부산대학교 도서관

This paper describes a simple approach of re-configurable bandpass filter based on stepped impedance res- onator (SIR) transmission lines, particularly suitable for X-Band military communication application. In the proposed design, shifting of frequency from downlink to uplink frequency response is achieved by strategically placing three Variable capacitor (Varicap), at locations where the capacitors do not affect the resonating response of the overall design. Variable capacitor is used in order to tune the capacitance for the frequency shift between uplink to downlink frequency. The operating frequency for X-Band downlink is 7.25 GHz to 7.75 GHz and uplink is from 7.90 GHz to 8.40 GHz. The filter is designed on a Rogers RO4003 substrate with dielectric constant r=3.38 and 0.508 mm thickness of substrate.