Synthesizing Asymmetric Side Lobe Pattern with Steered Nulling in Nonuniformly Excited Linear Arrays by Controlling Edge Elements

Jafar Ramadhan Mohammed,Khalil H Sayidmarie

doi:10.1155/2017/9293031

Jafar Ramadhan Mohammed, Khalil H Sayidmarie

Open Access

https://doi.org/10.1155/2017/9293031

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Abstract

In radar antennas, asymmetric side lobes are useful, where undesired signals such as noise and ground clutter should be minimized. Also, for practical implementation, the feeding network of such antennas should be efficiently designed. In this paper, a simple analytical method for synthesizing asymmetric side lobe pattern with a wide-angle steered null in the nonuniformly excited linear arrays is presented. In this method, the difference in the side lobe levels on both sides of the main beam is achieved by varying just the phase excitations of the two-edge elements. The major novelty of this paper lies in the fact that the required asymmetric side lobe pattern can be achieved by changing a single phase shifter resulting in a simple feeding network.

Highlights

The performance of the radar and communication systems is highly affected by the level of the interfering signals and ground clutter that need to be rejected
The first example starts with Dolph-Chebyshev excited array with designed SLL = −20 dB and N = 16 elements
It can be seen that the radiation pattern of the two-edge elements is matched well with that of the original Dolph-Chebyshev array across a wide angular range centered around θ = 65∘ and extending to many side lobes on right side of the main beam

Summary

Introduction

The performance of the radar and communication systems is highly affected by the level of the interfering signals and ground clutter that need to be rejected. To synthesize an array pattern with specific constraints on the side lobe structure, various optimization algorithms have been proposed in the literature These are particle swarm optimization [11, 12], genetic algorithm [13, 14], and simulated annealing [15] or the convex programming [16, 17]. Most of these optimization algorithms support the concept of fully controlled arrays, where the amplitude and phase excitations of all or most of the array elements are under control.

Problem Formulation

Asymmetric Side Lobe Pattern

Simulation Results

Original Dolph excitations

Conclusions