Broadband Filter Circuits using an Extended Suspended Substrate Transmission Line Configuration

Suspended stripline has proven to be a low loss transmission line, especially for filters. Making full use of both sides of the substrate, including standard stripline, coupled stripline and microstrip, very broadband components can be realized. This is demonstrated by a 2.5 GHz low-pass filter with high isolation up to at least nearly 17 GHz, high-pass filters up to 30 GHz and a broadband (3.5-7.5 GHz) bandpass without higher pass-bands up to 40 GHz.