Ka-Band Passive Phased-Array Antenna With Substrate Integrated Waveguide Tunable Phase Shifter

A low-cost and low-profile Ka-band passive phased-array antenna (PAA) using continuously tunable substrate-integrated waveguide (SIW) phase shifter is presented in this article. The phase shifting mechanism is based on perturbing the electric field of the slotted SIW (SSIW) line by putting a high dielectric constant slab over the slot of SIW. A systematic approach based on a simple transmission line (TL) circuit model which can support different modes is developed as a fast method for design optimization. It provides insightful physical understanding of the operating mechanism of the proposed phase shifter. In addition, a fully verified TL model of the 1 x 4 SIW PAA is presented and used to predict and optimize the overall reflection coefficients and radiation patterns at different scanning angles. The TL circuit model is verified by full-wave simulations. As a design example, a 1 x 4 SIW-based phased-array is designed, fabricated, and measured to validate phase shifter performance and capabilities. The prototype exhibits a continuous beam scanning range from -20° to +20° covering the whole operating band of 29-31 GHz.