Thinning and broadbanding antenna arrays by unequal spacings

This paper presents a theory for, and a method of designing a thinned or broad-band antenna array by means of unequal spacings. Using the theory of unequally spaced arrays developed by one of the authors, an antenna array can be designed to produce a desired beamwidth and sidelobe level with the average spacing many wavelengths apart. The patterns are expressed in a series of the Anger functions and its sidelobe level is shown to decrease approximately asN^{-0.5}\simN^{-0.4}whereNis the total number of elements, and the gain is approximately equal toN. It is also shown that the sidelobe level can be improved by varying the amplitude distribution. Numerical examples are given to illustrate the method.