Laser tunable thick film microwave resonator for printed circuit boards

The resonator of the present invention is preferably made of low cost alumina offering performance in a variable frequency oscillator application that is nearly equivalent to that of a high Q dielectric design. The resonator structure is tunable over a wide range with substantially no effect on oscillator phase noise or signal amplitude. The resonator utilizes a unique geometric structure which employs a transmission line preferably on alumina, conducting via holes (called castellations) and a topside ground pattern formed with a thick film of silver and/or palladium. A plurality of resonators may be formed by a step and repeat pattern then snapped apart for low cost, high volume manufacture. The resonator may be tuned in both a vertical and horizontal direction by removing topside metal from the resonator, to raise and lower the frequency, until the desired frequency is met. Low phase noise is preferably achieved by using a slab resonator that is short in length in combination with a fairly large loading capacitor. This provides maximum phase change versus frequency, and the best phase noise response of the oscillator.