Ultra-wideband Antenna Research Articles

Characteristics Mode Analysis-Inspired Compact UWB Antenna with WLAN and X-Band Notch Features for Wireless Applications

A compact circular structured monopole antenna for ultrawideband (UWB) and UWB dual-band notch applications is designed and fabricated on an FR4 substrate. The UWB antenna has a hybrid configuration of the circle and three ellipses as the radiating plane and less than a quarter-lowered ground plane. The overall dimensions of the projected antennas are 16 × 11 × 1.6 mm3, having a −10 dB impedance bandwidth of 113% (3.7–13.3 GHz). Further, two frequency band notches were created using two inverted U-shaped slots on the radiator. These slots notch the frequency band from 5–5.6 GHz and 7.3–8.3 GHz, covering IEEE 802.11, Wi-Fi, WLAN, and the entire X-band satellite communication. A comprehensive frequency and time domain analysis is performed to validate the projected antenna design’s effectiveness. In addition, a circuit model of the projected antenna design is built, and its performance is evaluated. Furthermore, unlike the traditional technique, which uses the simulated surface current distribution to verify functioning, characteristic mode analysis (CMA) is used to provide deeper insight into distinct modes on the antenna.

UWB Circular Fractal Antenna with High Gain for Telecommunication Applications.

The present study proposes a new, highly efficient fractal antenna with ultra-wideband (UWB) characteristics. The proposed patch offers a wide simulated operating band that reaches 8.3 GHz, a simulated gain that varies between 2.47 and 7.73 dB throughout the operating range, and a high simulated efficiency that comes to 98% due to the modifications made to the antenna geometry. The modifications carried out on the antenna are composed of several stages, a circular ring extracted from a circular antenna in which four rings are integrated and, in each ring, four other rings are integrated with a reduction factor of 3/8. To further improve the adaptation of the antenna, a modification of the shape of the ground plane is carried out. In order to test the simulation results, the prototype of the suggested patch was built and tested. The measurement results validate the suggested dual ultra-wideband antenna design approach, which demonstrates good compliance with the simulation. From the measured results, the suggested antenna with a compact volume of 40 × 24.5 × 1.6 mm3 asserts ultra-wideband operation with a measured impedance bandwidth of 7.33 GHz. A high measured efficiency of 92% and a measured gain of 6.52 dB is also achieved. The suggested UWB can effectively cover several wireless applications such as WLAN, WiMAX, and C and X bands.

Health Control of Tree Trunk Utilizing Microwave Imaging and Reverse Problem Algorithms.

The voids in their trunk significantly affect tropical trees' health. Both the wood and timber industries may face substantial financial losses because of the lack of an effective technique to inspect the defected trees through deep zonal monitoring. Microwave imaging offers the advantages of mobility, processing time, compactness, and resolution over alternative imaging methods. An ultra-wide band (UWB) imaging system consisting of UWB antennas and a reverse problem algorithm is proposed. Several conditions, such as the size of trunk samples (16-30 cm), number of targets, size of voids, heterogeneity of media, and number of layers, are considered in experimental studies. Based on these studies, cylindrical wooden models with 100 and 140 mm diameters, one void at the center, and three voids in different locations were 3D printed. After proving the system's ability through simulation and measurements on 3D models, a rubber-wood trunk with a length of 75 cm was cut into smaller pieces. The images created utilizing the measured data showed that the system could detect voids in the rubber trunk. Furthermore, the system indicated a high percentage of reliability and repeatability.

Triple Band-Notch UWB Antenna Embedded with Slot and EBG Structures

In this paper, a planar, compact pentagonal shaped ultrawideband antenna of microstrip line fed offering triple band-notched characteristics response is proposed and investigated. Triple band-notch response can be achieved by creating two inverted U-shaped slots of different size in pentagonal patch, and also electromagnetic band gap structure of hexagonal shape is created near the feed line of UWB antenna. To implement the proposed antenna, RT/DUROID 5880 substrate of 1.6 mm thickness is used. The designed antenna was successfully simulated, developed, and manufactured. The dimension of the suggested antenna is 36 mm × 33 mm × 1.6 mm and has a bandwidth of 3.1–10.6 GHz with a magnitude of S 11 < − 10 dB , the maximum pass band gain of 4.6 dB and with the exception of the 4.0–4.4 GHz (C-band satellite communication), 5.2–5.8 GHz (WLAN), and 8.0–8.25 GHz (X-band) frequency bands. The suggested antenna has a good return loss, a virtually omnidirectional radiation pattern, and a constant gain throughout operation.

A Novel Corner Etched Rectangular Shaped Ultrawideband Antenna Loaded with Truncated Ground Plane for Microwave Imaging

Microwave imaging has become a popular research issue in recent decades as a result of its several benefits over traditional imaging technologies. To analyze biological tissues in depth, a microwave imaging instrument is employed. The test determines the presence and location of morphological alterations in specific biological tissues. Ultrawideband (UWB) microwave imaging is a new technique that produces improved results while avoiding the use of ionizing radiation. Antennas play a critical part in these systems, and as a result, antenna optimization has become a hot topic due to the device's proximity to the human body. Recent research has revealed a number of initiatives to improve the electromagnetic sensors employed in these systems, whether as single or array components. In this article, the development of a compact ultrawideband (UWB) antenna functioning in the frequency range of 3.25–14.63 GHz is proposed. The reported antenna comprises of a rectangular patch and a modified ground plane "etched on an FR4" substrate excited by a 50 Ω feed line. The overall dimension of the antenna is 0.44 {lambda }_{0}times 0.38 {lambda }_{0}times 0.02{lambda }_{0}. The proposed antenna has been fabricated on FR-4 substrate. Measured and simulated results are in good agreement. The proposed antenna is compact and displays good radiation characteristics along with good gain.

Design UWB antenna with notch band for WiMAX application

During the last two decades, radar, remote sensing, and imaging applications have all made use of ultra-wide band (UWB) technology. UWB systems are susceptible to interference from narrowband signals, hence this work provides a single-notch antenna for the UWB system. There are two stages to the design process. After creating the baseband antenna, it is necessary to create a notched band UWB antenna by carving a slot into patch antenna. In the UWB range (3.1-10.6) GHz, the UWB antenna has the dimensions of 20x30 mm with substrate thickness 1.6 mm made from FR4 lossy. The design relative permittivity was 4.3, a rectangular patch with a portion of the ground is used in the design. A typical slot-shaped resonator is connected to the patch to reject a frequency band (3.273-3.81) GHz which is a world interoperability for microwave access (WiMAX) to solve the problem of the interference with other bands in UWB system For WiMAX applications. The suggested UWB filter will achieve notch band response centered at the resonance frequency of 3,4 GHz. Analysis CSTS v2020 software was used to carry out the simulation. Priority should be given to what has been learned rather than what has been accomplished.

Energy-Efficient, Precise UWB-Based 3-D Localization of Sensor Nodes With a Nano-UAV

Smart interaction between autonomous centimeter-scale unmanned aerial vehicles (i.e., nano-UAVs) and Internet of Things (IoT) sensor nodes is an upcoming high-impact scenario. This work tackles precise 3-D localization of indoor edge nodes with an autonomous nano-UAV without prior knowledge of their position. We employ ultrawideband (UWB) and wake-up radio (WUR) technologies: we perform UWB-based ranging and data exchange between the nano-UAV and the nodes, while the WUR minimizes the sensors’ power consumption. UWB-based precise localization requires addressing multiple sources of error, such as UWB-ranging noise and UWB antennas’ uneven radiation pattern. The limited computational resources aboard a nano-UAV further complicate this scenario, requiring real-time execution of the localization algorithm within a microcontroller unit (MCU). We propose a novel UWB-based localization system for nano-UAVs, composed by: 1) a lightweight localization algorithm; 2) an optimal flight strategy; and 3) a ranging-error-correction model. Our 3-D flight policy requires only five UWB measurements to feed the localization algorithm, which bounds the localization error within <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {28 \, \text {c} \text {m} }$ </tex-math></inline-formula> and runs in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {1.2 \text {m} \text {s} }$ </tex-math></inline-formula> on a Cortex-M4 MCU. Localization accuracy is improved by an additional 25% thanks to a novel error-correction model. Leveraging the WUR, the entire localization/data-exchange cycle costs only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {24 \, \text {m} \text {J} }$ </tex-math></inline-formula> at the sensor node, which is 50 times more energy efficient than the state of the art with comparable localization accuracy.

A Compact Penta Band Notched UWB Antenna Using Modified U-Slots and EBG Structures

The proposed compact Ultra-Wide Band (UWB) antenna is having the ability to reject five bands operating in UWB and it is having a rectangular monopole antenna. To achieve the required Penta band notch characteristics and the multi operational bands, two square shaped mushroom type EBG’s are placed in the vicinity of the feedline and three modified U-Shaped Slots are etched on the radiating surface. The two-mushroom type EBG’s are responsible for attaining two notch bands at 3.5 GHz (3.38-3.6 GHz, Wi-MAX), 5.0 GHz (4.85-5.18GHz, lower WLAN) and modified U-Shaped slots are responsible for attaining three notch bands at 2.5 GHz (2.3-2.67 GHz, ISM band), 3.0 GHz (2.8-3.08 GHz, Radar surveillance band), 4.0 GHz (3.88-4.1 GHz, C-band satellite downlink). The step wise implementation of the Penta notch band UWB antenna along with the relative analysis is discussed. The results show that the proposed antenna is a very good one for UWB applications which requires multi operational bands with selective band rejections.

In Situ Measurement of Absorbing Properties of Materials Based on Near-Field Reflection Method

To meet the requirements of the in-situ measurement of the absorbing properties of materials and break through the limitations of the transmission line probe method in ultra-wideband and high-precision measurement, this paper presents in-situ measurement technology for the absorbing properties of materials based on near-field reflection testing. A miniaturized ultra-wideband antenna, a decoupling structure and a shielding cover are designed, and an in-situ measurement probe is constructed. By integrating the probe with a microwave transceiver module as well as a control processing module, a handheld broadband microwave reflectivity test instrument is developed and its performance is verified. The measurement accuracy of the proposed instrument is higher than that of transmission line probes, the deviation of its test results from those of standard arch systems is less than 1.5 dB in the reflectivity range of 0 to -20 dB; its test frequency band is wider, and its frequency band covers 2-18 GHz. The instrument is suitable for accurately measuring the absorbing properties of materials with thicknesses of less than 1.5 mm.

A Novel Compact Ultra-Wideband Frequency-Selective Surface-Based Antenna for Gain Enhancement Applications

This article presents a compact ultra-wideband (UWB) circular monopole antenna with a frequency-selective surface (FSS) for gain enhancement. The proposed antenna has a circular patch with circular cuts at the edges and is excited by a microstrip feed. The bottom plane is truncated and further modified by two triangular cuts at the sides and one rectangular cut in the middle to improve the radiation characteristics of the UWB antenna. The antenna is designed on an FR-4 substrate with a thickness of 1.6 mm, a relative permittivity of 4.3, and planner dimensions of 30 mm × 30 mm. To improve the proposed antenna’s gain, an FSS is designed that consists of periodic unit cells of metal printed on the upper layer of an FR-4 substrate with dimensions of 0.11λ × 0.11λ at the lowest operating frequency of 3.3 GHz. The FSS shows a very low transmission coefficient and linearly reducing reflection phase with increasing frequency over a frequency range of 3.3–10.8 GHz. The gain of the proposed antenna is increased from 3 dB to 8.1 dB at 9 GHz by placing the antenna on the FSS. Moreover, the prototype of the proposed antenna is fabricated, and the experimental results are measured, which show close agreements with simulated results. The FSS-based antenna has directional radiation patterns, making it a potential candidate for ground-penetrating radar and UWB applications.

Development of a Triple Band Notched UWB Antenna

In this paper, a microstrip line-fed rectangular-shaped ultra-wideband (UWB) antenna offering triple-band notch characteristics is proposed. The notching was done primarily to provide rejection for Wi-Max (3.3-3.7 GHz), WLAN2 (5.15-5.825 GHz), and ITU (8.025-8.4 GHz) through the combination of slots and a modified electromagnetic band gap (M-EBG). The antenna was simulated using HFSS and CST modelling tools. The antenna was able to notch three frequencies from narrow band communication systems (Wi-Max, WLAN2, and ITU), causing interference within the UWB band. The gain of the system over the operating frequency, the current distributions, and the impedance covered were studied to assess the effectiveness of the antenna. The proposed antenna is simple and compact, with a total antenna size of 19 mm by 24 mm and a wide bandwidth (3.2 to 12.5 GHz). Satisfactory results have been obtained when its performance was analyzed. A stable radiation characteristic is observed with a radiation efficiency of 94% when operating at a UWB resonant frequency of 6.85 GHz with a total gain between -10 dB and 5 dB within the range of the frequency band of 3.2 to 12.3 GHz.

A Dual Notch Band UWB Antenna for Local Area Cognitive Radio Network Applications

Over the years, Cognitive radio technology has dramatically influenced wireless systems in which antenna plays a significant role for interviewing spectrum sensing and underlay operations. An ultra-wideband (UWB) antenna with extended dual notch band feature is proposed in this work to meet the requirements of cognitive radios without interference from the crowded spectrum. The proposed antenna consists of stair-stepped rectangular patch with circular cut off the patch at the lower edges to which a complementary split ring resonator (CSRR) and a Patch Stub are loaded to achieve notch bands. It has an optimum dimension of 18mm by 18 mm, fabricated on FR4 material which operates between 2.64 GHz and 11.87 GHz with two notch bands at 3.293.61 GHz and 4.956.05 GHz, respectively for 5G carrier and WiFi carrier. The measured results show a peak total gain of 3.93 dBi and more than 92% radiation efficiency in the entire operating range. This is well suited for Local area cognitive radio networks; the simulated and measured results were found to be in good agreement and satisfactory.

Flexible and Small Textile Antenna for UWB Wireless Body Area Network

In this paper, a miniaturized textile microstrip antenna is proposed for wireless body area networks (WBAN). The ultra-wideband (UWB) antenna used a denim substrate to reduce the surface wave losses. The monopole antenna consists of a modified circular radiation patch and an asymmetric defected ground structure, which expands impedance bandwidth (BW) and improves the radiation patterns of the antenna with a small size of 20 × 30 × 1.4 mm3. An impedance BW of 110% (2.85–9.81 GHz) frequency boundaries was observed. Based on the measured results, a peak gain of 3.28 dBi was analyzed at 6 GHz. The SAR values were calculated to observe the radiation effects, and the SAR values obtained from the simulation at 4/6/8 GHz frequencies followed the FCC guideline. Compared to typical wearable miniaturized antennas, the antenna size is reduced by 62.5%. The proposed antenna has good performance and can be integrated on a peaked cap as a wearable antenna for indoor positioning systems.

A Quadruple Notch UWB Antenna with Decagonal Radiator and Sierpinski Square Fractal Slots

A novel quadruple-notch UWB (ultrawideband) antenna for wireless applications is presented. The antenna consists of a decagonal-shaped radiating part with Sierpinski square fractal slots up to iteration 3. The ground part is truncated and loaded with stubs and slots. Each individual stub at the ground plane creates/controls a particular notch band. Initially, a UWB antenna is designed with the help of truncation at the ground plane. Miniaturization in this design is achieved with the help of Sierpinski square fractal slots. Additionally, these slots help improve the UWB impedance bandwidth. This design is then extended to achieve a quadruple notch by loading the ground with various rectangular-shaped stubs. The final antenna shows the UWB range from 4.21 to 13.92 GHz and notch frequencies at 5.02 GHz (C-band), 7.8 GHz (satellite band), 9.03, and 10.86 GHz (X-band). The simulated and measured results are nearly identical, which shows the efficacy of the proposed design.

A flower bud-shaped flexible UWB antenna for healthcare applications

Remote surveillance of the elderly and others with health difficulties is becoming increasingly important in these epidemic days. To address these issues, low-cost, lightweight, and portable wearable devices are in huge demand. This paper realizes the design and analysis of a flexible ultra-wideband (UWB) antenna for healthcare applications. The proposed hexagonal microstrip antenna encompasses two cuts on the top left and right side of the hexagon which looks like a flower bud. The antenna is fabricated using a flexible foam substrate with a dielectric constant of 1.07 and has a dimension of 38 times 30 times 1.7,{text{mm}}^{3}. With a unique patch shape and corner cut in the partial ground, the present design strives to optimize the antenna structure to accommodate UWB (3.1 to 10.6 GHz) operating spectrum from 2.6 to 11.3 GHz. The proposed antenna has achieved an FBW of 125.17% with a total gain of 5.24 dB. The antenna is also evaluated on the line of bending and SAR over a tissue of 1 g and 10 g. The antenna operated admirably, with an average SAR value below the safety limits of 1.6 W/kg and 2 W/kg for the tissues, respectively.

Automated and Optimized Regression Model for UWB Antenna Design

Antenna design involves continuously optimizing antenna parameters to meet the desired requirements. Since the process is manual, laborious, and time-consuming, a surrogate model based on machine learning provides an effective solution. The conventional approach for selecting antenna parameters is mapped to a regression problem to predict the antenna performance in terms of S parameters. In this regard, a heuristic approach is employed using an optimized random forest model. The design parameters are obtained from an ultrawideband (UWB) antenna simulated using the high-frequency structure simulator (HFSS). The designed antenna is an embedded structure consisting of a circular monopole with a rectangle. The ground plane of the proposed antenna is reduced to realize the wider impedance bandwidth. The lowered ground plane will create a new current channel that affects the uniform current distribution and helps in achieving the wider impedance bandwidth. Initially, data were preprocessed, and feature extraction was performed using additive regression. Further, ten different regression models with optimized parameters are used to determine the best values for antenna design. The proposed method was evaluated by splitting the dataset into train and test data in the ratio of 60:40 and by employing a ten-fold cross-validation scheme. A correlation coefficient of 0.99 was obtained using the optimized random forest model.

Zero-Biasing Split Ring Resonator using Metamaterial Element for High Gain Superstrates Ultra-Wideband Antenna

Complex materials with artificial structures known as metamaterials (MTM) have unique properties that draw several scientists to use them in a variety of research fields. In addition, MTM can go beyond some of the restrictions placed on tools used in technical practise while improving the characteristics of microwaves. The Internet of Things (IoT) application calls for the construction of zero-index Split Ring Resonator (SRR) MTM element superstrates with an ultra-wideband antenna. Keep in mind that the MTM simulates behaviour that is not found in nature, namely the zero-reflection phase (dB) on the resonance frequency. For this project, an antenna with an SRR MTM unit cell operating at 2.70 GHz is built. The SRR has four inductance-related loops (r1, r2, r3, and r4), and gaps (slots) are added to the ring to produce the capacitance effect. Parametric research has been done for the SSR in the interim to identify the best design with zero indexes, permittivity and permeability at the desired frequency. The MTM unit cells array design's 7 x 4 and 10 x 5 dimensions achieved a dB of 0° at the 2.70 GHz frequency range. A 7 x 4 MTM unit cell makes up the first design, MTM Antenna Design 1, which at 2.70 GHz recorded a gain of 5.70 dB and a return loss (S11) of -20.007 dB. The return loss (S11) at a frequency of 2.70 GHz was -19.734 dB in the second design, an MTM antenna consisting of 10 x 5 MTM unit cells, which recorded a gain of 5.66 dB.

Miniaturized Coplanar Waveguide-Fed UWB Antenna for Wireless Applications

This study presents a compact ultra-wideband (UWB) antenna fed by a coplanar waveguide (CPW) with huge bandwidth for the demands of modern wireless communities. To overcome some technical limitations of the employed substrate and UWB antenna design, a slotted patch resonator was used to create and simulate this antenna based on Locked-Key topology. It has been printed on a 1.5 mm-thick FR4 substrate with a dielectric constant of 4.4. A feeder with characteristic impedances of 50 Ω has been employed. A CST electromagnetic simulator has been employed to simulate and analyze the antenna design. It is operated within the UWB spectrum with a bandwidth of 10.354 GHz, spanning 3.581 to 14 GHz. The overall surface area is 27 × 25 mm2. The gain and maximum efficiency within UWB are better than 3 dBi and 82%, respectively. The antenna is fabricated, and the simulated results are correlated with the measured ones. Finally, the equivalent circuit models for the antenna and rectifier circuit are simulated and measured.

Slot Antenna for Ultra-Wideband Automobile Applications at 24 GHz

This research article discusses the investigations on the design of an Ultra-Wideband (UWB) antenna and its performance analysis from 20 to 30 GHz frequency range which is suitable for Short Range (SR) RADAR applications. This is designed by incorporating a rectangular slot on rectangular patch and reducing the ground plane size. The antenna characteristics namely return loss, current distribution, E-plane and H-plane far field patterns, gain over frequency, group delay in the operating frequency and radiation efficiency are investigated through simulations. Brief discussion regarding FCC guidelines related to the use of 24 GHz frequency band is provided. The antenna occupies the size of 10 X 10 X 1.6 mm3. Necessary parametric analyses were performed to confirm the finalized dimensions as optimum. The impedance bandwidth characteristics was measured using VNA (Vector Network Analyzer) and the obtained –10 dB bandwidth agrees with the simulated result.

An Advanced 3-D Electromagnetic Analysis and Experimental Validation of a Bipolar Subnanosecond Pulse Generation System

This article presents an advanced 3-D electromagnetic co-simulation approach developed using the CST software to evaluate the characteristics of a bipolar subnanosecond pulse forming system for application in the biomedical and defense domains. To the best of the authors’ knowledge, the simulation technique presented in this article, which integrates transient switching devices in the 3-D electromagnetic model of the bipolar subnanosecond pulse forming system, was not presented previously in the open literature. The design of the bipolar subnanosecond pulse forming system is based on a thorough analytical calculation with predictions verified using the 3-D numerical modeling to generate a voltage of up to 500 kV peak-to-peak amplitude with a duration of around 1.8 ns when connected to a 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> load. A good agreement between the experimental results and the CST predictions was obtained, providing the correctness of the proposed modeling technique. Future plans involve connecting the bipolar subnanosecond pulse forming system to an ultra-wideband (UWB) antenna.