If the array factor of a linear array has zero's at 90 degrees and 180 degrees with element spacing 0.25wavelength, Design the array

The design of a linear array with zeros at 90 degrees and 180 degrees with element spacing of 0.25 wavelength can be achieved by following these steps:

1. Determine the number of elements: The number of elements in the array can be determined by the desired beamwidth and sidelobe level. In this case, since we want zeros at 90 and 180 degrees, we need at least two elements.

2. Determine the spacing between elements: The spacing between the elements is given as 0.25 wavelength. This is less than half the wavelength, which means the array will not have grating lobes.

3. Determine the excitation coefficients: The excitation coefficients can be determined by the desired array factor. In this case, we want the array factor to have zeros at 90 and 180 degrees. This can be achieved by setting the excitation coefficients such that the array factor is zero at these angles. This can be done by setting the phase difference between the elements to be 90 and 180 degrees.

4. Determine the array geometry: The array geometry can be determined by the desired radiation pattern. In this case, since we want zeros at 90 and 180 degrees, the array should be a linear array with elements placed along a line.

5. Verify the design: Finally, the design should be verified by plotting the array factor and checking that it has zeros at 90 and 180 degrees.

Please note that this is a simplified explanation and actual design may require more detailed calculations and considerations.