A four-element mimo antenna for ultra-wideband communications with a rejection band

Abstract

This thesis presents the design and development of a four-element multiple-input multiple-output (MIMO) ultra-wideband antenna with a rejection band. This antenna is proposed for the application of ultra-wideband (UWB) technology, an advanced short-range wireless communication technology with fast and stable data transmission. The antenna operates in a wide frequency range from 3.1 to 10.6 GHz, which is intended for UWB communication technology. In addition, it can suppress the WLAN frequency band (4.8 to 6.2 GHz). This frequency suppression is necessary to avoid interference from WLAN signals, which usually have a higher power density. The antenna provides a bidirectional radiation pattern with dual-linear polarization. The proposed MIMO antenna consists of four printed monopoles, two on each side of the FR-4 substrate, as radiators. Each monopole is fed by a coplanar waveguide (CPW). The overall size of the antenna is compact with dimensions of 51 mm x 51 mm. Band rejection is achieved by introducing inverted L-shaped notch elements on both sides of the radiators. An inverted Y-shaped element is used to achieve good isolation between the radiators. Moreover, the radiators are orthogonally arranged on opposite sides to improve isolation and create two orthogonal polarizations. The designed MIMO antenna was modeled, analyzed, and optimized using Ansys HFSS software. The antenna prototype was then fabricated and tested in an anechoic chamber. The measured results show reasonably good agreement with the simulated results. The present antenna is also compared with some selected antennas from previous works.