Novel four-port reconfigurable filtering MIMO antenna for multi-standard automotive communications

Abstract

This paper presents the design and characterization of the four-port MIMO antenna constructed using filtering antenna elements. The proposed antenna consists of a UWB antenna whose feedline is integrated with low-pass and bandpass filter sections. The UWB antenna is constructed using a novel radiating patch with a sufficiently large radiating aperture to achieve better gain characteristics. The low-pass filter is constructed using a stepped impedance slotted line section with a passband covering the lower edge of the UWB band. On the other hand, the bandpass filter is designed using hair-pin coupled line sections to cover the mid-frequency ranges of the UWB band. The proposed antenna operates in three modes and the bandwidth selection is accomplished using PIN diodes. By properly choosing the excitation voltage and the proposed antenna can work in UWB mode (2.1 GHz–10 GHz) for low power applications, IoT/WLAN mode (2.1 GHz–3.9 GHz), WLAN/DSRC mode (5–6.5 GHz). The proposed filtering antenna is extended to construct a four-port vertically polarized antenna to improve the link reliability. The MIMO metrics of the proposed four-port antenna is evaluated and the results are presented. The prototype MIMO antenna is fabricated and tested for impedance and radiation characteristics. The measured antenna gain is greater than 3.5 dBi in all four ports. Furthermore, the onboard performance of the proposed antenna is evaluated and the results are presented.