A Partially Magnetized Ferrite LTCC-Based SIW Phase Shifter for Phased Array Applications

The theory and design of a half-mode substrate-integrated waveguide ferrite low-temperature cofired ceramic-based phase shifter are presented in this paper. Unlike typical ferrite-based designs, the biasing is done through embedded windings in a multi-layer substrate that not only obviates the requirement of bulky electromagnets, but also prevents loss of bias fields at the air-to-ferrite interface. The phase shifter is operated in the partially magnetized state of ferrite substrate. Through the combined effect of embedded windings, half-mode waveguide operation, and partially magnetized state, the required bias fields have been reduced by 90% as compared with conventional ferrite-based designs employing electromagnets. A complete analytical model, backed up by electromagnetic simulations and measured results from a prototype, is presented in this paper. The fabricated prototype demonstrates a phase shift of 83.2 degrees at a center frequency of 13.1 GHz and a figure of merit of 83.2 degrees/dB. As a proof-of-concept, the proposed phase shifter design is monolithically integrated with a two-element antenna array to demonstrate a measured beam steering of 30 degrees. The phase shifter design is highly efficient in terms of required bias fields, and it has a small form factor and can be easily integrated with other electronic components and systems.