A Compact Two-Port MIMO Antenna with Suppressed Mutual Coupling for IoT Applications

Abstract

Compact antenna with good performance characteristics is always preferred for small IoT (Internet of Things) sensor nodes. The novelty of this proposed work is not in terms of design but in terms of application as Log-Periodic antennas has been so far used for UHF/VHF (Ultra High Frequency/Very High Frequency) and TV reception applications, and in this paper, the advantages of Log-Periodic structure have been exploited for IoT applications. This antenna design consists of two Log-Periodic like structured radiating elements on an FR4 substrate of 1.6 mm thickness. The compact antenna of size of 15 mm x 17 mm covers a bandwidth ranging from 2.01 GHz to 4.04 GHz including the WiMAX (2.3 GHz-2.4 GHz, 2.5 GHz-2.7 GHz and 3.4 GHz-3.6 GHz) and WLAN (2.4 GHz and 3.6 GHz) frequency bands. This system employs Defected Ground Structure (DGS) technique to obtain the required range of bandwidth of operation, for improving the isolation and obtaining mutual coupling suppression between the two individual elements. This miniaturized cheap antenna has a very low ECC (Envelope Correlation Coefficient) value and all other MIMO (Multiple Input Multiple Output) parameters in acceptable range. The isolation obtained over the entire range of operation is below -30 dB, and the performance efficiency is as good as 92.8% with a maximum gain of 2.9 dB. The simulated and measured results of the antenna system are also found to be in good agreement. The MIMO system can be considered as a good candidate for medium range IoT applications for its small size and good performance.