Adaptive Multiobjective Framework for Designing Dual-Band Sparse Shared-Aperture Phased Antenna Arrays With Non-Harmonically Related Frequencies

This paper presents an Adaptive Multi-Objective Framework using Genetic Algorithms (AMOF-GA) for the design and optimization of dual-band Sparse Shared-aperture Phased Antenna (SSAPA) arrays operating at non-harmonically related frequencies. The methodology is demonstrated through a practical case study at frequencies <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = 2.6 GHz (5G NR Band n41: 2496–2690 MHz) and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> = 4.4 GHz (5G NR Band n79: 4400–5000 MHz). The AMOF-GA first develops a sparse antenna (SA) array design algorithm, achieving a reduction in the number of antenna array elements by 36% and 35% for the lower and higher frequency arrays, respectively, while maintaining approximately key performance metrics such as directivity and sidelobe levels. The SA arrays are then integrated into a shared-aperture configuration through novel multi-objective optimization techniques. To enhance beam steering capabilities and reduce sidelobe levels, an additional phase shift optimization method using genetic algorithms (GA) is employed. The novel integration of non-harmonically related frequencies in an SSAPA array design addresses challenges related to inter-element spacing and mutual coupling, achieving mutual coupling levels of less than −20 dB. Experimental results validate the theoretical and simulated findings, confirming the effectiveness of the proposed AMOF-GA for modern communication systems that require flexible frequency allocation and multi-band functionality. The implementation achieves beam steering capabilities up to ±60° with sidelobe levels maintained below -10 dB across the scanning range. This adaptive framework provides a robust solution for next-generation wireless communication systems operating at various non-harmonic frequency combinations, aiming for efficient spectrum utilization and reduced hardware complexity.