A Substrate Integrated Waveguide Frequency Switchable Filter using Vanadium Dioxide Tuners

A 22-22.6 GHz frequency switchable substrate integrated waveguide (SIW) filter has been designed and fabricated. The filter is using vanadium dioxide (VO 2 ) integrated tuners to switch integrated capacitive posts at the center of SIW resonators. The conductivity of the vanadium dioxide tuners is sharply increased, by 5 orders of magnitude, when the material is heated at a temperature higher than 68°C, abruptly changing the center frequency of the filter in the proposed configuration. The 6.3% fractional bandwidth 2-pole bandpass filter insertion loss is 2.95 dB when the VO 2 disk is insulating, and 3.8 dB in the conductive state. The filter return loss are better than 7.5 dB in both configurations. The temperature sensitivity has been tested and it is shown that the device has to be kept below 40°C for maintaining acceptable loss level in the insulating state.