Design of a Wideband Inductively Coupled Loop Feed Patch Antenna for UHF RFID Tag

A planar wideband patch antenna for ultra-high frequency (UHF) radio frequency identification (RFID) tag for metallic applications is presented in this research work. Three different shape patches are inductively coupled to a triangle loop to form wide impedance bandwidth for universal application UHF (860-960 MHz) RFID. The structure of proposed antenna exhibits planar profile to provide ease of fabrication for cost reduction well suited for mass production. The simulation of the antenna was carried out using Finite Element Method (FEM) based software, Ansoft HFSS v13. The simulated and measured impedance bandwidth of 113 MHz and 117 MHz (Return Loss≥6 dB) were achieved to cover the entire UHF RFID operating frequency band worldwide. The simulated and measured radiation patterns at the operating frequency of 915 MHz are in good agreement. Moreover the simulated minimum antenna gain at the bore sight direction in free space and when mounted on 200 x 200 mm2 metal plate are -15 dBi and -14dBi respectively which is enough to provide reasonable read range over the entire UHF RFID system operating band

The Circularly Polarized Corner-Truncated Rectangular Patch Antenna with Double Slits for UHF RFID System

This paper presents a circularly polarised rectangular patch antenna for ultra-high-frequency (UHF) radio frequency identification (RFID) applications using for Thailand standard. The antenna consists of a corner-truncated patch with double slits and a ground plane. The rectangular patch is fed by a single probe. The circular polarisation can be achieved by using three techniques such as adding double slits, using square shape and using a slanted cutting corner. The antenna has a compact size and appropriate for RFID system of Thailand standard. The measurement results show that |S11| (dB) is less than -10 dB. The antenna gain is 8.83 dBic with the unidirectional radiation pattern. The 3-dB axial ratio beamwidth is 65º over the frequency band of 914.4 - 929.9 MHz covering the UHF RFID applications for Thailand standard

Structural behaviour of beam with HDPE plastic balls subjected to flexure load

This paper presents the structural behavior of reinforced concrete beam embedded with high density polyethylene balls (HDPE) subjected to flexural load. The HDPE balls with 180 mm diameter were embedded to create the spherical voids in the beam which lead to reduction in its self-weight. Two beam specimens with HDPE balls (RC-HDPE) and one solid beam (RC-S) with dimension 250 mm x 300 mm x 1100 mm were cast and tested until failure. The results are analysed in the context of its ultimate load, load-deflection profile, and crack pattern and failure mode. It was found that the ultimate load of RC-HDPE was reduced by 32% compared to RC-S beam while the maximum deflection at its mid span was increased by 4%. However, RC-HDPE is noticed to be more ductile compared to RC-S beam. Both types of beams experienced flexure cracks and diagonal tension cracks before failur

A Dual Resonant Microstrip Antenna for UHF RFID in the Cold Chain Using Corrugated Fiberboard as a Substrate

Each year, about 76 million people contract a food borne illness in the United States; about 325,000 require hospitalization; and about 5,000 die. Tracking goods throughout the food supply chain increases the efficiency of recall of tainted goods and thus will help reducing food borne illness. Passive UHF RFID has been widely accepted to be a technology capable of increasing supply chain efficiency. Passive UHF RFID tags designed for supply chain application are tuned to work well on corrugated fiberboard boxes that are ubiquitous in the supply chain. Commercially available passive UHF RFID tags are either sensitive to the content/environmental conditions of the corrugated fiberboard box or economically unfeasible. In this thesis we propose a novel dual-resonant planar UHF RFID microstrip antenna designed to be both insensitive to the content/environmental conditions of the corrugated fiberboard box and economically feasible. We provide simulated performances and experimental validations to show that the proposed microstrip antenna design is a viable and technically superior solution compared to conventional stripline dipole antennas widely used in commodity tags

Compact metallic RFID tag antennas with a loop-fed method

Several compact, low profile and metal-attachable RFID tag antennas with a loop-fed method are proposed for UHF RFID systems. The structure of the proposed antennas comprise of two parts: (1) The radiator part consists of two shorted patches, which can be treated as two quarter-wave patch antennas or a cavity. (2) A small loop printed on the paper serves as the feeding structure. The small loop provides the needed inductance for the tag and is connected to the RFID chip. The input impedance of the antenna can be easily adjusted by changing loop dimensions. The antenna has the compact size of 80 mm × 25 mm × 3.5 mm, and the realized gain about -3.6 dB. The measured results show that these antennas have good performance when attached onto metallic surfaces. © 2011 IEEE.published_or_final_versio

UHF RFID Antenna Impedance Matching Techniques

Radio Frequency Identification (RFID) systems use electromagnetic signals to wirelessly identify and track RFID-tagged objects. A reader transmits a carrier wave request signal to an RFID tag, which then transmits a unique identification signal back to the reader. Applications include supply chain inventory management, automated toll booth fee systems, sports event timing, restricted access control, pet monitoring and retail theft prevention. An RFID tag includes an antenna connected to a Radio Frequency Integrated Circuit (RFIC). RFID tags in the ultra-high frequency (UHF), industrial, scientific and medical (ISM) 902-928MHz band and global Electronic Product Code (EPC) 860‑960MHz band are powered passively (power extracted from carrier wave) and cost less than 15 cents per tag. Low cost UHF ISM RFID tags are an effective solution for tracking large inventories. UHF ISM tag antennas are typically planar dipoles printed onto a plastic dielectric substrate (inlay). Power exchange and transmit range is maximized when a tag antenna’s input impedance is conjugate matched to the RFIC input impedance. Since RFIC input impedance includes capacitive reactance, optimized antenna input impedance includes compensating inductive reactance. The T-match network adds inductive matching microstrips to conjugate match the RFIC. Narrowband (±1.5% of center frequency) and broadband (±5% of center frequency) lumped element designs also use inductive matching strips. Narrowband, lumped element design is accomplished through Smith Chart matching assuming lumped antenna elements. The broadband lumped element design is accomplished through a circuit transformation to an equivalent network and tuning the transformed circuit to resonate from 865MHz to 955MHz, with a center frequency of 910MHz. This thesis demonstrates a start-to-finish design process for narrow (±1.5% of center frequency) and broadband (±5% of center frequency) RFID tag antennas [3]. Furthermore, antenna matching element geometries are parametrically swept to characterize input impedance frequency response. Thesis accomplishments include (a) narrow and broadband antenna designs, (b) Keysight’s Advanced Design System (ADS) Momentum simulations, (c) antenna fabrication, and (d) differential probe impedance setup and antenna impedance measurements. Additional items include (e) impedance adjustments (f) tag range testing and (g) narrow vs. broadband matching technique comparisons. Antennas were fabricated in Cal Poly’s Graphic Communication Department by silk-screening silver conductive ink onto DuPont Melinix Polyethylene Terephthalate (PET) plastic. Impedance simulations are compared to fabricated antenna impedance measurements and range testing results

A quarter-wave Y-shaped patch antenna with two unequal arms for wideband Ultra High Frequency Radio-frequency identification (UHF RFID) operations

The radio-frequency identification (RFID) system which has become pervasive in the auto identification technology has been noticed to have several limitations. These limitations can be broadly divided into two major areas namely; application specific problems and general RFID problems. Application specific problems are common to the environment in which RFID tags are deployed such as metal, aqueous and irradiation environments. Whilst, the general problem of RFID tags include low gain, regional specifications and so on. In this paper, a new antenna prototype has been design and stimulated. The proposed antenna showed tendency of exhibiting improved gain from the previous RFID UHF antenna which is 0-1 dBi to -3 dBi and impedance bandwidth of 140 MHz. The proposed antenna is Y shaped patch with unequal monopole arms which are responsible for the different frequencies that the antenna operates and a quarter wavelengths was adopted rather than the popular half wavelength for size reduction. The fractional return-loss bandwidth for S11<10 dB and radiation efficiency are about 95% was obtained