Null steering in phased arrays by controlling the element positions

Abstract

Null steering methods usually involve costly and complicated amplitude and/or phase control systems. A technique is presented for null steering based on the element position perturbations. The technique frees the phase shifters to be used solely for steering the main beam toward the direction of the desired signal. It also removes the limitations of the other techniques by independently steering the main beam and the nulls to arbitrary independent directions. This technique is also capable of obtaining sidelobe cancellation and wideband signal rejection

Antenna Array Pattern Synthesis and Wide Null Control Using Enhanced Particle Swarm Optimization

“…Linear antenna array of 2N isotropic elements is considered in this paper. The array is positioned symmetrically along the z axis, and the array factor for this structure can be expressed as (9) where…”

“…Wide nulls are formed in conventional techniques by placing multiple adjacent nulls in the radiation pattern [1] or by using evolutional optimization techniques [2]. The nulling methods are generally based on controlling the complex weights (amplitude and the phase control) [3,4], the amplitude only [5,6], the phase-only [7,8], and the position only of the array elements [9,10]. Interference suppression with complex weights is the most efficient because it has greater degrees of freedom for the solution space.…”

Linear and Circular Array Optimization: A Study Using Particle Swarm Intelligence

“…The deterministic methods include analytical methods [1][2][3][4][5][6][7][8] and semianalytical methods [9][10][11][12][13][14][15]. The deterministic methods in general become quite involved and computationally time consuming as the number of the elements in the array increases.…”

A Plant Growth Simulation Algorithm for Pattern Nulling of Linear Antenna Arrays by Amplitude Control

“…By assuming that the phase or position perturbations are small, the nulling equations can be linearized. The phase-only control [4,6,10,14,16] utilizes the phase shifters while the position-only control [5,6,9] needs a mechanical driving system such as servomotors to move the array elements. Phaseonly null synthesizing is less complicated and attractive for the phased arrays since the required controls are available at no extra cost, but it has still common problem.…”

“…Pattern nulling techniques available in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] include controlling the amplitude-only, the phase-only, the positiononly, and the complex weights of the array elements. Interference suppression with complex weights is the most efficient because it has greater degrees of freedom for the solution space [1,7].…”