circuits

In conventional multiplexer designs that use a direct-feed filter in each channel selection, matching circuits are typically crucial for achieving low loading effects between channel circuits. However, existing matching designs are often complex, and time-consuming optimizations are required when the number of multiplexer channels exceeds three. This paper proposes and verifies two four- and one five-channel multiplexers with simple and effective matching designs.