A Waveguide Magic-T With Coplanar Arms for High-Power Solid-State Power Combining

Abstract

In this paper, a compact waveguide magic-T for high-power solid-state power combining is proposed. The coplanar arms of the $E$ and $H$ ports are realized by the $E$ -plane power divider and ridge waveguide coupling structure. The input port of the $E$ -plane power divider is used to realize the difference port of the magic-T, and the ridge waveguide port is utilized to realize the sum port. Based on a theoretical analysis, a modified magic-T with two coaxial ports, one ridge port, and one rectangular port is designed and fabricated. Low-power tests show that from 7.8 to 9.4 GHz, when the difference port and the sum port are excited, the insertion loss of the magic-T is less than 0.2 dB. The isolation between the sum/difference ports and the two input ports is better than 40 and 26 dB. As for the in-phase and out-of-phase excitation, the amplitude and phase imbalances are less than ±0.05 dB and 1°. High-power experiments indicate that the power capacity is no less than 14 kW with a 1- $\mu \text{s}$ pulsewidth. The measured results agree with the simulations.