A Compact SIC Magic-T for W-band Phased Array Applications

This paper presents the conceptual design of a simple, compact and planar SIC magic-T structure based on the image substrate integrated dielectric (iSINRD) EM-periodic guide. Unlike conventional planar magic-Ts, the proposed magic-T does not require, metallic posts, slots or embedded dielectric phase shifters. It rather relies mainly on the boundary of the arms to achieve the typically high magic-T isolation. The frequency of operation is designed at 94 GHz.. Using Alumina dielectric (ε
_r
=9.8), and with the E-arm being on the same plane as the H-arm, a very compact magic-T is conceived which makes it amenable for seamless integration of millimeter-wave circuits. The lateral dimensions of each arm are 0.41 × 0.64 mm
²
. Perforation is done using square air-vias, each having a side length of 0.35 mm. The total size of the circuit is 4.41 × 4.67 mm
²
. The 3-dB bandwidth of the proposed magic-T is ~1 GHz, centered at 94 GHz, and the return loss is better than 15 dB.