Millimeter-Wave Beam-Scanning Antenna With Unconventional Array-of-Array Architecture Optimized by Null-Pull Strategy

The phased array technologies usually suffer from high fabrication costs, high-density integration, and heat dissipation, which limit their use, particularly for large-scale phased arrays at the millimeter-wave frequency bands. This article introduces the concept of an unconventional array-of-array (AoA) architecture, which addresses these challenges by employing a sparsely excited array topology. The AoA architecture classifies antenna elements into different categories, including active elements, inactive elements, and displaced elements. The active elements are clustered by the 1-to-2 power dividers. Then, the array is divided into multiple super subarrays to maintain the realizability of the phased array at the E-band. After that, the array topology is optimized by the null-pull array partition strategy, which considers the impact of the radiation characteristics of antenna elements, subarrays, and super subarrays on the array partition. Based on these methods, the proposed architecture can ensure the wide-scanning ability of ±60° in the horizontal plane and ±30° in the vertical plane by the amplitude-phase synthesis. Next, the wideband magnetoelectric (ME) dipole with the slot-coupled feedline is designed as the antenna element, which operates from 66 to 76 GHz. Finally, a $16\times 16$ array prototype with 79.63% channel reduction is designed, fabricated, and measured to verify the correctness of the theory and simulation. It offers a promising solution with enhanced engineering feasibility for high-density system integration in millimeter-wave communication systems.