A Near-Field Focusing Circularly Polarized Radial Line Slot Array Antenna

This paper presents the implementation of a near-field focusing (NFF) antenna on basis of radial line slot array (RLSA). The proposed NFF-RLSA antenna is derived from the conventional single-layer spiral-patterned RLSA with circular polarizations, and near-field focused radiation characteristics is realized by adjusting the arrangements of radiating slot pairs and hence the amplitude and phase distribution of RLSA aperture. The designed NFF-RLSA antenna is 14.4λ0 in diameter and 0.17λ0 in height, where λ0 donates the wavelength in free space at the operating frequency, namely 10GHz. Simulation results show that the focus spot is 22.5λ0 away from the antenna aperture, while a focusing gain of 31.2dBi is achieved, and the size of focus spot is 2.48λ0 in width and 11.3λ0 in depth of focus, respectively.