Baiqiang You

Numerical Synthesis of Dual-Band Reflectarray Antenna for Optimum Near-Field Radiation

A dual-band reflectarray antenna with a double layer, employing concentric square rings as reflecting elements, is proposed. With a procedure of the steepest decent method (SDM), the impressed phases of the reflecting elements are synthesized for the proposed antenna to radiate an optimum field pattern in the near zone of array aperture. The reflectarray antenna is designed for two frequency bands, covering 915 MHz and 2.4 GHz, which both can be used in RFID applications.

A novel printed folded dipole antenna used for modern RFID system

For the minimization of RFID tag antenna, we designed a printed folded dipole antenna working at 2.4 GHz. And a mirror compensation technology was introduced to improve the radiation feature of antenna with better return loss characteristic and directivity. The simulated results show that when VSWR (vertical standing wave ratio) is less than 2, the antenna bandwidth is up to 0.39 GHz absolutely and to 15.48% relatively. Considering engineering processes, the influences of dielectric constant, board thickness, folding degree and other parameters on the properties of this antenna are particularly studied. On the basis, a dual-frequency folded dipole antenna is proposed, which can work in two main frequency for RFID system, i.e. 915 MHz and 2.4 GHz. Moreover, an antenna sample made on this novel structure has been tested and the results show that the bandwidth of antenna is improved in further, along with hemisphere directional radiation characteristics.

Design of reflectarray antennas to achieve an optimum near‐field radiation for RFID applications via the implementation of SDM procedure

This paper presents the design of reflectarray antennas to radiate an optimum near-field distribution by using the procedure of steepest decent method to synthesize the impressed phases of reflectarray elements. In particular, the closed-form formulations used in the electromagnetic modeling were developed for an efficient design. The design was further implemented to realize a reflectarray of microstrip patch elements, which is illuminated by the radiation of a feed antenna at the 2.4 GHz band in the radio frequency identification applications. Numerical investigations as well as experimental measurements over a prototype are presented to validate the feasibility of the developed models and the implemented antenna structure.

Hybrid Approach for the Synthesis of Unequally Spaced Array Antennas With Sidelobes Reduction

A hybrid approach is presented to synthesize unequally spaced array antennas with low sidelobes. The exact locations of all the elements for unequally spaced array antennas can be quickly determined with the composite Taylor-Exponent configuration arrangement. Furthermore, an amplitude taper with tremendously simple configuration was designed to reduce the sidelobes for unequally spaced array antennas. Numerical results show that the proposed hybrid approach is effective for the modified synthesis of unequally spaced array antennas, with the sidelobes reduced to be lower than -30 dB.

Research on Corona Poling for PMMA/DR1 Host-Guest Polymer Films

Aimed at corona poling of PMMA-based modified polymer films, we deduced optimized polarization conditions and a new practical and effective way to improve the polarization efficiency. First of all, the influence of DR1-dopant in host-guest way on the optical loss of PMMA/DR1 polymer films, prepared by sol-gel method combining with spin coating, was analyzed. Then through a series of single-pin corona poling experiments on two types of PMMA/DR1 host-guest films, the optimized polarization temperature and time for their higher orientation order parameters are determined. Based on this, some polarization analysis for PMMA/DR1 films was conducted by using improved multi-pin corona poled instrument. The better results prove that multi-pin corona poling at 95℃ for 30 min is benefit for improving the polarization efficiency of PMMA/DR1 host-guest films, also for experimental cost reduction due to lower polarization voltage.

The Microstrip Antenna with PBG Used for 3G System

Aiming at the request of the antenna used for 3G system, we first analyze the characteristics of microstrip antenna and design methods of size structure, and then design the microstrip antenna with PBG by using MWO. The detailed analysis inquiries into the influence on the reflection coefficient S11 by key parameters, such as the length of PBG sides, the structural periodicity of PBG, the feeding point of antenna, the dielectric constant and thickness of circuit board have been studied. Finally, the design principles and advantages of the microstrip antenna with PBG are summarized.

Design of printed notched-monopole UWB antenna

To meet the requirement of ultra band wide (UWB) communications, a printed monopole antenna of tapered and notched radiator is designed. The simulated and measured results show that the proposed antenna achieves a broad operating bandwidth of 3.07–10.92 GHz for the 10-dB return loss. This antenna features omni-directional radiation patterns and high radiation efficiency. The parametric studies indicate that to maintain the UWB impedance performance the width of the residual lower-side metal patch must be larger than one eighth of the higher resonant wavelength. To miniaturize the antenna size, for the rectangular ground plane the width can be a bit smaller than half of the lower resonant wavelength and the height a bit larger than a quarter of this wavelength.

The Application of PBG Configuration in Planar Spiral Antenna

For the requirement of 3G mobile terminal at present, we have designed a new kind of WCDMA mobile terminal spiral antenna with PBG structure, which is capable of working in 1920-2170 MHz frequency broad band. Applying PBG configuration in planar spiral antenna, the characteristics is improved significantly and the size is also reduced. It makes the band width reach 250 MHz, which covers the whole emitting and receiving frequency band of WCDMA system. This antenna has been simulated and designed by using simulation design software, and the experiment results are agree well with the simulation results, which show that the varied period configuration of PBG is more benefit to improve antenna performance.

A petal-shaped left-handed metamaterial based on split ring and semicircular resonator

In this paper, the design of a petal-shaped left-handed (LH) metamaterial (MTM) is presented. The proposed petal-shaped structure consists of an outer circular ring and four inner semicircular resonators, with the former split into four arms and the latter of diameters close to the ring. These four resonators are cross loaded to constitute the whole structure with four-fold symmetry. The simulation results show that the single-sided MTM has a LH working frequency range of 17.3 to 19.1 GHz. And then the surface current, electric and magnetic field distributions are demonstrated and analyzed. In addition, a parametric discussion based on the gap width of the split circular ring and the diameter length of the semicircular resonator is given in order to study the relation between the LH resonance and structure dimensions. The designed planar LH MTM has a great potential in MTM-mushroom structure applications.

Dielectric Properties and Microstrip Patch Antenna Performances of 0.95MgTiO3-0.05CaTiO3 Microwave Ceramics

τMicrowave dielectric properties of 0.95MgTiO3-0.05CaTiO3 ceramics and their performances as H-shaped microstrip patch antenna were investigated. Best values of dielectric constant (εr) and quality factor (Q×f) of 19.00 and 66800GHz, respectively, were obtained for the microwave ceramics sintered at 1300°C for 3h. A near-zero temperature coefficient of resonant frequency (τf) of -4.7ppm/°C was obtained for the ceramics with sintering 1280°C for 3h. A new kind of H-shaped microstrip patch antenna with two resonant frequencies was fabricated by using of this kind of ceramics as antenna substrate. The return loss bandwidth of the patch antenna was extended with the increasing of substrate thickness at both resonant frequencies of the antennas, around 1.530GHz and 2.750GHz, respectively.