Pui-Yi Lau

A Low-Cost Printed CP Patch Antenna for RFID Smart Bookshelf in Library

This paper presents a small wideband circularly polarized patch antenna printed on the low-cost FR-4 material for radio-frequency-identification smart bookshelves in libraries. The antenna is composed of four top-loaded patches sequentially rotated with a phase difference of 90° and double shorted to the ground. It operates at a center frequency of 0.915 GHz. The impedance bandwidth (SWR < 2) is 26.8%, the axial-ratio (AR) bandwidth (measured AR < 3 dB) is 11.6%, and the 3-dB beamwidth is 115°. The antenna gain is about 4 dBi, and the overall dimension is reduced by ~60% in length, in comparison with that of the conventional sequential patch antenna.

A wideband high gain double EBG reflector antenna

A dipole antenna with a double electromagnetic band gap (EBG) reflector is presented for wide operating bandwidth and high gain. The antenna is excited by a printed dipole centrally positioned above the planar double-layered EBG structures which is partially loaded with a ground plane. The simulated and measured results show that a wide impedance bandwidth of 44.4% (SWR<2) over the frequency range from 2.8GHz to 4.4GHz is achieved. Stable radiation patterns with low cross-polarization levels and an achieved gain of ∼8.5 dBi over the ground plane of 1.167λ, X1.167 λ, is found across the entire operating bandwidth.

A smart bookshelf for library RFID system

In this paper, the novel smart shelf for library UHF RFID system is presented. The smart shelf is installed with the own designed RFID system including readers, antennas, and own developed software. The Run-Run Shaw Library in our University is chosen as a beta site as it offers an excellent environment for conducting in-situ field tests on various performance indicators. With the installation of this smart shelf, the users can locate the materials with a user friendly interface within few minutes. Time switching for the smart shelves is proposed for reducing the number of readers. Electromagnetic wave materials ferrite is employed to the shelves to reduce the interruption from each other.

Integral equation solution of scattering by general bi-isotropic bodies

A combined field integral equation method based on the equivalent principle is presented for the solution of scattering by a general bi-isotropic body. The resulting combined equations are established through splitting given fields into two wavefields, each of which corresponds to respective isotropic mediums. For the modeling of arbitrarily shaped surfaces, the triangulated patches are employed and the Rao-Wilton-Gllison function is selected as the basis function and testing function when the moment of method is applied to solve the resulting integral equations numerically. Numerical results for Pasteur-type bodies are compared with the existing data and good agreements are obtained. Also, the Tellegen-type bodies are calculated. The effects of constitutive parameters on the bistatic cross section are investigated and discussed.

Elliptical helical antenna with parasitic wire for CP band enhancement

In this paper, elliptical helical antenna with parasitic element is proposed to radiate the circularly polarized waves. By winding a parasitic wire properly in parallel with the elliptical helical antenna, the axial ratio bandwidth is enhanced, and simple single feeding mechanism is maintained. The simulation by IE3D shows that the CP bandwidth can be increased from 13.6% to 25%, and the directivity is enhanced by 2dB in the frequency band when the eccentricity of the cross-section is 0.94.