High-performance suspended stripline wideband bandpass filter with new miniaturisation technology

A simple wideband tubular suspended stripline (SSL) bandpass filter using novel miniaturisation technology is presented. In this design, the equivalent circuit of the proposed filter is considered as the conventional tubular bandpass filter circuit. A new miniaturisation technology called 'different height of cavity' is applied to the filter design. A SSL filter is designed and fabricated with the passband from 0.6 to 1 GHz. The insertion loss is better than 0.6 dB in the passband while the return loss is mostly higher than 20 dB. The group delay variation is <0.2 ns. Good agreement between the simulated and measured result is observed, which proves the validity of the technique.