A new method of directivity synthesis

A completely new synthesis method, called the successive approximation method, is developed in this article. By introducing a control function and using a step-by-step approach program, various directivity functions can be obtained in which the envelope of the peaks of the sidelobes fits with a specified curve, with equisidelobe directivity functions, and with the directivity functions corresponding to the maximum directivity factor for specified sidelobe levels. This method is applicable for various forms of arrays and can be used with amplitude shading, phase shading, and unequally spaced arrays. Numerical calculations have been made for linear arrays to permit study of the directivity functions with the maximum directivity factor for specified sidelobe levels. Then, these directivity functions are compared with equisidelobe directivity functions. Calculations show that, when specified sidelobe level is low enough, the directivity function with the maximum directivity factor is just the equisidelobe directivity function.