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UHF RFID tags need to be attached or embedded into various objects. Unlike traditional free-standing antennas, UHF antenna shapes and form factors may vary significantly. There have been no systematic methods that facilitate the design practice of antenna with unconventional shapes. In this paper, using the geometries of 26 English letters (in capital) as examples, we explore the general methodology of shape-specific antenna design. More specifically, we show that 26 letter geometries can be categorized into 9 groups, and the antennas in each group can be divided and conquered into standard baseline geometries. Through prototypes and measurements, we demonstrate that each letter-shaped antenna, although exhibiting different gains and radiations, can achieve satisfactory performance, as compared to standard UHF dipole antennas. Specifically, letters “M” and “J” achieve the longest reading range of more than 20 meters with a good radiation pattern, which is comparable or even better than many commercial UHF RFID tags.

This manuscript presents the design and implementation of a passive, modular, computational ultra high frequency (UHF) radio frequency identification (RFID) research platform. The proposed platform consists of a software defined radio (SDR) reader and a modular UHF RFID tag. Such a tag can be subdivided into a number of modules (e.g., Modulator, Rectifier, etc.), which have been separated and optimized for easy connectability using sub-miniature A (SMA) connectors and standard jumper wires. Experimental results of module specific parameters show the accessibility of each section and prove the platform’s value for designing novel UHF RFID solutions.

In this article, we discuss how one can make, with modern and low-cost tools, a software-defined ultra high-frequency (UHF) RF identification (RFID) reader. Since we have chosen to leave the discussion of the top-level reader implementation until the very end, an introductory outline is warranted to help guide our audience. We first provide the uninitiated with some background context by answering four questions: What is UHF RFID? How does it work? What happened with UHF RFID? And, finally, what's next? That is, how do we envision the technology evolving in the future with the support of a broad community? Second, we describe the fundamental metrics and performance budgeting of RFID readers. Following this, we provide an overview on how to design, make, and automatically tune two critical components of UHF RFID readers: the antenna and transmit leakage canceller. Third, we delve even further into details of the transmit leakage canceller. Finally, we describe the complete high-level architecture of a proposed low-cost reader.

A novel design of reconfigurable circularly polarised antenna is proposed and developed in the present work. The circularly polarised antenna consists of two linearly polarised inverted‐L antenna elements with double‐folded arms. To improve the impedance matching and radiation characteristics, the double‐folded structure plays a significant role. Circular polarisation is achieved by properly adjusting the lengths of two arms, quadrature currents can be produced on two orthogonal elements. The developed linearly polarised antenna elements are low‐profile and small in size, the circularly polarised antenna structure is minimised to be about 70 mm in length, 70 mm width and 18 mm in height (70 × 70 × 18 mm). The feeding configuration is simplified by using coaxial probe instead of an external polariser, better values are obtained between the theoretical calculations and simulated results, which validate the design concept. The designed reconfigurable circularly polarised double folded inverted‐L antenna is compared with twin inverted‐L shaped structure. The simulated results show that the circularly polarised antenna resonates at 2.39 GHz and has a wide impedance bandwidth of 6.00% S 11 with −32.16 dB and VSWR

In this work, a circularly-polarized ultra-high frequency (UHF) partial discharge (PD) antenna is proposed to detect the PD in 0.6 GHz - 1.7 GHz. The proposed PD antenna consists of an Archimedean spiral antenna, a balun, and a cavity. The Archimedean spiral antenna is embedded by FR-4 as substrate and superstrate for miniaturization. The microstrip-to-paired strips balun is designed to yield good performance in the return loss, insertion loss, and amplitude and phase imbalances which are of great necessity for low axial ratio. The cavity is employed to obtain unidirectional radiation patterns and prevent external signal interference. However, it is found that the originally-designed cavity-backed antenna does not work properly near 1.35 GHz due to resonance phenomena in the cavity. In this work, the cavity is modified to tackle this problem. The proposed UHF PD antenna is fabricated and measured and the results show that it provides good impedance matching, realized gain, radiation pattern, and circular polarization.

In this study, we present a new circular monopole antenna with triple-band characteristics that can operate in both the ultra-high frequency (UHF) and ultra-wideband (UWB) bands and is integrated into a radio frequency identification (RFID) system reader module. In fact, the antenna was equipped with a patch and a CPW feed to meet the bandwidth specifications for RFID applications at UHF/UWB. To connect with RFID tags, this antenna is manufactured and inserted into the RFID reader board. Experiments show that the UHF-RFID efficiency of the monopole antenna is comparable to that of current commercial solutions.

In this work, a compact omnidirectional UHF antenna on the strength of spoof surface plasmon polaritons (SSPPs) is suggested. The measured −10dB impedance bandwidths is about 10.3% which is from 832 to 922 MHz. The simulated total efficiency is greater than 80% over the operating band. Good omnidirectional pattern is observed in the measured results on the H-plane, which is in accordance with the simulated results, and a dipole like pattern is observed on the $H$ -plane. It also shows that, at the resonance frequency of the antenna of 860 MHz, a compact size of $112.6\ \text{mm} \times 62\ \text{mm} \times 1 \text{mm}\, (0.323\lambda_{0}\times 0.178\lambda_{0}\times 0.002\lambda_{0})$ was achieved.

Radio frequency-identification finger-augmented devices (R-FAD) identify a particular wearable technology suitable to turn the human fingers into enhanced sensing surfaces to restore lost senses in impaired people as well as to augment the existing ones. The communication channel of R-FAD, involving a reader’s antenna placed onto the wrist and tag antennas stuck onto the fingers, is here characterized in the UHF radio frequency identification (RFID) band by means of both numerical simulations, accounting for several options of the system, and an experimental campaign with volunteers asked to reproduce natural gestures of the hands. The study identifies the most appropriate placement of the devices and, above all, it quantifies the robustness of the link against the human variability. The channel follows a lognormal cumulative probability law indicating that the minimum required power to establish a reliable RFID link is 18–27 dBm depending on the chip sensitivity. Measurements finally revealed a remarkable correlation of the minimum required power from the reader with the volume of the hand.

Currently, the method of partial discharges is actively developed to diagnose the insulation of high-voltage electrical equipment of stations and substations. Recently, artificial neural networks have been used to recognize partial discharges and analyze their characteristics and predict the development of insulation defects. To train neural networks, in turn, model partial discharge sources with well-known characteristics are often used. The presented work is devoted to the development of criteria for automatic recognition of the localization of a defect and a pre-breakdown situation in the insulation of high-voltage electrical equipment, based on the analysis of the characteristics of partial discharges.

Recently, RFID (Radio Frequency IDentiflcation) system is expected to serve as the distribution management system of the alternative to bar-codes. If a tag antenna that can be identified even when attached to the surface of metal or high lossy dielectrics is developed, high precision and automation of various product management can be expected. In this report, the development of the tag antenna for UHF-RFID system that can be attached to containers such as blood samples or liquid medicines is described.

The interest in the use of laser-scribing for the manufacturing of conductive patterns in electronics has been growing in the last years since this technique enables: i) inherent lithography without the use of masks, ii) a green-electronics approach, limiting the use of hazardous agents or reactives and iii) a cost-effective fabrication process with a very limited number of fabrication steps. In this contribution, we apply such a technique for obtaining RF devices on different substrates and using different precursors as either laser-activated or scribed conductive materials. The role of the laser influence on the photothermal process and the optimization of the electrical conductivity will be discussed. The techniques are applied for the realization of different samples of antennas in the UHF RFID band. The preliminary obtained results show interesting perspective for the future adoption of the laser-based production of flexible electronics RF devices.

A new method for cold chain logistics validation is presented in this paper. By combining RFID technology and polymer physical properties, a passive UHF RFID tag was designed on a special polymer that irreversibly shrink at certain temperature. With a power of 100 mW transmitted by a RFID UHF reader, the tag responds to 6 cm and after exceeding a threshold temperature, the read range decreases to 1.3 cm, As the tag is still responding but at a lower read range, we can deduce that it was not deliberately degraded and the decrease of read range is due to a temperature variation.

In this paper, we explain how to design a UHF RFID tag antenna for ARC requirements, which are industry tag certification specifications. We focus on a $50\ \text{mm}\times 30\ \text{mm}$ tag design that passes specs A through I. We explain how to model tag performance on complicated items that are part of ARC specs (such as jeans), and present modeling and simulation results which are in good agreement with measured data.

This paper presents a simple and robust design of dual-linear polarized UHF antennas, based on the magnetoelectric dipole concept, for near-field measurements. Two specific probes have been designed and manufactured in order to cover the 350 –750 MHz frequency bands. Measurements are currently in progress and only few preliminary results are discussed.

This paper presents the application of miniaturization techniques to UHF printed antennas designed for installation onto 8-U nano-satellites. The first structure studied is a rectangular dielectric resonator antenna and the second one is a compact reactive loaded slot antenna. Both radiators are used to compose four-element planar arrays. The analyzed topologies are compared, whereby the array composed of slot antennas yielded the lighter solution with good electromagnetic performance.

A novel ultra-high-frequency (UHF) RFID reader antenna is proposed. The antenna has a unique property as being able to change its axial ratio (AR) without affecting its gain, beamwidth or impedance matching performance, enabling the isolated study of the effect of different axial ratios in RFID tag reading.

This paper reports a compact square-shaped microstrip patch antenna covering 0.9 GHz and 2.4 GHz bands for radio frequency identification (RFID) reader applications. The proposed antenna is a two-layered structure comprised of a hexagonal ring patch on the top and a slotted square patch on the bottom. The compactness is achieved by using four shorting pins at appropriate locations. The simulated results show that the antenna exhibits impedance bandwidth (S 11 < -10 dB) of 16.33 % and 6.25 % in the ultra-high frequency (0.9 GHz) and industrial, scientific and medical (2.4 GHz) bands, respectively. The shorting pins also enhance the resonating bandwidth and gain of the proposed RFID antenna. Regardless of very low-profile, the gain values at 0.9 GHz and 2.45 GHz are 5.55 dB and 8.38 dB, respectively.

Epidermal RFIDs, if integrated within the next-generation (5G) wireless architecture, would enable low-cost healthcare applications for remote monitoring of patients, real-time telesurgery, and augmented sensing abilities. This paper explores, through simulations and preliminary experiments, epidermal 5G-RFIDs operating both at microwave and mmWave frequencies. In particular, it identifies the maximum gains of epidermal antennas at their optimal sizes, the achievable read ranges of passive 5G-RFID links, and their possible data-rates. Moreover, it demonstrates the compliance with electromagnetic exposure regulations and explores the benefits of epidermal arrays. Loop transponders at microwave frequencies (3.6 GHz) could provide the same read distance (one meter) of their UHF counterparts while having a smaller footprint (17 $\times$ 17 mm2) and reaching a theoretical data-rate as high as 0.5 Gbps. At 28 GHz and 60 GHz, instead, arrays could be used to both achieve comparable performances and enable beamsteering.

An effective codesign approach for harvesting systems is described in this article, which is based on a CMOS differential-drive rectifier and an inductively coupled loop (ICL) antenna. The proposed approach acts on both the rectifier and the antenna and aims at optimizing the system performance in terms of efficiency and input sensitivity for a given load specification. Moreover, a rectifier solution is also proposed to enhance the circuit performance by properly driving the transistor bulks without additional components. An RF harvesting system operating at 868 MHz was implemented, which is made up of an ICL antenna on FR-4 substrate and a rectifier fabricated in the 0.13- $\mu \text{m}$ CMOS technology. Measurements in the anechoic chamber show an overall efficiency performance of 34% with an RF input power as low as −21.5 dBm while considering 2.4 V and 1 $\mu \text{A}$ as load specifications.

A gaseous plasma antenna array (PAA) is an aggregate of plasma discharges and possibly conventional metallic radiating elements, and it constitutes a promising alternative to metallic antennas for applications in which fast reconfiguration of radiation pattern, and gain is desired; such properties can be achieved by exploiting the electronic switch on/off condition of plasma discharges, and tuning of the plasma parameters. Here, the authors present a reconfigurable PAA that features a central metallic half-wavelength dipole working around 1.45 GHz, surrounded by a planar circular lattice of cylindrical plasma discharges. Customised plasma discharges have been realised, and filled with argon gas at 2 mbar so as to have a complete control on the plasma discharge properties (e.g. plasma frequency, collisional frequency). The magnitude of the reflection coefficient, and the gain pattern on the H -plane have been investigated numerically and experimentally; numerical and experimental results exhibit a good agreement and show that the central intrinsically omnidirectional antenna can provide simple beamforming capabilities upon turning on a subset of plasma discharges; as these plasma discharges are turned on, the authors have observed a maximum gain of ~5 dBi, a half-power beam width of 80°, and an angular steering resolution of ~15°.

The circularly polarized (CP) UHF RFID tag antenna attracts extensive attention among the ultra-high frequency (UHF) radio frequency identification (RFID) antenna since there is a good polarization matching with the CP reader. Consequently, farther radiation rang and the higher flexibility and reliability are given to UHF RFID system when the antennas are circularly polarization. Some examples of design of CP radiation in UHF RFID tag antennas are mainly introduced in this paper in recent years. At the same time, according to their characteristics, the common design structures of several UHF RFID CP tag antennas are summarized. For example, utilizing square or circular ring microstrip line, using perturbation structures like truncated patch or rectangular groove on a microstrip patch, and dipoles structures can achieve CP radiation. The design method is discussed based on the radiation performance, and the advantages and disadvantages of their structures were analyzed.

The authors propose the design of a compact mechanically frequency and pattern reconfigurable patch antenna. The frequency tuning is achieved by changing the positions of two adjustable shorting screws which are used to modify the length of the antenna radiating patch. Simulated and measured results are carried out to validate the proposed approach. When the screws are symmetrically positioned, the measured operating frequency can be tuned from 2.95 to 5.16 GHz without degrading the radiation characteristics over the entire comparatively wide measured tuning range of 54.5%. The antenna main radiating beam can be tilted from θ = 0° to θ = 30 ° when the screws are asymmetrically positioned. The measured gains and efficiencies range from 3.01 to 5.53 dBi and 68 to 74%, respectively. The overall antenna size is only 0.39 λ 0 × 0.39 λ 0 × 0.02 λ 0 .

A new geometry of wideband circularly polarised antenna with an asymmetric meandered-shaped monopole is proposed in this communication. The wideband characteristics of the antenna are accomplished by the two asymmetric meandered-shaped perpendicular arms of monopole and defected ground structure having slanting edge. The proposed prototype offers good performance in terms of impedance bandwidth (close to 102.04% in the frequency range 2.4-7.4 GHz) and the 3 dB axial-ratio (AR) bandwidth (close to 37.5% in the frequency range 4.9-6.9 GHz). The realised impedance and AR bandwidths cover the WLAN/Wi-MAX bands and Wi-Fi band (5.5 GHz).

The objective of this work is to address the issue of using the human hand as an antenna, the hantenna. The method used is based on an experiment involving a wireless link between a traditional antenna and the human hand functioning as an antenna. Measurements were performed over six subjects in an anechoic chamber. The results show very clear trends. In the frequency band 800 MHz–2 GHz the human hand does improve the link performance, mainly by providing a better matching to the feeding cable. The main conclusion is that expressed in realised gain, the improvement of the link may go up to 15–20 dB, which is very considerable. The significance of the work is that it shows how to use the human hand as an antenna in certain non-critical telecom applications.

A high efficiency and transparent sea-water monopole antenna operating at 2.4 GHz for wireless local area network (WLAN) applications is proposed in this Letter. The antenna has high transparency (>85%) achieved by using sea-water as its conductive medium contained within a clear acrylic tube. To improve the radiation efficiency of the antenna, a short metal tube with a metal disk at the base was loaded into a feeding probe to achieve greater excitation. The antenna is simulated and its properties are verified through this experiment. Measurement results show a -10 dB bandwidth of 1.1 GHz (2.1-3.2 GHz) and a high radiation efficiency (>71%) over the entire WLAN band (2.4-2.5 GHz). These results demonstrate the proposed antenna as an attractive alternative to conventional metal monopoles for WLAN applications.

In view of the need for communication with distributed sensors/items, this paper presents the design of a single-port antenna with dual-mode operation, representing the front-end of a future generation tag acting as a position sensor, with identification and energy harvesting capabilities. An Archimedean spiral covers the lower European Ultra-Wideband (UWB) frequency range for communication/localization purposes, whereas a non-standard dipole operates in the Ultra High Frequency (UHF) band to wirelessly receive the energy. The versatility of the antenna is guaranteed by the inclusion of a High Impedance Surface (HIS) back layer, which is responsible for the low-profile stack-up and the insensitivity to the background material. A conformal design, supported by 3D-printing technology, is pursued to check the versatility of the proposed architecture in view of any application involving its deformation and tracking/powering operations.

Emerging RFID applications in the UHF band in some cases require very specific antenna solutions. This letter considers the identification and tracking of patients inside hospital facilities using wristbands, which impose strict tag size and cost limitations. We propose a solution for passive tags based on a normal-mode helical antenna as an alternative to bulky and/or expensive solutions that can be found in the literature. The robustness of the resulting wristband will be assessed in a particular implementation by measuring the maximum read range for a variety of subjects with different physical constitutions.

The authors present the design of a tunable 433 MHz antenna that is tailored for wearable wireless sensor applications. This study first presents a detailed analysis of the measured impedance characteristics of a chosen antenna under test (AUT) in varying proximity to a human test subject. Instead of limiting the analysis to the head and hand only, this analysis measures the AUT impedance at varying distances from 11 different body positions. A novel antenna equivalent circuit model is then developed that enables both the free-space and total on-body AUT impedance variation to be rapidly computed using a circuit simulator instead of the requirement for computationally intensive finite-element methods for example. The design and characterisation of a tunable matching network that enables AUT impedance matching for 11 different positions on the human body is then outlined. Finally, a fully-autonomous 433 MHz tunable antenna is demonstrated. The antenna occupies a small printed circuit board area of 51 × 28 mm and is printed on standard FR-4 material with the tuner completely integrated into the antenna itself. Prototype measurements show an improvement of 3.9 dB in power delivery to the antenna for a load voltage standing wave ratio of 17:1, with a maximum matching loss of 0.84 dB and S 11 (−10 dB) ≥ 18 MHz for all load conditions.

A highly compact and broadband antenna suitable for a prosthetic device to restore vision in the blind is presented. By embedding three straight sections of meandered microstrip patch line at the feed point, the proposed antenna gives three separate bands at 2.45, 4.2, and 5.8 GHz. The square patch loop is etched in the centre for miniaturisation. Three U-shaped patch stubs are utilised for frequency tuning. Three bands are merged together by adopting two square annular rings in the ground to obtain a wider bandwidth (2–8 GHz) incorporating unlicensed industrial, scientific and medical (ISM) and UWB bands.

A bent crossed dipole antenna for dual linear polarisation applications is introduced. The proposed efficient techniques incorporated into the design provide the antenna with high port isolation and low cross-polarisation. A better than 56 dB measured port-to-port isolation is achieved in the frequency range of 2.7–3 GHz. The cross-polarisation level remains 40 dB below the copolarisation peak in both principal planes. A pair of matched copolar beams in the corresponding principal planes is obtained owing to the use of identical and symmetrical structures in orthogonal directions. These features along with simple geometry and inexpensive PCB fabrication make the proposed antenna a promising candidate for multi-mission applications.

A single-feed dual-band circularly polarised (CP) patch antenna is proposed. The antenna consists of a corner-truncated square patch antenna and a superstrate composed of a lattice of 2 × 2 metallic patches surrounded by parasitic elements. The driven patch generates one resonant mode. The metasurface with parasitic elements excites two additional resonant modes (TM 10 and TM 20 ). The combined resonances result in minimum axial ratio points, and a good dual-band CP operation is achieved. Simulations show that the antenna has a CP operating bandwidth of 40 MHz centred at 3.72 GHz (1.07%), and a CP operating bandwidth from 5.37 to 6.05 GHz (11.9%). The simulated gain is ∼7.05–7.1 dBic for the low-frequency band and 4.17–6.07 dBic for the high-frequency band, respectively. Measurements and simulations are in good agreement.

A compact and broadband VHF/UHF antenna operating from 270 MHz to 1.56 GHz for $\mathbf{VSWR}\leq 3$ has been designed. Radiating element of the antenna is a planar meander line which exhibits multiple narrowband resonances and has been built on FR4 substrate. When the meanderline radiating element is loaded by an additional FR4 layer on top, the resonances shift down in frequency. If the top dielectric is metallized at one end, these resonances shift further down. This effect is enhanced if a metallized bottom dielectric is also employed. And for this case, the resonances eventually merge and form a broadband response.

A novel ultra-high-frequency (UHF) RFID reader antenna with 2 dimensional (2D) beam-scanning capability and a wide 3 dB axial ratio (AR) beamwidth of over 136 degrees is presented. The proposed antenna consists of three concentric metal rings, each having a branch wire to stimulate circular polarization (CP) and a separate feed. The antenna is able to perform a 2D beam-scan with a relatively stable gain (9-11 dBic) from 0 degree to 360 degree in azimuth, and -40 degree to 40 degree in zenith. The minima of the antenna's AR beamwidth follows the peak gain direction, giving an equivalent 3 dB AR beamwidth of 136 degree for every phi cut, wider than current state-of-the-art. Moreover, the proposed antenna array presents a 50 Ohm impedance with no impedance matching network, and requires only two phase shifters to steer, significantly reducing the design complexity. The antenna's -10 dB return loss bandwidth is from 860 MHz to 880 MHz, covering the lower band UHF RFID frequencies in the European Telecommunications Standards Institute (ETSI) region.

In the context of an UHF remotely powered UWB tag, this paper presents the design of the UHF antenna used to harvest energy on the tag side, and the design of the antenna used to receive emitted UWB pulses on the reader side. They have been used to characterize an UHF remotely powered UWB pulse generator whose the measurement results conclude this article.

International audience; In this paper, the use of a four-switchable beam antenna dedicated to Wireless Sensor Network (WSN) in the 2.4 ISM band (2.4-2.485 GHz) to improve link quality between nodes is presented. It consists of two fed monopoles and two loaded parasitic ones. Reconfigurability is achieved using reflector and director elements activated by PIN diodes. The structure is capable of steering its radiation pattern in the azimuth plane, covering a 360◦ angle with four beams (0°, 90°, 180° and 270°). The total gain achieved is 4 dBi for each beam in the azimuth plane. The performed campaign test pointed out an improvement of the link quality, visible through the RSSI.

Radio frequency identification (RFID) technology brings tremendous applications in location-based services. Specifically, ultra-high frequency (UHF) RFID tag positioning based on phase (difference) of arrival (PoA/PDoA) has won great attention, due to its better positioning accuracy than signal strength-based methods. In most cases, such as logistics, retailing, and smart inventory management, the relative orders of the objects are much more attractive than absolute positions with centimetre-level accuracy. In this paper, a relative positioning (RePos) approach based on inter-tag distance and direction estimation is proposed. In the RePos positioning system, the measured phases are reconstructed based on unwrapping method. Then the distances from antenna to the tags are calculated using the distance differences of pairs of antenna’s positions via a least-squares method. The relative relationships of the tags, including relative distances and angles, are obtained based on the geometry information extracted from PDoA. The experimental results show that the RePos RFID positioning system can realize about 0.28-meter ranging accuracy, and distinguish the levels and columns without ambiguity.

Novel hexaferrite substrates and impedance matching networks are both means to deliver electrically small antennas (ESAs). The performance characteristics of each are often restricted to a discussion on the reflection coefficient S11, without consideration of full radiative characterisation. In this work the radiation efficiency and pattern of a hexaferrite patch ESA and impedance-matched sub-resonant Rogers RT5880 patch were compared. The efficiencies of each technique were found to be low, while the pattern of the sub-resonant patch displayed considerable divergence from the half-wavelength behaviour of the hexaferrite patch. The stability of the magnetically-tuned radiation pattern of the hexaferrite patch was then demonstrated over a tuned bandwidth of 32.1%.

In this study, a microstrip-fed complementary Yagi–Uda antenna backed with milled cavities is presented. This antenna is intended to radiate as near as possible to the end-fire direction while keeping a low profile and small size. The radiator and reflector elements are U-shaped slots while the director is a rectangular slot. These slots are printed on top of a very thin bendable commercial substrate. The radiator is fed by a microstrip line printed on the bottom side of the substrate. A thick metallic plate in which cavities are milled is placed below the substrate and connected by pin wires to the upper metallisation of the substrate. An S-band prototype is designed, fabricated and measured providing an operational bandwidth of 3% around 2.44 GHz, a maximum gain of about 8 dBi is achieved in the main beam which points towards 46° away from the broadside direction. Finally, simulation results of array and different conformal configurations are presented demonstrating the advantages of the microstrip feeding and the thin substrate material. Bending of the antenna along H-plane and E-plane for different curvatures is evaluated.

This paper presents the design of circularly polarized elliptical flat antenna with capacitively-fed that radiates unidirectional beam for UHF RFID band (860-960 MHz). The proposed antenna is excited with a capacitively-fed (square ring slot) technique for covered the UHF RFID band. The elliptical radiating plate generates the circularly polarized radiation and the double pairing rectangular slits for made good axial ratio. The experimental results show the |S 11 | bandwidth of 12.68% (852.40-967.80 MHz), the 3-dB Axial ratio (AR) bandwidth (BW) of 11.42% (858.60-962.50 MHz) and an average again of > 6.00 dBic.

This paper proposes low cost high gain patch antenna with probe fed for UHF RFID reader, it fabricated on inexpensive FR4 substrate. The RFID reader antenna 254 x 254 mm.2 in size is fed by the probe fed technique with SMA connector attached to the antenna. The measured results indicate of the S 11 excels than -10 dB extensive the impedance bandwidth from 890 MHz – 975 MHz, as well as half power beam width about 60° cover the frequency range. From the measurement results, AR less than 3 dB has a bandwidth of 900 MHz - 920 MHz showed that the antenna has a satisfactory performance with the maximum realized gain about 9 dBi at 0 degrees. The proposed antenna is lightweight, low-cost and easy to fabricate, it is suitable for RFID system applications.

This paper presents the results for the US Naval Research Laboratory developed digital VHF/UHF antenna selector out-of-tree module developed for use in GNURadio. Testing was performed at NRL in August 2018. The results for the test show that the antenna selector successfully switched the input signal during reception without loss of the voice/radio signal. The switching was performed with each call to the out of tree module and would switch all samples for that specific call from the best antenna input to the output. The module was optimized using calls to memcpy to ensure no loss in performance due to loops. The input signal power computation was computed using the built-in FFTW library and additional function calls.

Low-profile monopoles operating over a wide bandwidth are highly desirable for integration into various metallic/conductive platforms, e.g. on vehicle roofs. A simple realization of omnidirectional radiation patterns is offered by center-fed shorted patch antennas, which have been first proposed in the 1950's [1]. This type of antenna has been revisited many times since then and recent designs achieve high performance combining wide bandwidth of operation and ultra-low profile. The general principle of operation of low-profile monopoles can be generally interpreted as physical realization of a magnetic current loop [2].

International audience; in this paper, the design and optimization of anefficient dual-band Planar Inverted-F Antenna (PIFA), moreadapted to the operation in a complex environment and workingin the unlicensed 868 and 915 MHz ISM bands for IoT applications in Europe and USA are presented. It consists of a metal plate whose length has been optimized to work at a frequency of 915MHz and to which a second plate charged with a capacitor of 0.8pF has been added to create a second resonance at the frequency of 868MHz. The dimensions and positions of the short-circuit and the feeding strip of the PIFA have been optimized to maximize the radiation efficiency of the antenna. A good impedance matching and high radiation efficiency were obtained in both 868 and 915 MHz frequency bands.

A display frame ultra-high frequency (UHF) radio frequency identification (RFID) reader antenna design is proposed for museums in this paper. Given its conformal design, the antenna can seamlessly hide and blend with the museum environment. RFID asset tracking, personnel tracking and anti-theft surveillance, can be accomplished without altering the display artifacts or disturbing the aesthetics of the museum. The series fed patch antenna array, arranged in a circular fashion makes the RFID tag detection viable in any orientation at the near zone. At far-field distances, the antenna can detect tags up to 6 meters. The antenna has a bandwidth of 28 MHz and is designed for Region-2 RFID frequencies. It uses an unconventional substrate that is lightweight, non-toxic, chemically resistant and self-extinguishing if exposed to fire. More than one frame antennas can be operated using multi-port RFID readers to realize a distributed antenna system within the museum.

This paper presents a flexible printed sensor tag antenna design for Ultra high frequency radio frequency identification (UHF RFID). This sensor tag is battery-powered for accurately logging temperature data such as in cold-chain applications.