Novel Compact Tunable Filter Prototype Realized with Vanadium Dioxide

This paper presents a design, fabrication, and characterization of a reconfigurable filter for use at 25 – 50 GHz. This prototype bandpass filter (BPF) incorporates two poles, and has two bands. In band insertion losses (IL) are simulated as 1.0 and 1.2 dB respectively, and the measured losses are 4.0 dB and 2.5 dB. There is a canonical 12 dB per octave IL roll-off from the pass band. This novel filter uses vanadium dioxide, a phase change material, to vary the length of its coupled transmission lines (TLs). The prototype filter is partially fabricated, and measurements are presented.