A Compact Multiband Cavity Filter using Interdigital Technique for LTE, S-Band and WLAN Systems

摘要

This paper presents a compact multiband cavity filter using techniques for changing capacitance at different parts of the cavity such as interdigital iris structure to support the use of multi-frequency communication. The filter is designed at fundamental frequency of 1.8 GHz (LTE), the second resonant frequency of 2.2 GHz (S-Band) and the third resonance frequency of 2.45 - 2.9 GHz. The capacitance of the cavity can be varied by changing the width of the wall gap, pole size, finger gap and impedance, which impacts in the second and third resonance frequency shifting. This multiband cavity is made of aluminium nitride material with the size of 47.05×48.26×28.97 mm for high energy handling. The good efficiency is derived from the insertion loss (S21) of −0.05 dB and the return loss (S11) of −12 dB.