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

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

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

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)

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

Metamaterial Based Ultra-Wideband Antennas for Portable Wireless Applications

Antennas are essential for wireless communication systems. The size of a conventional antenna is dictated mainly by its operating frequency. With the advent of ultra-wideband systems (UWB), the size of antennas has become a critical issue in the design of portable wireless devices. Consequently, research and development of suitably small and highly compact antennas are challenging and have become an area of great interest among researchers and radio frequency (RF) design engineers. Various approaches have been reported to reduce the physical size of RF antennas including using high permittivity substrates, shorting pins, reactive components, and more recently, metamaterials (MTM) based on composite right-/left-handed transmission-lines (CRLH-TLs). MTM exhibit unique electromagnetic response that cannot be found in the nature. In this chapter, the properties of CRLH-TL are used to synthesize novel and highly compact planar UWB antennas with radiation properties suitable for wireless mobile devices and systems

A new wideband planar antenna with band-notch functionality at GPS, Bluetooth and WiFi bands for integration in portable wireless systems

Empirical results are presented for a novel miniature planar antenna that operates over a wide bandwidth (500 MHz to 3.05G Hz). The antenna consists of dual-square radiating patches separated by two narrow vertical stubs to reject interferences from GPS, Bluetooth and WiFi bands. Radiating patches and stubs are surrounded by a ground-plane conductor, and the antenna is fed through a common coplanar waveguide transmission line (CPW-TL). The two vertical stubs generate pass-band resonances enabling wideband operation across the following communications standards: cellular, APMS, JCDMA, GSM, DCS, PCS, KPCS, IMT-2000, WCDMA, UMTS and WiMAX. Embedded in the ground-plane conductor is an H-shaped dielectric slit, which has been rotated by 90°, whose function is to reject interferences from GPS, Bluetooth and WiFi bands. Measurements results confirm the antenna exhibits notched characteristics at frequency bands of GPS (1574.4–1576.4 MHz), Bluetooth (2402–2480 MHz) and WiFi (2412–2483.5 MHz). The impedance bandwidth of the antenna is 2.55G Hz for VSWR < 2, which corresponds to a fractional bandwidth of 143.66%. Measured results also confirm that the antenna radiates omnidirectionally in the E-plane with appreciable gain performance over its operating frequency range. The antenna has dimensions of 15 mm × 15 mm × 0.8 mm

Efficient Wireless Power Transfer via Magnetic Resonance Coupling Using Automated Impedance Matching Circuit

In this paper, an automated impedance matching circuit is proposed to match the impedance of the transmit and receive resonators for optimum wireless power transfer (WPT). This is achieved using a 2D open-circuited spiral antenna with magnetic resonance coupling in the low-frequency ISM band at 13.56 MHz. The proposed WPT can be adopted for a wide range of commercial applications, from electric vehicles to consumer electronics, such as tablets and smartphones. The results confirm a power transfer efficiency between the transmit and receive resonant circuits of 92%, with this efficiency being sensitive to the degree of coupling between the coupled pair of resonators

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