Scan performance of a W-band trans-twist monopulse microstrip patch reflect-array

A W-band trans-twist reflect-array that performs the dual role of focusing the beam and twisting the polarization by 90° is realized using formulations of moment method in spectral domain. An array comprising of around 6000 patches is designed at W-band. The performance analysis and loss estimates are carried out. A multi-mode corrugated horn was designed as a feed for the reflect-array. An E-plane engraved waveguide comparator generated sum and difference patterns in orthogonal planes. The radiation pattern performance is found to be excellent. But when the plate is progressively tilted to scan the beam for close loop tracking, the monopulse patterns are affected because of relative movement between trans and twist plates. This paper describes the microstrip patch reflect-array and feed design and performance analysis for various scan angles up to ±30° degrees.