Decoupling Structure Research Articles

Hybrid Decoupling Structure Based on Neutralization and Partition Schemes for Compact Large-Scale Base Station Arrays

This letter proposes a hybrid decoupling structure consisting of a neutralization dielectric board, metal baffle, and feeding network to enhance the isolation in a compact large-scale base station array. Both the neutralization- and partition-based schemes are utilized to reduce the mutual coupling between antennas. The neutralization dielectric board provides a new signal path to cancel the original mutual coupling, and the metal baffle is employed to suppress the propagation of the space electromagnetic wave. The antenna elements in the vertical direction are excited by a feeding network. A 4×4 dual-polarized antenna array with a horizontal edge-to-edge distance of 0.38 free-space wavelength is designed and fabricated to demonstrate the effectiveness of the proposed structure for large-scale arrays for base station application. Simulated and measured results show that the voltage standing wave ratio is less than 1.7, and the isolation between any two ports in the array is better than 20 dB within the entire operating frequency band. Stable radiation patterns with a good front-to-back ratio and cross-polarization ratio are achieved.

A compact dual band MIMO antenna for 5G/WLAN applications

AbstractTo satisfy the increasing requirements of wireless communication, a compact dual band MIMO antenna is presented in this paper. The presented antenna consists of two symmetric radiating elements operating at both 3.5 and 4.5 GHz bands. To enhance the isolation between the two radiating elements, an I-shaped decoupling structure is introduced. The measured −10 dB reflection coefficients frequency bands are 3.3–3.8 and 4.3–5.8 GHz. The measured isolation S21 between the two radiating elements are better than 15 and 17 dB at the lower and higher frequency band, respectively. The overall dimension of the proposed antenna is 50 × 22 × 1.59 mm3. The measured result indicates that the proposed antenna can be a good candidate for 5 G/WLAN wireless communication.

A non-uniform strip-array decoupling structure of the MIMO antenna-arrays for the DSRC application

ABSTRACT In this paper, a non-uniform strip-array decoupling structure (SADS) of the MIMO antenna-arrays for the dedicated short-range communication (DSRC) applications in intelligent transportation systems (ITS) is presented. The SADS is composed of metal strips with non-uniform longitudinal layout, which has a simple strip-array geometry, low design and fabrication complexity, and easy to be applied to the design domain without destroying the original antenna-array. The design of the strip thickness, strip-array layout and number of strips is realised by the proposed simple and effective optimisation method. The mutual coupling between the elements can be effectively suppressed to less than −32 dB by the proposed structure in the required bandwidth (5.795 GHz~5.815 GHz). The results show that, compared with the no-strip and uniform SADS, the non-uniform SADS can improve the maximum mutual coupling reduction by 23 dB and 13 dB, respectively. Both the simulated and measured results verify the effectiveness of the proposed SADS, which makes it very suitable for the large-scale MIMO antenna-arrays.

Design of a Six-Port Compact UWB MIMO Antenna With a Distinctive DGS for Improved Isolation

A low-profile printed six-port ultrawideband (UWB) antenna with a novel decoupling structure for enhancing port-to-port isolation is analyzed in this paper. Six symmetrical pyramidal form UWB antennas with defective ground structures interspersed with parasitic components served as a unique decoupling structure in the proposed design. The grounded branches and modified rectangular stubs on the ground plane generate closed and open current distribution channels, causing the uniform current flow to be disrupted and the coupling effect to be neutralized. The projected six-port antenna has an electrical dimension of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.68\times 0.89 \times 0.01\,\,\lambda ^{3}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> is computed using a lower frequency of 2.9 GHz), having a below -10 dB impedance bandwidth of 116% from 2.9 to 11 GHz. Across the impedance bandwidth, the average port-to-port isolation is better than 20 dB. The antenna design has acceptable radiation properties with a peak gain of 8.3 dBi at a frequency of 7.5 GHz. Further, the projected design is also exposed to the time domain characteristics and diversity metrics. Among the different ports, the values of the group delay and fidelity factors are less than 1.5 ns and more than 0.92, correspondingly. The values of the diversity parameters such as ECC < 0.075, DG approximately 10 dB, MEG <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ &lt; -3$ </tex-math></inline-formula> dB, TARC <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ &lt; -10$ </tex-math></inline-formula> dB, CCL < 0.3 bps/Hz, and ME <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ &lt; -2$ </tex-math></inline-formula> dB ensure that the projected design is appropriate for the MIMO applications. The designed antenna is fabricated and measured, and the results are in line with the simulation.

Quad-Port MIMO Filtenna With High Isolation Employing BPF With High Out-of-Band Rejection

A quad-port multiple-input multiple-output (MIMO) filtenna with compact dimensions of <inline-formula> <tex-math notation="LaTeX">$50\times50$ </tex-math></inline-formula> mm² is arranged. In this MIMO filtenna, each element is placed orthogonal to its adjacent one to enhance the isolation. The MIMO element is configured based on the novel COVID-19 virus shape with a co-planar waveguide (CPW) feeding structure and dimensions of <inline-formula> <tex-math notation="LaTeX">$17\times22$ </tex-math></inline-formula> mm². The element bandwidth ranges from 3.3 GHz to more than 60 GHz. Three frequency notches are designed at 3.5 GHz for WiMAX, 5.5 GHz for WLAN, and 8.5 GHz for X-band applications. A bandpass filter (BPF) with high out-of-band rejection is used as a decoupling structure (DS) to improve the isolation to more than 30 dB across most of the bandwidth. The BPF is designed based on LC lumped elements, and then implemented using planar strip lines. The proposed MIMO filtenna system provides an impedance bandwidth of 2.4&#x2013;18 GHz, a peak gain of 5 dBi, and an envelope correlation coefficient (ECC) less than 0.00021. In turn, channel capacity loss does not exceed 0.2. The MIMO filtenna is fabricated and measured showing a good agreement between the measured and simulated results.

Mutual Coupling Reduction of a Circularly Polarized MIMO Antenna Using Parasitic Elements and DGS for V2X Communications

In this article, a 4-port circularly polarized (CP) multiple-input multiple-output (MIMO) antenna at 5.9 GHz is presented for the vehicle to everything (V2X) communications. A novel hybrid decoupling structure consisting of circular ring parasites and defected ground structure (DGS) is used to reduce the mutual coupling between the MIMO elements. The circular ring parasites are incorporated between the antennas to reduce the mutual coupling between perpendicular antennas. Whereas, the DGS significantly reduces the mutual coupling between adjacent antennas. These circular ring parasites and DGS affect the electromagnetic field distribution and consequently reduce the mutual coupling. The effectiveness of the decoupling structure is explained through transmission coefficient and surface current distribution. The simulated and measured results show that the proposed MIMO antenna provides overlapping S11 (&#x2013;10 dB) and axial ratio (3-dB) bandwidth of 2.04% (5.82 &#x2013; 5.94 GHz) with a peak gain of 7.68 dBic. Moreover, the fabricated MIMO antenna offers excellent diversity performance, isolation between antenna elements is very high (&#x003E;34dB), envelope correlation coefficient (ECC) is lower than 0.001, and diversity gain is 9.99 dB, very close to the ideal value of 10 dB. Furthermore, the link budget for the proposed MIMO system is calculated to check the suitability for V2X communications which shows that the antenna can communicate between them over a distance of 1.5 kilometers with a 21 dBm of transmit power. Owing to these qualities, the proposed MIMO antenna can be an excellent choice for V2X MIMO communications.

Co- and Cross-Polarization Decoupling Structure With Polarization Rotation Property Between Linearly Polarized Dipole Antennas With Application to Decoupling of Circularly Polarized Antennas

A decoupling structure with polarization rotation (DSPR) property is proposed to reduce the mutual coupling between co- or cross-polarized antennas. The proposed DSPR generates a neutralization wave with two orthogonally polarized components that can be controlled to cancel the original mutual coupling. The DSPR is placed above the arrays with orthogonal and parallel dipole elements. After applying the DSPR, the mutual coupling at the center frequency of 3.5 GHz is reduced to −40 dB for both arrays, and the overall mutual coupling is better than −26 dB within the band of 3.3–3.7 GHz, and the reflection coefficients remain below −12 dB. The antennas maintain stable radiation patterns within the operation bandwidth with a 0.5 dB increase of the realized gain. Since the DSPR can effectively reduce both co- and cross-polarization coupling, the mutual coupling between circularly polarized antennas in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 \times 4$ </tex-math></inline-formula> array is reduced to below −35 dB thanks to the DSPR. Finally, a prototype of the antenna array with orthogonal dipole elements loaded with the DSPR is fabricated and measured. The measured results are in excellent agreement with the simulated ones, demonstrating the effectiveness of the proposed DSPR for isolation enhancement between cross-polarized antennas.

Wideband Self-Decoupling Dielectric Patch Filtennas With Stable Filtering Response

Wideband self-decoupling of bandwidth-enhanced dielectric patch (DP) filtennas with stable filtering response are proposed in this letter. The TM101 and TE121 modes of the DP are combined to design a wideband antenna while its high-order TM111 mode is used to introduce an intrinsic upper radiation null, leading to a good filtering response. Sequentially, 1×2 DP filtennas have been taken as an example to verify that improving the isolation can keep the filtering performance of the filtenna array basically consistent with the original filtenna element, which is a design concept proposed for the first time in this paper. To maintain almost the same filtering response when the antenna elements are spaced closely, the wideband self-decoupling between the antenna elements is obtained by properly choosing the parameters (i.e. dielectric constants of the DP and substrate), without adding extra decoupling structures. For validation, 1×2 closely-spaced filtennas are fabricated and tested. The measured results denote that the prototype has impedance bandwidth (| <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | < -10 dB) of about 21.2% from 4.47 GHz to 5.53 GHz and in-band isolation is over 20 dB. Benefiting from the self-decoupling scheme, the difference of the in-band gain and stopband suppression between the element and 1×2 DP filtennas is reduced significantly, showing stable filtering response of the filtennas.

Broadband and Compact Circularly Polarized MIMO Antenna With Concentric Rings and Oval Slots for 5G Application

A broadband and compact size circularly polarized (CP) two-port multiple input multiple output (MIMO) antenna with a footprint of 25 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times20$ </tex-math></inline-formula> mm is investigated. The designed oval-shaped MIMO antenna employs concentric rings with oval slots (CROS), along with a circular radiator and two open-ended parallel protruded stubs. The CP radiation is achieved by embedding three oval slots, in which two of them are deployed at the left and right side of the concentric rings, whereas the third one is deployed at the top section of the concentric rings. The measured 10-dB impedance bandwidth of the proposed MIMO antenna was 46.30% (3.12–5.00 GHz), and its corresponding 3-dB axial ratio bandwidth (ARBW) was 41.34% (3.30–5.02 GHz). Furthermore, very wide beamwidths of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$137^{\circ }\pm 0.2$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$154^{\circ }\pm 0.2$ </tex-math></inline-formula> were measured in the right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) radiation patterns, respectively. The minimum achieved isolation between the antenna elements is 18.50 dB without using any additional decoupling structure, and the calculated envelope correlation coefficient (ECC) < 0.03.

8-Port MIMO Antenna Having Two Notched Bands for Chipless UWB-RFID Tags

An 8-element Multiple Input Multiple Output (MIMO) antenna is implemented for Chipless-RFID Tags (CRT) that function in the Ultra-Wideband (UWB) frequency range. The single UWB antenna contains a rectangular radiator in which two ellipses are cut from the two lower corners. Also, two circles are etched from the upper corners of the ground. This antenna is designed by placing eight antenna elements at 45&#x2218; direction (clockwise and anticlockwise) and a thin line-shaped decoupling structure is used to enhance isolation at lower frequencies. Also, a T-shaped structure is used to enhance the notched band characteristics. The working frequency of the antenna is from 3.5 GHz to 10.5 GHz with WiMAX and WLAN notched bands using U-slot and Split Ring Resonator (SSR) metamaterial, respectively. The antenna obtains a peak gain of 5 dB (single element). This antenna has radiation efficiency from 76.4% to 92.7%. This antenna design will inspire the designers of chipless RFID (CRFID) to produce low-cost tags.

Bandstop Filter Decoupling Technique for Miniaturized Reconfigurable MIMO Antenna

In this work, a switchable bandstop filter is used as a decoupling structure for developing a miniaturized reconfigurable multiple input multiple output (MIMO) antenna. Initially, a dual band ((2.43-2.60 GHz and 3.51-3.79 GHz)) single monopole antenna structure is developed on FR4 substrate. Then the single monopole antenna and its replica are accommodated in a small space with an edge to edge separation distance of 11 mm to form a 2 port MIMO antenna. Now, a switchable bandstop filter is used as a decoupling network between two closely spaced monopole antenna elements to prevent mutual coupling and reconfigure the antenna characteristics. The dual pole switchable bandstop filter is configured in such a way that one of its poles lies at 2.5 GHz in one state (Mode 1) and at 3.68 GHz in another state (Mode 2) under the switching action of two PIN diodes. Controlling the ON/OFF states of the PIN diodes in the bandstop filter, high isolation is achieved alternately in lower (2.43-2.60 GHz) and upper (3.51-3.79 GHz) frequency bands of the MIMO antenna. Also, stub network is used to improve impedance matching in the upper frequency band. The proposed isolation technique helps the antenna to yield high isolation (>30 dB), fair gain (>2.97 dBi), reasonable radiation efficiency (>86.8 %), low envelope correlation coefficient (< 0.16), high diversity gain (DG >9.88 dB), low Mean effective gain ratio (MEG 1/MEG 2 < 0.05 dB) and low channel capacity loss (CCL < 0.06 bits/s/Hz) for both the operating frequency bands. The overall dimension of the antenna is restricted to 44mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 22mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.36\lambda _{o}\,\,\times \,\,0.18\lambda _{o}$ </tex-math></inline-formula> ) for its easy integration in compact wireless devices. This type of reconfigurable MIMO antenna is best suited for cognitive radio communication, which promotes efficient spectrum utilization.

A Wider Impedance Bandwidth Dual Filter Symmetrical MIMO Antenna for High-Speed Wideband Wireless Applications

This research article reports a compact fractal 4 × 4 UWB extended bandwidth MIMO antenna with physical dimensions of 44 × 44 mm2 for high-speed wireless applications. The reported antenna comprises four fractal radiating elements that are symmetrical and placed orthogonal to each other with a respective rectangular ground printed on the opposite plane. A higher isolation is achieved between the radiating elements by the placement of a fractal patch orthogonally and no separate decoupling structure is required. The antenna offers a −10 dB transmission capacity of 2.84–15.88 GHz. The fractal radiating element, which is embedded by an inverted T-type stub placed within a rectangular slot and an etched rotated C-type slot, provides band-stop filters for WiMAX (Worldwide inter-operability for Microwave Access) and WLAN (wireless local area network)-interfering bands. The key parameters of diversity performance are compared by simulation and measurement (fabricated prototype) of ECC (envelope correlation coefficient), DG (directive gain), TARC (total active reflection coefficient) and CCL (channel capacity loss). The antenna offers an omnidirectional radiation pattern with an average gain of 3.52 dBi.

A simple and effective broadband decoupling structure for UWB-MIMO antenna

Abstract A new type of closed square ring decoupling structure is proposed in this letter, which can effectively reduce the coupling of antennas. The designed antenna is composed of two elliptical monopoles and a common ground loaded with a broadband parasitic decoupling structure. Considering the impedance matching, each antenna element is changed from the original rectangular microstrip feed to a tapered microstrip feed and etched a circular slot on the elliptical monopole patch. By comparison with the original antenna without any decoupling structure, through loading the broadband decoupling structure on the ground, the antenna isolation is improved by 10 dB in most frequency bands. Comparing simulation and measurement results, the antenna achieves better than 25 dB isolation over the whole operating band (3.3–12 GHz). By manufacturing and testing the antenna designed in this article, the excellent performance parameters obtained also prove that the antenna can be used in portable devices.

A simple conformal-strip fed composite antenna with wideband & enhanced isolation for MIMO applications

A composite antenna with wide impedance bandwidth and enhanced isolation for multiple-input-multiple-output (MIMO) applications is introduced in this article. A simple conformal-strip fed rectangular dielectric resonator (rDR) with a conducting conformal-patch, which provides wide impedance bandwidth (3.21-6.19 GHz), is utilized as an antenna element. The proposed MIMO antenna is formed by arranging two symmetrical composite antenna elements side by side along with a simple decoupling structure (based on a wide rectangular slot and two metallic strips) in between them. The proposed MIMO antenna delivers good inter-port isolation (greater than 18 dB) over the entire operating bandwidth. Also, a well satisfactory outcome of the envelope correlation coefficient (ECC) is obtained over this bandwidth. Moreover, the proposed antenna exhibits a stable broadside directional radiation pattern over the entire operating bandwidth.

Metasurface-based coupling suppression for wideband multiple-input-multiple-output antenna arrays

Wideband decoupling requires simultaneous improvements in the performance of an antenna array in its operating band. In this paper, a metasurface structure is proposed to accomplish this difficult task in wideband dual-layer coupled patch multiple-input-multiple-output (MIMO) antenna arrays. The decoupling mechanism is analyzed based on network and field theories, and dual-band response is achieved by incorporating multilayer hybrid split-ring resonators to create a meta-atom equipped with single negative property. By introducing the metasurface into the H-plane coupled MIMO array, the working bandwidth improves from 21.7% to 25.4%, mutual coupling is suppressed to less than −20 dB, gains mostly improve, and radiation patterns are modified. Moreover, the metasurface-based decoupling structure is extended to the E-plane coupled and two-dimensional arrays, exhibiting the same decoupling capability in the 22.9% and 23.6% bandwidths, respectively. Compared with existing metasurface-based decoupling works, the proposed metasurface, which is designed to be coplanar with the array, brings about no change to the array profile and possesses a wider decoupling bandwidth. These results indicate its potential in efficiently decoupling multielement wideband MIMO antenna arrays.

Mutual Coupling Reduction in MIMO Microstrip Patch Array Using TM10 and TM02 Modes

A novel decoupling method is investigated for the multi-input multi-output (MIMO) microstrip patch antenna (MPA) array. This method makes use of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> modes, which are simultaneously excited in the rectangular MPA. It is found that by adjusting the frequencies of the two modes, their <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> -fields coupled to the adjacent passive MPA can counteract each other to generate a specific null-field region. When the feeding position of the passive MPA is located in the null-field region, the MPA cannot be excited effectively, and hence an extremely low mutual coupling is obtained without requiring any extra decoupling structure. To validate the feasibility of this decoupling method, an E- and an H-plane-coupled <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 2$ </tex-math></inline-formula> MIMO MPA arrays are respectively simulated, fabricated, and measured. The isolation of the E-plane-coupled array is enhanced from ~11 to 57 dB, while that of the H-plane-coupled array is improved from ~18 to 51 dB.

Isolation enhanced compact dual-band quad-element MIMO antenna with simple parasitic decoupling elements

In this work, a simple parasitic decoupling structure integrated compact dual-band quad-element Multiple-Input Multiple-Output (MIMO) configuration with improved isolation is proposed for 3.5 and 5.8 GHz bands of Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN) applications. The lower and higher frequency bands accomplish an impedance bandwidth of 400 MHz (3.35 – 3.75 GHz) and 450 MHz (5.6 – 6.05 GHz), respectively. A slot integrated curve-shaped compact (11 × 20 mm2) dual-band monopole antenna is explored to implement the proposed compact MIMO configuration. A parasitic decoupling structure comprising T and inverted L-shaped thin metal strips is introduced between the orthogonally placed antenna elements. It exhibits dual stopband characteristics to enhance the isolation significantly at the targeted frequency bands despite the compact footprint (34 × 34 mm2) of the MIMO geometry.The optimized decoupling structure improves the isolation between the elements by 31.5 and 32 dB in the lower and higher bands than the MIMO geometry without decoupling elements. The antenna provides good radiation characteristics with peak gains of 4.18 and 3.62 dBi within the bands. The computed diversity metrics, such as envelope correlation coefficient (< 0.01), diversity gain (> 9.93 dB), mean effective gain ratio (-0.13 to 0.16 dB), channel capacity loss (< 0.4 b/s/Hz), and total active reflection coefficient (< -10 dB), ensures good diversity performance. The fair agreement between the simulated results using HFSS EM solver and the measured results on the fabricated prototype validated the proposed MIMO configuration.

A Low-Profile Decoupling Structure for Mutual Coupling Suppression in MIMO Patch Antenna

In this article, a new low-profile decoupling structure originated from the phase shift concept for the patch antenna array is proposed. To clearly illustrate the operation principle, the phase of the signal transmitted from Patch 1 to Patch 2 has been initially studied and the decoupling condition for two closely spaced patch antennas in H-plane has also been obtained. Afterward, the decoupling element concisely composed of a half-wave microstrip line and a shorting pin is developed. Attributing to the introduction of additional signal path by the new decoupling structure, mutual coupling between two adjacent patches is effectively suppressed. To verify the feasibility of the proposed design scheme, demonstrators of two-element patch antennas with and without decoupling structure are, respectively, implemented and analyzed. Results indicate that compared with the coupled array, the isolation between two patch elements is enhanced from 7 to 18 dB at the center frequency of 3.16 GHz under the edge-to-edge separation of only 0.027 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> . Besides, owing to the single layer layout, the profile of the whole antenna structure is as low as 0.02 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> . Ultimately, the proposed decoupling scheme has been applied to the three-element counterpart, so as to demonstrate and validate its effeteness of isolation enhancement for multielement patch array.

Efficient Fully decoupled and second-order time-accurate scheme for the Navier–Stokes coupled Cahn–Hilliard Ohta–Kawaski Phase-Field model of Diblock copolymer melt

In this work, we aim to develop a highly efficient numerical scheme for the flow-coupled phase-field model of diblock copolymer melt. Formally, the model is a very complicated nonlinear system that consists of the Navier–Stokes equations and the Cahn–Hilliard type equations with the Ohta–Kawaski potential. Through a combination of a novel decoupling technique and the projection method, we develop the first full decoupling, energy stable, and second-order time-accurate numerical scheme for this model. The decoupling technique is based on the design of an auxiliary ODE, which plays a vital role in obtaining the full decoupling structure while maintaining energy stability. The high efficiency of the scheme is not only reflected by its linear and decoupled structure but also because it only needs to solve a few elliptic equations at each time step. We strictly prove that the scheme satisfies the unconditional energy stability and give a detailed implementation process. Numerical experiments further verify the convergence rate, energy stability, and effectiveness of the developed algorithm.

Five-port MIMO antenna for n79-5G band with improved isolation by diversity and decoupling techniques

A compact five-port multi-input multi-output (MIMO) antenna for n79 (4.4–5 GHz) 5G band exhibiting pattern and polarization diversity with good isolation is proposed in this paper. This MIMO antenna system comprises of four linearly polarized (LP) endfire monopole antenna elements and one broadside L-shaped slot circularly polarized (CP) antenna element, which provides both pattern and polarization diversity. A T-shaped slot as a decoupling structure is further used to improve the interport isolation by 4 dB. The return loss bandwidth for all antenna elements is in the desired frequency range, and antenna elements provide isolation better than 23 dB. The pattern and polarization diversity provide a low envelope correlation coefficient and good isolation between any two-port of the MIMO antenna. For experimental verification, the proposed 5-port MIMO antenna system is fabricated and measured, which provides decent agreement with the simulated performance.