Focusing Properties of Dual-Square and Dualcircular Ring Arrays

The designers of focused antennas have extensively employed the principles of antenna arrays in various attempts to improve the performance of the focused antennas. This paper presents an investigation and comparison of the properties of focused dual-ring arrays. The first one is a circular dual-ring array focused by using only one phase shifter. The second dual-ring array has a square shape, where three cases of the inner ring were considered. The CST and MATLAB software were used to investigate the designed and simulated arrays, whose outer size was fixed at 6 wavelengths. The comparison considered the results of the lateral size of the focal spot, the depth of field DOF, and the number of required phase shifters, thus reducing complexity of the feed network and cost. The circular array achieved a smaller DOF, at only one phase shifter, and a smaller number of elements. However, each of the three dual-ring square arrays achieved focused spot having a smaller transversal width, on account of a larger element number and correspondingly more phase shifters. The proposed arrays can find applications in medical imaging, hyperthermia, and industrial testing.