A laminated waveguide magic-T in multilayer LTCC

A compact waveguide magic-T design composed of open-ended microstrip lines and laminated waveguide in multilayer LTCC technology is proposed. Two orthogonal slots are used to excite even- and odd-symmetric field patterns, respectively, resulting in a good isolation between each other. An X-band waveguide magic-T is developed in LTCC to validate the proposed topology. The measurements agree well with simulation results and present superior performance. The fabricated magic-T provides a broad bandwidth of low phase imbalance (plusmn2.5deg) and magnitude imbalance (-0.3~0.75 dB). The sum and difference ports also give a good isolation greater than 34 dB over an extremely wide frequency range over 8 to 13 GHz.