5.8 GHz bandpass filter design using planar couple microstrip lines

Using microstrip lines to design a planar coupled bandpass filter encounters some approximation errors due to the tolerance in PCB processing and coupling effects. Sometimes it causes unacceptable errors and it can take significant effort to reduce this error. We use admittance inverters to design a 5.8 GHz bandpass filter for a Chebyshev attenuation response of 0.5 dB. Modification of section lengths, widths and gaps by applying an iterative method used previously for synthesizing a coupler to compensate coupling effects and the tolerance in PCB processing. The ADS simulation tool and implemented filter measurements are performed to verify the adapted modified method and show very good results to our filter specifications. The method can be used to design any other bandpass filter.