Slot‐loading based compact wideband monopole antenna design and isolation improvement of MIMO for Wi‐Fi sensing application

Abstract

AbstractThe dense establishment of the Wi‐Fi devices creates an opportunity to map the surrounding environment using Wi‐Fi signals as sounding waveforms. Recently, the Channel State Information (CSI) measurement analysis from Wi‐Fi networks has been widely used for detecting and possibly tracking the presence of obstacles between a transmitter and a receiver. According to the IEEE 802.11bf Task Group, Wi‐Fi sensing will utilize a band between 5.925 and 7.125 GHz, making the CSI measurement finer‐grained with the additional large bandwidth. In this paper, a wideband compact antenna is designed targeting the 5.9–7.1 GHz band based on the slot‐loading technique. Later, a wideband multiple‐input multiple‐output (MIMO) antenna is designed using defected ground structures, protruded ground, and electromagnetic band gap structures for isolation improvement, and the measured isolation shows 30–45 dB between the elements in the operating frequency range. The envelope correlation coefficient is less than 0.001 with the diversity gain being nearly 10. The fabricated single antenna has a compactness of 0.3 in both dimensions (14 mm  14 mm), measured bandwidth of 1.55 GHz (5.95–7.5 GHz) with a peak gain of 2.2 dBi at 6.8 GHz, and 90% efficiency in the operating frequency range whereas the wideband MIMO antenna has a size of 14 mm  37 mm with 0.5 spacing between the elements.