A novel microstrip bandpass filter design using asymmetric parallel coupled-line

A novel parallel coupled-line bandpass filter with suppression at the 2^nd harmonic frequency is presented in this paper. This structure offers a simple design methodology and corresponding implementation. An example of a 900 MHz prototype bandpass filter is used to demonstrate the performance of the new structure. The measured results agree well with the simulation, where, up to 40 dB suppression is recorded at the 2^nd spurious response, whilst the matching achieves an interesting level close to 29 dB.