Exact Synthesis of a Low-Pass Prototype for the Accurate Design of Single-Sided Filters

This paper presents an exact technique for the synthesis of a low-pass prototype for single-sided filters which are characterized by requirements given in one passband and one stop band, both of finite extent. With these filters, it is possible to obtain high selectivity and low insertion loss at the same time (even with low unloaded Q resonators). The number of resonators for a given attenuation requirement is much smaller than what classical bandpass topologies require. It is also shown how the low-pass prototype can be employed to design single-sided filters in coaxial and microstrip technology. Simulated and measured results are presented to show the soundness of the technique herein introduced