This article describes the use of dielectric rods to reconfigure combline filters both with respect to center frequency and bandwidth. In this context, a new filter topology is developed in order to maximize the achievable reconfiguration range. The design of a prototype is discussed in detail, clearly demonstrating the feasibility of center frequency and bandwidth reconfiguration, with the same filter structure, while maintaining an equiripple return loss. In addition to theory, a combline filter prototype is also fabricated, tuned and measured in several configurations showing excellent agreement with simulations, thereby fully validating both the basic concept and the design procedure.
