Abstract

     A quad-element multiple-input-multiple-output (MIMO) antenna with fractional bandwidth (FBW) of 52.42% (3.35–۵٫۷۳ GHz) is proposed for LTE, WLAN (4.9/5 GHz), and 5G (sub-6 GHz) applications. The bandwidth is improved by introducing a tapered feed line and rectangular stubs in the partial ground plane. The maximum isolation of the proposed MIMO antenna is 27 dB. The diversity performance characteristics of the proposed antenna are studied in terms of the envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), isolation between the ports, and channel capacity loss (CCL) and the values obtained are 0.003, 9.98 dB, ±۳ dB, −۴ dB, −۱۰ dB, and 0.10 bits/s/Hz respectively. A model of the proposed antenna is fabricated on the FR-4 substrate having a dielectric constant of 4.4 and a loss tangent of 0.02 with an electrical dimension of 0.45λ۰ × ۰٫۴۵λ۰٫ The measured results demonstrate a decent likeness to simulated ones in the entire operating frequency range.

Introduction

     The current scenario for mobile communication is to achieve a higher data rate, capacity, low latency, and high resolution. The fifth-generation (5G) mobile communication has been deployed around the world to fulfill the above advantage [1,2]. It has been shown [3,4] that to improve the information throughput in a multipath environment for 5G operations, the MIMO antenna system should be adopted. MIMO antenna systems should have a minimal inter-element distance, low correlation values, and better isolation between inter elements [5]. The primary advantage of adopting an MIMO network over a normal one is that it can enhance wireless connection capacity while consuming less spectrum. The system’s link dependability and data rate can be enhanced by increasing the number of antennas on the transmitter/receiver, which results in more signal routes and thus higher performance. Hence MIMO techniques become very vital for wireless communication systems which are suffering from frequency constraints [6,7].

Conclusion

     A compact quad-element MIMO antenna of 40 × ۴۰ × ۱٫۶ mm3 for 5G, LTE, and WLAN frequency bands is designed, fabricated, and measured. The measured results demonstrate a decent likeness to simulated ones in the whole frequency range. The proposed design’s performance was evaluated and described in terms of impedance bandwidth, surface current distribution, reflection coefficient, gain, efficiency, and radiation characteristics. The MIMO provides good diversity performance with a low envelope correlation coefficient and a better diversity gain. Furthermore, within the operating frequency band, the proposed antenna obtained a maximum channel capacity of > 20 bits/s/Hz. The antenna has a total efficiency of 85.12% and a peak gain of 2.74 dBi. As a result, it is recommended as a candidate for 5G, WLAN, and LTE applications.