This paper presents a compact orthomode junction with low pass filters for high power applications. It consists of a circular waveguide step, a matching element for a high frequency band, and coupling sections straddle the circular waveguide step. These dimensions were optimized to achieve wideband performances and to support a high power rating. The structure without rectangular to circular transition is simple and comprised of two milled layers to divide E-plane of corrugated low pass filters. It can be easily manufactured and has low losses. The fabricated Ku/Ka-band orthomode junction was measured including power handling test of 2,kW at Ku-band. The measurement results demonstrated return loss of 21,dB and loss of 0.2,dB in the Ku- and Ka- band.

This paper presents a printed circuit board (PCB) integrated multi-layered strip line tandem coupler, which used simple compensating ground through-hole (GTH) elements. The GTH elements on one end of the coupled line can generate additional capacitance between the signal line and the ground, which effectively compensates for the parasitic capacitance around the crossed signal lines on the opposite end of the coupled line. It has been experimentally demonstrated that the proposed coupler fabricated for the X-band is effective to improve both the reflection and the isolation characteristics.

A novel directional coupler loaded with feedback capacitances on the coupled lines is presented. Its effect of enhancing the coupling is qualitatively shown by deriving an equation for the coupling. Besides, a method to compensate for the phase difference between the even and odd modes of the coupler is presented. To demonstrate, a novel tandem 3-dB coupler consisting of the proposed coupled lines is designed and described. In addition, a waveguide (rectangular coaxial line) 8×8 HYB matrix using planar double-layer structure that is composed of the proposed tandem 3-dB couplers and branch-line couplers, which is operated in S-band, is designed and fabricated showing excellent performance.