This study presents the synthesis and design of novel bandpass prototype networks with reconfigurable centre frequencies in two distinct states whose absolute bandwidth is maintained constant. The passbands of the prototypes can also be tuned around the centre frequencies of the two distinct states with minimal absolute bandwidth variation. This is achieved by virtue of a new distributed resonator structure which is thoroughly studied and analysed in this work. The presented circuit concepts are validated through the simulation of a stub-loaded evanescent mode waveguide filter modelled on high frequency structure simulator (HFSS) realising an absolute bandwidth of 242 MHz in two distinct states that are centred at frequencies of 1150 and 1495 MHz.
The filter is manually reconfigured between the two distinct states upon terminating stubs within its resonator structures as either open-circuits or short-circuits. The filter is also discretely tuned in each of the two states upon manually altering the values of the loading capacitors of its resonators. The absolute bandwidth of the filter exhibited a maximum variation of only ±28 MHz over the frequency tuning range spanning 977.5 to 1667.5 MHz.