Designing MIMO Antenna with High Isolation Decoupling Structure

SummaryA small size neutralization line integrated flower‐shaped MIMO antenna is designed and analyzed for sub‐6 GHz type 5G NR frequency bands like n79 (4400–5000 MHz), n78 (3300–3800 MHz), n77 (3300–4200 MHz), and WLAN (5150–5825 MHz) applications. The novel approach of theory of characteristic mode analysis (TCMA) is introduced to provide physical insight of the designed structure and its characteristics behavior. Due to the suggested modifications in the geometry, the isolation among the patches is greatly increased. The overall miniaturized dimension of the MIMO antenna is 25 × 40 mm2. The edge‐edge spacing among the elements is 0.0233λ. The prototype antenna is fabricated and measured that shows good agreement compared with simulated results. The designed MIMO antenna without the presence of decoupling structure offers an isolation of 28 dB, gain of 3.6 dBi, and radiation efficiency of 69.7% at the resonant frequency. The proposed MIMO antenna covers a broad range of frequency band from 3.296 to 5.962 GHz with −10 dB impedance bandwidth of 2666 MHz and maintains a good isolation of greater than 50 dB for the entire operating band. The tested radiation efficiency and gain are 85.3% and 6.22 dBi at 3.5 GHz. Moreover, the diversity parameters of the neutralization line integrated MIMO antenna, that is, channel capacity loss (CCL) isolation, mean effective gain (MEG), total active reflection coefficient (TARC) diversity gain (DG), and envelope correlation coefficient (ECC), are analyzed and discussed in this article.

Background. Previously, Many MIMO designs were presented for 4G applications. Out of stated 4G MIMO antennas, few designs presented are not suitable for use in mobile phones due to their large size as compared to the standard sizes of current generation mobile phones. The rest, Ceramic based mobile phone antenna and a multi-band MIMO antenna with PIFA structures have significant heights and non-planner structure which makes them unsuitable for mobile phones as they are getting thinner with advancement in technology. Some MIMO antennas were designed with simpler structure and suitable size but they do not have adequate bandwidth. Here there is a need to develop a MIMO system with an adequate bandwidth to cover all 2G, 3G and 4G bands as well as compact to be suitable for mobile communication.Objective. The purpose of the paper is to design a compact planner MIMO antenna Suitable for Mobile communication with enhanced gain and an enhanced bandwidth to cover all 2G, 3G and 4G bandsMethods.i. A monopole was designed with proper dimensions, which was designed to operate at focus recurrence of 1.8GHz. That covers the wide scope of data transfer capacity from 1.1 GHz to 2.7 GHz at -9 dB reference line. Then an inverted L shape structure known as SIR stub technique is used to enhance the bandwidth.ii. The inverted L shape structure which is extended from the ground plane is put around the monopole which generates the low resonant frequencies and also broadens the bandwidth. Bandwidth is broadened to 0.8 GHz to 3.5 GHz.iii. For the purpose of more impedance matching, a small patch is etched from the ground plane opposite to the feeding and all the parameters are optimizedResults. that lower 0.9GHz radiation pattern is omnidirectional while at higher frequencies it is quasiomnidirectional, a steady gain greater than 2.8dBi over the entire frequency band i.e from .8 GHz to 3.5 GHz, avery high gain of 6.7 dBi at 0.9 GHz. The compact wide band planar MIMO antenna has over 80% efficiency over most of the working recurrence For handy application ECC value less than 0.5 is adequate for mobile phones. The measured ECC is less than 0.36 over complete operating frequency band, which is all right for mobile phonesConclusions. The paper presents compact planner two port MIMO antenna with wideband width and high gain. The proposed antenna achieved a wide bandwidth from 0.8GHz to 3.5GHz covering 2G/3G/4G bands and Wi-Fi (2.45GHz). High isolation between antenna elements, lower ECC and high diversity gain makes the design of the compact planner wide band MIMO antenna a suitable possibility for mobile phone applications.

We propose a low-cost, dual band (2.4–5.2 GHz) and dual band (2.4–5.8 GHz) MIMO antennas by using two identical T shaped antenna with high isolation. MIMO is a technique that is used a multiple number of antennas as a transmitter and a receiver. Using artificial magnetic conductor as a reflector made our antenna low profile and high isolated. A dual-band MIMO antenna with high isolation by using artificial magnetic conductor (AMC) is proposed.

A novel compact microstrip MIMO antenna with high isolation and low envelope correction coefficient has been proposed and presented in this paper. The proposed antenna is compact in size with 3.22x4.86 mm2, operating over the frequency band of 60GHz. The MIMO antennas have been designed andsimulated using electromagnetic design and verification platformIE3DTM. Two ports MIMO antenna with the size of 3.22x1.93 mm2 resonates at 58.1 GHz covering a band of 57-59.3 GHz, with the bandwidth of 2.3 GHz, gain of 5.2 dBi, and directivity of 8.67 dBi. It also provides aninput reflection coefficient of -18.41 dB with isolation of -19.98 dB. Proposed four port MIMO antenna resonates at 58 GHz covering a range of 56.9 GHz to 59.2 GHz, with a bandwidth of 2.3 GHz, gain of 5.44 dBi, and the directivity of 9.75dBi. It provides goodisolationranging from -19 dB to -30 dB with input reflection coefficient of -18.09 dB. The envelope correlation coefficient (ECC) of the proposed four-port MIMO antenna is below 0.06 in far-field radiation characteristics. The proposed MIMO antenna has been analyzed for its diversity performance in terms of ECC, mean effective gain, and diversity gain.

In this article, a novel metasurface absorber is designed for RCS reduction as well as high isolation in a 4-elements MIMO antenna. A unit cell of metasurface absorber is amalgamated by concentric circular and elliptical-shaped rings with four 300 ohms lumped resistances. Absorbance at the intended frequency band (i.e. 8.75 GHz-9.00 GHz) of metasurface absorber is more than 90.0% and its reflectivity is tending to zero. Therefore, the isolation between antennas due to this absorbance is improved by 12 dB, and the total isolation of the antenna is achieved less than 23 dB. Similarly, the Radar cross-section (RCS) of the antenna is also significantly reduced by 10dBm2. This MIMO antenna with an absorbing structure is fabricated on a richly existing FR4 substrate with dimensions of 55 × 40 × 1 mm3. The performance of the designed MIMO antenna is also judged by diversity parameters similar to Envelope correlation coefficient (ECC), Directive gain (DG), Mean effective gain (MEG), Channel capacity loss (CCL), Total Active Reflection Coefficient (TARC), and channel capacity, etc. for the proposed frequency band. The simulated and measured ECC of the proposed MIMO is less than 0.073 which exhibits that this antenna is suitable for military application in radiolocation and navigation.

Design and performance of four port MIMO antenna for IOT applications

This paper represents the design and implementation of dual-polarized-triple-frequency 2×2 Multiple-Input-Multiple-Output (MIMO) antenna with extremely high isolation capabilities having total dimensions of 50×155mm2. Proposed antenna succeeds triple band frequency operations including GSM (IEEE-802.21), WiMAX (IEEE-802.16) and WLAN (IEEE-802.11n) bands of modern wireless communication system. Circular polarization has been hosted in WiMAX and WLAN bands with ≤ 3dB axial ratio (AR) while GSM band obeys linear polarization; hence dual-polarized operation has been accomplished with the same geometry. Highly isolated structure has been investigated by means of inverted ground planes and integration of parasitic strips amongst the radiating antennas. Fabricated 2×2 MIMO antenna achieves triple band operations that is, GSM (1.78–1.82 GHz), WiMAX (3.3–3.7 GHz) and lower edge of WLAN (5.15–5.35 GHz) with S11, S22 ≤ −10dB for aforementioned bands and attains S21 ≤ −42dB isolations within electrifying ports. Designed antenna fulfills directional radiation patterns along E-plane and omnidirectional in H-plane with highest −49dB cross polarization levels. Antenna has simulated on MOM based CADFEKO software. Simulated peak gain of 4dBi has been acquired with 78% of peak efficiency. Designed 2×2 MIMO antenna has linear and constant group delay with superior time domain response for a Gaussian pulse.

This paper presents a compact, uni-planer wide band Multiple-Input-Multiple-Output (MIMO) antenna. The designed antenna array has a compact size of (26mm x 31mm) covering a wide frequency band from 3.1GHz - 11GHz. A partial ground plane shared by two radiating patches is used. A ground stub and a single column Electromagnetic Bandgap (EBG) structure in between the two radiating patches results in very low mutual coupling in the designed antenna. The proposed MIMO-antenna was evaluated through different performance metric indicators like channel capacity loss, far-field radiation pattern, S-parameters, envelope correlation coefficient, peak gain, diversity-gain and radiation efficiency. Our designed MIMO antenna has a very high isolation amongst the MIMO antennas ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}_{21} &lt; -25$ </tex-math></inline-formula> dB), a high Diversity-Gain (DG <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;9.995$ </tex-math></inline-formula> dB), a very low Envelope Co-relation Coefficient of (ECC < 0.001) and low Channel-Capacity-Loss (CCL < 0.1bits/s/Hz). The said antenna has an average radiation efficiency of 85.5% and a peak gain of (5.67dB) within the ultra-wideband (UWB) spectrum. A 0.8mm thick FR-4 substrate is used to fabricate the MIMO-antenna and tested in an anechoic chamber. The measured results closely match with the simulated results.

A dual-band two-port MIMO antenna with high isolation and efficiency is proposed in this article. Each antenna element is composed of a rotated U-shaped strip and an L-shaped strip. The MIMO antenna is optimized to operate in 2.5–2.7 GHz and 4.8–5 GHz, which can cover the 5G bands of China Mobile. The defected ground structure consists of a slant square loop with a T-shaped slit and a U-shaped slot. A rectangle parasitic strip is placed in the U-shaped slot. The use of defected ground structure and parasitic strip makes the antenna obtain good isolation which is better than −17.96 dB and − 20.1 dB at the lower and higher frequency bands. To evaluate the antenna diversity, envelope correlation coefficient (ECC) is analyzed which is lower than 0.0006 and 0.12 at the lower and higher frequency bands, respectively. The measured gains are 4.35 dBi and 4.6 dBi, while the measured efficiencies are 63.23% and 68.69% at 2.6 GHz and 4.9 GHz, respectively. The prototype of antenna is fabricated to verify the functioning of proposed antenna design.

In the paper, an extremely compact multiple-input-multiple-output (MIMO) antenna is proposed for portable wireless ultrawideband (UWB) applications. The proposed prototype consists of four monopole antenna elements, which are placed perpendicularly to achieve polarization diversity. In addition, the mutual coupling between antenna elements is suppressed by designing the gap between the radiation element and the ground plane. Moreover, a matching stub has been connected to the feedline to ensure impedance matching in high frequency. Both simulated and measured results indicate that the proposed antenna has a bandwidth of 3–20 GHz, with a high isolation better than 17 dB. In addition, the designed MIMO antenna offers excellent radiation characteristics and stable gain over the whole working band. The envelope correlation coefficient (ECC) is less than 0.1, which shows that the antenna can meet the polarization diversity characteristics well.

Design of a compact quad-radiating element MIMO antenna for LTE/Wi-Fi application

This communication proposes a two-port multiple-input-multiple-output (MIMO) antenna fabricated on a small size colored resin plastic button where full dielectric properties of the button substrate are evaluated before designing the MIMO antenna. The antenna uses partial ground plane and two coaxial feeds for the excitation of two semicircular shaped patch elements. A very simple copper ring around the four slots of the button is used to obtain very high port isolation. The antenna covers the frequency range from 7.96 to 8.76 GHz and fulfills the International Telecommunication Union (ITU) band (8-8.5 GHz) for fixed wireless communication application. It provides very high port isolation (>21 dB) and diversity gain (DG > 9.8 dB) over the whole band. The investigated envelope correlation coefficient (ECC) (<; 0.18) and channel capacity loss (CCL) (<; 0.24 b/s/Hz) are potentially very low. The mean effective gain (MEG) (±0.3 dB) over the entire application band is found in a well-accepted range. The prototype could be mounted on a textile material of on-body cloths for different wearable monitoring purposes. The simulated and measured outcomes are matched with a satisfactory level to mark the proposed two-element two-port button antenna as a suitable MIMO candidate for the specified application band.

This paper proposes a compact 4-port MIMO antenna resonating at 90GHz with its design and analysis. The proposed MIMO antenna employs a microstrip circular patch antenna containing rectangular slots as its single element. The antenna is designed on a Rogers RT/duroid 5880™ substrate and then modified for high isolation and nominal mutual coupling among ports. The single-element has a reflection coefficient of −52.3dB and an absolute bandwidth of 7.88GHz, while the 4-port MIMO configuration achieves an absolute bandwidth (<−10dB) of 12.8GHz, ranging from 83GHz to 95.8GHz. The proposed antenna shows peak gain of 9.465 dB at 90GHz and a peak gain of 10.172 dB within its whole operating band. Diversity performance parameters confirm excellent MIMO behavior, with ECC=0.00302, DG=9.99995dB, TARC =−12.6dB, and CCL=0.00364bps/Hz at the antenna's resonating frequency of 90GHz. The results demonstrate independent radiation patterns, low capacity loss, high signal reliability and isolation (Transmission Coefficients <−25dB), showing antenna's suitability for compact, high-speed, and low-loss communication systems in emerging 5G and 6G technologies.

Compared to antennas bearing a single port, MIMO antennas with several ports enable higher data throughput by exploiting spatial diversity. This capability is essential for next-generation implantable medical devices, where high channel capacity is a key requirement. A quad-element implantable MIMO antenna is designed and practically validated at 1420 MHz in this paper. It occupies a compact volume of 7×8×0.1 mm3 (5.6 mm3). The compactness is realized by combining high-permittivity substrate (Rogers 3010 with relative permittivity of 10.2) with meandered radiator paths, which increase the effective current length while maintaining a small physical size. All antennas have very small mutual coupling with isolation of more than 31.78 dB, which is mainly due to the spacing of 1 mm between the elements and the substrate, which is thin. The peak realized gain for each antenna element is -27.3 dBi. The simulation is performed within a capsule-like structure, which is embedded in the stomach tissue model. The experimental verification is carried out by embedding antenna within minced meat. The ECC, channel capacity, and link margin are also evaluated and found to be satisfactory. The proposed antenna ensures reliable communication performance, with the transmission range being as high as 2.5 m, link margin being 15 dB, and the data rate being 120 Mb/s. The proposed antenna ensures a good level of ECC, which is less than 0.1. The SAR is 52.3 W/kg at 1420 MHz. This design is favorable for implants because of the small size, good impedance matching, high isolation, low correlation, good level of gain, and good link performance.

A compact four-unit MIMO antenna operating in the 2.45-GHz ISM band for implantable applications is proposed. Two radiators are integrated on the same antenna, and each radiator is shared by two antenna elements, greatly reducing the overall size of the implantable MIMO system. High isolation between two antenna elements is achieved by etching a “+”-shaped slot in the radiator, extending a stub on the ground and embedding two electromagnetic band gaps (EBG) between the radiator and the ground. The proposed MIMO antenna has a dimension of 18.5 × 18.5 × 1.27 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The simulated impedance bandwidths are 18.64% (2.14-2.58 GHz). The simulated maximum mutual coupling is below -15.99 dB at ISM band. The envelope correlation coefficient has been researched and the results indicate the independence between the antenna elements.