Reconfigurable filter design using resonators as coupling structures

A highly-reconfigurable resonant-coupling bandpass filter design approach is presented in this paper. With this novel inter-resonator coupling technique, the coupling bandwidth is controlled through the odd-mode resonant frequency. The employed first-order coupling resonator also acts as an intrinsic switch when its resonant frequency coincides with the center frequency of the bandpass filter. Furthermore, each coupling resonator implements an extra transmission zero, which increases the filters selectivity and can block jammers. The presented analysis is experimentally validated by an eight-resonator array that is capable of realizing a reconfigurable filter design with a) an octave frequency tuning range of 119.04 MHz to 239.05 MHz, b) tunable bandwidth from 23 MHz to 40 MHz achievable at all states and 20 to 42 MHz for most states, and c) tunable filter order from second to fourth order.