Ultra-wideband Monopole Research Articles

Development and investigation of a compact band-notched MIMO antenna attaining wideband isolation for UWB applications

The sequential layout of a portable ultra-wideband (UWB) monopole antenna, transforming into a compact band-notch (3.15–4.3 GHz rejecting the Wi-Max and the C-Band) multiple-input multiple-output (MIMO) antenna is described in this paper. The diversity layout is designed within a compact size of 39 (l) × 18 (W) mm2. Due to the opposite orientation of the two radiators in the diversity configuration and the use of a rectangular parasitic strip near the feed lines, high and wideband isolation (of >20 dB) is attained over the entire UWB spectrum. The proposed layout depicts a stable omnidirectional radiation pattern and a maximal gain of 1.82 dB. The envelope correlation coefficient (ECC) is found to be below 0.18 for the entire UWB spectrum. Empirical verifications in terms of vital diversity parameters and analogy with competing layouts strengthen the candidature of the intended MIMO layout for UWB wireless portable applications.

A low-profile ultra-wideband hexagonal-patch antenna for UAV-based applications

ABSTRACT A compact, low-profile, and ultra-wideband antenna is always desirable for airborne Unmanned Aerial Vehicles (UAV) applications. In this paper, an ultra-wideband monopole antenna is presented with the benefit of a compact and low-profile design structure. The antenna design enables efficient communication without interfering with the UAV’s other components. The antenna is designed using a slotted-hexagonal-patch fed from a co-planar microstrip feed. The bow-tie-shaped slot along with a few other rectangular-shaped parasitic slots are loaded in the hexagonal patch for bandwidth enhancement. The coplanar feed with top ground offers minimum interference with the UAV structure. The non-conducting bottom plane allows seamless integration without causing any interference to the antenna. An equivalent circuit model (ECM) of the proposed antenna is also developed. The antenna structure is fabricated and the measured results are validated. A good agreement between the measured and simulated results is observed. The antenna covers an ultra-wideband ranging from 3 GHz to 13.5 GHz with a maximum gain of 4.0dBi. The size of the antenna is 0.24λ0 ×0.29λ0 ×0.01λ0. The developed antenna, therefore, demonstrates that it is a strong contender for ultra-wideband UAV-based applications.

A Compact Dual-polarized Probe-fed UWB Antenna System for Breast Cancer Detection Applications

This article proposes an electrically small, probe-fed Ultra-Wideband (UWB) monopole antenna on a slotted truncated ground plane for breast cancer detection. The physical footprint of the proposed antenna element is 33 mm × 35 mm × 0.5 mm. This element is designed on the low-cost FR4 Epoxy substrate with a thickness of 0.5 mm. The proposed antenna has an electrical size of 0.33λ × 0.35λ × 0.005λ at the lowest frequency of operation; the radiator offers an impedance bandwidth of 8.34 GHz, which implies a fractional bandwidth of 115.5%. A compact dual-polarized antenna topology with two orthogonally placed probe-fed monopole antennas is proposed to achieve polarization diversity. The impedance characteristics of the individual radiating elements are maintained in spite of the electrical proximity of the radiators. The numerically computed and experimentally measured results of dual-polarized electrically small UWB antenna agree quite well. The proposed dual-polarized antenna topology is investigated for its utility in breast cancer detection in simulation.

Mechanical Robustness Enhanced Flexible Antennas Using Ti3C2 MXene and Nanocellulose Composites for Noninvasive Glucose Sensing.

Electromagnetic sensors with flexible antennas as sensing elements have attracted increasing attention in noninvasive continuous glucose monitoring for diabetic patients. The significant radiation performance loss of flexible antennas during mechanical deformation impairs the reliability of glucose monitoring. Here, we present flexible ultrawideband monopole antennas composed of Ti3C2 MXene and cellulose nanofibril (CNF) composite films for continuous glucose monitoring. The flexible MXene/CNF antenna with 20% CNF content can obtain a gain of up to 3.33 dBi and a radiation efficiency of up to 65.40% at a frequency range from 2.3 to 6.0 GHz. Compared with the pure MXene antenna, this antenna offers a comparable radiation performance and a lower performance loss in mechanical bending deformation. Moreover, the MXene/CNF antenna shows a stable response to fetal bovine serum/glucose, with a correlation of >0.9 at the reference glucose levels, and responds sensitively to the variations in blood glucose levels during human trials. The proposed strategy enhancing the mechanical robustness of MXene-based flexible antennas makes metallic two-dimensional nanomaterials more promising in wearable electromagnetic sensors.

A Hybrid QOGWO-GPR Algorithm for Antenna Optimization

Optimization of antenna performance is a non-linear, multi-dimensional and complex issue, which entails a significant investment of time and labor. In this paper, a hybrid algorithm of quasi-opposition grey wolf optimization (QOGWO) and Gaussian process regression (GPR) model is proposed for antenna optimization. The QOGWO is prone to global optimality, high precision for complex problems, and fast convergence rate at the later stage. The GPR model can reduce time cost of antenna samples generation. After being optimized by the proposed approach, a stepped ultrawideband monopole antenna and a dual-band MIMO antenna for WLAN can achieve wider bandwidth and higher gain or isolation at low time cost, compared to other intelligent algorithms and published literatures.

Ultrawide-band Wearable Antenna with Uniplanar Compact Electromagnetic Band Gap

Ultrawide-band technology, commonly known as UWB, sends data over a wide frequency range for many applications. WBAN applications use wearable antennas because they have flexible materials and are suitable for telemedicine technology and have many advantages such as small size, lightweight, able to work at a wide enough frequency, easy fabrications, and affordable costs. In this research, the hexagonal patch ultrawide-band monopole planar wearable antenna was designed using Cordura Delinova 2000 textile material for the substrate and copper tape for the groundplane and patch. The Uniplanar Compact Electromagnetic Band Gap (UC-EBG) as a metamaterial was added to the design of the monopole planar antenna in this final project which aims to improve antenna parameters, increase efficiency, and reduce the effects of radiation on the body. From the measurement results on the antenna with the addition of the UC-EBG structure at the bottom of the patch, it produces a 6% fractional bandwidth increase and able to work in the frequency range of 3-10 GHz off-body conditions and 2-11 GHz on-body conditions. In the SAR test at 45 mm, it was found that the value decreased from previously 1.535 W/Kg to 1.31 W/Kg at a frequency of 3.5 GHz and previously from 1.421 to 1.267 W/Kg at a frequency of 5 GHz on a wrist phantom object which is a good value for SAR. The resulting increase in antenna gain after the addition of the UC-EBG structure. The radiation pattern on the antenna is bidirectional.

A Dual-notched Ultra-wideband Monopole Antenna Based on Frequency Selective Surface Technology

A Dual-notched Ultra-wideband Monopole Antenna Based on Frequency Selective Surface Technology

A novel compact semicircular defected ground structure ultrawideband monopole antenna integrated with Ku band for breast cancer detection

SummaryA compact and novel ultrawideband (UWB) antenna integrated with Ku band for microwave imaging applications is reported. The reported antenna consists of a novel patch structure along with a tapered feed structure on top of FR‐4 substrate having a compact dimension of 16 × 22 mm2 and novel semicircular defected ground structure (SC‐DGS) etched below the substrate. The proposed antenna covers a wide impedance bandwidth of 15.07 GHz spanning from 3.51 to 18.58 GHz with a fractional bandwidth (FBW) of 136%. The intended antenna performance is analyzed for S11, peak gain, efficiency, and radiation patterns in frequency domain, and group delay, isolation (S21), and linear phase response in time domain. The simulated and measured results of reported antenna are well matched for the usage in practical portable UWB applications. More importantly, the proposed antenna system is simulated for the detection of breast cancer tissue by comparison of S21 results, current densities, and specific absorption rate with and without tumor conditions. These findings show that the radiator and the whole system work well in detecting the breast tumor.

Novel Dual Band Frequency Selective Surface and its Applications on the Gain Improvements of Compact UWB Monopole Antenna

In this work, a highly directional ultra-wideband (UWB) microstrip patch antenna as a single-element is suggested. The proposed antenna’s gain is enhanced with a novel dual-band frequency selective surface (FSS) placed beneath it. The FSS design has a hexagonal structure with meander line inductances and a capacitance-like structure connecting all of the corners to the middle. There is no metallic layer on the other side of the substrate, which shows transmission zeros at 4.95 GHz and 12.7 GHz, and a modified U-shaped monopole antenna is developed. First, the performance characteristics of the antenna and FSS are analyzed from the simulation results, and they are validated experimentally after fabrication, followed by measurement. The compact configuration comprises an antenna loaded with the proposed FSS results S11 less than -10 dB from 3.15 GHz to 22.65 GHz, covering the UWB band together with the X, Ku-band with a bandwidth of 19.5 GHz (151.16% FBW). The antenna’s overall physical dimensions would be 38.8 mm×38.8 mm×25.2 mm (0.407λo×0.407λo×0.265λo), with λo denoting the lowest frequency’s free-space wavelength. The FSS loading results in a 9.9 dBi maximum gain at 10 GHz. The antenna’s small size increases bandwidth, and its high peak gain makes it ideal for use in real-time applications.

A Miniaturized Thin-Film UWB Monopole Antenna Implemented with High-Dk Adhesive

This paper presents the design of a miniaturized polyimide-based antenna for ultra-wideband (UWB) communication. Miniaturization is achieved through the utilization of adhesive material with a high dielectric constant (high-Dk). The goal of this work is to investigate the impact of such material on the antenna performance and to optimize its design for UWB operation. The manufacturing of the antenna using the proposed structure is developed, and the prototype of an antenna for the UWB high band (6–9 GHz) is measured and analyzed. By leveraging the high Dk of the adhesive material, the simulation and measurement results show that the proposed antenna with a high-Dk adhesive film can achieve compact dimensions with good performance in terms of the gain and time domain characteristics. The results of this study show the potential of exhibiting a reduction in the size of the antenna and will contribute to the advancement of miniaturized UWB antenna technology.

On the Experimental Investigation of Bone Fracture Recovery Process Using an Ultra-Wideband Planar Monopole Antenna

In this paper, a noninvasive bone fracture monitoring system is developed using a planar monopole antenna. The proposed antenna provides an ultra-wideband response, and its overall size is 18 × 19 × 0.8 mm3. The proposed ultra-wideband monopole (UWM) antenna has a maximum measured gain of 3.77 dBi, and the maximum SAR value for an input power of 18 dBm is less than 1.6 (W/kg) (1 g). A bovine tibia is experimentally tested using a proposed UWM antenna to monitor the fracture recovery process and then further analysed using principle component and linear regression analysis. In addition, a microcontroller with a wireless communication module is developed to monitor the data in an Android application. The proposed system could be a promising approach for developing a portable, noninvasive monitoring device.

Compact UWB Monopole Antenna with Tunable Dual Band Notched Characteristics for WiMAX and WLAN Applications

The present work shows a planar compact ultra-wideband (UWB) monopole antenna with controllable dualband-notch frequencies at 3.3 GHz for WiMAX and 5 GHz for WLAN. In the proposed antenna, the lower notchband (at a frequency of 3.3 GHz) is made by cutting a thin horizontal strip on top of the radiating patch. The uppernotch band (at a frequency of 5 GHz) is made by putting two narrow parasitic strips in the shape of an “I” oneither side of the radiating patch. The incorporation of three varactor diodes between the radiating patch and three metallic strips provides the flexibility of adjusting the notch frequencies. The notch band tunability between 3.15 GHz and 3.69 GHz and between 4.93 GHz and 5.59 GHz, respectively, is achieved by changing the bias voltageof the varactor diode between 0 V and 30 V. The gain and efficiency characteristics of the designed antenna alsoexhibit band rejection at the respective notch frequencies. The design principle is validated by fabricating andmeasuring a prototype of the proposed dual-band, notched UWB antenna. For three different bias voltages of thevaractor, the simulated and experimental findings are in reasonable agreement. The proposed works demonstratebetter-notch characteristics as compared with other reported works over the UWB range

A novel method for optimization of flat monopole antennas with the help of a universal definition for geometric shapes

In this research, a novel method is proposed optimization of flatted ultra-wideband monopole antennas. In this method, the shape of the antennas is described in general terms. This general description allows the antennas to take all kinds of shapes during the optimization process and finally, an optimal form for an ultra-wideband monopole is obtained. The parameters of this general description are obtained according to the design constraints in a two-stage optimization process (including global and local optimization). The optimization to achieve the acceptable impedance matching in the working band and reduction of the distortion of the radiation waves is to be done. Due to the efficiency of the optimization method, by applying strict-tightening constrictions on the size of the antenna, smaller antennas with the same performance as the best flat monopole antennas are designed. The main optimization program runs in Matlab Software, but the analysis of antennas at each stage of optimization is executed in the CST Microwave Studio Software. For this purpose, with the help of Visual Basic for Applications programming, an automated link is created between the MATLAB Software and CST Microwave Studio Software. The optimization results showed the ability of this method to design very small antennas with desired functional characteristics. The results showed that the return loss for the entire operational spectrum is below − 10 dB. Also, the correlation coefficient of the proposed planar super wideband monopole antenna has different values in different radiation angles.

Characteristic-Mode-Analysis-Based Compact Vase-Shaped Two-Element UWB MIMO Antenna Using a Unique DGS for Wireless Communication

The modern electronic device antenna poses challenges regarding broader bandwidth and isolation due to its multiple features and seamless user experience. A compact vase-shaped two-port ultrawideband (UWB) antenna is presented in this work. A circular monopole antenna is modified by embedding the multiple curved segments onto the radiator and rectangular slotted ground plane to develop impedance matching in the broader bandwidth from 4 to 12.1 GHz. The UWB monopole antenna is recreated horizontally with a separation of less than a quarter wavelength of 0.13 λ (λ computed at 4 GHz) to create a UWB multiple input and multiple output (MIMO) antenna with a geometry of 20 × 29 × 1.6 mm3. The isolation in the UWB MIMO antenna is enhanced by inserting an inverted pendulum-shaped parasitic element on the ground plane. This modified ground plane acts as a decoupling structure and provides isolation below 21 dB across the 5–13.5 GHz operating frequency. The proposed UWB MIMO antenna’s significant modes and their contribution to antenna radiation are analyzed by characteristic mode analysis. Further, the proposed antenna is investigated for MIMO diversity features, and its values are found to be ECC < 0.002, DG ≈ 10 dB, TARC < −10 dB, CCL < 0.3 bps/Hz, and MEG < −3 dB. The proposed antenna’s time domain characteristics in different antenna orientations show a group delay of less than 1 ns and a fidelity factor larger than 0.9.

A novel MIMO antenna with switchable UWB/5G modes for vehicular terminals

AbstractThis paper demonstrates the design and development of a dual‐operating mode multiple‐input and multiple‐output (MIMO) antenna. The MIMO antenna comprises a novel ultrawideband (UWB) antenna with selectively chosen feedlines to obtain bandwidth reconfiguration. The novel UWB monopole evolved from a rectangular monopole whose radiating portion and the ground plane are shaped to obtain broadband impedance matching from 2.3 to 10.7 GHz (Mode 1). The antenna is excited using a 50‐Ω microstrip line. An additional feed path is created and deployed to achieve bandwidth selectivity with a tuning fork bandpass filter (BPF) operating between 2.8 and 4 GHz. Bandwidth selection is performed using a pair of positive–intrinsic–negative diodes. Thus, in the reconfigured state, the monopole is connected to the excitation source through the BPF, restricting the operational bandwidth to 2.8–4.0 GHz (Mode 2). A vertically polarized four‐element MIMO antenna with pattern diversity characteristics is constructed, and the performance parameters are studied. The proposed multiantenna is fabricated and tested in the laboratory. The proposed MIMO antenna offers a measured gain of over 3.51 dBi and total efficiency above 78%. The proposed multielement antenna is suitable for UWB communications, including ISM, LTE2700, and sub‐6 GHz 5G communications at 3.5 GHz in the vehicular environment.

Miniaturized Ultrawideband Microstrip Antenna for IoT-Based Wireless Body Area Network Applications

In this paper, we present an extremely compact ultrawideband (UWB) monopole microstrip patch antenna for a wireless body area network (WBAN). The proposed antenna is fabricated on a flexible Rogers RT-5880 dielectric substrate of thickness 0.5 mm and has an overall size of 20 × 15 × 0.5 m m 3 . The proposed antenna achieves a wideband characteristic with the help of a modified ground plane with a monopole pair. The monopole antenna is fed through a microstrip line and has a good impedance matching over a frequency band of 3.2 to 15 GHz (and beyond), with an axial ratio below 3 dB and a high efficiency of 77–95%. This antenna is designed to cover almost the complete UWB range; bandwidth for antenna is 11.52 GHz (3.48-15 GHz). The antenna has a realized gain of 2.3–7.2 dBi throughout the frequency band and has been tested for conformality. Measured results are found to be in good correlation with the simulated results. The antenna has also been tested for specific absorption rate (SAR) values within the simulation to compare with Federal Communications Commission (FCC) limits and verify their suitability for the Internet of Things- (IoT-) based wearable body area network.

A novel filtering monopole antenna for 5G communications

PurposeThis study aims to design a compact filtering monopole antenna for 5G communication. The design is most suited for various applications within the frequency range of 2.2–3.8 GHz. It offers enhanced bandwidth and reasonable gain with wide-stopband performance.Design/methodology/approachA low-pass filter (LPF) of complementary split ring resonator (CSRR) with short-circuited stub lines is integrated with a compact defected coplanar waveguide fed truncated circular monopole ultrawideband (UWB) antenna. The reference UWB antenna etched on an FR4 substrate was coupled to the designed LPF to transform the UWB antenna into a wideband antenna. The effect of coupling is analyzed based on the real and imaginary responses of the terminal impedance (ZT) curve. Three short-circuited stub lines of asymmetric lengths are added to the CSRR LPF to suppress harmonics, thereby enhancing the stopband performance and impedance matching between the elements. The proposed filtering antenna is fabricated using a photolithography process, and the corresponding results are measured using a network analyzer (N9951A). The radiation parameters of the proposed filtering monopole antenna are tested in the anechoic chamber. The simulated/measured results are compared and are found in agreement with each other.FindingsThe proposed design suppresses 6.5f0 harmonics, resulting in wide stopband performance and increased gain selectivity at the transition edge. A peak suppression of −41 dB and an average suppression of −18 dB were attained throughout the stopband. An operating fractional bandwidth of 54.5%/143% with a peak gain of 3 dBi/5 dBi was obtained. The proposed filtering antenna supports 5G applications such as WiMAX, WLAN, n7, n38 IMT-E, n30 WCS, n40 TDD, n41 TDD, n48 TDD, n78 TDD and n90 TDD.Originality/valueThe proposed design is novel and compact and has a wide application in 5G communication. With the filter, the antenna operates in wideband, and without the filter, it operates in UWB. Besides, it offers enhanced stopband performance with high gain selectivity at the transition edge. Comparatively, a 50% improvement in bandwidth, 52% improvement in size reduction and 33% improvement in harmonic suppression are attained.

A Transparent Antenna Using Metal Mesh for UWB MIMO Applications

This paper presents a transparent ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna based on a wired metal mesh (MM) structure. Transparent antennas (TAs) can be integrated on various building materials with little visual impact to facilitate flexible massive indoor wireless device deployment. The proposed antenna achieves 77% transparency by hollowing out both metal and substrate into a mesh shape, while maintaining more than 83% radiation efficiency. The MIMO antenna consists of 4 elements, each being a co-planar waveguide (CPW) fed UWB monopole and adjacent elements being placed orthogonally to produce dual polarisation. The operating band of the MIMO antenna spans over 3.2-11.2 GHz. A parasitic decoupling structure aligned with the mesh grid is designed to enhance the isolation between MIMO elements without degrading the transparency. Within the entire operating band, the isolation between any two elements is more than 20 dB. The peak gain varies from 3.3 dBi to 7.2 dBi within the bandwidth. The envelop correlation coefficient (ECC) is less than 0.004. The channel capacity and time domain response are analysed. The antenna can be easily fabricated by conventional PCB and laser cutting techniques with a low cost.

A novel circular fractal ring UWB monopole antenna with dual band‐notched characteristics

AbstractThis paper presents a novel circular fractal ring monopole antenna for ultra‐wideband (UWB) hardware with dual band‐notched properties. The proposed antenna consists of four crescent‐shaped nested rings, a tapered feeding line at the front of the dielectric material, and a semicircular ground plane on the backside. In this design, the nested rings are used both as a radiation element and a band rejection element. The proposed antenna has a bandwidth of 9.03 GHz, which works efficiently in the range of 2.63 GHz–11.66 GHz with the dual notched bands of Worldwide Interoperability for Microwave Access (WiMAX) at 3.15 GHz–3.66 GHz and wireless local area network (WLAN) at 4.9 GHz–5.9 GHz, respectively. The antenna has a compact size of 20 mm × 30 mm × 1 mm (0.177 × 0.265 × 0.0084 λ0) and is implemented using a flame‐retardant type 4 (FR4) material. It has a maximum gain of approximately 4 dB in its operating range, and experimental results support the simulation predictions with high accuracy. The findings of this study imply that the designed antenna can be utilized in UWB applications.

A Compact Quad-Port UWB MIMO Antenna With Improved Isolation Using a Novel Mesh-Like Decoupling Structure and Unique DGS

The progress in mobile communication and the Internet of Things facilitates multiple features. The trending technology demands wider bandwidth so that user experiences uninterruptedly. The wider bandwidth and the isolation are two key characteristics of modern device antennas. The design of an ultrawideband (UWB) and four-port MIMO antenna is presented in this brief. The semicircular monopole patch is modified by including a guitar shape slot on a radiator and a half-circle slot in the lowered ground plane. The structural transformation affects the current path and enhances impedance matching, resulting in a broader bandwidth. The UWB monopole is replicated to construct a four-port multiple input and multiple output (MIMO) antenna. The separation between the interelement is less than the quarter wavelength. As a decoupling structure, the implicit mutual coupling in the MIMO elements is minimized by parasitic elements on the radiator and defected ground plane (DGS). A novel mesh-like structure embedded in radiating plane and DGS couples the current from an excited antenna and suppresses through the DGS correspondingly and improves the isolation. The overall geometry of the antenna is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$45 {\times } 45 {\times }1$ </tex-math></inline-formula> .6 mm3. The UWB MIMO has a measured impedance bandwidth of 113% between 4.5-16.4 GHz and greater than 20 dB of isolation throughout the bandwidth. Besides the mutual coupling reduction, radiation characteristics and all MIMO diversity parameters are studied. The performance of MIMO diversity characteristics is relatively good, with envelope correlation coefficient<0.002, diversity gain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {\mathrm {\simeq }}10$ </tex-math></inline-formula> , mean effective gain<−3 dB, total active reflection coefficient<−10 dB, channel capacity loss <0.2 bps/Hz, and multiplexing efficiency<−0.5. The experimental and simulated findings are in line and make the projected design suitable for UWB MIMO applications.