A Super-Wideband and High Isolation MIMO Antenna System Using a Windmill-Shaped Decoupling Structure

Abstract

In this paper, a novel super-wideband multiple-input multiple-output (SWB-MIMO) antenna system with high isolation has been proposed, each antenna element consisting of a spade-shaped radiation patch, a defected ground structure (DGS) as well as a windmill-shaped decoupling structure. The elliptical slot etched on the radiation patch and the rectangular DGS are jointly utilized to make better the radiation performance and impedance bandwidth. Both of four-element and eight-element SWB-MIMO antenna systems are simulated and analyzed, respectively. A prototype of the four-element SWB-MIMO antenna system with total dimensions of 58 mm × 58 mm × 1 mm was fabricated to verify the concept of design using an FR4 material substrate. Measurement and simulation results indicate that the proposed SWB-MIMO antenna system can work in the frequency band ranging from 2.9 to 40 GHz with a mutual coupling of lower than-17 dB. Also, excellent performance has been achieved with a low envelop correlation coefficient (ECC) of lower than 0.04, high multiplexing efficiency (ηmux) of more than-3.0 dB, stable gain of up to 13.5 dBi as well as quasi-omnidirectional radiation properties. This design provides an important guideline for obtaining a super-wide MIMO antenna. INDEX TERMS Multiple-input multiple-output (MIMO) antenna, high isolation, super-wideband (SWB), defected ground structure (DGS), windmill-shaped decoupling structure, meander technology.

Design and Implementation of Quad-Element Super-Wideband MIMO Antenna for IoT Applications

“…A comparison of the proposed antenna and previously designed SWB MIMO antennas is given in Table II. The proposed MIMO antenna has numerous benefits over the antennas reported previously [21][22][23][24][25][26], in terms of compact size, bandwidth ratio, notched bands, isolation between antenna ports, and the number of resonators. In the proposed antenna, the signals (at 2.4 GHz, 5.5 GHz, and 7.5 GHz) are rejected without using any active devices or filtering circuitry.…”

“…A dualport antenna consisted of elliptical-shaped radiators was reported [24], where WLAN and Wi-MAX bands were notched from the SWB by etching split-ring resonator (SRR) and spiral microstrip defected structure from the patch and the feeding, respectively. A MIMO antenna consisted of four spade-shaped radiators and a windmillshaped decoupling element was presented [25], where an elliptical slot was etched on the antenna element to improve its radiation performance. A MIMO antenna consisted of four semi-elliptical resonating elements was reported in [26], where triple notched bands were achieved by etching an L-shaped element and a complementary split-ring resonator (CSRR) on the patch.…”

“…However, the SWB MIMO antenna configurations reported so far mainly comprised of two antenna elements [21][22][23][24] and one or two notched bands [24]. A few SWB antenna designs were presented with four resonating elements [25][26] and triple notchedband features [26], but their large sizes may limit their applications in compact IoT modules. Also, the ground of the antenna elements in [21], [23], [25] are not interconnected, therefore, these antennas might not be used for practical MIMO applications.…”

CPW Fed Compact UWB 4-Element MIMO Antenna with High Isolation

“…Recently, MIMO designs that support wider working frequency bands have received considerable research interests [15][16][17]. For example, a compact 4-element MIMO antenna has been proposed for portable wireless UWB applications with a wide frequency band that extends from 3.1 to 12 GHz [15].…”

“…In addition, a highly isolated compact 4-element planar UWB-MIMO antenna that operates over a bandwidth of 3-15 GHz has been reported [16]. In a recent study, a novel UWB-MIMO antenna system with high isolation has been proposed with a frequency range of 2.9 to 40 GHz and a mutual coupling that is less than −17 dB [17]. Moreover, it can also be observed from the recent literature that 4-element antennas have become the mainstream of UWB-MIMO antenna research.…”