Design of diplexers with prescribed crossover loss using singly terminated filters

Two new methods are described to design frequency symmetric diplexers with any realizable prescribed crossover attenuation. The two methods are based on the use of singly terminated low-pass (LP) and high-pass (HP) filter pairs that are readily available or that can be easily synthesized. In these methods, the pass-band corner frequencies of LP and HP filters are scaled to give the desired crossover attenuation. The approach can use filters with maximally flat or equiripple pass-bands and general stopbands, thus enabling one to design diplexers with or without transmission zeros easily. Some examples are designed and realized in suspended stripline structure