Study, Based On The Surface Of The Amplitude Weighted Array Beam Pointing

Beam forming technology is one of the hot spots in array signal processing. Commonly, beam forming methods are based on the far-field signals model mostly. The far-field model is valid only when the distance between spot points and the center of the array is much greater than dimensions of array. However, far field model can not satisfy all the needs in practical application. Therefore, the beam forming method research based on near-field become more and more important.A method of near-field beam forming about two-dimensional array was proposed based on amplitude weighting, which is different from the far-field phased beam forming. Only by control weight of each element was able to focus at any point in near-field space. After some mathematical transformation and reasoning, the formula for calculating the weights can be obtained. The radiation amplitude of every element can be calculated by solving a set of homogeneous second-order nonlinear equations. The simulation verified the correctness of this theory which is also applied for the far-field situation. Two examples indicate that it can infinitely approximate to the requested far-field radiation function by increasing the number of the array element. Combining the amplitude weighting with linear phase control in practice, it has been affirmed that the electric scanning can substitute the mechanical scanning, and the complexity and cost of the phase-shifter and controller in solely can be reduced significantly.