Design of semi-circular patch UWB MIMO antenna with rectangular stub

Abstract

많은 연구자들은 고효율 무선통신 시스템을 위한 새로운 안테나를 지속적으로 개발하고 있으며, 무선통신 시스템의 채널 용량 향상과 링크 품질을 보장하고 IoT (Internet of Things) 기기의 진화에 따른 복잡하고 소형화된 안테나의 개발이 최우선 과제가 되고 있다. 특히, 최신 컴팩트 안테나 기술 중 MIMO (Multiple Input Multiple Output) 안테나에 대한 연구가 활발히 진행되고 있으며, 많은 무선통신 시스템은 UWB (Ultra Wide Band) 주파수 대역에서 활용되고 있다. 따라서, 본 논문에서는 두 안테나 사이에 직사각형 슬롯을 삽입하여 높은 격리도를 갖는 반원형 패치 UWB MIMO 안테나를 설계 및 제작하였다. 제안한 안테나는 HFSS (High Frequency Structure Simulator) 를 사용하여 설계 및 시뮬레이션을 진행하였으며, 반사계수, 방사패턴, ECC 및 DG등을 기반으로 안테나의 성능을 평가하였다. 제안한 안테나의 주요 특징은 DG 9.99 이상, ECC 0.003미만을 보임으로서 두 안테나 사이에 높은 격리도를 가지며, 주파수 대역폭은 5.4 ~ 11.9 GHz로서 UWB 안테나의 주파수 대역에 충족함을 확인하였다. 또한, 시뮬레이션 결과와 측정 결과가 비교적 일치하였으며, 전체 주파수 대역에서 높은 안테나 이득을 가짐으로서 UWB MIMO 안테나로서 활용할 수 있음을 확인하였다 |The demand for highly efficient wireless systems has motivated many researchers to work on newer antenna designs. Advancement in any sector is inevitable and with the need to improve channel capacity of communication systems, to ensure quality of the link and with the evolvement of IOT (Internet of Things) devices, development of complex, compact and miniaturized antennas have become a high priority. Among the newer compact antenna technologies, multiple-input, multiple-output (MIMO) antennas are quite popular in the current communication market. At present, many wireless communication systems work in the frequency bandwidth, which are usually under ultra-wideband (UWB). Thus, in this thesis, a new and simple design approach for UWB MIMO antenna is described, in which a simple rectangular stub is introduced between two antennas to achieve high isolation. The thesis paper presents an analysis of microstrip MIMO antenna of semi-circular patch structure with a simple rectangular stub introduced between two antennas to enhance the isolation of the MIMO antenna. Introduction of simple stub eliminates the use of complex coupling or decoupling structure, complex feeding network or parasitic materials to achieve the desirable isolation. The MIMO antenna is designed and simulated using finite element method based High Frequency Structure Simulator (HFSS). The performance of the antenna is analyzed based on the simulated and measured results of reflection coefficient, radiation patterns, multiplexing efficiency, ECC and DG. A novel feature of this design is that the UWB MIMO antenna has a high diversity gain of more than 9.99 (i.e. DG > 9.99), and the envelope correlation coefficient is lower than 0.003 (i.e. ECC < 0.003). The MIMO antenna also achieves wide impedance bandwidth from 5.4 to 11.9 GHz, which makes the antenna suitable for UWB applications. The high peak gain over the entire UWB and the upper part of the overall frequency band ensure that the antenna can be used in MIMO applications owing to the close agreement between the simulated and measured results.