Dual-Band RFID Tag Antenna Based on the Hilbert-Curve Fractal for HF and UHF Applications

A novel single-radiator card-type tag is proposed which is constructed using a series Hilbert-curve loop and matched stub for high frequency (HF)/ultra high frequency (UHF) dual-band radio frequency identification (RFID) positioning applications. This is achieved by merging the series Hilbert-curve for implementing the HF coil antenna, and square loop structure for implementing the UHF antenna to form a single RFID tag radiator. The RFID tag has directivity of 1.75 dBi at 25 MHz, 2.65 dBi at 785 MHz, 2.82 MHz at 835 MHz and 2.75 dBi at 925 MHz. The tag exhibits circular polarisation with -3 dB axial-ratio bandwidth of 14, 480, 605 and 455 MHz at 25, 785, 835 and 925 MHz, respectively. The radiation characteristics of the RFID tag is quasi-omnidirectional in its two orthogonal planes. Impedance matching circuits for the HF/UHF dual-band RFID tag are designed for optimal power transfer with the microchip. The resulting dual-band tag is highly compact in size and possesses good overall performance which makes it suitable for diverse applications

Bandwidth extension of planar antennas using embedded slits for reliable multiband RF communications

In this paper a technique is described to extend the impedance bandwidth of patch antennas without compromising their size. This is accomplished by embedding capacitive slits in the rectangular patch with a truncated ground-plane, and exciting the antenna through a meandered strip-line feed. The proposed antenna was fabricated on standard FR-4 substrate with permittivity of 4.6, thickness of 0.8 mm and loss-tangent of 0.001. The performance of the prototype antenna was verified through measurements. Characteristics of the antenna include an impedance bandwidth of 5.25 GHz (800 MHz–6.05 GHz) for VSWR<2 corresponding to a fractional bandwidth of 153.28%, peak gain of 5.35 dBi, radiation efficiency of 84.12% at 4.45 GHz, and low cross-polarization. These attributes make the antenna applicable for stable and reliable multiband applications in the UHF, L, S and major part of C-bands. The antenna offers advantages of low cost, low profile, ease of manufacturing, durability and conformability

High gain dual parasitic patch loaded wideband antenna for 28 GHz 5G applications

Proceedings of: 2021 International Symposium on Antennas and Propagation (ISAP), 19-22 October, 2021, Taipei, Taiwan.This work presents the design of a high gain wideband antenna for 28 GHz band application. The antenna structure was inspired from a conventional circular patch which is modified using consecutive loading of two parasitic patch. The presented antenna offers a wideband to completely cover the globally allocated band spectrum for 28 GHz 5G applications. Moreover, the broad side radiation pattern, relatively compact size and high gain makes the proposed work potential candidate for future 5G applications.This project has received funding from Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant Agreement No 801538. Also, this work is partially supported by Antenna and Wireless Propagation Group (AWPG). https://sites.google.com/view/awpgrp

On-Demand Frequency Switchable Antenna Array Operating at 24.8 and 28GHz for 5G High-Gain Sensors Applications

A miniaturized in size linear multiple-input multiple-output (MIMO) antenna array operating on demand at 28 GHz and 24.8 GHz for 5G applications is presented and investigated in this research work. The antenna array has the capability to switch and operate efficiently from 28 GHz to 24.8 GHz with more than 15 dB gain at each frequency, having 2.1 GHz and 1.9 GHz bandwidth, respectively. The unit cell of the proposed antenna array consists of a transmission line (TL) fed circular patch connected with horizontal and vertical stubs. The vertical stubs are used to switch the operating frequency and mitigate the unwanted interaction between the adjacent elements of the antenna array to miniaturize the overall dimension of the array. The proposed antenna array is compared with the recent works published in the literature for 5G applications to demonstrate the features of miniaturization and high gain. The proposed array is a potential candidate for 5G sensors applications like cellular devices, drones, biotelemetry sensors, etc.This project has received funding from Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant 801538

Wideband Planar Array Antenna Based on SCRLH-TL for Airborne Synthetic Aperture Radar Application

This paper presents empirical results of a novel planar microstrip array antenna based on a simplified composite right/left-handed transmission-line (SCRLH-TL) for application in circularly polarized synthetic aperture radar (CP-SAR) systems operated in UHF, L, S and C-Bands. The array antenna consists of 6×6 matrix of spiral shaped radiating elements that are excited through proximity-coupled, single feed-line. Pattern synthesis technique is used to determine the excitation coefficients (amplitude and phase) to apply to the individual array elements to achieve the required pattern shape. The array antenna has dimensions of 111.5×96.06 mm2. The measured impedance bandwidth of the antenna is 3.85 GHz for S11 < -10 dB from 300 MHz to 4.15 GHz, corresponding to a fractional bandwidth of 173%. Maximum gain and radiation efficiency measured are 4.8 dBi and 79.5%, respectively, at 2.40 GHz. The antenna has a 3-dB axial-ratio bandwidth of 3.94 GHz from 144 MHz to 4.66 GHz. The antenna’s beamwidth in azimuth and elevation planes vary between 60° and 120° across its operational frequency range from 300 MHz to 4.15 GHz. The antenna design fulfills the challenging electrical and physical specifications required for CP-SAR employed onboard unmanned aerial vehicle (UAV)

A Novel Monofilar-Archimedean Metamaterial Inspired Leaky-Wave Antenna for Scanning Application for Passive Radar Systems

A novel backfire-to-endfire leaky-wave antenna is presented with ability to scan from -25ο to +45ο. The antenna is based on metamaterial transmission-lines (MTM-TLs) and is implemented using Monofilar Archimedean spiral and rectangular slots, spiral inductors and metallic via-holes. The slots act as series left-handed capacitances, and the spirals with via-holes provide the shunt left-handed inductances to realize the metamaterial antenna. A prototype antenna was fabricated prototype on FR4 dielectric substrate, which has an electrical size of 0.0302λo×0.0357λo×0.0008λo, where λo is free space wavelength at 165 MHz. Measured bandwidth of the antenna is 710 MHz (165-875 MHz) corresponding to a fractional bandwidth of 136.5%. The main advantage of the antenna is its ability to scan over a wide angle from -25 degrees to +45 degrees with acceptable gain and radiation efficiency of 1.2 dBi and 50.1%, respectively, measured at 400 MHz. The wide scanning attributes of the antenna make it suitable for passive radar applications to scan across the VHF-UHF bands for FM-Radio, television, mobile phones and GPS applications

A technique to suppress mutual coupling in densely packed antenna arrays using metamaterial supersubstrate

A simple and practical technique for reducing the mutual coupling between neighbouring antennas is presented for application in densely packed antenna arrays. This is achieved by locating between the radiation elements a smaller patch with metamaterial decoupling structure (MTM-DS). In this case the radiating elements are circular patches and the MTM-DS is constructed from a hexagonal slit resonator. The consequence of implementing the MTM-DS patch is significant reduction in mutual coupling between adjacent radiating patches by 60%, improvement in impedance match by 200% and substantial increase in the antenna’s fractional bandwidth by 369%. Since the ground plane is unaltered the front-to-back ratio is unaffected too. The proposed technique is easily realizable and can be used effectively in beam scanning applications

Band enhancement of a compact flexible antenna for WLAN, Wi-Fi and C-band Applications

Proceedings of: 2021 International Symposium on Antennas and Propagation (ISAP), 19-22 October, 2021, Taipei, Taiwan.Design and analysis of a wideband compact flexible antenna is presented in this paper. The bandwidth enhancement of conventional triangular quarter wave monopole antenna is achieved by utilizing the combination of a fractal structure along with open ended stub. Moreover, the flexibility analysis was studied to show the stability of presented work for conformal analysis. Furthermore, compact size, wideband, stable performance in flexibility condition makes the proposed work potential candidate for WLAN, Wi-Fi and C-band Applications.This project has received funding from Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant Agreement No 801538. Also, this work is partially supported by Antenna and Wireless Propagation Group (AWPG); https://sites.google.com/view/awpgrp

Planar Antennas with Enhanced Bandwidth and Radiation Characteristics

Wireless companies want next-generation gadgets to download at rates of gigabits per second. This is because there is an exponential growth in mobile traffic, however, existing digital networks and devices will not be efficient enough to handle this much growth. In order to realize this requirement, the next generation of wireless communication devices will need to operate over a much larger frequency bandwidth. In this chapter, novel wideband and ultra-wideband (UWB) antennas that are based on loading the background plane of a monopole radiator with concentric split-ring resonators are presented. It is shown that this modification improves the fractional bandwidth of the antenna from 41 to 87%; in particular, the operational bandwidth of the proposed antennas is double that of a conventional monopole antenna of the same size

High performance on-chip array antenna for terahertz integrated circuits

In this letter a novel on-chip array antenna is investigated which is based on CMOS 20μm Silicon technology for operation over 0.6-0.65 THz. The proposed array structure is constructed on three layers composed of Silicon-Ground-Silicon layers. Two antennas are implemented on the top layer, where each antenna is constituted from three sub-antennas. The sub-antennas are constructed from interconnected dual-rings. Also, the sub-antennas are interconnected to each other. This approach enhances the aperture of the array. Surface waves and substrate losses in the structure are suppressed with metallic via-holes implemented between the radiation elements. To excite the structure, a novel feeding mechanism is used comprising open-circuited microstrip lines that couple electromagnetic energy from the bottom layers to the antennas on the top-layer through slot-lines in the middle ground-plane layer. Simulation results show the proposed on-chip antenna array has an average radiation gain, efficiency, and isolation of 7.82 dBi, 32.67%, and -33 dB, respectively