Bandwidth switchable MIMO antenna for automotive internet of things/ultra‐wideband communications

Abstract

A novel low-pass filter integrated ultra-wideband (UWB) antenna is presented in this paper for automotive internet of things (IoT)/UWB communications. The proposed filtering antenna comprises a UWB radiating element whose feedline is integrated with a low-pass filter section. The UWB antenna is constructed using a novel-radiating patch with curved edges to achieve reflection coefficient bandwidth extending from 2 to 13.2 GHz. A T-shaped low-pass filter with a 3 dB cutoff frequency of 3.85 GHz is designed and deployed adjacent to the feedline of the UWB radiator. The frequency selection is accomplished using PIN diodes, which enables feed selection making the antenna operate at two states, viz. narrow band (2.45 GHz), and UWB (2–13.2 GHz) states. Furthermore, a four-port vertically polarized MIMO antenna is constructed and the MIMO performance parameters are estimated. In both the operating states, the antenna offers an average gain (gain averaged over the four ports of the MIMO antenna) greater than 3 dBi throughout the operating bandwidth. A prototype MIMO antenna is fabricated and the results are presented. From the results, it can be inferred that the proposed antenna is suitable for high data rate IoT and UWB communications in the automotive environment.