Proposal to expand frequency tuning range in millimeter-wave band tunable filter

Rapid advances in millimeter-wave wireless communication technologies require accurate spectrum analysis in the frequency domain over 100 GHz. A tunable pre-selection filter is a key device in building such a spectrum analyzer. We have previously reported on a new tunable filter with a 24% wide tunable frequency range in the frequency band over 100 GHz. In this paper, we describe use of a ridge waveguide to achieve frequency tuning over a wider bandwidth and demonstrate an example design for a filter with a relative bandwidth of38% (75 to 110 GHz).