Radiation from circular arc antenna arrays

The properties of radiation from circular arc antennas are discussed by using an asymptotic expansion method. Approximate pattern calculations of these antennas have usually been made by employing related techniques, such as the method of stationary phase. However, the stationary phase method has certain limitations, and it is not as accurate as the method presented here. The asymptotic expansion gives relatively accurate results when the radius of the arc source is large with respect to the wavelength. This requirement is usually satisfied if the antenna is to have a high directivity. The asymptotic expansion converges rapidly for observation angles away from the broadside direction, so that it is easy to determine the side-lobe energy distribution. The results given here can easily be applied to circular arc arrays with either uniform or nonuniform spacings of the elements along the arc by applying the Poisson sum formula. This is true because the resulting integrals governing the radiation fields from a circular arc array are similar to the ones discussed here.