Two‐port ring shaped MIMO antenna with quad‐band.

This article presents a quad‐band multiple‐input multiple‐output antenna with two‐element. Its radiator, composed of four rings, realizes multi‐band function, and isolation between the two antenna elements is improved by using the cross‐shaped defective ground structure and the goblet shaped stub at the center of the back ground plane. The total size of the design is only 25 mm × 32 mm, but it can obtain good performance in the four frequency bands (4.6‐5.0 GHz, 6.82‐7.83 GHz, 10.3‐10.8 GHz, and 14.1‐16.96 GHz), which can be concluded from the simulation and measurement results on the desired bands: (a) the input reflection coefficient (S11) less than −17 dB, (b) the isolation (S21) better than −15 dB, (c) the envelope correlation coefficient below 0.04 and the peak gain greater than 1.23 dBi. The proposed antenna is suitable for wireless communication of small unmanned aerial vehicle operating in the beyond‐line‐of‐sight range. The first of the four bands (4.6‐5.0 GHz) is used for 5G cellular network communication and the other three bands can be applied for downlink of X‐band (7.25‐7.75 GHz) satellite communication, X‐band (8‐12 GHz) and Ku‐band (12‐18 GHz) satellite communication, respectively. [ABSTRACT FROM AUTHOR]