Continuously Tunable X-Band Filter Using a 3D Spiral Ribbon

A new type of continuously tunable filter is described here. Such filter is composed of a body with a ribbon, passing in its center, which can produce custom evolution of the filtering function such as center frequency tunability or bandwidth tunability. Simulations for these two possibilities are presented to underpin the concept. A frequency tunable filter presenting a shift of 700 MHz around 12 GHz has been realized and measured. The optimization method used for this kind of filter is also given and discussed.