Inverted suspended circular polarized antenna with the integration of metasurface (MS) structure technique

Abstract

In this paper, an analysis of metasurface (MS) structure on inverted suspended circular patch with square slot antenna (Basic antenna) design is proposed to investigate its effects towards the circular polarized antenna performance. Circular polarization design is choose for this project because of its advantages which can offer better mobility and weather penetration compared to linear polarized. The antenna was designed based on inverted suspended circular patch technique. The air gap between substrate and copper ground plane is separated with distance of 10mm. L-probe technique is used in this antenna design to feed the 50Ω SMA probe signal into the antenna feedline through the circular patch structure. The MS structure (Design A and Design B) is added in between the patch and copper ground plane of the antenna. The proposed antenna had been designed and simulated by using Computer Simulation Technology (CST) software. Target application for this antenna is for Wireless Local Area Network (WLAN) at operating frequency of 2.4 GHz. Antenna performances in term of return loss, resonant frequency, bandwidth, gain, directivity, axial ratio, total efficiency and radiation pattern at the design frequency are analyzed. Simulation result show that the proposed Basic antenna with and without MS structure can achieve axial ratio below 3dB and total efficiency above −3 dB at designed frequency. With the addition of Design A and Design B MS structures, the Basic antenna resonant frequency is shifted from 2.398GHz to a lower frequency which is 2.24 GHz (Design A) and 2.18 GHz (Design B). The return loss of Basic antenna is −35.64dB at 2.4 GHz dropped to −13.06dB for Design A and −8.54dB for Design B due to the shifting of the resonant frequency. The antenna bandwidth reduced from 556 MHz (basic antenna) to 411 MHz (Design A) and 317 MHz (Design B). Realized gain for Basic antenna, Design A and Design B are 7.76 dB, 7.69dB and 7.03dB respectively. With the addition of Design A and Design B MS structure to Basic antenna, the axial ratio bandwidth (ARBW) increasesto 1320 MHz and 1160 MHz. Axial ratio bandwidth (ARBW) below 3dB of the Basic antenna is 1120 MHz respectively.