Ultra-wideband Multiple-input Multiple-output Research Articles

Highly isolated electrically compact UWB MIMO antenna for wireless communications applications

A multiple-input multiple-output Ultra-Wide Band (UWB) antenna with a compact size of 0.8λ x 0.7λ is proposed. The presented structure is constituted with patch geometry on a planar surface. The radiator consists of three counter U-shaped conducting strips united with a patch structure where two are positioned nearby and the third geometry covers the remaining conducting strips. A corrugated design has been created on a ground plane in which zigzag pattern slots are engineered to receive high isolation of more than 20 dB. The configured antenna radiates over a wide frequency spectrum of 3.10 GHz–11.85 GHz. It offers a fractional bandwidth of 195 % with a gain of 2.80 dBi, 3.08 dBi, and 2.72 dBi for targeted resonances. The antenna radiation patterns and MIMO diversity parameters are also presented. The acceptable values of ECC (<0.05 abs), MEG (−6 dB to −8 dB), CCL (<0.02 bits/sec/Hz) were found. The fabricated model was tested inside an anechoic chamber environment to receive the measured response with optimum accuracy through multiple iterations. The measured response shows a strong correlation with numerically computed responses finding the presented antenna suitable for WiMAX, WLAN (max protocol) and radar applications.

Transparent and flexible fish-tail shaped antenna for ultra-wideband MIMO systems

Abstract The article presents an innovative transparent, flexible antenna design tailored specifically for ultra-wideband multiple-input multiple-output (MIMO) systems. Using polyethylene terephthalate substrates as the base material, we enhance the antenna’s radiation performance, transparency, and flexibility. Broadband impedance matching is achieved through a hollow ground plane fed by a fish-tail radiator and coplanar waveguide. Additionally, significant MIMO antenna isolation in ultra-wideband scenarios is achieved through the vertical arrangement of units and neutral lines. The MIMO antennas we manufactured exhibit minimum transparencies of 71.1% and 85.9% with and without reflectors, respectively. Measurement results demonstrate that the antenna operates within the 3–20 GHz frequency range, with over 24 dB of isolation, 2 ± 2 dBi of peak gain, and 45% ± 5% of radiation efficiency, suitable for applications in wearable devices, vehicle intelligence, and other fields.

A novel BP algorithm‐based UWB MIMO ground‐penetrating imaging system

AbstractUltra‐wideband (UWB) multiple input multiple output (MIMO) radar has been widely used in detection systems due to its advantages, such as low cost and high data acquisition capability. The detection system is applied in various ground‐penetrating applications, including mine detection and earthquake rescue. In this paper, a novel UWB MIMO radar system based on step‐frequency continuous wave is designed for underground target detection. To improve the penetration depth and high‐range resolution, a new miniature Vivaldi antenna with a bandwidth of 1–3 GHz is designed and integrated into the ground‐penetrating imaging system. Furthermore, a multiscale weighted time‐domain back projection (BP) algorithm is proposed to suppress artifacts and reduce the computational complexity of the BP algorithm. The designed system is tested by detecting stationary targets. The experimental results agree well with the simulation. The reconstructed images show that the designed MIMO radar system can successfully image underground targets.

DESIGN OF HIGHLY ISOLATED UWB MIMO ANTENNA USING STUBS BETWEEN GROUND PLANES

This study introduces an in-depth analysis and evaluation of a novel High-Isolation Ultra-Wideband (UWB) Multiple Input Multiple Output (MIMO)antenna design featuring the integration of Stubs between ground planes.The objective is to develop an antenna system capable of achieving high isolation between closely spaced antenna elements for MIMO applications while maintaining a wide operating bandwidth. The proposed antenna is composed of four slot antenna elements with a common rhombic slot, each fed by a microstrip-fed line to greatly reduce the overall size of the antenna.It has a compact size of (34 x 34 x 1.6 mm3).The wide frequency range of Ultra-wide band lies in the range of 3.1 to 10.6 GHz and wide channel bandwidths of 500 MHz.The combination of ultra-wideband multiple-input and multiple-output(UWB MIMO) technology has high transmission rate,good communication quality and large channel capacity.Investigation will be done with respect to correlation parameter coefficients,radiation characteristics,efficiency,realized gain and the active reflection coefficient. In essence,the Highly Isolated MIMO Antenna marks a significant stride in antenna technology and in the field of wireless communication.CST(Computer Simulation Technology) is used to design the proposed antenna. Keywords-Antenna,Isolation,UWB,MIMO,Stubs,S-Parameter Results.

A low profile circularly polarized metasurface-based ultra-wideband 4x4 MIMO antenna for 5G NR band FR2 frequencies

This article presents a polarization conversion metasurface-based low-profile ultra-wideband circularly polarized (CP) multiple-input multiple-output (MIMO) antenna with high performance that is specifically designed for operating in 5G New Radio (NR) bands in frequency range 2 (FR2). For these frequency bands, the 4-port MIMO antenna is being proposed for the first time and is capable of being operated in all of the newly created radio frequency bands in the 5G FR2 region. The main advantage of the proposed configuration is that it requires no isolation/decoupling circuit and the antenna elements are placed orthogonal to their adjacent elements. The 4x4 MIMO antenna offers a good impedance bandwidth of 111.09 % ranging from (12.87–45.02) GHz below − 10 dB reflection coefficient with a minimum isolation of –23.77 dB and maximum isolation of −52.53 dB. The maximum peak realized gain of the 4x4 MIMO antenna without metasurface is 8.14 dBi in the operating band. An improvement of 47 % in the peak realized gain was observed after stacking the metasurface on top of the radiating patch. The proposed antenna produces a circular polarization (CP) in the desired operating band. The 3-dB axial ratio impedance bandwidth for the lower band in millimeter wave (mm-Wave) is 14.13 % ranging from (23.22 – 26.75 GHz) and for the upper band is 7.92 % ranging from (40.82 – 44.19 GHz). Initially, the proposed antenna is designed for a single element and it is extended for a 4-element MIMO with added 4x4 metasurface unit cells for improvement of gain and polarization conversion. The simulated and measured results are in good agreement. In addition to that, the envelope correlation coefficient (ECC), channel capacity loss (CCL), total active reflection coefficient (TARC), mean effective gain (MEG), and diversity gain (DG) are calculated and simulated for the proposed four-element MIMO antenna. The designed metsurface-based circularly polarized MIMO antenna covers all 5G new radio frequency bands in FR2 and hence the designed antenna is applicable for 5G NR band FR2 in mm-Wave communications.

A Compact Highly Isolated Four-Element Antenna System for Ultra-Wideband Applications

A small, orthogonally polarized, ultra-wideband (UWB), four-port multiple-input multiple-output (MIMO) printed antenna is presented in this study. The envisioned antenna is built up of four microstrip fractal-based circular patch elements, each of which is fed by a microstrip line with a 50-ohm impedance. The use of a defective ground plane allows for the ultra-wideband frequency response to be obtained. In order to achieve maximal isolation, the amount of surface current that flow between the antenna’s four components is limited by arranging radiating elements orthogonally. The four-port MIMO system is printed on a FR4 substrate with a loss tangent of 0.02 and an overall dimension of 20 × 30 × 1.6 mm3. A port-to-port isolation of less than 25 dB was achieved as a consequence of this orthogonal orientation of antenna elements, and the impedance bandwidth is achieved up to 158% (3.1–12 GHz). The suggested ultra-wideband multiple-input multiple-output (UWB-MIMO) antenna achieved a maximum gain of 8 dBi over the operational frequency range (3.1–12 GHz); the findings that were measured and those that were simulated accord with one another rather well. The findings also give an overall strong diversity performance, with the ECC &lt; 0.25, DG &gt; 9.9, and CCL &lt; 0.2 values all being within acceptable ranges.

A 4-Element UWB MIMO Antenna System with High Isolation Performance

This paper proposes a 4-element multiple-input multiple-output (MIMO) antenna system, which is intended for ultra-wideband (UWB) applications. The antenna has a dimension of 92 × 70 × 1.6 mm3. It achieves element isolation via the defected ground structure (DGS) and symmetric E-shaped branch structures design. The realized operating bandwidth is from 3 GHz to 18 GHz, with 15 dB isolation within the whole wide band. The envelope correlation coefficient (ECC) is less than 0.01 with diversity gain (DG) greater than 9.95. The prototype is fabricated and measured to verify its potential applications for UWB MIMO communication.

Compact MIMO UWB antenna integration with Ku band for advanced wireless communication applications

This paper introduces a compact Multiple Input Multiple Output (MIMO) Ultrawideband (UWB) antenna seamlessly integrated with the Ku band, tailored for wireless communication applications. The MIMO antenna employs octagonal radiators, crafted from a tapered microstrip line-fed rectangular patch, etched on an economically efficient FR4 substrate measuring 40 × 23 mm2. The octagonal configuration is achieved by introducing a rectangular patch to the central radiator, while parasitic stubs are strategically employed to mitigate coupling among MIMO elements. The antenna demonstrates an extensive operational bandwidth spanning 3.28–17.8 GHz, covering UWB, extended UWB, and Ku-band spectrums globally allocated for heterogeneous applications. With a peak gain of 4.93 dBi and an efficiency of 95.34%, the proposed MIMO antenna showcases superior performance. Key performance parameters, including a low envelope correlation coefficient (ECC) of 0.003 and a substantial diversity gain (DG) of 9.997 dB, are thoroughly analyzed. Comparative assessments against recent works validate the novelty and potential of the proposed antenna for integration into compact wireless systems. This study underscores the success of the antenna design in achieving a harmonious balance of compactness, wide operational bandwidth, and high performance, positioning it as a promising candidate for diverse wireless communication applications.

Ground plane alteration extremely wideband SPAS pair-based MIMO antenna with improved isolation and band notched characteristics

A novel and effective Slotted Pentagonal Adjacent Structure (SPAS) pair based Ultra Wideband (UWB) Multiple-Input Multiple-Output (MIMO) antenna is presented in this research paper. The proposed antenna with a compact size of 0.25 λ0 × 0.50 λ0 mm2 consists of a two slotted pentagonal patch element along with ground plane alteration (GPA). Four hexagonal metallic rings with opposite split orientation are embedded in the patch elements to achieve three notch bands. This proposed loop-based split ring resonator (SRR) design focuses on miniaturization or compactness while maintaining effective notch performance. According to the experimental results, the suggested UWB MIMO antenna's impedance bandwidth ranges from 4.0 GHz to 40.25 GHz cover with triple notch bands IEEE INSAT extended C-band (6.05 GHz to 7.16 GHz), X-band (8.9 GHz to 10.28 GHz) and K-band (24.65 GHz to 26.95 GHz). High isolation of > 24 dB is achieved by integrating a parasitic strip with ‘O’ shaped SRR slot in between the radiating elements. The fabricated compact antenna has good radiation patterns, high gain, TARC < −10 dB, high efficiency and low envelope correlation coefficient which is suitable for advanced wireless communications.

Six-element MIMO antenna structure with squared ring structure with multiband and high gain characteristics for C/X/Ku/K band applications

Using ring resonator structure, we have presented a structure of the six-element multiple input multiple output (MIMO) antenna structure. The proposed structure is numerically investigated and experimentally verified for antenna performance in the 1 to 25 GHz wideband frequency range. We have designed and verified the five antenna structure types, which consist of the various forms of ring/patch with different ground plane geometries. Various performance parameters like gain, directivity, reflections, and electric field distributions are analyzed for MIMO antennas. Essential performanceparameters observed for the MIMO antennas are also presented in this manuscript to identify the behaviour of the structure with different physical conditions. These parameters are also investigated for the identification of suitable ranges for the multi-channel transmission capability of the communication system. Return loss and Gain values are< −12 dB and ∼ 20 dBi achieved with ∼12 GHz of the operating bandwidth. Overall, the antenna offers minimum return loss values of −25 dB for the operating band of 19 to 25 GHz with anoperational bandwidth of 6 GHz. The designed antennas are tested using a ground patch and a rectangular patch in a scattered manner, and the obtained results are utilized in the Ultrawideband MIMO antenna applications. These antennas are also used in various band operations in satellite communication, including C/X/Ku/K bands.

A Novel Densely Packed 4 × 4 MIMO Antenna Design for UWB Wireless Applications.

In this article, a compact 4-port UWB (Ultra-Wide Band) MIMO (Multiple Input Multiple Output) antenna is proposed. A low profile FR-4 substrate is used as a dielectric material with the dimensions of 58 × 58 mm2 (0.52λ × 0.52λ) at 2.8 GHz and a standard thickness of 1.6 mm. The proposed design characterizes an impedance bandwidth starting from 2.8 to 12.1 GHz (124.1%). Each of the four elements of the proposed MIMO antenna configuration consists of a monopole antenna with PG (partial ground) that has a slot at its center. The corner of each patch (radiator) and ground slot are rounded for impedance matching. Each unit cell is in an orthogonal orientation, forming a quad-port MIMO antenna system. For reference, the partial ground of each unit cell is connected meticulously with the others. The simulated results of the proposed quad-port MIMO antenna design were configured and validated by fabrication and testing. The proposed Quad-port MIMO design has a 6.57 dBi peak gain and 97% radiation efficiency. The proposed design has good isolation below 15 dB in the lower frequency range and below 20 dB in the higher frequency range. The design has a measured ECC (Envelop Correlation Co-efficient) of 0.03 and DG (Diversity Gain) of 10 dB. The value of TARC (Total Active Reflection Coefficient) over the entire operating band is less than 10 dB. Moreover, the design maintained CCL (Channel Capacity Loss) < 0.4 bits/sec/Hz and MEG (Mean Effective Gain) < 3 dB. Based on the obtained results, the proposed design is suitable for the intended high data rate UWB wireless communication portable devices.

Design of UWB MIMO antenna using lean wearable textile substrate for reduced SAR

PurposeThis paper aims to propose a two-element dual fed ultra-wideband (UWB) multiple input multiple output (MIMO) antenna system with no additional decoupling structures. The antenna operates from 3.1 to 10.6 GHz. The antenna finds its usage in on-body wearable device applications.Design/methodology/approachThe antenna system measures 63.80 × 29.80 × 0.7 mm. The antenna radiating element is designed by using a modified dumbbell-shaped structure. Jean cloth material is used as substrate. The isolation improvement is achieved through spacing between two elements.FindingsThe proposed antenna has a very low mutual coupling of S21 < −20 dB and impedance matching of S11 < −10 dB. The radiation characteristics are stable in the antenna operating region. It provides as ECC < 0.01, diversity gain >9.9 dB. The antenna offers low average specific absorption rate (SAR) of 0.169 W/kg. The simulated and measured results are found to be in reasonable match.Originality/valueThe MIMO antenna is proposed for on-body communication, hence, a very thin jean cloth material is used as substrate. This negates the necessity of additional material usage in antenna design and the result range indicates good diversity performance and with a low SAR of 0.169 W/kg for on-body performance. This makes it a suitable candidate for textile antenna application.

High isolation frequency-reconfigurable UWB-MIMO antenna with on-demand WiMAX band elimination

Abstract In this article, a planar dual-element frequency reconfigurable multiple-input multiple-output (MIMO) antenna for ultra-wideband (UWB) applications is studied. The frequency band can be switched between UWB operation and single band rejected UWB performance using a pair of PIN diodes in the MIMO configuration. The presented antenna is comprised of two similar slotted circular radiators, having tapered microstrip feedlines and separate partial ground planes. An RT/Duroid 5880 substrate with size 54 × 54 mm2 is used for the design purpose. Rotational symmetry between the radiators and diagonally oriented t-shaped decoupling structure behind the substrate have been utilized for high isolation purpose. The designed MIMO antenna exhibits UWB performance in mode 1. In other mode, the antenna operates in the frequency range 2.46–10.44 GHz with Worldwide Interoperability for Microwave Access (WiMAX) band rejection. Thus, the MIMO antenna exhibits on-demand single band rejection behavior depending on the switching conditions of the diodes. The measured isolation is greater than −20 dB in both the modes. The presented MIMO configuration possesses compact and planar geometry with high gain, good isolation, ultrawideband performance with reconfigurable band elimination, high efficiency and efficient diversity performance parameters. The suggested antenna is a good choice to be utilized for portable UWB MIMO applications.

A planar UWB-MIMO antenna with high isolation and reconfigurable single band-elimination characteristics

A compact ultra-wideband (UWB) triple mode frequency reconfigurable multiple-input multiple-output (MIMO) antenna with electronically controllable single band elimination properties is presented in this work. The reported antenna comprises of two rotationally symmetric identical modified circular radiators each having tapered microstrip feed lines and separate partial defected ground structures (DGS). The slotted radiating patches consist of C-shaped parasitic strips placed at their centers. Two PIN diode switches were utilized to join and detach the C-shaped strip and slotted circular radiator, and thus total four PIN diodes are employed in the dual-port MIMO configuration to achieve switchable operation between UWB and single band-notched UWB characteristics. The recommended antenna possesses ultrawide bandwidth with Snn ≤ −10 dB except at the rejected bands and attains isolation better than −21 dB in all reconfigurable modes. The proposed MIMO antenna shows good diversity behavior which has been proved through the study of various parameters, such as envelope correlation coefficient (ECC), CCL and diversity gain with values fulfilling the acceptable standard for practical usage. High diversity gain and ECC value below 0.0006 are obtained for all the modes. The suggested antenna structure is ideally suited for ultrawideband MIMO systems with on-demand suppression of WiMAX or WLAN signals.

An Ultra-Wideband MIMO Bowl-Shaped Monopole Antenna with Sturdy and Simple Construction

Anultra-wideband (UWB) bowl-shaped monopole antenna with a sturdy, simple, and lightweight structure is proposed, and then is used to compose the 3 × 3 multiple input multiple output (MIMO) antenna. The wide bandwidth is determined by the outline of the monopole, which has a quarter wavelength and high-order modes. The inner part of the bowl-shaped monopole is removed for a light weight. The simulated and measured results show that an ultra-wide band of 2.3–8.1 GHz (5.8 GHz, 111.5%) and a high isolation of greater than 20 dB between the antenna elements of the MIMO antenna can be achieved.

A Multi-Target Detection Method Based on Improved U-Net for UWB MIMO Through-Wall Radar

Ultra-wideband (UWB) multiple-input multiple-output (MIMO) through-wall radar is widely used in through-wall human target detection for its good penetration characteristics and resolution. However, in actual detection scenarios, weak target masking and adjacent target unresolving will occur in through-wall imaging due to factors such as resolution limitations and differences in human reflectance, which will reduce the probability of target detection. An improved U-Net model is proposed in this paper to improve the detection probability of through-wall targets. In the proposed detection method, a ResNet module and a squeeze-and-excitation (SE) module are integrated in the traditional U-Net model. The ResNet module can reduce the difficulty of feature learning and improve the accuracy of detection. The SE module allows the network to perform feature recalibration and learn to use global information to emphasize useful features selectively and suppress less useful features. The effectiveness of the proposed method is verified via simulations and experiments. Compared with the order statistics constant false alarm rate (OS-CFAR), the fully convolutional networks (FCN) and the traditional U-Net, the proposed method can detect through-wall weak targets and adjacent unresolving targets effectively. The detection precision of the through-wall target is improved, and the missed detection rate is minimized.

Mutual coupling reduction in a textile ultra-wide band MIMO antenna

This paper presents a mutual coupling reduction technique in a textile ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna system implemented on a textile substrate. The compact textile UWB MIMO antenna consists of two patch antennas implemented on a felt textile substrate. The compact size and close placement of the antennas in a MIMO system cause higher mutual coupling which deteriorates the performance of the communication systems. To minimize the mutual coupling, Parasitic Elements and Defected Ground Structures are used in the designed textile UWB MIMO antenna. The MIMO antenna performed very well over almost the whole UWB frequencies ranging from 3.29 GHz to 13.3 GHz. The simulated and the measured parameters showed a good impedance matching with an impedance bandwidth of 133.4%. The results showed an improvement of 20 dB isolation at certain frequencies without impacting the reflection coefficient S11 and the antenna impedance bandwidth. The MIMO antenna has good diversity performance parameters in terms of Envelope Correlation Coefficient (ECC), Diversity Gain, Mean Effective Gain (MEG) and radiation pattern and the results indicate that the textile antenna is suitable for UWB MIMO applications. The overall size of the antenna is 30x60 mm2. Fully embroidered structure provides freedom of movement and comfort, so it is a good fit for Wireless Body Area Network applications.

A Compact Planar Monopole UWB MIMO Antenna for Short-Range Indoor Applications.

A compact, four-element planar MIMO (Multiple Input, Multiple Output) antenna that operates in an ultra-wideband is presented for diversity application. The orthogonal position of the unit cells replicates the single antenna thrice, thereby decreasing mutual coupling. A UWB MIMO antenna measuring 35 × 35 × 1.6 mm3 is built using a microstrip line (50 Ω impedance) on an FR4 substrate having a thickness of 1.6 mm. The ground plane and radiator of this antenna are adjusted in several ways to bring it within its operating constraints between the frequencies of 3.1 GHz and 10.6 GHz. This technique makes the antenna small and covers the entire ultra-wideband (UWB) frequency range. The NI USRP was used to test the proposed MIMO antenna to determine its real-time performance. Based on the computed results, we conclude that this proposed antenna has outstanding characteristics in terms of performance and is suitable for wireless ultra-wideband indoor communication and diversity utilization with a small size.

Four ports MIMO printed antenna with high isolation for UWB and X-band systems

AbstractIn this work, a compact size 4 ports multiple input multiple output (MIMO) slot antenna with the connected ground for Ultra-Wide Band (UWB) and X band applications is introduced and discussed. The single antenna is a cross-shaped slot antenna in the ground plane and a 50 Ω microstrip line with a small L-stub is used to feed the antenna on the other side. The suggested MIMO antenna has four identical elements arranged to be orthogonal to each other to enhance the MIMO system performance. The antenna elements are connected with a small strip to compose the proposed connected ground antennas. The suggested MIMO antenna has an overall size of 47 mm × 47 mm. The antenna has tested and simulated bandwidth with S11 &lt; −10 dB extended from 4– 14 GHz and has isolation greater than 20 dB between ports without utilizing the decoupling elements and with good consistency between results. The MIMO antenna has peak gain and efficiency, envelope correlation coefficient, diversity gain, and channel capacity loss of 5.6 dBi and 80%, &lt;5 × 10–3, 10 dB, and &lt;0.4 bit/s/Hz, respectively which prove that our antenna can be suggested for the UWB MIMO applications.

UWB MIMO optical transparent antenna based on ITO film

An optical transparent antenna using indium tin oxide (ITO) for ultra-wideband (UWB) multiple-input multiple-output (MIMO) applications is proposed. The ultrathin ITO film is coated on a 67×67mm2 glass substrate and over 85% transparency is achieved. The antenna consists of four coplanar waveguide (CPW)-fed antenna elements with rotationally symmetric placement. The adjacent elements are placed orthogonally to produce dual polarisation and reduce coupling. The MIMO antenna operates from 1.5 to 11GHz which covers the UWB applications. The coupling between the elements is less than -23dB. Mean effective gain (MEG), envelope correlation coefficient (ECC) and diversity gain (DG) achieve excellent values which guarantee good MIMO performance. The prototype is verified and the measured results are analysed.