Ultra High Frequency Radio Frequency Identification Reader Antenna Research Articles

Nature-inspired spider web shaped UHF RFID reader antenna for IoT and healthcare applications

This paper proposes a nature-inspired spider web-shaped ultra-high frequency (UHF) radio frequency identification (RFID) reader antenna and battery-free sensor-based system for healthcare applications. This antenna design consists of eight concentric decagons of various sizes and five straight microstrip lines.These lines are connected to the ground using 50 Omega resistors from both ends, except for one microstrip line that is reserved for connecting a feeding port. The reader antenna design features fairly strong and uniform electric and magnetic field characteristics. It also exhibits wideband characteristics, covering whole UHF RFID band (860–960 MHz) and providing a tag reading volume of 200 times 200 times 20 mm{^3}. Additionally, it has low gain characteristics, which are necessary for the majority of nearfield applications to prevent the misreading of other tags. Moreover, the current distribution in this design is symmetric throughout the structure, effectively resolving orientation sensitivity issues commonly encountered in low-cost linearly polarized tag antennas. The measurement results show that the reader antenna can read medicine pills tagged using low-cost passive/battery-free RFID tags, tagged expensive jewelry, intervenes solution, and blood bags positioned in various orientations. As a result, the proposed reader antenna-based system is a strong contender for near-field RFID, healthcare, and IoT applications.

High Gain Passive UHF RFID Reader Antenna Using Novel FSS for Longer Read Range

Frequency Selective Surface (FSS) is widely used to enhance the gain of antenna & reduces Electromagnetic Interference (EMI). In this work, a novel Frequency Selective Surface (FSS) is designed, analyzed, and fabricated along with passive Radio Frequency Identification (RFID) reader antenna operating at global Ultra-High Frequency (UHF) for wireless RFID applications. The antenna & FSS sheet is fabricated on less costly FR4 substrate with resonant bandwidth of 860–960 MHz. The Fabry–Perot arrangement of FSS sheet with antenna increases the gain & directivity without modifying the antenna profile or increasing radiation patch size. The maximum measured gain is 9.8 dB & 7.2 dB with the Reflection coefficient (S11) of −35 dB & −15 dB at 910 MHz & 950 MHz respectively. The proposed antenna of dimension 40 mm by 40 mm is fabricated & tested for further experimental validation with measured read range longer than 8 m. The novelty in proposed work is integration of FSS with passive UHF RFID technology which can be effectively used in wireless RFID applications for improved read range, higher gain, lower power consumption & better immunity within the resonating band. The proposed antenna effectively isolates out-of-band frequencies from in-band frequencies over a required bandwidth reducing Electromagnetic Interference (EMI) for UHF RFID applications.

UHF RFID tag localization using pattern reconfigurable reader antenna.

Passive ultra high frequency (UHF) radio frequency identification (RFID) tags have the potential to find ubiquitous use in indoor object tracking, localization, and contact tracing. We propose a machine learning-based method for RFID indoor localization using a pattern reconfigurable UHF RFID reader antenna array. The received signal strength indicator (RSSI) values (from 10,000 tags) recorded at the reader antenna units are used as features to evaluate the machine learning models with a train-test split of 75%-25%. The training and testing data is generated by a wireless ray tracing simulator. Five machine learning models: random forest regressor, decision tree regressor, Nu support vector regressor, nearest regressor, and kernel ridge regressor are compared. Random forest regressor has the lowest localization error both in terms of average Euclidean distance (AED) and root-mean-square error (RMSE). For random forest regressor, localization error results show that 90% of the tags are within 1 meter of their true position, and 67% are within 50 cm of their true position based on Euclidean distance.

High-Gain Circularly-Polarized Square Patch UHF RFID Reader Antenna Design for Smart Factory Applications

In this paper, a UHF (Ultra High Frequency) RFID (Radio-frequency identification) circular polarization reader antenna is presented. The proposed antenna is a low cost, easy to manufacture UHF RFID reader antenna in the European UHF RFID band. The proposed antenna design employs an air-substrate patch antenna. The antenna size of 250x250x7mm. The proposed antenna works from 850 to 874 and 880 to 893 MHz with return loss less than -10 dB, thus covering the European UHF RFID band. The proposed antenna return loss bandwidth is 37 MHz. The gain of the designed antenna is 7.88 dBi at 867 MHz. Also, with a bandwidth of 864-870 MHz, the axial ratio (AR) is less than 3dB. This means that the antenna has circular polarization at 867 MHz. Each result has been calculated on CST Studio Suite 2020. The antenna recommended for use in smart factory applications promises a good antenna among RFID reader antennas.

An Ultra-Rugged UHF RFID Reader Antenna: A New Design for Convention Center Loading Docks [Wireless Corner

At present, the ultrahigh frequency (UHF) radio-frequency identification (RFID) technology is more popular than several other autoidentification (auto-ID) technologies. An ultrarugged UHF RFID reader antenna is made from a concrete substrate that is sandwiched between a stubbed quarterwave radiator and a folded ground plane is proposed for fixed UHF RFID readers. This linearly polarized antenna operates between 865 and 868 MHz with a 3.5-dBi peak gain and a 160-MHz, -15-dB |S11| bandwidth. The 3.5- and 2-dBi gain bandwidth are 80 and 140 MHz, respectively. The antenna is intended to be used in convention center loading docks and is thus tested for extreme environmental conditions, such as temperature, humidity, condensation, and rain as well as the effect of superstrates and metals. More than one concrete tile antenna can be operated by using one RFID reader to realize a distributed antenna system (DAS). The antenna is conformal and can blend with the environment without affecting the existing aesthetics. The antenna creates a wide circumferential read zone (s5.6-m diameter) and reads tags up to 6.5 m at the boresight in free space.

Pattern Reconfigurable UHF RFID Reader Antenna Array.

The growing research interest in passive RFID (Radio Frequency Identification)-based devices and sensors in a diverse group of applications calls for flexibility in reader antenna performance. We propose a low-cost, easy-to-fabricate, and pattern reconfigurable UHF (Ultra High Frequency) RFID reader antenna in the RFID ISM band (902-928 MHz in the US). The antenna offers a 54 MHz bandwidth (890 - 944 MHz) and 8.9 dBi maximum gain. The proposed reconfigurable antenna can radiate four electronically switchable radiation beams in the azimuth plane. The antenna is LHCP (Left Hand Circularly Polarized) with axial ratio (AR) in the ranging from 0.45 dB to 7 dB in the RFID ISM band. Simulation and measurements are presented, and they are in good agreement. The proposed reader array performance is compared against a commercially available reader antenna. The pattern reconfigurable UHF RFID reader antenna not only increases the coverage area for conventional RFID applications but also opens the door to on-body RFID sensor implementation and indoor localization applications.

Fixed UHF RFID Reader Antenna Design for Practical Applications: A Guide for Antenna Engineers With Examples

An overview of Ultra High Frequency (UHF) Radio-Frequency Identification (RFID) practical applications and the reader antenna design requirements are presented in this paper. As each application is different and their physical, environmental, electrical, and Radio-Frequency (RF) requirements will also differ, a design methodology is proposed by analyzing all the requirements for a practical reader antenna. Reader antenna performance measures and test procedures are also formulated. As an example, an embeddable reader antenna is designed and fabricated for self-billing kiosk application in a retail environment. The designed antenna is measured in terms of various RF and RFID performance metrics and validated that it meets all the requirements sought by the application.

Multiobjective Optimization Design for Electrically Large Coverage: Fragment-Type Near-Field\/Far-Field UHF RFID Reader Antenna Design

The design of an ultrahigh-frequency (UHF) radio-frequency identification (RFID) reader antenna covering an electrically large near-field area is challenging for near-field UHF RFID applications. In such a design, magnetic field distribution on a large coverage area is required to be as uniform as possible. For some specific UHF near-field RFID applications, given radiation pattern characteristics are expected. A fragment-type wire structure is quite suitable for these demands because uniform magnetic field distribution and given patterns could be generated through optimizing the fragmented wires in a designated electrically large area to obtain corresponding current distribution. In this article, the concept of a fragment-type structure as well as some design guidelines are reviewed and summarized. Then, two omnidirectional fragment-type wire antennas with different cell size and two directional fragment-type wire antennas are designed. Both simulation and experiment results show that there is no reading null within an electrically large near-field zone having a perimeter of four operating wavelengths at 915 MHz (i.e., 320 mm x 320 mm). The omnidirectional designs are promising in the applications of UHF near-field RFID tag detection in self-confined volumes, and the directional designs are potential in the systems of UHF near-field/far-field RFID.

Low-profile UHF RFID reader antenna with CP radiation and coupled feeding technique

A low profile annular-ring patch antenna with circularly polarized (CP) radiation for radio frequency identification (RFID) reader applications in the ultra-high frequency (UHF) band (922-928 MHz) is presented in this article. Perturbation method is applied by loading a pair of triangular open-notch into the outer circumference of ring patch, and good impedance matching can be determined by using the coupled feeding technique. The overall size of this proposed antenna is 150 mm × 150 mm × 10.4 mm. The measured results show desirable 10-dB impedance bandwidth and 3-dB axial ratio (AR) bandwidth of 3.5% (908-941 MHz) and 0.65% (922-928 MHz), respectively. Stable antenna peak gain and efficiency of 7.2 dBic and 87% are also exhibited, respectively.

Broadband circularly polarized antenna with moon-shaped parasitic element

A broadband circularly polarized (CP) circular patch antenna with an L-shaped ground plane and parasitic element is studied. The use of this L-shaped ground is to achieve short probe feed connection to the circular patch, while maintaining a certain height between the circular patch and ground plane, so that good impedance matching and bandwidth enhancement can be attained. To achieve CP radiation, two notches are initially loaded diagonally into the circular patch, and to further enhance the CP bandwidth, a novel technique of loading a small size moon-shaped parasitic element into the notched circular patch is proposed. By doing so, the CP bandwidth of proposed antenna can be tremendously increased by approximately 10%. The experimental results show that the proposed CP antenna can yield impedance bandwidth and CP bandwidth of 835–1150 MHz and 839–968 MHz, respectively, with good gain level of 7.6 dBic. Therefore, this proposed wideband CP antenna can be used for UHF (ultrahigh frequency) RFID (radio frequency identification) reader antenna that operates within the universal RFID bands (840 − 960 MHz). © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:387–395, 2016

Slits Loaded Circularly Polarized Universal UHF RFID Reader Antenna

A simple structure circularly polarized (CP) UHF (ultrahigh frequency) RFID (radio frequency identification) reader antenna that operates within the universal RFID bands (840-960 MHz) is investigated. Here, the technique of loading a corner truncated square patch antenna into an L-shaped ground plane is initially studied to achieve good impedance matching with broad CP bandwidth. To further enhance both the impedance bandwidth and CP bandwidth, a novel technique of loading three narrow slits into the corner truncated square patch is proposed. By meticulously arranging these three slits in a certain manner, from the experimental results, besides achieving a gain level of approximately 8.6 dBic, the proposed antenna can also yield an impedance bandwidth from 685 to 1125 MHz, while good CP bandwidth between 836 and 986 MHz is also demonstrated.

A Slot Loaded Circularly Polarized Patch Antenna for UHF RFID Reader

The design of a simple UHF (ultrahigh frequency) RFID (radio frequency identification) reader antenna that operates within the 900 MHz band (902-928 MHz) is studied. To generate circular polarization (CP) radiation, a novel method of loading a semicircular slot into the main circular radiating patch is proposed. To allow optimum impedance matching with enhanced CP bandwidth, the L-shaped probe-feed technique is employed in this design. From the experimental results, besides achieving a gain level of more than 7 dBic, the proposed antenna can also yield an impedance bandwidth (10-dB return loss) from 880 to 1100 MHz, while good CP performances between 901 to 930 MHz are exhibited. To further validate the experimental results, parametric studies are also carried out via simulation.

UHF RFID Reader Antenna for Near-Field and Far-Field Operations

In this letter, a radio frequency identification (RFID) reader antenna designed for near-field and far-field operation at the European ultrahigh frequency (UHF) band is presented. Segmented loop technique is implemented for near-field operation, whereas a patch antenna is included inside the loop for far-field operation. The fabricated antenna works from 864 to 873 MHz with reflection coefficient less than 10 dB, thus covering the European UHF RFID band. Its linearly polarized radiation pattern provides a 4-dBi gain. The reading capabilities of the antenna are up to 9 cm and 6 m for near-field and far-field applications, respectively.