INVESTIGATION OF MULTILAYER MAGIC-T CONFIGURATIONS USING NOVEL MICROSTRIP-SLOTLINE TRANSITIONS

Two novel compact magic-T configurations designed as a two layer structure are proposed in this paper. They consist of a microstrip tee-junction and resonance circuit composed of a microstrip line combined with rectangular or radial stubs. These microstrip circuits are respectively printed at the top and bottom layers of the structure, and coupled via a slot located in the common ground plane. The microstrip patch and slot are placed parallel to each other forming novel microstrip-slotline transitions, which provide broadband operation of the magic-Ts. Transmission line equivalent circuits are used to explain the performance of the proposed hybrids. It is shown that magic-T with a radial stub demonstrates wider operation bandwidth and better performance than the structure with a rectangular stub. In order to validate their performance, the prototypes of both configurations were manufactured and measured. Experimental and simulation results show that the resulting magic-T using a radial resonator has a fractional bandwidth of over 40% for 0.2\,dB amplitude and 1° phase imbalance. The experimental results are in good agreement well with equivalent circuit and full-wave simulations.