A COMPACT AND WIDEBAND FLAT LENS ANTENNA BASED ON APERTURE COUPLED PATCHES FOR X-BAND APPLICATIONS

Abstract

This paper presents a wideband and compact flat lens antenna for X-band applications. An 8×8 array of this antenna is designed and realized by using aperture coupled patches from the multilayer Frequency Selective Surface concept. The basic antenna element configuration of this design consists of two back-to-back printed patches with a common ground plane coupling. A pair of identical slots is embedded on the ground plane to provide the necessary phase error compensation between receive and transmit apertures. The lengths of the two slots are varied simultaneously to investigate how much phase shift range can be achieved with this simple design structure. The antenna elements are simulated using the electromagnetic simulation software CST Microwave Studio. A 209° transmission phase range was achieved with transmission coefficient variations of better than -2.25 dB. The gain of the feeding horn antenna used is 9 dB at 10 GHz. Upon the implementations of the lens structure, the gain of the overall antenna system has increased to 16 dB. Our simulation shows a 3-dB transmission bandwidth of around 33% could be achieved for the unit cell. Radiation pattern simulation of the antenna system shows a good symmetry between E and H-plane with a half-power beamwidth of 19.2° and 19.0° in E-plane and H-plane respectively. The gain is greater than 9 dB from 8 to 12 GHz with maximum gain of 16 dB is achieved at 10 GHz. The proposed antenna design uses a simple and less fabrication complexity mechanism for phase error correction.