A NOVEL QUASI-ELLIPTIC WAVEGUIDE TRANSMIT REJECT FILTER FOR KU-BAND VSAT TRANSCEIVERS

In this paper, a novel compact quasi-elliptic waveguide low-pass transmit reject fllter (TRF) by using T-shape units is proposed for Ku-band very small aperture terminal (VSAT) transceivers. The equivalent circuit model of the T-shape unit is investigated and shows a topology similar to that of the elliptic low- pass fllter. In order to reduce the di-culty in physical realization, which is commonly encountered with a standard elliptic low-pass fllter, an approximate elliptic low-pass fllter prototype is presented. Accordingly, a synthesis approach is developed to obtain the initial dimensions of the fllter. To optimize the performance of the fllter, full- wave electromagnetic simulation is used to flne-tune the dimensions of the fllter. An eleven-order Ku-band low-pass TRF is designed and fabricated using a WR-75 waveguide. Measured results show it has a low insertion loss of less than 0.3dB in the pass band and a high attenuation slope of 78dB/GHz. Moreover, the miniaturized size of the fllter is only 38mm £ 38mm £ 42mm (WR-75 ∞ange size is 38mm £ 38mm).