A tandem 3-dB hybrid coupler using coupled lines with series capacitance

A novel tandem 3-dB hybrid coupler using coupled lines with series capacitance, which is based on a rectangular coaxial line to possess high power handling capability, is presented. The desired coupling degree of the tandem 3-dB hybrid is realized by loaded stubs on the coupled lines. The tandem 3-dB hybrid loaded stubs achieves high tolerance of multipactor in a case of satellite-mounted and ease of fabrication, because the stubs enhance the coupling degree without narrowing the gap between coupled lines. The stubs work equivalently as series capacitance to the coupled lines. A novel way to load series capacitance to coupled lines in order to enhance the coupling degree has been proved the availability. A design of the proposed 3-dB hybrid is described. The proposed tandem 3-dB hybrid coupler fabricated in S-band has realized excellent performances.