A Square-Rate Arrangement Method for Large-Spacing Planar Phased Array Grating Lobes Homogenization

This article proposes a square-rate arrangement method to suppress the grating lobes in the planar phased array with large element spacing. Compared with the uniform array with periodic lattice, the large-spacing array requires fewer elements, which implies the reduction of radio frequency transmitter/receiver (T/R) modules and caters to the low-cost design. For the large-spacing arrays, the most critical problem is to avoid grating lobes as the beam scans. For this reason, the appearance of grating lobes in rectangular- and parallelogram-lattice arrangements is analyzed, and a new square-rate arrangement method is proposed, in which the specific position of the square-rate array is deduced to homogenize the grating lobes. In the end, the presented method is verified by numerical calculations, full-wave simulations, and representative measurements of an 8 $\times16$ array. With the square-rate arrangement, the array with interelement spacing of one wavelength is implemented to achieve the beam steering up to ±75° in the E-plane and ±27° in the H-plane. More significantly, the sidelobe levels are controlled below −10 dB within the entire 2-D scanning volume. Compared with the uniform array configuration, nearly 40% of T/R modules are reduced in the proposed array.