Compact Four-Element Mimo Antenna System Based on Substrate-Integrated-Waveguide Cavities

Abstract

A compact four-element multiple-input-and-multiple-output (MIMO) antenna system is proposed based on substrate-integrated-waveguide (SIW) cavities. By bisecting a square SIW cavity, two rectangle half-mode cavities with opened edges are formed. They are arranged side by side sharing a row of metallic vias. Then two narrow T-shaped slots are etched along symmetry planes to divide these two cavities into four quarter-mode sub-cavities. Excited by feeding ports, four antenna elements with compact size are constructed, which radiate incident wave through opened cavity edges and etched slots. Moreover, antenna isolation can be easily improved by adjusting slot length though these elements interconnect. A prototype with the cavity size of 0.22λ 0 × 0.86λ 0 × 0.04λ 0 has been fabricated. The fabricated MIMO antenna system exhibits the center frequency of 3.51 GHz, port isolation of 14 dB, envelope correlation coefficient of 0.03, peak gain of 4.9 dBi, and high efficiency of 77.4%. The compact size and effective isolation improvement make the proposed design attractive for practical applications.

Design Challenges and Possible Solutions for 5G SIW MIMO and Phased Array Antennas: A Review

“…However, the bandwidth obtained is less than the required minimum of 100 MHz for the 5G band, and the E-plane radiation pattern is tilted at θ = 20º from the broadside direction (θ = 0º). Using fraction-mode structures, one of [39] authors developed various SIW MIMO antennas [40][41][42][43][48][49][50][51][52] from 2019 to 2020. Except [49], which was developed using lossy FR4 substrate, the rest of the works are built on low loss F4B substrate.…”

“…Further, in [41], the antenna design of [40] was arranged in the horizontal direction; however, they are flipped such that the open radiating edges of the SIW cavities become opposite (see Table II.b [41]) and developed four-element QMSIW MIMO antenna. Additionally, a parametric study on slot length was carried out, and maximum isolation of 18 dB was achieved.…”

“…Further, a compact two-element SIW cavity MIMO antenna was introduced in [48], where the authors tried to solve the narrow bandwidth problem SIW cavity antennas faced in earlier reported papers [39][40][41][42]. This work presented a technique to enhance the antenna bandwidth.…”

“…Inherently SIW-based antennas offer narrow bandwidth due to the high quality (Q) factor of SIW structures. It is visible in the literature survey that many SIW MIMO antennas in the sub-6 GHz band, where a minimum of 100 MHz is required, suffer from this drawback [39][40][41][42][43][44]. Few efforts are indeed executed to enhance the antenna bandwidths [48,49].…”

Design and Investigation of Dual-Band 2 × 2 Elements MIMO Antenna-Diplexer Based on Half-Mode SIW

“…In [23][24], both bandwidth and size are improved, but these studies have not been investigated for MIMO communication. In [25][26][27][28][29], dual-band, 4-elements MIMO antennas have been reported, where different techniques based on defected ground structures have been discussed to improve the inter-port isolation.…”