Band-Widening of Ceramic Resonator Loaded NRD Guide Band-Pass Filter at 60 GHz

Although TE0n¿ mode ceramic resonators are usually used at centimeter frequencies, they have a difficulty in making wide-band band-pass filters in the millimeter-wave region due to the weak coupling factors between TE0n¿ mode resonators and input/output waveguides. In order to overcome such difficulty, a band-widening technique of the ceramic resonator loaded band-pass filter has been proposed. The EHnm¿ modes were regarded as spurious modes so far, but it is clear that the coupling factors are larger than those of the Te0n¿ modes from the results of experimental considerations in this paper. By using the : EH11¿ mode ceramic resonators, 5-pole, 1dB chebyshev ripple NRD guide band-pass filter has been fabricated for the applications to broad-band millimeter-wave communication systems at 60GHz. The filter has great advantages such as the wide pass-band beyond 2GHz and low excess insertion loss less than 0.3dB.