Grating Lobe Suppression for Wideband Large-Spacing Beam Scanning Array Using Subarray Null Adjustable Method

In this letter, a subarray null adjustable method is proposed to solve the grating lobe problem for wideband large-spacing beam scanning arrays. With the reshaped subarray by this method, large null depths of the pattern are formed to align with the grating lobe regions. The proposed reflective phase shifter loaded four varactors adjusts these nulls continuously, accurately and flexibly. Then, a wide-angle coverage of continuous nulls sufficiently suppress grating lobes in the whole bandwith. A two-element subarray with the bandwidth of 40% (2.8–4.2 GHz) is introduced, and an 8 × 4 planar array formed by this subarray is fabricated and measured as the verification prototype. Finally, the proposed planar beam scanning array realizes grating-lobe-free scanning of ±45° in the
yoz
-plane (with the array spacing of one wavelength at the highest frequency) and ±53° in the
xoz
-plane over the entire wideband range, respectively.