Mutual Coupling Reduction Research Articles

A novel beam design method for mmWave multi-antenna arrays with mutual coupling reduction

To overcome the mutual coupling (MC) of multiple antennas in millimeter wave (mmWave) communication systems, a novel beam design method with low complexity is proposed in this paper. Firstly, an equivalent channel model incorporating the effect of MC is analyzed and established, and then an optimal precoding / combiner vector for beamforming is derived. On this basis, by using greedy geometric (GG) algorithm, a novel hybrid beam design method is proposed. Finally, the performance of proposed method is analyzed and compared with other traditional ones. The simulation results show that the proposed method has better suppression of the MC effect as well as lower complexity.

Mutual coupling reduction between patch antennas based on microstrip structures

AbstractA practical design of reduction mutual coupling is presented between patch antenna elements by using symmetrical microstrip structures in the paper. The patch antenna design consists of the following: two antenna patches, a rectangular substrate plane, a pair of three orders symmetrical microstrips, and a common ground. By using the proposed scheme, approximately 35 dB mutual coupling reduction is achieved at central frequency of 7.3 GHz while maintaining gain of 2.3 dB and directivity of 5.53dBi. Return loss slightly decreases by 2.91 dB from −23.12 to −20.21 dB. In contrast, it exerts no effects on gain radiation characteristics in a no microstrip setup. Simulation results of this technique are verified validated using experimental measurements.

Isolation improvement of a two‐port PIFA for MIMO using a planar EBG ground

AbstractIn this article, the mutual coupling reduction of a two‐port planar inverted‐F antenna (PIFA) using a planar electromagnetic bandgap (EBG) structure is presented and investigated for multiple input multiple output/diversity applications. The planar EBG structure is designed for etching on the ground plane of the device. The EBG and the antenna design parameters are identified and the frequency scalability of the design is illustrated by showing two separate designs at 2.45 and 3.50 GHz. The optimized 2.45 GHz design demonstrates 25 dB more coupling reduction compared to the state of the art PIFA with a slot on the ground. Analyses of efficiency and effective diversity gain are also performed which show excellent performance.

Broadband Low-RCS Phased Array With Wide-Angle Scanning Performance Based on the Switchable Stacked Artificial Structure

A novel and simple switchable stacked artificial structure (SAS) is proposed and studied in phased arrays to realize a smart integration of broadband radar cross section (RCS) reduction and scanning range expansion. The proposed SAS is composed of a frequency selective surface (FSS) and a metamaterial absorber (MA). The lower part of the SAS can be switched between an FSS and a surface-waveguide (SWG) high-impedance surface (HIS) hybrid structure which can be used for wide-beam antenna design and array mutual coupling reduction. The upper part of the SAS can be seen as an MA. A linear phased array is presented and investigated based on the proposed switchable SAS. When the phased array is switched to its working mode, the SWG-HIS hybrid structure plays an important role to support a wide-angle scan from −75° to +75° with low sidelobes. When the phased array is shut down, the FSS-MA stacked structure can realize a low-RCS design in the frequency range of 0–11.2 GHz. An array prototype which operates at 4.6 GHz is fabricated and measured. The measured results have validated the radiation and scattering performance of the designed phased array.

An 8-Element Dual-Band MIMO Antenna with Decoupling Stub for 5G Smartphone Applications

An 8-element dual-band multiple-input–multiple-output (MIMO) antenna operating in the 5G New Radio band n77 (3300–4200 MHz) and 5 GHz band (4800–5000 MHz) in mobile handsets is presented. The 8-element MIMO antenna is formed by employing four sets of dual-antenna arrays (DAAs) that are symmetrically printed along the two long side–edge frames of the smartphone. Each DAA is composed of two double-branch monopoles and a T-shaped decoupling stub, in which good mutual coupling reduction can be realized via the decoupling structures. Furthermore, the decoupling structures can also aid in improving the impedance matching of the array units for achieving wideband operation.

Design of Steered Array Lens Antenna System with Isolation Enhancement

A new compact economical patch array antenna with beam steering ability and mutual coupling reduction between the patches is presented in this article. By incorporating modified hexagonal spilt ring resonator metamaterial structure in one of the 1 X 2 patch array enables the property of beam steering as well as mutual coupling reduction. Similarly, by incorporating modified hexagonal split ring metamaterial structure in both the patch of 1x2 patch array antenna mutual coupling reduction of around 21dB at 2.4GHz without beam steering capability is observed. The spacing of 0.25λo between the patches of an antenna array, around 24 dB lower mutual coupling at the operating frequency is obtained. Both left and right modified patch produces a beam scanning of -200 to +200 respectively. The fabricated prototype antenna results are validated with simulation results using experimental measurements.

Mutual coupling reduction in metamaterial antenna for terahertz application

We investigate in this work an effective approach to reduce mutual coupling between two metamaterial antennas operating at the THz frequency band by incorporating a metasurface designed using an electric inductive capacitive resonator. The metasurface is designed to provide a band stop functionality in the operating bandwidth of the antenna. The proposed method shows that the improvement of mutual coupling is at least 10 dB compared with conventional antennas. Thus, this proposed approach can be utilized to mitigate mutual coupling between antennas in THz application. Moreover, to enhance the antenna performances in terms of return loss, directivity, gain, and radiation efficiency, the antenna is designed with a mushroom structure based on the zeroth-order resonant characteristic of a composite right/left-handed transmission line. The electromagnetic behavior of the antenna is studied and an analytical equivalent-circuit model is also proposed.

Defected Ground Structure Based Two Element Microstrip Antenna Array with Reduced Mutual Coupling

In this paper two element microstrip antenna array with dumbbell shaped defected ground structure (DGS) is on reduction of mutual coupling is presented. The proposed of DGS antenna is simulated by an soft HFSS simulation software. this work is obtain a miniaturized microstrip patch antenna array using DGS for S Band is 2.2GHz.Initally the patch antenna array is designed at C band resonates at 5.2 GHz and the proposed of DGS is integrated in the ground plane of patch antenna for size reduction and this miniaturization is at cost of gain antenna and in order to improve the gain of miniaturized radiator. Patch radiator is further modified to radiation properties, so finally the resonance frequency of an initial microstrip antenna array shifts to 3.75 GHz to 7.15 GHz with the gain of 2.92 dB and its miniaturization performance is up to 63% and its conventional microstrip is successfully accomplished. The prototype antenna is fabricated with the FR-4 substrate and this technique is validate experimentally and measured results with good agreement as stimulated results.

Mutual Coupling Reduction of 1×2 Microstrip Array Antenna Using MMAS-SSR

The issue that often arises and that is recently discussed in the development of antenna array is mutual coupling between elements. Elements of an antenna array are designed to be very close to one another in order to achieve a higher gain. However, such design could lead to an emerging problem of mutual coupling, resulting in a decreased efficiency and a change in beam pattern, mainly when using microstrip antenna. In order to reduce the mutual coupling effect, elements of the antenna are isolated using metamaterial absorber split square resonator structure (MMAS-SSR). In the experiments performed, two simple linear array microstrip antennas have been configured in a linear array, and a single line of metamaterial absorber structure was placed between them as an isolator. The observation has been conducted over experiments with and without the line of metamaterial absorber structure. The simulation and the measurement results obtained show that there is a mutual coupling reduction of 8 and 6 dB, respectively.

Design and Research of Modified Split Ring Resonator for Reduction of Mutual Coupling in Microstrip Patch Antenna Array

In this document, we proved a new technique for eliminating the impact of mutual connection amongst elements in an antenna array by integrating the Metamaterial Hybrid Split Ring Resonator (HSRR). The HSRR suggested unit-cell consists of a single circular ring resonator, each rounded with two symmetrical divisions, with one hexagonal ring resonant. The insulation of over 13 dB without affecting the working frequency and radiation features shall be accomplished by integrating the HRSR metamaterial framework near the correct side of the standard radiating patsch of the antenna array running at 2.4 GHz. The efficiency of the HSRR antenna array proposed has been numerically assessed

Miniaturized Microstrip Patch Antenna Array for ISM Band Using Complementary Split Ring Resonator

These days patch antenna arrays are widely used in various communication systems. In this research design of miniaturized microstrip patch antenna array is presented. Miniaturization is achieved by reducing the mutual coupling between patch antenna elements. Complementary Split Ring Resonator is used to reduce the mutual coupling between patch elements in array. The mutual coupling between patch elements with and without resonator is calculated using High Frequency Structure Simulator. It has been observed that the mutual coupling between elements is reduced by 20 dB at 2.4 GHz by using resonator. Due to reduction in mutual coupling, patch antenna elements can be fabricated in less space which leads to compact antenna array system design. A miniaturization of 4.34% is achieved for two element Patch array without affecting the power gain and directivity of patch antenna array.

Reduction of mutual coupling between patch antennas using defected ground structure in L‐ and S‐bands

AbstractMutual coupling (MC) is a common phenomenon in array antennas, which severely reduces antenna performance. Therefore, reducing MC is an important direction in array antennas. This article presents a novel defected ground structure (DGS) suppressing the MC between L‐ and S‐band microstrip patches. The antenna operates in two frequency bands with both relative bandwidths of approximately 10%. To reduce the overall size, the antennas of the two bands are designed together, using the same ground, reflective cavity, and dielectric substrates. By introducing six DGSs in the middle of the ground, the surface currents of the two frequency bands are cutoff, thus reducing the MC. A prototype is fabricated and measured. From the measured results, the isolation of more than 26.18 dB can be achieved in the L‐band from 1.6 to 1.8 GHz, and the isolation of 12.3 dB can be achieved in the S‐band from 2.05 to 2.25 GHz with the adoption of the DGS. The impedance bandwidth with return loss greater than 15 dB is 11.76% and 9.3% in the L‐ and S‐bands, respectively, which provides valuable reference for the design of other dual‐band antennas.

Mutual coupling reduction in circularly polarized dielectric resonator MIMO antenna

In this article a novel circularly polarized (CP) rectangular dielectric resonator antennas (RDRA’s) array has been designed. A unique conformal feeding strip has been used to excite the RDRA’s having a distance of λ/2. Various techniques are investigated to reduce mutual coupling (MC). Different formations, comprise of reorientation of the antennas have been employed to suppress MC and to enhance CP bandwidth. By the unique orientation the mutual coupling has been reduced by ~ 14 dB. A broadband circular polarization over a bandwidth of ~ 18.8% in conjunction with an impedance matching bandwidth of ~ 11.3 % has been achieved. The design has been modeled and simulated using computer simulation technology (CST). Two different simulation techniques i.e. finite integration technique (FIT) and Finite element method (FEM) have been used to compute and validate the results respectively. A significant resemblance in results have been observed.

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.

Novel double-side EBG based mutual coupling reduction for compact quad port UWB MIMO antenna

In this article, novel compact quad-port double-side Multiple-input-multiple- output (MIMO) antenna designed with Electromagnetic Band Gap (EBG) structure to improve isolation for Ultra Wide Band (UWB) applications. The presented MIMO configuration comprises four polygon shape radiating elements and partial slotted EBG stub ground structure. Both sides of the FR4 substrate are symmetrical, each side consisting of two radiators, and one partial ground plane is related with the other two components attached on the opposite side. The EBG decoupling structures are used on both the front and the back side of the board to diminish the correlation coupling among the radiators. The proposed MIMO antenna performance has also been studied regarding impedance bandwidth, current distribution, radiation model, envelope correlation coefficient (ECC), peak gain and TARC. The proposed MIMO antenna system has an impedance bandwidth of 3.1–11 GHz, peak gain of 2.5–6.8 dBi and less than 0.004 ECC. Furthermore, the proposed MIMO antenna shows UWB bandwidth, an almost omnidirectional radiation pattern, high isolation, uniform gain, and multi-polarization. The proposed double-sided MIMO antenna was tested in an indoor environment using NI USRP to verify performance in real time.

Bandwidth Enhancement and Mutual Coupling Reduction Using a Notch and a Parasitic Structure in a UWB-MIMO Antenna

The correlation between the antennas of multiple-input, multiple-output (MIMO) systems in limited spaces and size degrades the performance and capacity by either using complex coupling or decoupling structures. For isolation improvement, this paper presents the simple design of a compact high-isolation ultra-wideband (UWB) MIMO antenna with a circular parasitic element at the back side of the radiating patch, thereby creating the reverse coupling and helping reduce the mutual coupling at the upper part of the frequency bands, and a small rectangular notch at the ground plane to extend the impedance bandwidth of the monopole antenna. This approach eliminates the use of complex coupling or decoupling structures and complex feeding networks. A novel feature of our design is that the MIMO antenna exhibits a very low envelope correlation coefficient (ECC < 0.007) with high diversity gain (DG > 9.99) and wide impedance bandwidth of 139 % from 3.1 to 17.5 GHz applicable for not only UWB application, but also next generation wireless communication, 5G. The high peak gain over the entire UWB and the upper part of the overall frequency band ensure that the antenna can be used in MIMO applications owing to the close agreement between the simulated and measured results.

Mutual Coupling Reduction of DRA for MIMO Applications

In this paper, A multiple input Multiple Output (MIMO) antenna using two Square Dielectric Resonators (SDRs) is introduced. The mutual coupling between the two SDRAs is reduced using two different methods; the first method is based on splitting a spiral slot in the ground plane, then filling the slot with dielectric material, "E.=2.2". The second method is based on inserting a copper parasitic element, having the same shape of the splitted Spiral, between the two SDRAs. The effect of replacing the copper parasitic element with Carbon nanotubes (CNTs) parasitic element "SOC12 doped long-MWCNT BP" is also studied. The antenna system is designed to operate at 6 GHz. The analysis and simulations are carried out using finite element method (FEM). The defected ground plane method gives a maximum isolation of l8dB at element spacing of 30mm (0.6λo), whereas the parasitic element method gives a maximum isolation of 42.5dB at the same element spacing.

Wideband mutual coupling reduction and scan blindness elimination in a microstrip patch phased array antenna with truncated soft surface structures

This article introduces a new type of soft surface as truncated soft surface (TSS) for the mutual coupling reduction in stacked aperture-coupled microstrip patch phased array antennas. Also, a meandered TSS (MTSS) is introduced with a reduced size compared to the TSS. Conventional soft surfaces not only prevent the propagation of waves in the soft longitudinal direction but also guide the waves in the transversal direction. So, the mutual coupling decreases in the soft longitudinal direction and increases in the transversal direction. Truncation in the transversal direction prevents the waves from guidance on TSSs. Simulation results show that using this technique helps to decrease the mutual coupling in the E-plane of a phased array antenna without any noticeable increase in the H-plane coupling. Also, there is no blind spot in the desired scan range and the embedded element pattern will not have any null in the scan range. Using this technique, the acceptable scan range for an antenna substrate with a low relative permittivity of 2.33, can be increased up to 45°. Finally, measurement results show that using TSS leads to an 8-dB decrement in the E-plane mutual coupling.

On the design of a reject band filter for antennas mutual coupling reduction

In this article, a novel concept for mutual coupling reduction between antenna elements is proposed at 2.45 GHz for Wi-Fi applications. A reject band filter (RBF) is used in order to reduce the mutual coupling between two monopoles for multi-input multi-output (MIMO) systems. The proposed RBF inclusions are developed to have zero refractive index response over a specific frequency band. The inclusions considered here are composed of open-loop resonators; each one with the same iteration level of Minkowski-like pre-fractal structures coupled with an open-stub transmission line to increase the band selectivity. The inclusions are inserted between λ/2-spaced monopole elements at 2.45 GHz. A significant mutual coupling reduction is realized by incorporating only two RBF cells. Such effective response is attributed to the electromagnetic wave cloaking at 2.45 GHz using the developed RBF inclusions. An extensive theoretical study using both numerical and analytical methods is invoked to obtain the best performance of the proposed MIMO antenna structure. Finally, the experimental and numerical results are agreed excellently.

Suppression of mutual coupling in rectangular dielectric resonator antenna arrays using Epsilon-Negative metamaterials (ENG)

ABSTRACTA double slotted symmetrical split ring resonator with an inductive stub in its inner ring is presented as a Single Negative Electric (SNG) metamaterial to suppress mutual coupling between two E-plane coupled microstrip line fed rectangular dielectric resonator antenna (RDRA) array. The proposed SRR exhibits two resonant frequencies and wide stop-bands. The -10 dB bandwidth of S21 from 2022MHz to 2720 MHz and from 2187 MHz to 3839 MHz are obtained for the first structure, #1, and the second structure, #2, respectively. By introducing an ENG layer between the two RDRAs, the experimental reduction in mutual coupling is more than 23 dB with a small frequency shift (∼ 20 MHz), while the impedance matching is improved. The radiation efficiency and total efficiency are increased while the far-field pattern in the E-plane is not disturbed.