Simultaneous Multi-Beam Pattern Synthesis of Subarray via Alternating Projection

Abstract

For a large-scale array, the subarray technology can save the radio frequency (RF) channels. However, the use of subarray technology often tends to reduce the beamforming performance of the array. In some specific scenarios, it is necessary to use simultaneous multi-beam technology for target search. Exploring methods to simultaneously achieve multi-beamforming while reducing radio frequency channels is a worthwhile research endeavor. This paper introduces an innovative application of hybrid beamforming structure to the realm of beam synthesis and proposes an algorithm for simultaneous multi-beam pattern synthesis in subarrays. This method weights the received signal of the array twice. Initially, the analog signal received by each antenna unit undergoes the first weighted, accomplished by incorporating a phase shifter after each antenna. After the initial weighted, the analog signals proceed into their respective subarray channels, where they undergo a second step of weighted after being converted into digital signals. The second step of weighted involves digital beamforming of the subarray signals, utilizing multiple sets of weights, to achieve simultaneous multibeam. The algorithm can obtain an element weighted vector and a subarray weighted matrix. Based on the alternating projection (AP) algorithm, the property of the Kronecker product, and the definition of the Khatri-Rao product, the optimal element weighted vector and subarray weighted matrix can be obtained by solving the 2-norm minimization problem.

Keywords

• Subarray
• synthesis algorithm
• multiple simultaneous patterns
• alternating projection