Design of Microstrip Sextaplexer Based on Coupled Band-pass Filters with Common Feedline Technique

A microstrip sextaplexer based on coupled band-pass filters with common feedline technique is proposed in this letter. The input and output feedline of coupled band-pass filters are set to system impedance and all filters are combined together with a common feedline. With this technique, each band-pass filter can be individually designed and no matching circuit is needed. Furthermore, to create more coupling area, the lowest frequency of band-pass filter is allocated at the very first of the feedline. As a result, the proposed sextaplexer has 0.59 λ
0
× 0.48 λ
0
in size, while keeping high isolation better than 36 dB for each channel.