Multiple-input Multiple-output Dielectric Resonator Antenna Research Articles

Reconfigurable High Isolation MIMO Dielectric Resonator Antenna for UWB and Wideband Applications

This paper presents a compact multiple-input multiple-output (MIMO) two-element dielectric resonator antenna (DRA) for wideband (WB) and ultra-wideband (UWB) operations. The dielectric resonators (DRs) are fabricated on the top side of the low-cost substrate (FR4) and the etched ground plane on the bottom of the substrate. Featuring two compact U-shaped DRs with a U-shaped defective ground surface (DGS) it has a wide impedance bandwidth of 112.84% (3.02–10.88 GHz). When the diode is connected between U-shaped metallic parasitic strips and the feedline edge, it provides a wide impedance bandwidth of 23.62% (5.6–7.1 GHz). Two parasitic metal elements are placed on the upper surface of the DR to improve the transmission coefficient better than −22 dB between the two ports. This compact antenna has a total volume of 4704.55 mm3 (29 × 29 × 5.594). The proposed MIMO DRA has WB and UWB features, making it easy to monitor and detect signals in the environment.

Mutual Coupling Reduction in MIMO DRA through Metamaterials.

A single negative metamaterial structure with hexagonal split-ring resonators (H-SRRs) is inserted within a two-port multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) in order to achieve a reduction of mutual coupling between closed multiple antenna elements. Between closed, tightly coupled, high-profile antenna elements, the single negative magnetic inclusions (H-SRRs) are embedded. By incorporating magnetic structures within antenna elements, the mutual coupling is significantly diminished. Mutual coupling reduction is attained by inserting an array of hexagonal split-ring resonators between the inter-spacing elements. An operative approach for the reduction of the mutual coupling between two × two MIMO DRAs initially operating at 5.2-GHz band is provided. To make the simulated design replica of the fabricated prototype, an air gap is introduced between the substrate, DRs, and H-SSRs. The addition of the air gap shifts the simulated results to 5.9 GHz, which closely resembles the measured values. The mutual coupling reduction is realized by integrating a meta-surface amid the two × two MIMO DRAs, which are settled in the H-plane. The meta-surface embraces an array of hexagonal split-ring resonator (H-SRR) cells that are unified along the E-plane. The H-SRR structure is designed to offer band-stop functionality within the antenna bandwidth. The proposed design has an overall dimension of 40 × 58.3 × 4.75 mm3 (1.5λ × 1.02λ × 0.079λ). By stacking the DRA with a one × three array of H-SRR unit cells, a 30 dB reduction in the mutual coupling level is attained without compromising on the antenna performance. The corresponding mutual impedance of the MIMO DRA is better than 30 dB over 5.9-6.1 GHz operating bandwidth. The proposed design has a DG of 10 db, ECC < 0.02, CCL < 0.02 bits/s/Hz, and an MEG of 0 dB. The overall design has a promising performance, which shows its suitability for the target wireless application.

Mutual coupling and RCS reduction of MIMO dielectric resonator antenna for S-band applications

This paper designs and analyses a two-port dielectric resonator-based multiple-input, multiple-output (MIMO) antenna. A tilted L-shaped aperture is used to excite the cylindrical-shaped ceramic. This type of feeding structure produces the circularly polarized (CP) waves and HEM11δ mode inside the ceramic. The proposed antenna shows two main features: (i) the polarization diversity concept reduces the isolation level by 15 dB; (ii) integration of frequency-selective surface (FSS) reduces the radar cross-section (RCS) value by an amount of 7.5 dBsm within the operating band. The fabricated structure confirms the working band of the proposed antenna from 2.8 to 3.2 GHz. 3-dB axial ratios is achieved between 2.8 and 3.05 GHz. The proposed antenna's good diversity parameter value and stable radiation characteristics make it applicable for S-band wireless applications

A novel inverted elliptical frustum shaped multi-band MIMO DRA with bandwidth and isolation enhancement

This paper presents the design and development of a two element MIMO (Multiple Input Multiple Output) antenna system designed using Elliptical frustum shaped DRA (Dielectric Resonator Antenna). In the proposed MIMO system, adjacent antenna elements are separated by0.29λ0.The archetype operates in the microwave frequency range 7.96–15.67 GHz giving a maximum isolation of 37.38 dB at 11.08 GHz frequency with a wide impedance bandwidth of 52.6%. Various diversity performance parameters like Envelope Correlation Coefficient (ECC), Diversity Gain (DG) are evaluated to understand the performance of the antenna under MIMO environment. Fabricated archetype is developed and good agreement is found between the simulated and measured results.

Compact Rack Shaped MIMO Dielectric Resonator Antenna with Improved Axial Ratio for UWB Applications

In this paper, a rack shaped two radiator element multiple input multiple output (MIMO) dielectric resonator antenna (DRA) is reported with improved axial ratio (AR) characteristics for ultra-wideband applications. The proposed MIMO antenna structure is implemented with the help of two rectangular shaped radiator elements which are further changed into rack shaped dielectric resonator (DR) that support three modes HEM111, HEM121, and HEM212, at 7.3, 9.3, 10.74 GHz respectively. The approach of rack shaped DRA has improved the transmission coefficient for the UWB range. Inverted T-shaped metallic strip apart from giving elliptically polarized (EP) characteristics also helps in controlling both the axial ratio bandwidth and impedance bandwidth (101.87%). The simulated and measured outcomes validated that the proposed antenna can be utilized for 3.54–10.89 GHz ultra-wideband (UWB) frequency range. The MIMO diversity parameters are implemented as ECC ≤ 0.0059, DG ≥ 9.93 dB, TARC (0, 30, 60, 90, 120, 150, and 180) degrees, GD (0.96 to − 2.1 ns) and CCL (≤ 0.4 except of 8.8–9.6 GHz). All the obtained MIMO antenna parameters are within the acceptable limit and also provides high data rate applications in C and X bands.

Dual‐port MIMO dielectric resonator antenna for WLAN applications

A dual-port multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) for 5 GHz IEEE (802.11a/h/j/n/ac/ax) is discussed in this article. Two prototypes of single feed DRA and dual feed MIMO DRA are fabricated and measured results are compared with the simulated data. The proposed single feed DRA and dual feed MIMO DRA exhibits wide impedance bandwidth (IBW). Antennas have been fabricated on Rogers RT Duroid substrate with Eccostock made DRA placed over the substrate. DRAs are excited by aperture coupled feed to achieve wide bandwidth and high efficiency. The measured IBW of uniport DRA and dual-port MIMO DRA are 26.6% (4.75-6.21 GHz) and 27.5% (4.7-6.2 GHz) respectively. Maximum gain of the antenna is 7.4 dBi. The results of the antennas are in good agreement with simulated data and they are suitable for WLAN applications. These antennas are also compact with area of substrate 32.8 cm2.

A MIMO Dielectric Resonator Antenna With Improved Isolation for 5G mm-Wave Applications

A multiple-input–multiple-output dielectric resonator antenna with enhanced isolation is proposed in this letter for the future 5G millimeter (mm)-wave applications. Two rectangular dielectric resonators (DRs) are mounted on a substrate excited by rectangular microstrip-fed slots underneath DRs. Each DR has a metal strip printed on its upper surface moving the strongest part of the coupling field away from the exciting slot to improve the isolation between two antenna elements. The proposed antenna obtains a simulated impedance bandwidth ( S 11 ≤ –10 dB) from 27.25 to 28.59 GHz, which covers the 28 GHz band (27.5–28.35 GHz) allocated by the Federal Communications Commission for the 5G applications. A maximum improvement of 12 dB on the isolation over 27.5–28.35 GHz is achieved. The mechanism of the isolation improvement and the design procedure are given in this letter. A prototype is manufactured and measured as a validation of the proposed decoupling method.

A Compact Circularly Polarized MIMO Dielectric Resonator Antenna Over Electromagnetic Band-Gap Surface for 5G Applications

We present a wideband circularly polarized (CP) multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) with enhanced diversity. In the DRA element, two diagonal edges of the DR were truncated at 45° to obtain a wider axial ratio larger than 0.65 GHz. The DRA element was excited by a cross-ring slot with specific slot-arm ratio through microstrip-line (MSTL) implemented at the backside of the FR4 substrate to generate CP fields. Small triangular stands at the edge of the DR were employed to hold it in place to avoid any degradation from the uncontrollable bonding agent used for attaching DR onto the FR4 substrate. The DRA achieved an impedance bandwidth better than 0.8 GHz with an antenna gain of 4.83 dBi. Using the DRA with the MSTL feed, two-element CP-DRA array was implemented with electromagnetic band-gap (EBG) structure etched onto the ground plane of the MSTL. The proposed architecture achieves isolation better than 26 dB over the desired frequency band without any performance degradation while maintaining its compact size in the array. Various diversity analysis was carried out on the implemented circularly polarized MIMO DRA. The measured results demonstrated that the proposed singly fed DRA with EBG on the ground plate is suitable for implementing wideband circular polarized MIMO antennas in a compact size.

DESIGN OF A DUAL-BAND MIMO DIELECTRIC RESONATOR ANTENNA WITH PATTERN DIVERSITY FOR WIMAX AND WLAN APPLICATIONS

In this paper, a dual-band multiple-input multiple-output dielectric resonator antenna (DRA) with pattern diversity is presented. L-shape of the DRA produces patterns diversity at the lower band whereas, at the upper band, it is caused by exciting TEx 121/TEy 211 mode in the DRA. Two copper strips are pasted at the corner of the dielectric radiator to improve matching at both the bands. A cylindrical air-gap introduced in the radiator improves isolation up to 25 dB and 20 dB at lower and upper frequency bands, respectively. The MIMO system possesses pattern diversity and isolation without applying any special decoupling technique. The design covers the WiMAX and WLAN bands at 3.6 and 5.2GHz, respectively. Simulated and measured reflection coefficients, envelope correlation, diversity gain and mean effective gain, are in good agreement.

A Dual-Band Multiple Input Multiple Output Frequency Agile Antenna for GPSL1/Wi-Fi/WLAN2400/LTE Applications

A novel dual-band, single element multiple input multiple output (MIMO) dielectric resonator antenna (DRA) with a modest frequency tuning ability is presented in this communication. The proposed antenna operates at GPS L1/Bluetooth/Wi-Fi/LTE2500/WLAN2400 frequency bands. A single dielectric resonator element is fed by two coaxial probes to excite the orthogonal modes. A couple of slots are introduced on the ground plane to improve the isolation between antenna ports. The slots also serve the purpose of reconfiguration in the lower band on placement of switches at optimized locations. The measured impedance bandwidth is 5.16% (1.41–1.49 GHz) in the lower band and 26% (2.2–2.85 GHz) in the higher band. The lower band reconfigures with an impedance bandwidth of 6.5% (1.55–1.65 GHz) when PIN diodes are switched ON. The gain, efficiency, correlation coefficient, and diversity gain of the MIMO DRA are presented with a close agreement between simulated and measured results.

A reduced size dual port MIMO DRA with high isolation for 4G applications

© 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:495-501, 2015. © 2014 Wiley Periodicals, Inc.A dual-port reduced size multiple input multiple output (MIMO) Dielectric Resonator Antenna (DRA) has been studied and proposed. The MIMO antenna consists of a Rectangular Dielectric Resonator antenna, which is fed by two symmetrical feed lines for orthogonal mode excitation. The proposed antenna is suitable for operation over various long term evolution (LTE) bands. A measured bandwidth of 264 MHz for |S 11 | <-10dB and isolation of 18 dB at 1.8 GHz has been obtained. Besides, the Envelope Correlation Coefficient, Mean Effect Gain and Diversity Gain have been studied for the presented MIMO DRA using the S-parameters. Based on these results, it can be concluded that the proposed antenna can be a suitable candidate for MIMO applications.

Design of a MIMO Dielectric Resonator Antenna for LTE Femtocell Base Stations

A novel multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) for long term evolution (LTE) femtocell base stations is described. The proposed antenna is able to transmit and receive information independently using TE and HE modes in the LTE bands 12 (698-716 MHz, 728-746 MHz) and 17 (704-716 MHz, 734-746 MHz). A systematic design method based on perturbation theory is proposed to induce mode degeneration for MIMO operation. Through perturbing the boundary of the DRA, the amount of energy stored by a specific mode is changed as well as the resonant frequency of that mode. Hence, by introducing an adequate boundary perturbation, the TE and HE modes of the DRA will resonate at the same frequency and share a common impedance bandwidth. The simulated mutual coupling between the modes was as low as - 40 dB . It was estimated that in a rich scattering environment with an Signal-to-Noise Ratio (SNR) of 20 dB per receiver branch, the proposed MIMO DRA was able to achieve a channel capacity of 11.1 b/s/Hz (as compared to theoretical maximum 2 × 2 capacity of 13.4 b/s/Hz). Our experimental measurements successfully demonstrated the design methodology proposed in this work.