Design methods for broadband 3dB branch-line and rat-race hybrids

Abstract

This paper considers band-broadening design methods for branch-line and rat-race hybrids such as 90-and 180-degree hybrids. For the 90-degree hybrid, utilizing external matching networks composed of coupled-transmission lines, broadband characteristics with a relative bandwidth of over 40% can be obtained for a 3 dB hybrid designed for operation at 3 GHz based on the equivalent admittance approach. For the 180-degree hybrid, a rat-race hybrid in which right-handed transmission lines are replaced with composite right-/lefthanded transmission lines also realizes broadband characteristics. The validity of these design procedures has been demonstrated by electromagnetic simulations and experiments.

A new Ka-band 180° hybrid coupler

“…After that a lot of works have been done in this area focusing �n the size reduction [2,3] and bandwidth improvement [4,5]. In some applications, the 1800 hybrid .…”