Highly Compact 4 × 4 Flower-Shaped MIMO Antenna for Wideband Communications

Abstract

This paper introduces an MIMO antenna with a highly compact size of 30 mm width and 30 mm length. Four symmetrical MIMO antenna radiators are utilized with decoupling stubs in the top and bottom planes of the substrate to improve the isolation level. The simulated and measured outcomes are validated to investigate the impact of the suggested MIMO antenna for wideband applications. The suggested MIMO antenna has an impedance matching less than −10 dB from 5.8 GHz up to 11 GHz, and the isolation between the four radiators exceeds 20 dB over this band. Moreover, the antenna provides an envelope correlation coefficient not exceeding 0.004, a diversity gain above 9.97 dB, and a mean effective gain of ≤−3 dB over the achieved frequency range. The suggested MIMO antenna exhibits a nearly omnidirectional radiation pattern in one plane and a bi-directional radiation pattern in the other plane with an acceptable average value of the realized gain (4 dBi) over the achieved frequency band. A comparison with the state-of-the-art is tabulated to show the distinct performance of the suggested MIMO antenna for wideband applications.

Keywords

• wideband communications
• decoupling structure
• multiple-input multiple-output (MIMO)