Magnetically tunable filters for cellular communication terminals

Magnetically tunable two-pole dielectric-resonator filters containing axially and circumferentially magnetized ferrite elements have been designed and investigated. Employing axially magnetized ferrites, a 20-MHz tuning range was obtained. The Q factor of resonators was 2500 and the tuning power was 1.8 W. Filters containing circumferentially magnetized discs demonstrated a 12-MHz tuning range with the Q factor over 8000 (tuning power 3.5 W) and 28 MHz with the Q factor 3500 (tuning power 3.5 W)