利用FFT快速计算，线性排列阵子方向图。-　This function computes and returns the gain radiation pattern for a

　linear array

　It uses the FFT to computes the pattern

　　*INPUTS**********　　　　　　　　　　　　　　　　　　　

　Nr ==> number of elements　dolr ==> element spacing (d) in lambda units

　divided by lambda

　theta0 = steering angle in degrees　winid ==> use winid negative for no

　window, winid positive to enter your window of size(Nr)

　win is input window, NOTE that win must be an Nr X 1 row vector　nbits ==>

　number of bits used in the pahse shifters

　negative nbits mean no quantization is used

　　*OUTPUTS******************　　　　　　　　　　　　　　　　　　　　　　

　theta ==> real-space angle　patternr ==> array radiation pattern in dBs

　patterng ==> array directive gain pattern in dBs

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