Compact and Low-consumption 2-port Switchable Filter Bank with Tunable Notch Filters from 2GHz to 18GHz

This paper presents the first experimental results of a compact and low-consumption 2-port planar switchable filter bank composed by seven planar analog tunable notch filters. The device has been properly designed for defence applications in the range 2GHz÷18GHz and it is composed by eight paths. Seven of these paths are tunable notch filters whose overall tuning ranges cover the entire frequency spectrum 2GHz ÷ 18GHz. The four lowest frequency notch filters are realized in lumped technology on microstrip PCB and they do not present any spurious notch repetitions up to 18GHz. The three highest frequency notch filters are based on coupled-line resonators on microstrip PCB. In both cases high-Q commercial-available varactor diodes have been used to tune the frequency of the notch filters. The remaining eighth paths realize an in-out thru from 2GHz to 18GHz. The in/out switch SP8T matrices consists of commercially available SPDT and SP4T PIN-diode switches. Measured rejection in notched bands of 500÷600MHz is above 35dBc. The overall footprint is within 70×50mm and the maximum power consumption is below 1.5W.