Low-loss, broadly-tunable cavity filter operating at UHF frequencies

A four-pole tunable filter has been demonstrated at UHF frequencies which tunes 300 MHz to 700 MHz and exhibits mid-band losses between 0.5 dB and 0.9 dB. This filter incorporates piezo-electric tuning of capacitively-loaded cavities and frequency-tailored input/output coupling networks to maintain good impedance match across more than an octave tuning band. The unloaded quality factor of the filter cavities range from 340-550. The filter has an output intercept point greater than +54 dBm and can handle power levels of +26 dBm.