2010 Volume 7 Issue 6 Pages 454-459
Instead of a bulky TE-mode resonator with high Qu, a compact TM-mode resonator with moderate Qu is proposed. The contact between the ceramic rod and the metal cavity is a key point for the filter reliability. Elasticity of the contact portion is well utilized in this case to keep the smooth electrical contact. Also, temperature coefficient of TM-mode resonator is studied. The requirements for characteristics of the ceramic materials are a little different for TE-mode and TM-mode. Finally, high-reliable and temperature-stable TM-mode resonator has been developed. Its application to compact base station filter is demonstrated as well.