Shared Aperture Multibeam Forming of Time-Modulated Linear Array

Li-Juan Sun,Zhen-Kai Zhang,Hamid Esmaeili Najafabadi

doi:10.1155/2019/4101909

Li-Juan Sun, Zhen-Kai Zhang + Show 1 more

Open Access

https://doi.org/10.1155/2019/4101909

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Abstract

A novel technique is proposed in this paper for shared aperture multibeam forming in a complex time-modulated linear array. First, a uniform line array is interleaved randomly to form two sparse array subarrays. Subsequently, the theory of time modulation for linear arrays is applied in the constructed subarrays. In the meantime, the switch-on time sequences for each element of the two subarrays are optimized by an optimized differential evolution (DE) algorithm, i.e., the scaling factor of the sinusoidal iterative chaotic system and the adaptive crossover probability factor are used to enhance the diversity of the population. Lastly, the feasibility of the new technique is verified by the comparison between this technique and the basic multibeam algorithm in a shared aperture and the algorithm of iterative FFT. The results of simulations confirm that the proposed algorithm can form more desired beams, and it is superior to other similar approaches.

Highlights

In recent years, electromagnetic environments have been more complicated due to the increased number and complexity of antennas, and they have been vital to many elds [1, 2]
(7) Perform an inverse fast Fourier transform (FFT) on the excitation vector of the new subarray 1, determine whether the edge lobe peak of the updated antenna pattern changes with respect to the sidelobe peak at the previous iteration, and proceeds to the calculation; otherwise, output the result
Formed by the algorithm in this study are better. e peak sidelobe level (PSL) of the fundamental wave formed is − 13.48 dB, while the PSL of the positive first harmonic of subarrays 1 and 2 are − 12.52 dB. ese values are 3.01 dB, 1.56 dB, and 2.96 dB lower than the PSL of the beam corresponding to the iterative FFT algorithm, respectively. e above simulations reveal that the optimized di erential evolution (DE) algorithm has a better direction in the graph and has a faster convergence speed. e algorithm can adaptively adjust the mutation weight of the mutation operator according to the current state of the individual population, avoiding the early maturity attributed to the premature falling into the local optimum, and it exhibits better beam performance than other conventional methods

Summary

Introduction

Electromagnetic environments have been more complicated due to the increased number and complexity of antennas, and they have been vital to many elds [1, 2]. E literature [12, 13] discussed the method to reduce the PSL in linear antenna arrays by genetic algorithms (GA), whereas it cannot be applicable to the shared aperture multibeam forming. Ough the above-shared aperture methods can implement sparsely interleaved multi-subarray, there are unsolved problems (e.g., the large di erence in the pattern of each subarray, high PSL, and in exible beam steering). A new shared aperture method is proposed based on the time-modulated linear array (TMLA) for shared aperture multibeam forming. Numerous studies have been published on the pattern synthesis of time-modulated array antennas.

Mathematical Model of Time-Modulated Linear Array

Differential Evolution Algorithm

Conclusion