A miniaturized UHF dual‐band passive RFID tag antenna operating in the 866‐869 and 950‐956 MHz bands is proposed. It consists of an S‐shaped Folded Dipole Antenna (FDA) resonating at 912 MHz, which is intermediary between the two required frequencies. To obtain dual‐band response perturbation method is employed. The electrical length of the FDA changes on loading a 2‐turn spiral resonator (2‐SR) to it. The 2‐SR splits the tag resonance at 912 MHz into two resonance frequencies (867 and 956 MHz). The proposed design is simulated using HFSS and then fabricated. Measured reflection coefficients at 867 and 956 MHz are −13.25 and −13.34 dB, respectively, exhibiting a 10 dB bandwidth of 11 MHz from 859 to 869 MHz and a 5 MHz 10 dB bandwidth from 953 to 957 MHz. Maximum read ranges of 5 m in 866‐869 MHz and 3.3 m in 950‐956 MHz band have been measured.
In this article, a circularly polarized antenna for ultra‐high frequency radio frequency identification (RFID) tag is presented. The circular polarization is realized by two orthogonal, unequal length linearly tapered meander line cross dipoles. The meander structure with capacitive tip loading is used for size miniaturization of the antenna. A modified T‐match network is employed to feed the cross dipole structure. The measured 10‐dB return loss bandwidth of the cross dipole antenna is 17 MHz (908‐923 MHz) and the corresponding 3‐dB axial ratio bandwidth is 6 MHz (912‐918 MHz). The overall size of the proposed antenna is 0.17λ0 × 0.17λ0 at 915 MHz. The maximum read range between the reader and the tag with the proposed antenna is 4.7 m larger than the analogous linearly polarized tag antenna due to the reduction in polarization loss between the tag and reader antennas. Thus, a maximum read range of 15.66 m with the gain of 1.28 dBic is achieved at 915 MHz.
In this paper, a folded slot active tag antenna for 5.8 GHz radio frequency identification (RFID) applications is presented. It consists of an inverted U-shaped monopole radiator fed by a coplanar waveguide (CPW) feed line and extended ground planes. A 10 dB return loss bandwidth of 5.65-6.55 GHz is achieved. The overall volume of the presented antenna is 10.7 × 11 × 1.6 mm 3. A good agreement between the simulated and measured results is observed. The antenna has an omnidirectional radiation pattern at 5.8 GHz which makes it suitable for RFID applications. It has advantages of compact dimensions and wider bandwidth than previously reported structures.
Laser-beam or soliton propagation is best modelled for fast computation using
a split-step Fourier method based on an orthogonal transform technique known
as the beam-propagation method. The beam-propagation split-step Fourier-transform technique in one and two dimensions for the propagation of a soliton
or laser beam respectively in a nonlinear plasma and a split-step Hankel-transform-based algorithm for cylindrical-beam propagation close to circular
cross-sectional symmetry and its computational implementation are discussed.
Attention is particularly focused on the verification of the paraxial approximations
of the soliton or the laser beam using these techniques, after a brief
review of the beam-propagation method.
This article presents a novel dual antenna structure for dual ultra high frequency bands (f 1 = 866 MHz and f 2 = 915 MHz) for radio frequency identification tags. The proposed structure consists of two dual band antennas, one acting as a receiving antenna and the other as a backscattering antenna at both the frequency bands. The receiving antenna is designed to have input impedance complex conjugate to the impedance of tag IC in order to maximize power transfer between the antenna and the microchip. The backscattered antenna is designed to have real-valued input impedance at both the operating frequency bands to obtain maximum differential radar cross section leading to read range enhancement. The dual band receiving antenna is designed by embedding a pair of thin slits at a radiating edge of inset fed microstrip antenna. The backscattering antenna is comprised of two elements, one is a comb-shaped open ring element, and the other is a meander line structure which is within the open ring element. Compared to conventional antennas, the proposed dual antenna structure provides a read range enhancement due to improved maximum differential RCS. The proposed dual antenna produced 4.3 m and 6.8 m read range at 866 MHz and 915 MHz, respectively. K E Y W O R D S dual antenna, RCS, read range, UHF RFID.
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