Millimeter-Wave Phased Array With Wide and Stable Scan Range Based on IEP Gain Predistortion

Scan impedance mismatch inevitably results in gain loss, which significantly affects scanning performance of phased arrays. In this paper, a theoretical framework that relates the Array Beam Envelope (ABE), Isolated Element Pattern (IEP) and scan reflection coefficient is proposed. This framework provides guidance for shaping element radiation pattern and quantifying the impact of scan impedance mismatch, thereby enabling optimization of array scanning performance. Building upon it, a design method based on IEP gain predistortion technique is proposed to achieve a wide and stable scan range across the operating band. To validate the design method, an antenna with ultra-wide beamwidth of 224° and highly flexible beam shaping capability is proposed. Two phased arrays based on it are designed. The first phased array (Array I) achieves a flat-gain ABE, realizing a scan range of up to ±76° with only 1.0 dB gain fluctuation. The second phased array (Array II) achieves an ABE with a scan range of over ±81° throughout the operating band. A prototype of Array II is fabricated and measured, and the measured results agree well with simulations.