Composition and analysis of a new waveguide resonator filter with dielectric loading

Abstract

AbstractThis paper proposes and analyzes a new waveguide resonator filter for comparatively low microwave frequency use. It describes a practical example for its application. The new waveguide structure consists of thin center conductors embedded in cylindrical dielectric rods in contact with conducting parallel plates. This structure can be viewed as a dielectric‐filled coaxial cable provided its external cylindrical conductor extends to a parallel plate. By using the relaxation method calculations are conducted under the assumption of pure TEM fields. The calculated impedance, line coupling, effective dielectric constant and circuit Q are found to be in good agreement with experiment.In order to investigate the higher‐order mode of the filter using this guided structure, the lowest higher‐order is assumed to be the TM01 mode and the effect of the conducting plate is excluded; the wave‐numbers are calculated and compared with experiment. The Q of the 1/4‐wavelength resonator using this guide is higher than that of the dielectric‐filled coaxial line resonator and, without using the interdigital arrangement, couplings between resonators can nonetheless be realized. In the example of the 850‐MHz band filter, it is clear that this waveguide can be used to realize miniaturized, light‐weight, inexpensive and high‐performance filters.