Study of Microstrip Multiplexers for Satellite Communication Systems

Satellite communication is witnessing major developments in size and mass. In each satellite's payload, there are several multiplexers and filters that are used to define frequency, which combine and separate channels and prevent channel interference. This paper investigates different topologies of multiplexers based on microstrip bandpass filters. A four-channel multiplexer, composed of coupled lines microstrip bandpass filters was designed and simulated. The four-channel-multiplexer consists of one feeding line input and four output lines. Each channel filter used two resonators that perform at different frequency ranges. The resonators were located precisely to achieve good isolation between channels. A small number of resonators was used, which resulted in a small circuit size. This multiplexer design shows high flexibility in the passband frequencies because each pair of resonators was used for a specific frequency and the effect of loading between channels was relatively small with a circuit size of 2.1 cm × 2.1cm and over 40 dB isolation.