Novel FR4‐based low loss reconfigurable filter with four operating modes using movable transmission lines

Abstract

In the letter, a novel reconfigurable filter using movable transmission lines is proposed. The filter is based on substrate‐integrated‐suspended‐line structure with two inner layers, fabricated on low‐cost FR4 substrate. The suspension line and the cavity are completely covered by copper. The suspension line could be freely moved in the air cavity. In the novel structure, the coupled lines have a variable coupling coefficient. With the movements of two transmission lines, the filter has four operating modes and can be tuned, with low insertion loss of less than 0.45 dB, showing promising properties.