Dual-band MIMO Research Articles

DUAL-BAND RECONFIGURABLE MIMO ANTENNA FOR WIRELESS APPLICATIONS

This article presents design and simulation of a new compact four-element dual-band MIMO frequency reconfigurable antenna that can be reconfigured for WiMAX and LTE applications. The antenna includes four elements at the same FR4 substrate with an optimized overall size of 65x65x1.6 mm3 and an optimized partial GND plane of 30x11.125 mm2. The reconfiguration rate is between 2.41 and 3.99 GHz that can cover the WiMAX and LTE wireless devices by applying just one RF (PIN) switch to change the operating frequency. The antenna operates on the two states of the PIN diode under its two states ON and OFF with (2.7 GHz, and 2.8 GHz) resonant frequencies respectively. The proposed antenna produces acceptable simulation results for the MIMO system by achieving gain from (3-7.2) dBi, less than -14.5 dB coupling effect, less than 0.28 envelope correlation coefficient, and diversity gain range from 8.4-10.

Dual-Band, Dual-Polarized Two Element Slot Antenna for Fifth Generation Mobile Devices

This paper presents a two-element dual-band MIMO antenna with dual-polarization for 5G user equipment. Both operating frequencies are of sub-6 GHz band centered at 3.6 GHz and 5.5 GHz respectively and are independent of each other. Antenna polarizations depend on the placement of the feed elements on the PCB. The antenna is designed on FR-4 substrate to ensure its easy availability and keeping it cost-effective. The resultant radiation pattern of the antenna set is bi-directional with good gain and efficiency.

Frequency Selective Meta-Structure Embedded Two-Element MIMO Antenna with Enhanced Isolation and Pattern Diversity for WLAN/WiMAX Applications

ABSTRACT A two-element MIMO antenna, with improved isolation and pattern diversity, is designed and presented. The dual-band MIMO covers both the adjacent upper WLAN (5.2 GHz) and WiMAX (5.8 GHz) bands with clear isolation between them. The unit radiator of the MIMO is a co-planar waveguide-fed trapezoidal patch that achieves its resonant modes by adjusting the slope of the non-parallel sides. A frequency selective meta-structure is placed in-between the two radiating elements to reduce the mutual coupling and achieve pattern diversity. The MIMO offers peak gains of 1.56 and 5.16 dB at 5.2 GHz (5.1–5.34 GHz) and 5.8 GHz (5.68–5.9 GHz), respectively. The port-isolations achieved at WLAN and WiMAX bands are 26 and 23 dB, respectively. The correlation co-efficient (ECC < 0.05), diversity gain (DG > 9.99) and channel capacity loss (CCL < 0.03) also adhere to the criteria for MIMO operation. The measured results are in good agreement with the simulated ones.

Dual Band and Dual Diversity Four-Element MIMO Dipole for 5G Handsets.

The increasing popularity of using wireless devices to handle routine tasks has increased the demand for incorporating multiple-input-multiple-output (MIMO) technology to utilize limited bandwidth efficiently. The presence of comparatively large space at the base station (BS) makes it straightforward to exploit the MIMO technology’s useful properties. From a mobile handset point of view, and limited space at the mobile handset, complex procedures are required to increase the number of active antenna elements. In this paper, to address such type of issues, a four-element MIMO dual band, dual diversity, dipole antenna has been proposed for 5G-enabled handsets. The proposed antenna design relies on space diversity as well as pattern diversity to provide an acceptable MIMO performance. The proposed dipole antenna simultaneously operates at 3.6 and 4.7 sub-6 GHz bands. The usefulness of the proposed MIMO dipole antenna has been verified by comparing the simulated and measured results using a fabricated version of the proposed antenna. A specific absorption rate (SAR) analysis has been carried out using CST Voxel (a heterogeneous biological human head) model, which shows maximum SAR value for 10 g of head tissue is well below the permitted value of 2.0 W/kg. The total efficiency of each antenna element in this structure is −2.88, −3.12, −1.92 and −2.45 dB at 3.6 GHz, while at 4.7 GHz are −1.61, −2.19, −1.72 and −1.18 dB respectively. The isolation, envelope correlation coefficient (ECC) between the adjacent ports and the loss in capacity is below the standard margin, making the structure appropriate for MIMO applications. The effect of handgrip and the housing box on the total antenna efficiency is analyzed, and only 5% variation is observed, which results from careful placement of antenna elements.

A Hybrid Mutual Coupling Reduction Technique in a Dual-Band MIMO Textile Antenna for WBAN and 5G Applications

This paper presents a hybrid mutual coupling reduction technique applied onto a dual-band textile MIMO antenna for wireless body area network and 5G applications. The MIMO antenna consists of two hexagonal patch antennas, each integrated with a split-ring (SR) and a bar slot to operate in dual-band mode at 2.45 GHz and 3.5 GHz. Each patch is dimensioned at $47.2 \times 31$ mm2. This hybrid technique results in a simple structure, while enabling significant reduction of mutual coupling (MC) between the closely spaced patches (up to $0.1\lambda$ ). This technique combines a line patch and a patch rotation technique, explained as follows. First, a line patch is introduced at an optimized distance to enable operation with a broad impedance bandwidth at both target frequencies. One of the patches is then rotated by 90° at an optimized distance, resulting in a significant MC suppression while maintaining the dual and broad impedance bandwidth. The proposed MIMO antenna is further evaluated under several bending configurations to assess its robustness. A satisfactory agreement between simulated and measured results is observed in both planar and bending conditions. Results show that the MIMO antenna achieves an impedance bandwidth of 4.3 % and 6.79 % in the 2.45 GHz and 3.5 GHz band, respectively. Moreover, very low MC ( $S_{21} dB) is achieved, with a low ( $x$ - and $y$ -axes, the antenna bent maintained a realized gain of 1.878 dBi and 4.027 dBi in the lower and upper band, respectively. A robust performance is offered by the antenna against the lossy effects of the human body with good agreements between simulated and measured results.

Co-Designed 3+3 Port Dual-Band Broadside Tri-Modal Patch Antenna

A co-designed (3+3)-port antenna for dual-band operation that requires no feeding or decoupling network is proposed and verified. The antenna consists of six ports which are divided into two groups that resonate in two different frequency ranges. The basic radiating element is a tri-modal patch in a folded snowflake-shaped structure with the largest antenna dimension of 0.48λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> or 0.68λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> are the wavelengths in air at the center frequencies of the lower and upper operating bands, respectively. Measurement results show that the 10 dB impedance bandwidths of the two respective bands are 19.7% and 14.4%. The proposed antenna exhibits compact, multiport, multiband and broadside radiation characteristics which are not only suitable for dual-band MIMO applications, but also for energy harvesting systems with spatial and frequency diversities, or dual-function wireless systems with simultaneous information and power transfer.

Compact Double Shorted Loop Sub-6-GHz Dual-Band MIMO Quad-Antenna System

This paper presents the design of a compact double-loop sub-6-GHz dual-band MIMO quad-antenna system for 5G laptops. To meet the market demand for laptops with a high screen-to-body ratio, the sub-6-GHz dual-band MIMO quad-antenna system is realized to have a low-profile height of only 3 mm. To make the MIMO quad-antenna system suitable for laptops with a narrow bezel, the four antenna elements are printed on the same FR4 substrate, which is mounted on the upper edge of and coplanar with the display ground plane of a laptop. The four antenna elements have the same double shorted loop structure and the same size of $15\times $ 3 mm2. In the loop structure, a meandered path is embedded in one of the two shorted-end sections, and a series chip capacitor is embedded in the other. The low-frequency resonance mode can be adjusted by varying the meandered path, and the high-frequency resonance mode can be tuned using the meandered path and the series chip capacitor. The four antenna elements are aligned in the same direction with an end-to-end gap of 5 mm so that satisfactory isolation can be achieved without any additional isolation elements. The MIMO quad-antenna system, although measuring only $75\times $ 3 mm2 with the three gaps included, can cover 3400–3800 and 4800–5000 MHz for 5G dual-band operations. The measured isolations between the four antenna elements are larger than 10 dB, the envelope correlation coefficient (ECC) values calculated from the measured radiation patterns are all below 0.27, and the measured radiation efficiencies of all four antenna elements are over 42%.

Design of E-Shaped Dual-Band MIMO Antenna for 5G Smartphone Applications

Design of E-Shaped Dual-Band MIMO Antenna for 5G Smartphone Applications

Sub-6 GHz Dual-Band 8 × 8 MIMO Antenna for 5G Smartphones

In this letter, a dual-band 8x8 MIMO antenna that operates in the sub-6 GHz spectrum for future 5G multiple-input multiple-output (MIMO) smartphone applications is presented. The design consists of a fully grounded plane with closely spaced orthogonal pairs of antennas placed symmetrically along the long edges and on the corners of the smartphone. The orthogonal pairs are connected by a 7.8 mm short neutral line for mutual coupling reduction at both bands. Each antenna element consists of a folded monopole with dimensions 17.85 x 5mm2 and can operate in 3100-3850 MHz for the low band and 4800-6000 MHz for the high band ([S11] ˂ -10dB). The fabricated antenna prototype is tested and offers good performance in terms of Envelope Correlation Coefficient (ECC), Mean Effective Gain (MEG), total efficiency and channel capacity. Finally, the user effects on the antenna and the Specific Absorption Rate (SAR) are also presented.

Dual‐band CPW fed MIMO antenna with polarization diversity and improved gain

A dual-band MIMO slot antenna with polarization diversity and improved gain is proposed in this article. The antenna is composed of two C-type back-to-back connected slot resonators and offers resonances at 3.5 and 5.2 GHz. This antenna element is further used to design a MIMO antenna. By introducing one U-shaped slot between two antenna elements, isolation between the ports of this MIMO antenna is improved further. Finally, an artificial magnetic conductor (AMC) is placed below the MIMO antenna to enhance its gain. Gain enhancement of 1.5 and 2.2 dB is achieved at lower and upper band, respectively. S-parameters, radiation patterns, gain, envelope correlation coefficient, and channel capacity loss are investigated to conclude about its performances in MIMO applications. Dual band dual polarization (circular and linear), improved isolation, polarization diversity (right-hand circular polarization and left-hand circular polarization), gain enhancement all are presented in a simple design represents the novelty of the proposed MIMO antenna.

Compact planar frequency reconfigurable multiple‐input‐multiple‐output antenna with pattern and polarization diversity characteristics for WiFi and WiMAX standards

A compact planar frequency reconfigurable dual-band multiple-input-multiple-output (MIMO) antenna with high isolation and pattern/polarization diversity characteristics is presented in this article for WiFi and WiMAX standards. The MIMO configuration incorporates two symmetrically placed identical antenna elements and covers overall size of 24 mm × 24 mm × 0.762 mm. Reconfiguration of each antenna element is achieved by using a PIN diode which allows antennas to switch from state-1 (2.3-2.4 GHz and 4.6-5.5 GHz) to state-2 (3.3-3.5 GHz and 4.6-5.5 GHz). In state-1, the configuration offers isolation ≥18 dB and 20 dB in lower band (LB) and upper band (UB) respectively; whereas, in state-2, isolation ≥21 dB and 20 dB in LB and UB respectively is achieved. The same decoupling circuit provides high isolation in dual-band of two states, which makes overall size of the proposed design further compact. The antennas are characterized in terms of envelope correlation coefficient, radiation pattern, gain, and efficiency. From measured and simulated results, it is verified that the proposed frequency reconfigurable dual-band multi-standard MIMO antenna design shows desirable performance in both operating bands of each state and compact size of the design makes it suitable for small form factor devices used in future wireless communication systems.

A CLOSELY SPACED DUAL-BAND MIMO PATCH ANTENNA WITH REDUCED MUTUAL COUPLING FOR 4G/5G APPLICATIONS

A CLOSELY SPACED DUAL-BAND MIMO PATCH ANTENNA WITH REDUCED MUTUAL COUPLING FOR 4G/5G APPLICATIONS

Dual-band MIMO Antenna with Band-stop Decoupling Network

A dual-band MIMO antenna operating at 2.5 GHz and 5.8 GHz which can be used for WLAN application is presented in this paper. Simulation, fabrication and measurement are accomplished to verify the antenna performance. As a simplified design process, firstly a band-stop filtering network is presented to achieve port isolation. And a MIMO antenna is designed through appropriate adjustments. The antenna can provide more than 20 dB isolation at both operating frequencies.

Dual-Band Metasurface-Based Decoupling Method for Two Closely Packed Dual-Band Antennas

In this communication, a metasurface-based decoupling method (MDM) is proposed to reduce the mutual couplings at two independent bands of two coupled multiple-input-multiple-output (MIMO) antennas. The metasurface superstrate is composed of pairs of non-uniform cut wires with two different lengths. It is compact in size and effective in decoupling two nearby dual-band patch antennas that are strongly coupled in the H-plane with the edge-to-edge spacing of only 0.008 wavelength at low-frequency band (LB). The antenna is fabricated and measured and the results show that the isolation between two dual-band antennas can be improved to more than 25 dB at both 2.5–2.7 GHz and 3.4–3.6 GHz bands, while their reflection coefficients remain to be below −10 dB after the metasurface superstrate is introduced. Moreover, the total efficiency is improved by about 15% in the low band and the envelope correlation coefficient (ECC) between the two antennas is reduced from 0.46 to 0.08 at 2.6 GHz and 0.08 to 0.01 at 3.5 GHz. The proposed method can find plenty of applications in dual-band MIMO and 5G communication systems.

Design & analysis of a dual-band MIMO antenna to reduce the mutual coupling

A compact dual wide-band multiple-input-multiple-output (MIMO) radiator is presented in this article. The MIMO radiator is developed on a 1.5 mm thick FR-4 substrate. The proposed structure is composed of U-shaped patches which are connected with small rectangular slit loaded circular rings and partial ground plane with chamfer edges. This arrangement is placed symmetrically at a far distance of 2.5 mm to achieve dual-operating bands with a high amount of isolation, radiation efficiencies and group delay between two radiators. The proposed compact dual-band radiator is resonating at 2.5/6.4 GHz frequencies and it provides isolation greater than 20 dB over the operating bands. The proposed design has a size of 0.45 λ0 × 0.291 λ0 × 0.03λ0 mm and |S11| of about 41.25 dB and 14.58 dB. This design has a wide impedance matching in the range of frequencies from 2.38 GHz to 3.17 GHz & 5.14 GHz to 7.39 GHz with |S21| < 15 dB. The performance of diversity is calculated through diversity gain (DG) higher than 9.99, and Envelope Correlation Coefficient (ECC) which is less than 0.04 over the operating bands.

Design of high isolation dual-band MIMO antenna using single neutral line

A dual-band MIMO antenna with a high isolation is presented in this paper. The proposed MIMO antenna consists of two identical E-shaped micro-strip antennas which are designed on an FR4 substrate. The antenna is designed for radiating at 2.6 GHz and 5 GHz that can be used for the applications of 4G and 5G systems, respectively. Neutral line technique is used for mutual coupling reduction between the E-shaped antenna. Good isolation characteristics are obtained by using single micro-strip line connected between two elements of MIMO antenna. The antenna is fabricated and measured, and good agreement is achieved between the experimental and simulated results.

A novel ITI-shaped isolation structure placed between two-port CPW-fed dual-band MIMO antenna for high isolation

In this paper, a novel structure of CPW-Fed MIMO antenna is presented for dual-band applications covering 2.4/5.8 GHz ISM band, 2300 MHz LTE-4G band, HiperLAN (5–6 GHz) and IEEE C-bands. A Rectangle-Split-Ring-Resonator (RSRR) slot has been embedded in the patch antenna to create a band-notch centered around 3.74 GHz in order to isolate the high traffic of 3.5 GHz WiMAX band and convert a wideband antenna into a dual-band antenna which is mainly focused on the WLAN bands. A modified ground structure is implemented to control and achieve a higher impedance bandwidth (IBW) up to 64% in the upper band, ranging from 3.90 to 7.55 GHz while the lower band, ranges from 2.24 to 2.90 GHz with an IBW of 26%. A novel ITI-shaped isolation structure is designed and placed between the patch antennas, which are separated by a center-to-center distance of 0.35λ0, helping in achieving a minimum measured isolation of 24 dB across the dual-band. The design has been fabricated on an FR-4 substrate of dimension 72 × 56 × 0.8 mm3 with a minimum measured gain of 2.5 dBi across the operating bands.

Wide and Dual-Band MIMO Antenna with Omnidirectional and Directional Radiation Patterns for Indoor Access Points

Wide and Dual-Band MIMO Antenna with Omnidirectional and Directional Radiation Patterns for Indoor Access Points

A Dual-Band MIMO Antenna With Enhanced Isolation for 5G Smartphone Applications

In this paper, a compact dual-band MIMO antenna array for 5G smartphone applications is proposed. The MIMO antenna consists of eight folded monopole antennas operating at 3.45-GHz band (3300~3600MHz). And the antenna elements with a size of $6.8\times 6.6\times4$ mm3 (about $0.078\lambda \times 0.075\lambda \times 0.046\lambda $ at 3.45 GHz), are disposed along each edge of the system circuit board. By introducing the decoupling structures, the isolation between inner antenna elements is improved from 10dB to 15.1dB in 3.45-GHz band (3300~3600MHz). Meanwhile the inner antenna units can generate an additional operating band covering 2400~2700MHz due to the coupling effect between the antenna elements and the proposed decoupling structures, which is promising for solving the problem of terminal space shortage. To verify the design principle of the proposed MIMO antenna array, the antenna is fabricated and measured. The measured results of efficiency and ECC are analyzed as well to demonstrate the performance of the proposed MIMO array. Channel capacity, user proximity and SAR analysis and are also given in this paper.

Design Compact Dual Band MIMO Antenna with High Isolation

Design Compact Dual Band MIMO Antenna with High Isolation