Ultra-wideband Antenna Research Articles

Machine learning enabled compact flexible full ground UWB antenna for wearable applications

Abstract This work introduces a novel compact ultra-wideband (UWB) antenna designed for wearable applications, employing a bioinspired structure and machine learning (ML) techniques to achieve exceptional performance in the 3.10–10.42 GHz range. The antenna is fabricated by positioning conductive fabric on a polydimethylsiloxane polymer of 1 mm thickness to augment high flexibility and durability. Additionally, it pioneers integrating a complete ground plane to mitigate back radiation toward the human body, presenting a compact (35.5 × 30.5 × 1 mm3) UWB antenna design compliant with IEEE 802.15.6 standards. The design methodology includes using bandwidth enhancement techniques such as chamfering edges, slots, and adding stubs in the feed, along with applying ML to optimize the antenna’s dimensions for desired return loss characteristics. The proposed antenna demonstrates exceptional resilience to human body loading and physical deformation. The simulation and measurement results have good agreement. The K-nearest neighbour method beat the other ML algorithms maximum accuracy of 99.62% to predict the S11. According to the author’s best knowledge, this is the first compact UWB antenna with full ground specified by IEEE.802.15.6 with ML reported.

A split ring resonator slot based fabricated crescent microstrip patch antennas for UWB wireless system applications

This paper clarifies significant bandwidth and optimum gain for a split ring resonator slot based fabricated microstrip patch antenna for ultra wide band (UWB) wireless telecommunication system applications. The antenna has a circular slot partially cut into a circular patch and radiates in the UWB frequency range. The design system features a steady radiation pattern and an impedance bandwidth of 3.3 to 10.96 GHz. The proposed UWB notch antenna is at 4.6 GHz, 7.29 GHz, and 9.36 GHz, with an impedance bandwidth of 3.3 to 10.96 GHz. The UWB notch antenna offers linear phase response and a group delay of fewer than 1 ns. It is practical for UWB applications due to less group delay and stable radiation patterns. FR4 material with a 4.4 relative permittivity. The reported antenna is measured following the manufacturing of the prototype design using HFSS simulations. The suggested fabricated antenna minimizes return loss. The findings demonstrate that when combined with VSWR 2, the reflection coefficient covers the band ranges from 3.3-10.96 GHz.

Investigation of optically transparent metasurfaces for gain improvement of an ultrawideband antenna for wireless body area networks and vehicular communications

Abstract Due to higher frequencies which cause signal deterioration, 5G enabled antennas are prone to substantial attenuation. To circumvent this problem, several access points, signal repeaters, and base stations must be installed closer together on building windows, streetlights, and other infrastructure. Optically transparent antennas preserve the aesthetics of the windows by offering the requirements for access points and base stations for providing network connectivity to the cars and pedestrians passing by those buildings. Here we report an ultrawideband (UWB) high gain optically transparent antenna operating from 4-12 GHz. Indium tin oxide (ITO) coated glass has been used as an optically transparent substrate for designing the antenna and metasurface. Two optically transparent metasurfaces have been proposed for band-stop filtering action across the UWB frequency range 4-12 GHz. In absence of the metasurface, the antenna operates in the frequency band ranging from 3.8 to 15 GHz. Average gain enhancement is 5.2 dB with radiation efficiency higher than 93% across the UWB frequency band from 4-12 GHz. Numerical simulations have been carried out for analysis of the proposed antenna and metasurfaces. These simulations have been validated by experimental measurements of the fabricated prototypes.

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.

A Four Port Flexible UWB MIMO Antenna with Enhanced Isolation for Wearable Applications

This article presents a four-port multiple-input-multiple-output (MIMO) flexible antenna design for Ultrawideband (UWB) application using Polydimethylsiloxanes substrate. The single UWB antenna structure consists of modified circular radiator with elliptical slot and partial ground plane. To achieve high isolation among antenna element, a Defective Ground Structure (DGS) is adopted to decouple the low frequency band. DGS comprises a centrally placed square shape slotted structure connected by horizontal and vertical lines, achieving isolation below -20 dB. The proposed antenna has a dimension of , bandwidth of 3.4–11.8 GHz (110.5%) and 4.3 dBi peak gain. Simulation and measurement findings show that the antenna performs well under bending situations with different curvature radius. At 4 GHz and 8.1 GHz, W/kg specific absorption rate (SAR) for 1/10 g tissue is examined. A low value of SAR is obtained at both the resonating frequencies. Additionally, an analysis is conducted on the diversity parameters, and the antenna demonstrates comparatively good results having mean effective gain (MEG) ratio < -3 dB envelope correlation coefficient (ECC) < 0.02, total active reflection coefficient (TARC) < − 10 dB, channel capacity loss (CCL) < 0.3 bps/Hz, and diversity gain (DG) > 9.99 dB, implying that it's appropriate for wearable MIMO applications.

Modeling and Characterization of Electrically Small Ultrawideband Antenna for Headstage-Based Wireless Neural Signal Recording System

Modeling and Characterization of Electrically Small Ultrawideband Antenna for Headstage-Based Wireless Neural Signal Recording System

A compact quad element MIMO CPW fed ultra‐wideband antenna for future wireless communication using machine learning optimization

SummaryIn this article, a compact quad element coplanar waveguide (CPW) fed ultra‐wideband (UWB) multiple input multiple output (MIMO) antenna for future generation wireless communication system using a machine learning (ML) optimization approach is presented. The proposed antenna is used for 5G new radio (n46/n77/n47/n78/n48/n79), Wi‐Fi 5, Wi‐Fi 6, and dedicated short range communications (DSRC) services, vehicle to infrastructure (V2I), vehicle to vehicle (V2V), and vehicle to network (V2N) in the entire operating frequency band. It is operating from 3.2 to 11.85 GHz. The bandwidth is 8.65 GHz, and the percentage of impedance bandwidth is 115%. The comparative analysis between dual and quad elements are presented. It is optimized through the various ML model K‐nearest neighbor (KNN), extreme gradient boosting (XGB), artificial neural network (ANN), and random forest (RF). The KNN ML model achieved a higher accuracy of 93%, and it accurately predicted the S parameters of the suggested UWB antenna. The MIMO parameters are calculated and found within the acceptable limits. There is a strong correlation between the simulated and measured results. Hence, the suggested antenna is a suitable candidate for future wireless communication systems.

Compact and flexible EBG backed ultra-wide band antenna for on-body communications

Compact and flexible EBG backed ultra-wide band antenna for on-body communications

Influence of Substrate Materials on the Performance of a Triple-Band Notched Frequency UWB Antenna

In this paper, the influence of different substrate materials on the performance of a triple-band notched frequency of ultra-wide band (UWB) antenna is presented. The antenna has a rectangular shape with dimension 31 by 24 mm and operates at UWB frequency band of 3.1GHz to 10.6GHz. The antenna was simulated using HFSS software. The effect of eight different substrate materials with different dielectric constant was examined on the antenna. Under each substrate, the performance of the antenna was investigated based on the antenna gain, directivity, radiation pattern, voltage standing wave ratio (VSWR), impedance bandwidth and S-parameter. Through thorough analysis, the results gave strong indication that UWB antenna performance is greatly affected by the type of dielectric substrate material chosen for design. The paper demonstrates the effect dielectric substrate material has on the antenna performance measurement like radiation pattern, gain, directivity and VSWR.

Compact Ultra-Wide Band Two Element Vivaldi Non-uniform Slot MIMO Antenna for Body-Centric Applications

This work presents a novel compact two-port Vivaldi Non-uniform Slot MIMO Antenna (VNSMA) to overcome the challenges of traditional ultra-wideband (UWB) antennas, such as large size, limited bandwidth (BW), high mutual coupling, and suboptimal performance in wearable devices. Designed based on Vivaldi non-uniform slot profile antenna (VNSPA) theory, this antenna offers superior performance metrics and significantly advances wearable antenna technology. The novelty of this work is investigating different positions for the two compact UWB VNSA to get better performance with smaller sizes, wider impedance matching BW, and lower mutual coupling (MC) where side by side at an angle of 180ᵒ is determined to be the best configuration. Detailed parametric studies were performed on this configuration for better performance, where the MC was further reduced by etching the ground plane with a vertical slot between the two antennas and L slots around the Microstrip to Slot (M/S) transition, respectively. Furthermore, BW and gain enhancements were obtained by etching exponential tapered and triangular slots at its two edges. Using the Finite Integration Technique (FIT), Computer Simulation Technology (CST) software is used for the simulations in this work. The VNSMA is tested on a CST Gustav human phantom and gives excellent results with low specific absorption rate (SAR) values at several UWB frequencies. The proposed VNSMA provides good, measured outcomes of S11 < -11.08 dB with wide BW of 12.5 GHz (2.33–14.83 GHz) covering high isolation of -23 dB (for most of frequency band), moderate-high gain of 5.89 dBi, radiation efficiency of 66-90%, low Envelope Correlation Coefficient (ECC) of 0.002 and high diversity gain (DG) of 9.99 dBi, stable radiation patterns, and average group delay of 1.2 ns. This innovative design, which optimizes antenna positioning and incorporates ground plane modifications, achieves remarkable improvements in BW, which covers multiple bands, including WLAN (2.4–2.485 GHz), X-band (8-12 GHz), and part of Ku band (12-18 GHz). The findings demonstrate the antenna's potential for various high-resolution microwave imaging applications, particularly in medical diagnostics like breast and brain cancer detection, showcasing its impact in wearable technology and healthcare.

A low-profile ultra-wideband magneto-electric dipole antenna for ground penetrating radar

ABSTRACT Ultra-wideband antennas that operate at low frequencies usually have a large geometry, which makes them very limited in practical engineering application environment where space is often constrained. In this paper, a novel low-frequency low-profile ultra-wideband magneto-electric (ME) dipole antenna is designed for the application in ground penetrating radar (GPR) to detect deeply buried targets. The antenna is designed at the operation frequency of 230 MHz, so that the objects that are buried as deep as 1.5 m can be detected. Compared to the traditional low-frequency _antennas, it has a profile as low as 740 mm × 140 mm × 150 mm ( 0.49 λ × 0.09 λ × 0.10 λ ). Based on the simulation analysis and validation measurements, the proposed ME dipole antenna has a wide impedance bandwidth for S 11 < − 10 dB from 135 MHz to 382 MHz even when environmental influence is considered. The antenna is further validated with a GPR experiment, where a pipeline with a diameter of about 200 mm at 1200 mm beneath the road surface is successfully detected by an impulse GPR system where the proposed antennas are integrated.

Miniaturised ultra‐wideband circular polarised koch fractal crossed dipole array

AbstractUltra‐wideband (UWB) systems utilise a broad frequency spectrum to achieve high data transmission rates and enhanced precision, creating a demand for specialised UWB antennas. Circularly Polarised (CP) antennas are considered essential for maintaining robust performance under varied environmental conditions. Among them, the crossed dipole is effective for UWB CP applications, but its relatively large size could limit its use in various systems. A miniaturised crossed dipole design employing the Koch fractal structure is proposed and the measurement results are presented. The prototype antenna achieved an effective bandwidth covering 88% of the frequency range from 1.4 to 3.6 GHz. Additionally, a 4 × 4 array using this design was tested in the same frequency band, demonstrating beam‐steering capabilities up to 30°. The proposed antenna has demonstrated effective deployment in diverse communication systems and phased array applications within ultra‐wideband (UWB) CP environments.

ReLoki: A Light-Weight Relative Localization System Based on UWB Antenna Arrays.

Ultra Wide-Band (UWB) sensing has gained popularity in relative localization applications. Many localization solutions rely on using Time of Flight (ToF) sensing based on a beacon-tag system, which requires four or more beacons in the environment for 3D localization. A lesser researched option is using Angle of Arrival (AoA) readings obtained from UWB antenna pairs to perform relative localization. In this paper, we present a UWB platform called ReLoki that can be used for ranging and AoA-based relative localization in 3D. To enable AoA, ReLoki utilizes the geometry of antenna arrays. In this paper, we present a system design for localization estimates using a Regular Tetrahedral Array (RTA), Regular Orthogonal Array (ROA), and Uniform Square Array (USA). The use of a multi-antenna array enables fully onboard infrastructure-free relative localization between participating ReLoki modules. We also present studies demonstrating sub-50cm localization errors in indoor experiments, achieving performance close to current ToF-based systems, while offering the advantage of not relying on static infrastructure.

Dual-Band Antenna Array Fed by Ridge Gap Waveguide with Dual-Periodic Interdigital-Pin Bed of Nails.

A dual-band (K-/Ka-band) antenna array is presented. An ultra-wideband antenna element in the shape of a double-ridged waveguide is used as a radiation slot, and a novel dual-periodic ridge gap waveguide (RGW) with an interdigital-pin bed of nails (serving as a filter) is used to realize dual-band operation. By periodically arranging the pins of two different heights in two dimensions, the proposed RGW with interdigital-pin bed of nails is able to realize and flexibly adjust two passbands. The widely used GW-based back cavity boosts the realized gain and simplifies the feed network design. A 4 × 4 prototype array was designed, fabricated, and measured. The results show that the array has two operating bands at 24.5-26.4 GHz and 30.3-31.5 GHz, and the realized gain can reach 19.2 dBi and 20.4 dBi, respectively. Meanwhile, there is a very significant gain attenuation at stopband.

A design of Ultra Wideband (UWB) antenna applied in coal mine underground

A design of Ultra Wideband (UWB) antenna applied in coal mine underground

Compact CPW-fed Antenna with Controllable WLAN Band-rejection for Microwave Imaging

This work presents the design and experimental validation of a compact frequency reconfigurable coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna with a capability to on-demand reject WLAN frequencies within the range of 5.15 GHz to 5.85 GHz, specifically tailored for applications in microwave imaging. The design and experimental results are presented and discussed. The bandwidth enhancement is obtained by using T-shaped slots between the feedline and the ground plane of the antenna, and the WLAN band is rejected by using an open loop resonator (OLR) placed on the antenna backside. Switching between UWB with and without WLAN band-notched modes is performed using a PIN diode and a bias circuit. The simulation results corroborate well with the experimental data and clearly showed an interesting frequency reconfigurable behavior for use in microwave imaging applications. An antenna performance simulation and analysis model is presented for breast tumor detection, and the tumor effect has been noticed for both operating modes of the antenna.

Detection of breast tumor with a frequency selective surface loaded ultra-wide band antenna system

Breast tumors are a significant cause to the global death rate among women. However, the fatality rate can be lowered through early detection. This paper presents an ultra-wideband, modified patch antenna of a compact size that can be used for microwave-sensing biomedical applications in the detection of breast cancer. A partial ground plane and slots are implemented in a transformed patch antenna to enhance the impedance bandwidth. The antenna is backed by a uniform frequency selective surface of 5 × 5 unit cells to achieve the necessary antenna characteristics, specifically directivity and gain, for microwave detection applications. Through optimization and fabrication, the final design maintained (|S11|< −10 dB) over the entire frequency band of 11.6 GHz (3.1–14.7 GHz) and achieved an average gain of over 5 dBi. Other metrics, such as group delay and the fidelity factor in different setups, are also simulated to observe the expected performance in the required frequency range. Finally, based on simulation, a model is suggested that comprises various configurations of antenna arrays, including one Tx antenna and one to seven Rx antennas. Further, breast phantom with different tumor sizes and locations were used in the simulation. The simulation results successfully validated the detection of breast cancer cells. We believe these technologies can open possibilities in healthcare applications for identifying tumors.

Compact Modified Elliptical-Shaped Ultra-wideband Filtering Antenna with Improved Band-Edge Selectivity

A compact filtering antenna with higher selectivity near band-edge frequencies for ultra-wideband (UWB) applications is presented and developed in this article. The antenna with filtering characteristics is formulated by integrating a rectangular-impedance resonator-based bandpass filter into the feedline of a modified elliptical-shaped monopole radiator. Initially, a modified elliptical-shaped monopole radiator is designed and numerically simulated to ensure the overall performance over the UWB band. The modified elliptical shape is used as a radiator to increase the electrical length while maintaining minimum physical size. The size of the UWB antenna is merely 0.518λ AL × 0.272 λ AL (where λAL is the guided wavelength at 2.62 GHz). Furthermore, to enhance the performance characteristics of the filtering antenna along with band-edge selectivity, geometrical parameters are optimized using a numerical simulation tool. It exhibits a simulated impedance bandwidth of 112% (3.05–10.81 GHz) with an electrical size of 0.676λ FL × 0.316λ FL (where λFL is the guided wavelength at 3.05 GHz). The experimental results of the fabricated UWB antenna and filtering antenna prototypes agree well with their simulated results.

A quad port dual band notch UWB MIMO antenna using hybrid decoupling structure

A four-port dual-band notch ultrawideband (UWB) multiple input and multiple output (MIMO) antenna for automotive applications is presented. Initially, a circular patch monopole antenna is designed and optimized by embedding a rectangular stub onto the radiator and lowering the ground plane to realize the UWB frequency spectrum. The dual-band frequency notch, from 4.6 to 5.9 and 6.8–8.8 GHz, is achieved using a half wavelength slot onto the feedline and a pair of H-shaped stubs across the feedline, respectively, to cover WLAN and complete x-band satellite communication. Further, the designed dual-band notch UWB antenna is transformed to a four-port MIMO antenna with interelement spacing much smaller than λ/4 (λ at 3.1 GHz) and a size of 0.46 × 0.41 × 0.01 λ3. Isolation improvement is achieved by a hybrid decoupling technique comprising a distinctive neutralization line (NL) and defected ground structure (DGS). The average isolation of the proposed design is better than 22 dB. Characteristic mode analysis of the proposed antenna is performed to analyze the specific significant mode and their contribution to the antenna radiation. The antenna design's diversity and time-domain properties are analyzed and found suitable for automotive applications. The antenna's electromagnetic interaction with the electrically large structure is studied by mounting the antenna onto an open-source automobile model, and the gain is determined to be more than 6.1 dB at the antenna's resonant frequencies.

An ultra-wideband antenna design optimization for biomedical applications using artificial neural networks

This paper presents an innovative method based on Artificial Neural Networks (ANN) for optimizing the design of microstrip antennas using HFSS software. The method leverages a dataset generated from comprehensive full-wave electromagnetic simulations to accurately predict antenna performance. In the ANN model, coefficients of reflection as input parameter, and five output parameters representing key geometrical variables of the antenna are utilized. The study demonstrates how ANNs effectively predict these variables, thereby enhancing design efficiency and significantly reducing the computational time required for antenna optimization. By providing a robust and efficient framework, the results highlight the promising potential of ANNs in optimizing antenna designs for diverse applications, including medical and wireless communication systems. Specifically, the proposed Ultra-Wideband (UWB) antenna operates over a frequency range from 5.17 GHz to 7.02 GHz and maintains an S11 value of -20.49 dB at 5.8 GHz within the Industrial, Scientific, and Medical (ISM) bands. This research contributes valuable insights into advancing electromagnetic performance through efficient antenna design methodologies.