Piezo-controlled microwave frequency agile dielectric devices

A novel approach, utilizing piezoelectric actuators to control filters, resonators, and phase shifters with the minimum insertion loss, is described. Tunable, low-loss microwave devices can be fabricated using composite structures in which effective dielectric constant, /spl epsi//sub ef/, is controlled by piezoelectrically induced changes in the energy distribution within the devices. With this approach, a high degree of tunability is possible while utilizing high Q dielectrics. These devices usually consist of two dielectric parts with an air gap between them. This gap has to be arranged to provide the largest perturbation in the electromagnetic field. By means of a fast piezoelectric mini-actuator, the size of the air gap is changed and as a result, the /spl epsi//sub ef/ can be tuned. This tuning is used for device control. Highly tunable (more than 20%) dielectric and metal ring resonators, as well as wide-band, low-loss phase shifters are realized experimentally.