Bandwidth-enhanced single-layer 3-dB tandem directional coupler as magic-T network

A new approach to the design of a very broadband magic-T network focused on a single-layer realization has been proposed. In order to obtain wide bandwidth, a recently developed technique of bandwidth enhancement of tandem connected loosely coupled directional couplers has been employed. It has been shown that utilizing single-section coupled-line couplers one can realize a planar tandem coupler featuring frequency characteristics similar to these of a two-section coupled-line couplers. The proposed approach has been verified by the design and measurement of a 3-dB tandem coupler operating within 0.6-2.0 GHz frequency range with amplitude imbalance of ±0.45 dB, and the theoretical analysis of differential phase shaping to obtain magic-T properties.