Performance Improvement of Multi-band MIMO Antennas for 5G Applications

Abstract

  A comprehensive argument is present in this paper for the development of a four-element Three major frequency band MIMO antenna that is suitable for the 5G and beyond upcoming wireless technology. This antenna, constructed using FR-4 material and measuring 38 x 38 x 1.67 mm3, operates in the UWB, Ku-band, as well as a portion of the Ka-band and lower millimeter band. A 4×4 MIMO antenna structure was used to evaluate the proposed technique; the antenna resonates at three bands. The array has dimensions of 0.4 × 0.4 × 0.039λ_g^3. The tested features of the proposed antenna system demonstrate compatible responses for broadband frequency ranges. The first band covers frequencies from 3.14 GHz to 9.14 GHz (6 GHz bandwidth) with the following characteristics: 97.7% bandwidth, 78% maximum radiation efficiency, and a total efficiency of 73%. A 2.27 dB peak gain, 10 dB average diversity gain (DG), and not more than 0.085the envelope correlation coefficient (ECC). Also, this antenna has more than 24 dB isolation boundary between the radiating elements. At the second band, this antenna realizes 58% bandwidth with operation range from 9.2 GHz to 16.7 GHz (7.5 GHz), while maintaining an 88.8%, 82.7% as maximum radiation efficiency, and total efficiency respectfully. A peak gain of 5.4 dB, around 10 dB average DG, and an ECC of less than 0.018. Moreover, a value of greater than 18 dB minimum decoupling between the adjacent elements. The proposed structure shows 11 GHz bandwidth at the third frequency band, which ranging from 20.15 GHz to 31.31 GHz, representing a bandwidth of 43.4%. A peak gain of 7.4 dB is reached. Maximum radiation efficiency of 86.3%, with a total efficiency of 83.5%. The average DG is about 10 dB, and the ECC is lower than 0.005. An isolation gap of more than 13 dB is reached between the radiating elements.