Search

This paper presents a high‐gain wearable circularly polarized bow‐tie antenna (WCPBTA) with metamaterial unit‐cells and 5 pins (5Ps) technique for telemedicine applications such as telemonitoring the elderly or the patients especially for emergency conditions of contagious diseases. The frequency range of the proposed antenna is 5.725–5.850 GHz, which belongs to the unlicensed‐national information infrastructure (U‐NII‐3) for the industrial, scientific, and medical (ISM) sub‐channels. A light‐weight and flexible felt with dielectric constant εr = 3, thickness 1.27 mm, and tan (δ) = 0.0095 is used as the substrate for patient comfort and wearability. The overall dimensions of the proposed antenna are 64 × 62 × 1.27 mm3 or 0.102 λg3 at 5.8 GHz. The maximum simulated gain at 5.8 GHz is 8.25 dB, which is more than 4 dB compared to that of the original bow‐tie antenna. Besides, the axial ratio (AR) and the specific absorption rate (SAR) are also analyzed, which meet the perfect requirement for medical applications. The fabricated prototype of the antenna shows good compatibility between simulation and measurement results. These characteristics make the proposed WCPBTA a good choice for wireless body area networks (WBANs) in telemonitoring applications especially with the aim of preventing the spread of contagious diseases. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of a metamaterial-based compact dual-band antenna for WBAN applications. The antenna is designed and fabricated on a 0.254 mm thick semi-flexible substrate, RT/Duroid® 5880, with a relative permittivity of 2.2 and a loss tangent of 0.0009. The total dimensions of the antenna are 0.26λo×0.19λo×0.002λo, where λo corresponds to the free space wavelength at 2.45 GHz. To enhance overall performance and isolate the antenna from adverse effects of the human body, it is backed by a 2×2 artificial magnetic conductor (AMC) plane. The total volume of the AMC integrated design is 0.55λo×0.55λo×0.002λo. The paper investigates the antenna's performance both with and without AMC integration, considering on- and off-body states, as well as various bending conditions in both E and H-planes. Results indicate that the AMC-integrated antenna gives improved measured gains of 6.61 dBi and 8.02 dBi, with bandwidths of 10.12% and 7.43% at 2.45 GHz and 5.80 GHz, respectively. Furthermore, the AMC integrated antenna reduces the specific absorption rate (SAR) to (>96%) and (>93%) at 2.45 GHz and 5.80 GHz, meeting FCC requirements for low SAR at both frequencies when placed in proximity to the human body. CST Microwave Studio (MWS) and Ansys High-Frequency Structure Simulation (HFSS), both full-wave simulation tools, are utilized to evaluate the antenna's performance and to characterize the AMC unit cell. The simulated and tested results are in mutual agreement. Due to its low profile, high gain, adequate bandwidth, low SAR values, and compact size, the AMC integrated antenna is considered suitable for WBAN applications. [ABSTRACT FROM AUTHOR]

In the present emerging trends of 5G communication, long-distance communication cannot be accomplished with a single antenna. To enhance the gain and efficiency, a multi-band double hook shaped micro strip array antenna with defected ground structure has been designed and analyzed in this work for 5G communication applications. A quarter-wave transformer with a good impedance matching network is employed to provide the antenna's radiating components, and the designed antenna is prototyped on a 0.2 mm thick polyimide substrate with a dielectric constant of 2.9. Antenna resonating in the quad band with 10 GHz bandwidth at first resonant band and 1 GHz bandwidth at other three resonant bands. Gain of 8.8 dB at 22 GHz, 11 dB at 28 GHz, 13 dB at 32 GHz and 14.2 dB at 38 GHz is attained from radiation characteristics. The antenna is flexible and conformal with respect to the host surface, providing excellent correlation in simulation and protype real time measurement. [ABSTRACT FROM AUTHOR]

Electric dipoles and magnetic dipoles are the most fundamental particles in electromagnetic theory. Huygens and Janus sources, formed by the orthogonal combination of electric and magnetic dipoles, both show good directionality in the near field. Although the Huygens source has been widely used in antennas and metasurfaces, the applications of Janus source are heretofore limited. In this paper we report the physical construction of an active Janus source. Through full-wave simulations within the parallel plate waveguide (PPW) environment, we show that our source achieves the directional electromagnetic near-field and quasi-isotropic far-field requisite of the Janus source. Using this fact, we demonstrate that two active Janus and Huygens sources in close proximity (about 0.10 to 0.25 wavelengths) achieve a near 1000-fold reduced mutual coupling compared to electric dipole sources. Particularly, the simultaneous achievement of strong mutual coupling suppression and quasi-isotropic radiation make the Janus source an ideal candidate for consideration in future compact multi-input multi-output (MIMO) communication systems. The distinct near- and far-field directionalities of three fundamental dipoles (electric, Huygens and Janus) can be used to manipulate electromagnetic waves. The authors juxtapose the properties for these dipoles and propose a realistic active Janus source which suppresses mutual coupling by close to 1000-fold for two closely-spaced antennas. [ABSTRACT FROM AUTHOR]

This paper presents design of a 4-element crescent-shaped two-sided multiple-input-multiple-output (MIMO) antenna, employing pattern and polarization diversity with improved element-to-element isolation, for UWB, X and Ku band wireless applications. The proposed crescent-shaped MIMO structure consists of two antennas on the top and remaining two antennas on the bottom sides of the substrate. The developed antenna operates in a frequency range from 2.8 to 15.2 GHz, covering the entire UWB 3.1–10.6 GHz, X-band and portion of Ku-band giving element-to-element isolation of more than 20 dB in most of the operating bands. Also, the proposed MIMO structure gives a maximum gain of 6.6 dBi with radiation efficiency from 75 to 95% in the operating band. The important MIMO parameters like envelope correlation coefficient (ECC < 0.005), channel capacity loss (CCL < 0.03 bits/s/Hz), mean effective gain (MEG < − 3 dB) and total active reflection coefficient (TARC < − 10 dB) are presented to estimate the performance of the developed UWB MIMO system. [ABSTRACT FROM AUTHOR]

This article presents the design steps of a planar circularly polarized (CP) bowtie‐shaped antenna for 2.4–2.5 GHz industry, science, and medicine band. Using these design steps, an antenna model is developed. The antenna design is extensively described, simulated, measured, and analyzed. The antenna is simulated using the HFSS software and produced by laser etching of copper on a low‐cost Taconic RF‐35 substrate. The presented method of this design is easy to fabricate and is tunable to different frequencies. The produced CP planar antenna has a size of 55 × 55 × 0.25 mm3, a measured axial ratio bandwidth ranging from 2.33 to 2.49 GHz, and a measured peak gain of 3.21 dBiC. The produced antenna is fully planar, compatible with the printing process and thus suitable for Internet of Things applications. [ABSTRACT FROM AUTHOR]

A dual‐band shared‐aperture antenna with a frequency ratio of 3 is presented in the letter. A low‐band antenna consists of two printed dipoles. An artificial magnetic conductor (AMC) is used to reduce the height of the low‐band antenna. A high‐band antenna consists of four printed dipoles. It is placed between the AMC elements and the antenna ground plane. The AMC elements and antenna ground plane form a Fabry–Perot cavity and allow increasing gain of the high‐band antenna. An additional structure is inserted between the antenna ground plane and the AMC elements to decrease heights of the Fabry–Perot cavity and the high‐band antenna simultaneously. The total size of the proposed antenna is 1.02λL × 1.02λL × 0.103λL (λL is the central wavelength of the low operating band). Simulated and measured results show that the designed antenna has 57% and 16.7% bandwidths in the low‐ and high‐frequency bands. [ABSTRACT FROM AUTHOR]

In this communication, a compact flower shaped printed antenna for ultra-wideband communication is proposed. The "flower-shaped" structure is capable of transmitting UWB-band signals. The designed antenna exhibits a return loss ranging from 2.3 to 11 GHz with an 8.7 GHz central frequency and has 130% relative bandwidth. The suggested design includes a patch in the shape of a flower with several slots fed by a microstrip line. Multiple slots have been designed for better resonances at lower modes. The antenna is constructed with an FR4 substrate, and a 50 Ω A-type connector feeds it. The optimum dimensions of the designed antenna are 12 × 16 × 1.6 cubic-millimeters and 0. 092λ ×.12λ × 0.012λ in lambda. The proposed structure also demonstrates stable radiation patterns across the operating bandwidth. The proposed radiator has a high gain of 2.67 dBi, and an efficiency of 85%. It is compact, lightweight, and easy to make. Therefore, it can be used for UWB applications. [ABSTRACT FROM AUTHOR]

In general, Metasurface Antennas (MSA) are designed to diminish the antenna shape by enhancing the operating band and directivity. As the efficiency decreases, the design complexity of MSA increases. In order to enhance the antenna design, a high-gain MSA is designed using the hybrid African Vulture's Optimization Algorithm (AVOA), and the Capuchin Search Algorithm (CapSA) is used for Radio Frequency (RF) energy harvesting. The dimensions of the designed antenna are 1.66 λ 0 × 1.25 λ 0 × 0.02 λ 0 with a resonating frequency of 5 GHz. To design the high gain MSA, the proposed Hybrid African Vulture's Optimization and Capuchin Search Algorithm (Hyb-AVOA-CapSA) is used to enhance the antenna parameters such as radiation efficiency, Bandwidth, gain, and return loss. Therefore, the proposed MSA design has achieved high efficiency and profit. Finally, the simulation has done on HFSS19 and ADS2020 version software; and evaluated using MATLAB. The proposed antenna gives a better efficiency of 70.12%, and resonate at 1.5 GHz of the axial ratio bandwidth at 5 GHz resonant frequency. The gain of the proposed antenna has increased from 6.86 to 7.6 dBi. While examining the comparative outcomes, the proposed approach has attained 22.4%, 23.7% high gain, and 18.85%, 12.6% lower return loss than the compared methods. Thus, the designed MSA is applied in RF energy harvesting applications because of its compact, low-profile, and simple structure. The Rectenna design uses a voltage doubler circuit at the receiver end and produces 5.55 V. [ABSTRACT FROM AUTHOR]

This paper presents a novel antenna design with an enhanced gain‐bandwidth product for modern communication networks, including 5G systems. The design is consistent with 17 unit cells of a composite right/left‐hand (CRLH) structure with an electromagnetic band gap of Hilbert inclusions. Therefore, the resulting design occupies an area of 40 × 200 mm2 of a Taconic RF‐43 substrate. The maximum antenna gain is 16 dBi at 5.5 GHz, which is very applicable for long‐range communication systems. Nevertheless, the antenna performance is controlled with optical switches of light‐dependent resistors (LDR) technology. Therefore, the antenna performance is tested with different switching seniors to investigate the possibility of reconfiguration scenarios at various frequency bands. However, the antenna gain is highly affected by changing LDR switching status; for example, at 5.5 GHz, the antenna gain is varied between 7 and 16 dBi. Thus, the proposed antenna is an excellent candidate for direct amplitude modulation. Finally, the antenna simulation results and measurements agree very well with each other. [ABSTRACT FROM AUTHOR]

The proliferation of wireless communication technologies has led to a surge in the need for multiband antennas. This study introduces an innovative multiband antenna design that incorporates a 4 × 4 Artificial Magnetic Conductor (AMC) surface to achieve reduced Specific Absorption Rate (SAR), high gain, and improved Front to Back Ratio (FBR). The multiband antenna design presented in this study spans a wide range of wireless frequency bands, including ISM, WLAN, WiMAX, Wi-Fi 6E, and 7. The antenna offers comprehensive coverage for various wireless communication applications with resonating frequencies at 2.4 GHz, 3.2 GHz, 5.5 GHz, 7.5 GHz, and 10 GHz. The AMC unit cell generates four zero-degree reflection phases with Double Negative (DNG) properties at 2.5 GHz, 3.8 GHz, 5.5 GHz, and 7.5 GHz. The compact design measures 29 × 37 × 1.6mm3 and is placed 13 mm above an AMC surface of size 64 × 64 × 1.6mm3. The proposed antenna design achieves an increase in gain of up to 8.55dBi at 6.01 GHz and a notable improvement of 31.5 dB in FBR at 4.5 GHz. The proposed antenna design achieves a -10 dB impedance bandwidth for a range of frequencies, including 2.34–2.43 GHz (3.77%), 2.81–3.83 GHz (30.72%), 4.82–6.21 GHz (25.20%), 7–7.65 GHz (8.87%), and 8.06–10.31 GHz (24.5%). An average percentage reduction in SAR at these frequencies with the AMC structure is 96.11%. The antenna sample was successfully fabricated, and the experimental results have been found to match well with the simulation results. Consequently, this design offers a promising solution for wearable off-body communication devices that require low-SAR, high-gain, and multiband functionality. [ABSTRACT FROM AUTHOR]

The proliferation of the Internet of Things devices and advancements in wireless communication have fostered the growth of Wireless Body Area Networks (WBAN). This research provides a triband antenna supported by a 4 × 4 Artificial Magnetic Conductor (AMC) array surface that has a low Specific Absorption Rate (SAR), a high Front to Back Ratio (FBR), and increased gain for use in wearable devices. For WBAN communications, the proposed antenna operates in the Industrial, Scientific, and Medical (2.4 GHz) band, the C (3.7–4.2 GHz), and the Wi-Fi 6E (5.925–7.125 GHz) bands. The dual-band AMC unit cell exhibits Double-Negative and angular stability behaviour at 2.45 GHz and 6.5 GHz. AMC-backed antenna achieved multiband functionality by incorporating slots into the unit cell and a defective ground structure into the antenna. The antenna was positioned 0.139λ0 above the AMC surface, which measured 0.556λ0 × 0.556λ0 × 0.013λ0 (at 2.45 GHz). The antenna exhibited good gain and return loss variations when mounted on curved surfaces. The proposed integrated design yielded substantial enhancements, as evidenced by the increase of 8.2 dBi in maximum gain, 25.2 dB in FBR, and over 93% in total efficiency. The AMC-backed antenna's − 10 dB impedance bandwidth is 18.4%, 21.2%, and 22.3%, with corresponding frequency ranges of 2.25–2.66 GHz, 3.66–4.53 GHz, and 5.9–7.35 GHz. Additionally, the AMC surface showed an average reduction in SAR of 93.22%. Vector Network Analyzer and Anechoic chamber measurements proved simulation accuracy. As a result, it is strongly recommended that the integrated antenna design be acknowledged in WBAN communications. [ABSTRACT FROM AUTHOR]

With the rapid advancements in wireless communication systems, the applications that have emerged recently such as the Internet of Things (IoT), machine-to-machine communication, vehicular communication and video on demand, etc. require very high data rates in short-range communication for better reliability. Antenna systems utilized in traditional communications are not suitable for these applications. Ultra Wide Band (UWB)–Multiple Input Multiple Output (UWB–MIMO) antennas have proved to fit these requirements owing to their improved capability and reliability in short-range communication. The major challenge in designing the UWB–MIMO antennas is to reduce the mutual coupling effects among multiple antennas. In this paper, various techniques for mutual coupling reduction are presented and analyzed such as Electromagnetic band-gap (EBG) structures, meta-materials, parasitic or slot, and stub structures, neutralization lines, etc. [ABSTRACT FROM AUTHOR]

In this work, the use of a configuration of a reflective metasurface (MS) layer is employed to design a highly directive wideband Fabry–Pérot cavity (FPC) antenna. With the use of only one MS layer and along with the achieved high directivity, the antenna's wide bandwidth, and antenna low size/cavity thickness profile are all optimized so that they are still competitive which is the main contribution of our work. The highly reflective MS layer is placed as a superstrate of a low-cost FR4 microstrip patch antenna, as the primary radiator, at a height of half-wavelength cavity condition. Thanks to the employed MS layer, most of the power is transmitted and a very small reflected power to the primary patch. The antenna is designed to serve the 28 GHz band of 5G wireless applications. At 28 GHz, the FPC antenna has a good directivity performance, with a peak simulated directive gain of 15.46 dB and measured directive gain is 14.3 dB which is a 9 dB enhancement in directivity compared to a conventional microstrip patch antenna. The antenna has a wide impedance bandwidth of 2.9 GHz which is almost three times the microstrip patch antenna bandwidth. The achieved results are for the same size of FPC antenna whose height is almost half wavelength and its overall size 2.33 λ × 2.33 λ. [ABSTRACT FROM AUTHOR]

Introduced in this letter is a thin, flexible, compact, and fully fabric I‐shaped quarter‐wavelength antenna, where a 3 × 3 array reflector, is in the antenna rear end. In free space, the I‐shaped antenna radiates at 2.45 GHz of the Industrial, Scientific, and Medical band with simulated realized gain of 1.65 dB and 90% worth of simulated radiation efficiency. The array reflector is utilized to diminish the specific absorption rate (SAR) in human evaluation scenarios. At the operating frequency, in free space, the antenna realized gain is improved by 75% after incorporating the artificial magnetic conductor (AMC) array. Moreover, over 1 g of tissue, a SAR reduction of 99.5% is attained at 2.45 GHz. Simulation and measured S11 and radiation pattern comparisons are highlighted in this letter. Based on the accomplished outcomes, the integrated antenna, comprised of the fully fabric I‐shaped quarter‐wavelength antenna and the AMC array, might be considered for wearable applications. [ABSTRACT FROM AUTHOR]

A printed ultra-wideband (UWB) multiple input multiple output antenna with isolation enhancement and pattern diversity is presented, which is based on characteristic modes (CM) for upcoming wireless mobile platforms. The presented antenna is composed of dual UWB antenna elements (AEs) – an antipodal Vivaldi and a circular-shaped monopole positioned on the two opposite edges of the antenna's rectangular-shaped ground surface. The two AEs are capable to stimulate distinct modes in the ground surface and therefore obtaining the required distinct radiation (far-field) patterns and highly isolated AEs without introducing any decoupling structure (DS). The measured results demonstrate that both AEs are UWB with an operating frequency from 2.6 to 11 GHz. The measured isolation is more than 30.1 dB with a maximum value of 55 dB in UWB. The peak realized gain is over 0.83 dBi. The radiation efficiency is greater than 75%. The Envelope Correlation Coefficient is <0.08. [ABSTRACT FROM AUTHOR]

Here presents a new miniaturized tri‐wideband antenna loaded with metamaterial meander lines. The antenna consists of a rectangular radiation patch loaded with two compact metamaterial components. The three frequency bands are the results of resonances of a rectangular patch at 5.5 GHz, interdigital meander slit at 3.6 GHz, and virtual grounded thin meander stub at 7.5 GHz. More size miniaturization is accomplished by a compact virtual ground structure and cutting the upper and left edges of the substrate. Furthermore, matching at all bands is improved by taking advantage of stepped microstrip feed line and truncated rectangular ground plane. Measured results shows the frequency ranges of 3.32–4.06 GHz (20%), 5.17–6.06 GHz (16%), and 7.17–10.32 (36%). The antenna is analyzed with an equivalent circuit model. In comparison to previous works, this antenna has a simple design, very compact size of 10 mm × 15 mm × 0.8 mm, three wide working bands, and matching levels better than −20 dB at all resonant frequencies. [ABSTRACT FROM AUTHOR]

Summary: This work proposes an electrical compact triple‐bands antenna founded on a composite left‐/right‐handed approach. This structure contains a rectangular patch combined with two unit cells based on the metamaterial properties that are used to produce wide electrical lengths in miniature physical sizes. Thus, the presented antenna is designed with a lower resonant frequency and miniature physical dimensions compared to conventional antennas. The suggested antenna has been produced on top of the FR4 substrate having tan δ = 0.022, εr = 4.58, and a size of 28 × 16 × 1.6 mm3. This structure provides three bandwidths of (2.391–2.54 GHz), (3.42–3.56 GHz), and (5.02–11.40 GHz). Additionally, a multi‐input multioutput (MIMO) antenna is designed by placing two similar radiating patches in a perpendicular shape. Therefore, this design approach has been used to achieve an important isolation among ports and less than −30 dB at frequency bands. The results of radiation patterns, envelope correlation coefficient, diversity gain, and channel capacity loss are below to 0.06, 10 dB, and 0.4 b/s/Hz respectively, which confirms that the MIMO antenna is compatible with wireless MIMO devices. These antennas have been modeled and experimentally confirmed, and the results have proven that the suggested antennas are useable and can support multi‐standard wireless applications. [ABSTRACT FROM AUTHOR]

A high gain antenna with Mu-near-zero metasurface (MNZ-MS) is introduced in this work. The proposed antenna can be utilized for future 5G applications. The patch antenna is designed on the upper face of the square substrate with a ground plane at the bottom face. To improve the antenna gain, a layer of MNZ-MS unit cells is placed above the antenna substrate with 0.48 λ 0 air space between the two layers, where λ 0 is the wavelength in free space at the resonance frequency of 26.3 GHz. The MNZ-MS layer consists of four double-sided split square resonators. The overall thickness of the proposed antenna is 0.66 λ 0. To approve the execution of the proposed antenna, a prototype model is manufactured and tested. The outcomes fulfill a reflection coefficient lower than −10 dB over the frequency spectrum of 26–28 GHz. A gain improvement better than 5 dB is obtained compared to the gain of the reference patch at the center frequency of 26.3 GHz. [ABSTRACT FROM AUTHOR]

This study presents a novel UWB flexible antenna with dual band-notched design for wearable biomedical devices. The proposed antenna is designed on Kapton Polyimide-based flexible substrate. This includes a CPW fed circular and triangle structure. The dual notched bands are realized by using two triangular-shaped spiral slots defected ground structures. The first notched band (2.4–3.7 GHz) is generated for rejecting WLAN and WiMAX, the second notch (5.15–5.725 GHz) is generated for rejecting HyperLAN/2. The designed UWB antenna has approximately a bandwith of 159% (2.05–14 GHz) in simulation. Thus, the designed UWB antenna meets FCC standards. The antenna has an omnidirectional radiation pattern with a maximum gain of 12.7 dB in 8.4 GHz. The proposed antenna is fabricated with the low-cost airbrush printed technique. In this technique, a higher gain value is obtained by controlling the thickness of the conductive layer. Effect of flexibility on the antenna performance is tested for different configurations in the simulation and anechoic chamber environments. According to the results obtained, the overall performance is not affected except for the shift in frequency. Since the antenna has a UWB structure, the frequency shift that occurs in bending is at a tolerable level. The proposed UWB antenna is suitable for wearable biomedical devices, with a high UWB performance. [ABSTRACT FROM AUTHOR]

This paper presents two flexible monopole antennas implemented on cotton substrate as sensors designed for radar-based microwave imaging and particularly breast imaging systems. The flexible antennas are basic building block of a radar-based microwave imaging system that could be integrated in clothes. Thus, these low-cost textile sensors could be used by women for self-monitoring and early breast cancer detection at an affordable price. The ultra-wideband fully textile sensors are designed as rectangular and circular monopole antennas. Both sensors have an impedance bandwidth ≤ − 10 dB from 2.2 to 8 GHz with an overall footprint of 50 × 50 mm2. Simulations for antenna in proximity to breast model with and without tumor as well as bending capacity are performed. The simulations are complemented with fabrication of a breast phantom and a tumor sample with parameters that mimic these of the human breast's healthy and malignant tissue. Measurements are compared to simulation results as well as the performance of antenna before and after subjected to washing. Finally, the specific absorption rate is also calculated and measured to ensure safety for on-body deployment. The proposed work demonstrates the potential to develop wearable microwave imaging system using fully textile antennas. [ABSTRACT FROM AUTHOR]

In this article, a new methodology for applying the phased array antenna method to MIMO technology with the ability to provide improved frequency diversity and isolation properties is discussed. The radiator serves to attenuate sub-3 GHz bands by providing 1800 phase difference in the input signal at both the ports simultaneously. A network of asymmetric dual split-split ring resonators is loaded beneath the antenna model to give consistent isolation characteristics between 3.5 and 5.8 GHz. At 3.5 GHz, the gain of 4.23 dBi while 5.6 dBi at 5.8 GHz is attained with the volume of (23 × 23 × 1.6) mm3. The electromagnetic coupling effect between the ports was measured to be − 15 dB without any decoupling structures throughout the bandwidth 3.2 and 6.2 GHz. The MIMO benchmarks such as Envelope Correlation Coefficient of 0.003, Diversity Gain of 9.8 dB, and Total Active Reflection Coefficient less than − 15 dB were obtained from the proposed radiator. [ABSTRACT FROM AUTHOR]

This work presents an electrically small antenna (ESA) for wireless applications, such as digital cellular systems (DCS1800), WiMAX, and sub 6 GHz – 5G new radio (NR) systems. The proposed antenna offers a triple band resonance centered at 1.825, 3.3, and 3.58 GHz. Here, impedance matching networks of printed microstrip line sections, such as inverted 'L', open-ended line, meandered line, and capacitive stub, are used to achieve impedance matching at the desired frequencies. The total surface area of the proposed antenna is 0.14λ × 0.06λ, where λ is the wavelength at 1.825 GHz. The designed antenna is tested for its impedance and radiation characteristics. The fabricated prototype offers fractional bandwidth (FBW, with VSWR < 2) of 1.6%, 6%, and 6.7% centered at 1.825, 3.3, and 3.58 GHz, respectively, whereas for VSWR 3:1, the achieved fraction bandwidth(s) is 8.2% and 24.5% for the DCS1800 and 3.3 GHz band, respectively. The stable and nearly omnidirectional radiation pattern for each operating frequency bands indicates the suitability of the proposed antenna for the intended application(s). [ABSTRACT FROM AUTHOR]

The μ -negative metamaterial (MNG) two-element MIMO antenna design was proposed in this article for WiMAX (2.5–2.8 GHz), WLAN (3.2–5.9 GHz), and ITU band (8.15−8.25 GHz) applications. The first design of the MIMO antenna operates at 2.7 and 4.9 GHz frequencies. In order to reduce the mutual coupling, a defective ground structure is used. For further isolation improvement, an MNG unit cell is placed in between the two radiating elements at a distance of 10 mm. The designed antenna elements have better than −23 dB coupling isolation between the two radiating elements. Moreover, with MNG an additional frequency of 8.2 GHz is obtained, which is useful for ITU band applications. The proposed antenna bandwidth is expanded by 19% in the lower operational band, 20% in the second operational band, and 32% in the higher frequency band with the MNG unit cell. From the analysis, the proposed antenna is suitable for WiMAX/WLAN/ITU band applications because of its low enveloped correlation coefficient, and highest directive gain and low mutual coupling between the radiating components. The proposed antenna was simulated, fabricated, and measured with the help of the Schwarz ZVL vector network analyzer and anechoic chamber. Both measured and simulated results are highly accurate and highly recommended for WiMAX/WLAN/ITU bands. [ABSTRACT FROM AUTHOR]

A multi‐band, small, high gain, low specific absorption rate (SAR), and circularly polarized (CP) textile wearable antenna fed using aperture coupled technique is designed on two layers of denim (εr=1.2, h = 0.787 mm as feeding layer) and felt (εr=1.3, h = 1.5 mm as a resonating layer) textile substrates. The antenna is designed on two layers with two relative permittivities to enhance the BW and reduce the negative mutual coupling. Afterward, another layer of denim with the complete ground of ShieldIt conductor is added to decrease the SAR value along with the directive gain. The antenna works for Industrial, Scientific, and Medical (ISM), 5G, and sub‐6 GHz communication systems as it operates at 2.45–2.55 GHz and 3.8 GHz (3.6–4.15 GHz), and 5.6 GHz (5.55–5.65 GHz), respectively. The proposed antenna has the maximum directive gain of 8.35 dBi, acceptable SAR values at a 10 mm distance from the human body for both standards. In addition, the antenna's CP is examined, showing AR values of <2.5 dB at the working BW. Finally, the proposed antenna is measured and compared with the simulation results. A good agreement exists between simulation and measurement results. [ABSTRACT FROM AUTHOR]

All textile integrated dual-band monopole antenna with an artificial magnetic conductor (AMC) is proposed. The proposed design operates at 2.4 and 5.8 GHz for wearable medical applications to monitor the heartbeat. A flexible and low-profile E- shaped CPW dual-band textile antenna is integrated with a 4 × 4 dual-band textile AMC reflector to enhance the gain and specific absorption rate (SAR). The SAR is reduced by nearly 95% at both 1 and 10 g. The design was measured on the body with a 2 mm separation. The simulated and measured results appear in high agreement in the case of with and without AMC array integration. The measurement was performed in the indoor environment and in an anechoic chamber to validate the design based on reflection coefficient and radiation pattern measurements. [ABSTRACT FROM AUTHOR]

This article presents a highly miniaturized dual-band electrically small antenna (ESA) for on-demand 3.6 and 5.8 GHz wireless applications. A partial rectangle-shaped structure is printed on the back face of the dielectric material, forming the antenna's ground (GND) plane. The radiating structure of the antenna consists of a C-shaped structure and a U-shaped ring connected to it, which is printed on the dielectric material's front face. The overall dimensions of the designed antenna are 0.160λo × 0.160λo × 0.02λo at the lowest operating frequency. The proposed antenna has a ka value of 0.56 at the lowest operating frequency, which is 3.59 GHz. Thus, the proposed antenna is considered as electrically small. The characteristic mode analysis is adopted to provide a clear understanding of the antenna's resonance behavior. The antenna has been fabricated and the simulation results were validated through measurements. Good agreement between simulated and measured results was obtained. Dual-band operation at 3.62 and 5.75 GHz was achieved, according to the measured reflection coefficient. The proposed antenna offers an adequate performance in terms of gain and efficiency, based on simulation and measurement results. Because of these characteristics, the antenna is well-suited to new wireless applications. [ABSTRACT FROM AUTHOR]

In this work, a printed ultra-wideband (UWB) antenna has been proposed exhibiting band notch characteristics. The proposed design covers the entire UWB band except for the 3.5 GHz band providing the band notch for the WiMAX band. This design consists of two-quarter elliptical patches placed symmetrically over the FR4 substrate. The elliptical shape of the patch is responsible for the UWB band achieved. The slot has been created on the optimized patch area to achieve the desired characteristics providing a notch for the WiMAX band. The slot in the patch is so perfectly designed that it gives the patch a perfect shape of butterfly wings. After designing, the proposed antenna was simulated and then fabricated. The fabricated and simulated results are in close agreement with each other which shows, the proposed UWB antenna is good enough for biomedical applications. [ABSTRACT FROM AUTHOR]

Future wireless communication systems need to be redesigned for millimeter wave carrier frequencies to accommodate higher bandwidth applications. The free space power loss for higher frequencies is higher compared to the sub-6 GHz commercial wireless systems. One of the approaches to realize a feasible data link is to design and deploy high gain antennas on the transceivers responsible for communication. To design high gain antennas with small form factor, it is important to closely consider the feeding technique of the antenna. In this article, various aspects of numerous feeding techniques are illustrated. Initially, a generic layout of the specific feeding method is explained followed by the nuances of feeding line design for a range of commonly available substrates. A comparison of different feeding techniques is also presented, followed by the merits and demerits of the respective feeding technique in the context of 28 GHz based antennas. Various design examples published in the recent literature are also presented. [ABSTRACT FROM AUTHOR]

Summary: We are discussing a compact, four elements with high‐performance ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna with dual band‐notched traits. The antenna has a partial ground plane and the radiator has truncation to enhance the matching through the frequency range 2.5–12 GHz. The coupling between ports was reduced by assorting the elements of the antenna in an orthogonal manner and applying four stubs between them. The proposed antenna achieves two band‐notched characteristics by introducing a T‐shaped strip etched in the radiating elements and adding an open‐loop resonator near the feeding line. The results, which were simulated and measured, indicate that the proposed design achieved a wideband from 2.5 to 12 GHz with two band‐notched characteristics within 3.3–3.6 GHz (WiMAX implementations) and within 5.2–5.8 GHz (Wireless Local Area Network [WLAN] applications). As well as, the proposed antenna has high isolation >20 dB and a low‐envelope correlation coefficient <0.005 through the band except for the band notches. These outcomes demonstrate the adequacy of the proposed UWB MIMO antenna for UWB MIMO applications. [ABSTRACT FROM AUTHOR]

In this paper, a novel metasurface-based Fabry−Perot cavity antenna loaded with toroidal metal structures is presented. The antenna is compact, wideband, and has high directivity and a high front-to-back ratio. The idea of the antenna is based on loading a microstrip narrow band patch antenna resonating at 4.5 GHz by a single layer metasurface superstrate and with a toroidal metal structure. The metasurface superstrate comprises a periodic array of square patch cells. Compared to conventional microstrip antenna, the front to back lobe ratio is increased from 7 to 20 dB and the directivity is increased by 7 dB. Also, the antenna impedance bandwidth is 34% which is increased four times. This is the first-ever antenna with enhanced bandwidth and directivity using a single layer of metasurface and that too made up of periodic cell array and has application as an energy harvester. [ABSTRACT FROM AUTHOR]

A compact ultra-wideband (UWB) square and circular slot ground plane planar antenna with a modified circular patch for UWB communication is presented. This antenna has a low reflection coefficient and high gain in the range of 8.94 GHz, starting from 2.85 to 11.79 GHz. The proposed antenna demonstrates UWB behavior with electrically small dimensions of 0.18 λ0×0.14 λ0×0.015 λ0 (λ0 is the free-space wavelength at 2.85 GHz). The fractional bandwidth of the antenna is 122.1%, with stable radiations. The antenna's maximum gain stands at 2.79 dBi, and the antenna's peak efficiency stands at 72%, respectively. It is lightweight, compact, and easy to manufacture. Hence, it can be used for the complete range of UWB applications and covers Wi-Max/WLAN/ X-Band and Ku-Band. [ABSTRACT FROM AUTHOR]

In this research work, the authors have presented the design of a compact flexible wearable fractal patch antenna used for body area networks (BAN) applications in the 2.45 GHz ISM band. For the size miniaturization of the antenna the crown fractal patch antenna geometry has been used. Five flexible substrate materials namely denim, polythene foam, cotton cloth, felt and fleece have been analysed as the substrates of the antenna and the antenna size miniaturization ranging from 24.1 to 29.7% has been achieved. The denim substrate based antenna occupies the minimum area as compared to that of all the other four designed antennas; hence, the denim substrate based antenna has been fabricated and experimentally tested. The measured parameters of the antenna show good agreement with the simulated values. The proposed fabricated denim substrate based antenna has also been analyzed for bending effect evaluation and it has been found that the horizontal and vertical bending up to the bending radius of 45 mm of the antenna does not significantly affect the performance of the antenna. The equivalent circuit analysis of the proposed antenna has been presented and the theoretical, simulated, and experimental results have been found in good agreement. [ABSTRACT FROM AUTHOR]

Antenna design has evolved from bulkier to small portable designs but there is a need for smarter antenna design using machine learning algorithms that can meet today's high growing demand for smart and fast devices. Here in this research, main focus is on developing smart antenna design using machine learning applicable in 5G mobile applications and portable Wi-Fi, Wi-MAX, and WLAN applications. Our design is based on the metamaterial concept where the patch is truncated and etched with a split ring resonator (SRR). The high gain requirement is met by adding metamaterial superstrates having thin wires (TW) and SRRs. The reconfigurability is achieved by adding three PIN diode switches. Multiple designs have been observed by adding superstrate layers ranging from one layer to four layers with interchanging TWs and SRRs. The TW metamaterial superstrate design with two layers is giving the best performance in gain, bandwidth, and the number of bands. The design is optimized by changing the path's physical parameters. To shrink simulation time, Extra Tree Regression based machine learning model is used to learn the behavior of the antenna and predict the reflectance value for a wide range of frequencies. Experimental results prove that the use of the Extra Tree Regression based model for simulation of antenna design can cut the simulation time, resource requirements by 80%. [ABSTRACT FROM AUTHOR]

Summary: A novel multiple‐input multiple‐output double asymmetrical cylindrical dielectric resonator antenna (MIMO‐DCDRA) with modified stub line feed is discussed and proposed in this work. Two unequal CDRA are placed diagonally to each other and are electromagnetically coupled with feeding arrangement via two asymmetrical circular apertures. By performing the optimization of the dimensional parameters, a significant impedance bandwidth of 70.84% ranging from 2.87 to 5.76 GHz and axial ratio bandwidth (ARBW) of 34.89% is obtained. Antenna gain is about 5.0 dBi within the operating frequency. The proposed MIMO‐DCDRA exhibits a low mutual coupling of (|S21| & |S12| < −20 dB) with the incorporation of a neutralization line. There are various diversity parameters that are also discussed in terms of mutual coupling, envelop correlation coefficient (ECC < 0.002), diversity gain (DG > 9.995), and channel capacity loss (CCL < 0.3 bits/s/Hz) over the entire impedance bandwidth. [ABSTRACT FROM AUTHOR]

A low-profile dual-band pixelated defected ground antenna has been proposed at 3.5 GHz and 5.8 GHz bands. This work presents a flexible design guide for achieving single-band and dual-band antenna using pixelated defected ground (PDG). The unique pixelated defected ground has been designed using the binary particle swarm optimization (BPSO) algorithm. Computer Simulation Technology Microwave Studio incorporated with Matlab has been utilized in the antenna design process. The PDG configuration provides freedom of exploration to achieve the desired antenna performance. Compact antenna design can be achieved by making the best use of designated design space on the defected ground (DG) plane. Further, a V-shaped transfer function based on BPSO with fast convergence allows us to efficiently implement the PDG technique. In the design procedure, pixelization is applied to a small rectangular region of the ground plane. The square pixels on the designated defected ground area of the antenna have been formed using a binary bit string, consisting of 512 bits taken during each iteration of the algorithm. The PDG method is concerned with the shape of the DG and does not rely on the geometrical dimension analysis used in traditional defected ground antennas. Initially, three single band antennas have been designed at 3.5 GHz, 5.2 GHz and 5.8 GHz using PDG technique. Finally, same PDG area has been used to design a dual-band antenna at 3.5 GHz and 5.8 GHz. The proposed antenna exhibits almost omnidirectional radiation performance with nearly 90% efficiency. It also shows dual radiation pattern property with similar patterns having different polarizations at each operational band. The antenna is fabricated on a ROGERS RO4003 substrate with 1.52 mm thickness. Reflection coefficient and radiation patterns are measured to validate its performance. The simulated and measured results of the antenna are closely correlated. The proposed antenna is suitable for different applications in Internet of Things. [ABSTRACT FROM AUTHOR]

In this paper, a small ultra-wideband (UWB) antenna with two stop bands by a compact electromagnetic bandgap (EBG) cell loaded with two new open meander slots is presented. With the coupling of the EBG cell to the feedline, the stop bands are formed. The designed EBG cell is a mushroom type that has the advantages of being able to independently control the stop bands, high responsiveness selectivity of stop bands, easy switching, the need for fewer EBG cells, and low impact on the working characteristics of the antenna. To have a better understanding of the proposed EBG mechanism, characteristic mode analysis is used. The size reduction of the suggested antenna is obtained by halving the reference antenna relative to the axis of symmetry. The measurement results for −10 dB adaptation are from 2.73 to 13 GHz with stop bands at 3.51 GHz (12.9%) and 5.34 GHz (14.1%). The radiation behavior of the minimized antenna is similar to that of a reference antenna. Minimized UWB antenna with transmission function and group delay with small variations in the operating frequency range is suitable for small multiple-input and multiple-output (MIMO) and diversity systems. [ABSTRACT FROM AUTHOR]

To adapt to the application of wireless body area network (WBAN), a wearable flexible dual‐band antenna is developed, which has a compact size of 17 × 29 × 0.15 mm3 and a better bandwidth of 61.2% and 43.1% at 2.4 and 5.8 GHz, respectively. The dual‐band characteristic is achieved by slotting technique without changing the contour size. A dual‐band metamaterial structure (MS) is designed to improve radiation performance and reduce the specific absorption rate (SAR) of the proposed antenna. To verify the validity of the MS, we build two simulation human models. The forward gain of the antenna is increased and the SAR is significantly decreased when adding the MS between antenna and human skin. The antenna is designed and fabricated on a flexible substrate, and its performance is verified for both flat and curved configurations. To examine its performance as a wearable antenna, it is measured on a human body. The measurements show an excellent agreement with the simulations. Good performances of designed antenna make it potential to application of the miniaturized wearable devices. [ABSTRACT FROM AUTHOR]

A connected ground 4-port wideband transparent antenna is proposed. The structure attains optical transparency due to AgHT-8 (Silver Tin Oxide) and Plexiglass. The geometry of a single radiating element consists of a U-shaped patch connected with a semicircular arc and an inverted L that is fed through a microstrip line. The antenna has a full ground plane along the vertical direction and is truncated along the horizontal directions. The antenna geometry is replicated to form three different 4-port MIMO structures where the first one has a separate ground profile while the latter comprises 2 different (O and H shaped) connected ground profiles. The proposed structure is decided after evaluating the isolation levels while achieving the required frequency bands of operation. At the lowest frequency, the antenna size is 0.092λ × 0.165λ. Impedance bandwidth of (121.36%) 0.69–2.82 GHz over a − 10 dB band with isolation better than 20 dB amid all elements is achieved. The antenna is assessed in terms of MIMO diversity, scattering, and transmission parameters by simulating the antenna followed by experimental results which depict a decent correlation. The average gain and efficiency above 0.5 dBi and 40%, respectively with optical transparency, connected ground, satisfactory isolation, and diversity parameters make the transparent 4-port MIMO antenna suitable for GSM (850/900/1800/1900), LTE (700/2300/2500), UMTS (2100), Bluetooth (2400) and WLAN (2400) applications where device aesthetics, location issues, and visual clutter need to be mitigated. [ABSTRACT FROM AUTHOR]

This paper proposes two different types of metamaterial (MTM) antennas for fifth-generation (5G) mid-band frequency operation. The radiating patch of the proposed antenna is based on the combined Minkowski-Sierpinski carpet fractal structure. On the ground plane, two different types of MTM structures: Complementary split-ring resonator (CSRR), and Strip-gap are etched to enhance the overall bandwidth and gain of the antenna. The introduction of these structures on the ground plane also leads to antenna miniaturization. Both the proposed MTM structure based antennas resonate at 3.5GHz. The overall size of the two fabricated prototypes is 28×29.5 mm2 / 28×28.5 mm2, which shows the compactness of the proposed design by 43% / 42% as compared to the conventional microstrip patch antenna (MPA). The measured bandwidth/gain achieved by the proposed combined Minkowski-Sierpinski carpet fractal antenna (CMSFA) having CSRR MTM and strip-gap etched on the ground plane are 370 MHz / 2.42dBi and 440 MHz / 3.75dBi, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the design and development of a flexible Ultra Wide Band (UWB) antenna using polydimethylsiloxane as a substrate. Copper foil having a thickness of 0.193 mm is used as conducting layers. The overall thickness of the antenna is 1.886 mm. The proposed UWB antenna covering from 1.5 to > 15 GHz. It has been analyzed at a few specific frequencies 1.8 GHz, 2.4 GHz, 3.6 GHz, 4.2 GHz, 4.8 GHz, 5.2 GHz, and 5.8 GHz for comparison. SAR is evaluated at these mentioned frequencies and it is below the recommended SAR value of 1.6 W/Kg. The performance of the antenna with comparative analysis is presented with the help of reflection coefficient, VSWR, Impedance, Gain, surface current distribution, far-field radiation pattern, and SAR analysis. [ABSTRACT FROM AUTHOR]

In this paper, a compact 4-port band-notched multi-input-multi-output (MIMO) antenna with asymmetric coplanar strip (ACS) feed is presented for ultra-wide band (UWB) applications. The MIMO antenna is comprised of four semi-elliptical radiators with ACS feed for UWB applications and it is printed on inexpensive FR4 substrate of size 48 × 52 mm2 with ɛr = 4.4 and 1.6 mm height. The impedance characteristics of the suggested MIMO antenna ranges from 2.7 to 11 GHz with a band-notched behavior from 3 to 4 GHz to reduce the interception with WiMAX applications, and the isolation level over the achieved band is more than 20 dB between any two adjacent elements. Moreover, the radiation pattern of the proposed UWB antenna is almost omnidirectional with an average realized gain of 3.5 dBi over the entire achieved frequency band. The proposed ACS-fed antenna is confirmed by fabricating and measuring it's impedance and radiation characteristics. Finally, good consistency between simulation and measured outcomes is obtained confirming the validity of the MIMO antenna for real-life UWB wireless systems. [ABSTRACT FROM AUTHOR]

A structurally compact, semiflexible wearable antenna composed of a distinctively miniaturized electromagnetic band gap (EBG) structure is presented in this work. Designed for body-centric applications in the 5.8 GHz band, the design draws heavily from a novel planar geometry realized on Rogers RT/duroid 5880 laminate with a compact physical footprint spanning lateral dimensions of 0.6 λ 0 × 0.06 λ 0. Incorporating a 2×2 EBG structure at the rear of the proposed design ensures sufficient isolation between the body and the antenna, doing away with the performance degradation associated with high permittivity of the tissue layer. The peculiar antenna geometry allows for reduced backward radiation and low specific absorption rate (SAR). With the inclusion of EBG, the gain of the antenna undergoes a considerable increase to 7.2 dBi with more than 95% reduction in SAR value. In addition, the front-to-back ratio also amplified to 13 dB. A rigorous analysis detailing the structural robustness is reported for varied bend angle configurations of the proposed antenna. To assess the suitability of the proposed design as a body-worn antenna, an experimental investigation is carried out on different parts of the body. Experimental findings are congruent with computationally obtained results, validating the applicability of the novel antenna structure for body-worn applications. [ABSTRACT FROM AUTHOR]

Summary: In this paper, an electrically small inverted L‐shaped asymmetric coplanar strip‐fed antenna with a split‐ring resonator structure is proposed for multiband applications. It possesses an extended monopole antenna and a rectangular split‐ring resonator (RSRR) structure. A monopole is responsible for generating the first and last resonance frequencies. Similarly, the RSRR structure produces center frequency (5.5 GHz) among three resonance frequency bands and improves impedance matching at a higher frequency. The antenna has an electrical size of 0.176 λ0 × 0.096 λ0 × 0.012 λ0. The proposed antenna has a triband resonance response at 2.45, 5.5, and 7.5 GHz with a bandwidth of 560 MHz, 680 MHz, and 3 GHz, respectively, which covers WiBro (2.3 GHz), WLAN (2.4/5.2 GHz), WiMAX (2.5/5.5 GHz), X‐band downlink (7.4 GHz), and ITU band (8.5 GHz). The antenna design is simulated and validated with measured results and has better radiation characteristics in all the required frequency bands. The presence of metamaterial property in the proposed RSRR is analyzed. The design is an electrically small antenna, and it has a radian sphere (ka) = 0.64. Further, the proposed antenna performances are compared with the various existing literature. [ABSTRACT FROM AUTHOR]

Modern era of wireless communication relies on the evolution of adaptive antennas. This influences the new age antenna designs to adapt themselves to the changing RF environment. Reconfigurable antennas are one such design where the operating frequency, radiation pattern, and polarization can be altered according to the user's requirement. Numerous research works have been contributed to the design of reconfigurable antennas. In view of that, this work proposes a detailed survey on reconfigurable antennas. The key motivation behind the survey is to provide an elaborate idea on the existing reconfigurable antenna designs so that the antenna researchers can perform possible analysis to overcome shortcomings or can enhance the performance of the existing designs. The evolution of reconfigurable antennas, the need for different reconfigurations and their design specifications are presented in this survey. Further, a comparative study on different switching mechanisms, deployment of various techniques to enhance antenna performance, diverse applications and existing design challenges are also addressed as a part of this review. Hence, this survey will be useful to the researchers in developing futuristic reconfigurable radiating structures that can be well suited for applications like Cognitive Radio, 5G and Multiple Input Multiple Output systems. [ABSTRACT FROM AUTHOR]

In this paper, a novel metasurface-based Fabry–Perot Cavity antenna is presented. The antenna is wideband, directive and has a high front-to-back ratio. The idea of the antenna is based on loading a microstrip narrow band patch antenna resonating at 4.6 GHz by a metasurface superstrate. The metasurface superstrate consists of an aperiodic array of holes in contrast to the periodic nature of unit cell previously explored in the literature. The metasurface is designed as a near-zero-refractive-index material (NZRIM). By controlling the phase reflection properties of the structure, improved radiation pattern, improved front-to-back lobe ratio (7–25 dB), improved directivity (by 3 dB) and antenna bandwidth (five times) are obtained compared to a conventional microstrip antenna. The enhancement in bandwidth and directivity simultaneously using just a single layer of metasurface superstrate demonstrated for the first time, to best to authors' knowledge, are obtained. [ABSTRACT FROM AUTHOR]

In this communication, a compact dual‐element MIMO antenna with decoupling structure has been proposed for handheld devices. The proposed decoupling structure acts as a resonator and as a decoupling structure. The proposed antenna consists of nested slots in the radiator and it supports the application such as LTE, WLAN, Wi‐Fi, and WiMAX. The total size of the antenna is 30 mm × 10 mm. The impedance bandwidth of the antenna is 300/400/700 MHz, respectively. The decoupling structure consists of a feed line printed on one side of the substrate and swastika‐shaped array on another side. The power fed to the feed line coupled to the swastika‐shaped array for achieving the operating bands at 0.9 GHz and (8‐10) GHz. Meanwhile, the decoupling array provides isolation more than 20 dB at (2.3‐2.6) GHz, (3.4‐3.8) GHz, and (5.15‐5.85) GHz. The edge to edge spacing between the antennas is 10 mm. The percentage bandwidth of the antenna is 12.2/11.1/12.7/22.2%. The MIMO performance metrics such as envelope correlation coefficient, effective diversity gain, apparent diversity gain, and mean effective gain are evaluated. The proposed antenna is fabricated and tested. The measured results correlate with the simulated results. [ABSTRACT FROM AUTHOR]

This paper presents a high-performance multiple-input multiple-output (MIMO) antenna with a compact size of 42 × 42 mm2. The proposed antenna operates in the frequency range of 3.2–12 GHz for ultra wide band (UWB) wireless communication systems. The proposed MIMO antenna has four identical elements arranged to be orthogonal to each other to achieve a good performance. To achieve high isolation, stubs between the four radiating elements were used. Measured and simulated results were analyzed to obtain the antenna performance in the form of studying radiation pattern, Envelope Correlation Coefficient (ECC), diversity gain, and channel capacity loss. Additionally, simulated peak gain and total efficiency are acquired. Results indicate that the proposed antenna has UWB bandwidth, high isolation higher than 17 dB, and low correlation coefficient; therefore, this antenna is suitable for UWB wireless applications. [ABSTRACT FROM AUTHOR]

A compact wideband dual-/quad-element multiple input multiple output (MIMO) antenna, using jeans textile material for WiMAX (IEEE 802.16d) and 5G application band, is proposed. The wideband nature of basic single element antenna with a frequency span of 2.74 to 4.41 GHz (47%) is analyzed in detail by using circuit model representation. Thereafter, in order to resolve different practical issues, such as multipath fading, shadowing and scattering of electromagnetic waves as well as human body effect, wideband compact quad-element MIMO antenna is presented. To improve isolation characteristics, meander line structures are integrated in-between the antenna elements. Isolation is achieved greater than 19dB over the whole application band. The diversity parameters such as envelope correlation coefficient (ECC < 0.2), diversity gain (DG > 9.6) and mean effective gain (MEG = ±0.3dB) are found within the satisfactory ranges. Measured outcomes are also good enough to confirm the antenna as a suitable contender for wearable scenarios. [ABSTRACT FROM AUTHOR]

This study presents a compact dual element wearable ultrawideband (UWB) multi-in multi-out (MIMO) antenna with increased port isolation. The suggested design consists of a jeans substrate in which a tree-fashioned stub comprising of eight branches is introduced in the middle position of the partially etched antenna ground for improving the characteristics of port isolation. The proposed design occupies the frequency spectrum operating from 1.71 to 12.63 GHz (impedance bandwidth of around 152.3%) and satisfies the bandwidth demands for WiMAX (3.2-3.8 GHz), WLAN (5.15-5.35/5.72-4.85 GHz), the C Downlink-uplink bands (3.7-4.2/5.9-6.425GHz), ITU bands (8-8.5GHz) and the downlink defense band (7.2-7.5GHz). The antenna is able to maintain isolation between the ports >22dB across the entire UWB frequency spectrum. The coefficient of the envelope correlation for the whole operating band was observed to be <0.012 along with a very high diversity gain >9.9. The channel power loss of the proposed wearable UWB MIMO antenna is found to be <0.27 bit/s/Hz. The suggested UWB MIMO antenna, fascinated with optimization, covers an area of 35 × 35 mm2. The suggested design is also able to perform satisfactorily when attached on-body. Simulation and testing fairly identified the performance of the antenna and rendered it to be an upstanding choice for wearable UWB applications. [ABSTRACT FROM AUTHOR]