Design of a Ka-Band Planar Magic-T Based on modified Gysel Structure

Abstract

In this paper, a Ka-band magic-T based on the modified structure of Gysel power divider is proposed. Due to the symmetrical structure, two equal in-phase outputs are achieved. The signal applied to the difference port, is split by an additional half-wavelength branch into two equal out-of-phase signals. The planar magic-T has a bandwidth of 30.3% (28–38 GHz), when the difference port and the sum port are excited, the insertion loss of the magic-T is less than −3.26 dB. The isolation between the sum/difference ports and the two input ports is better than 40 and 20 dB. As for the in-phase and out-of-phase excitation, the phase characteristics are close to the ideal 180° and 0° with only ±1.4° deviation across the band from 28 GHz to 38 GHz, the amplitude imbalances are less than ±0.05 dB.