High-Gain Filtering Reflectarray Antenna for Millimeter-Wave Applications

This article presents a novel design of filtering reflectarray antenna, an integrated module for the combination of filtering and high-gain radiation performance. The filtering reflectarray consists of two-section metal pixel waveguide elements, which can realize the optimized aperture reflection phase distributions in the operating band f1≤ f ≤ f2to yield high-gain radiation. Below the lower cutoff frequency f1, the reflection phase distributions drastically deviate from the required ones. Above the upper cutoff frequency f2, both the amplitude and phase distributions fail to provide strong coherent radiation. In the reflectarray synthesis process, a multi-frequency phase matching method (PMM) is further developed, in which the phase compensation for each pixel is implemented at three simultaneous in-band frequencies. Meanwhile, the effects of incident angle for elements are also taken into consideration during the reflectarray synthesis. The design of an 11λ× 11λ filtering reflectarray operating from 55 to 65 GHz was conveniently fabricated by 3-D printing technology, followed by metal coating with advantages of rapid prototyping, lightweight, and low cost. Both the simulated and measured results show that the proposed reflectarray can realize high-gain radiation within the desired frequency band but presents effective suppression of out-of-band signals, demonstrating its filtering capability.