# Window algorithm for unidimensional arrays

This function uses a window algorithm to obtain the weights and phases of each element in a linear array. The results of the function define the pointing of the array in the given direction.

``````Cmplx[] window(double d, double theta, double phi, int Num, double A, double B, int axis) {  //d:element spacing in units of lambda
//theta:beam angle (in degrees)
//phi:azimut angle (in degrees)
//N:number of array elements
//axix:indicates which axis is used-->1 for x axis
//                                 -->2 for y axis

//This function uses a window algorithm to calculate the weights and phases in an unidirectional array of antennas

double N=Num;
//double A=0.0;
//double B=1.0;
double L;
double[] a=new double[N];   //vector of N elements double type
double k;

if (axis==1){
k=(Math.sin(Math.toRadians(theta))*Math.cos(Math.toRadians(phi)));
}
if (axis==2){
k=(Math.sin(Math.toRadians(theta))*Math.sin(Math.toRadians(phi)));
}

double ang=Math.acos(k);   //ang=arccos(sen(theta)*cos(phi))
double cose=Math.cos(ang); //cose=cos(ang)
double ps0=(2*Math.PI*d*cose); //find the phase that we are going to use to direct the array in the desired direction

Cmplx[] z=new Cmplx[N];
Cmplx[] v=new Cmplx[N];        //vectors of N elements Cmplx type
double[] y=new double[N];
double[] fase=new double[N];  //vectors of N elements double type

if (N !=1){   //if the numer of elements in the array is different than one
L=d*(N-1);
}
if (N==1){    //if there is only one element in the array
L=d*N;
}

if (N % 2 ==0){     //if the number of elements in the array is even
for (int i=1; i<=(N/2); i++){
a[(N/2)+i-1]=A+B*Math.cos(((d*i)/(L/2))*(Math.PI/2));       //apply the formula of the algorithm to calculate the weigths
}
int cont=N-1;  //initialize cont to N-1
for (int j=0; j<N/2; j++){
a[j]=a[cont];  //equate the j element in the array a to the cont element in that same array
cont=cont-1;   //decrease cont
}
}
if (N % 2 !=0){     //if the number of elements in the array is odd
for (int i=1; i<=((N+1)/2); i++){
a[((N-1)/2)+i-1]=A+B*Math.cos(((d*i)/(L/2))*(Math.PI/2));    //apply the formula of the algorithm to calculate the weigths
}
if (N !=1){         //if there is more than one antenna in the array
int cont=N-1;  //initialize cont to N-1
for (int j=0; j<=((N-1)/2)-1; j++){
a[j]=a[cont];  //equate the j element in the array a to the cont element in that same array
cont=cont-1;   //decrease cont
}
}
}

for (int n=0; n<N; n++){
v[n]=new Cmplx(0,-((n-(N-1)/2)*ps0)); //create a complex vector, with 0 as the real part, where the imaginary part are the
//successive phases that we are going to multiply to the weights

z[n]=Cmplx.mul(a[n],(Cmplx.exp(v[n])));  //find the final result in the form of a complex number by multiplying the weights by the progressive phases,
//thus directing the array towards the direction indicated by theta and phi

fase[n]=(Math.atan2(z[n].imag, z[n].real)); //find the phase in radians
if (fase[n]<0){ // if the phase is less than 0
fase[n]=2*Math.PI+fase[n]; //add 2*pi
}
fase[n]=Math.toDegrees(fase[n]); //find the phase in degrees
if (fase[n]<0){fase[n]=0.0;}

y[n]=(Cmplx.abs(z[n]));  //find the absolute of the complexes, that is, the weights

}

writeFile("./mydatafiles/window.txt", y, fase); //write the weigths and phases in a text file
return z; //return the complex vector z, which contains the results of the algorithm

}``````

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