DESIGN OF MICROSTRIP DIPLEXER USING LOWPASS FILTER AND HYBRID BANDPASS FILTER

A miniature microstrip stepped impedance low pass filter and coupled resonator band pass filter diplexer has been developed. The merit of the circuit lies in the simplicity of the design procedure and the simplicity of the simulation with most commercial soft ware packages. The matching circuit design of a low pass band pass diplexer may be a challenge in conventional designs because wideband (from zero to approximately the cutoff frequency of the low pass filter) open circuit condition is required to be achieved in bandpass channel circuit. The measured results are in good agreement with the simulated responses.