Qiu Jinghui

A Novel Printed Fractal Log-Periodic Dipole Antenna

This paper presents the research on a novel miniaturized printed log-periodic antenna with fractal tree structure for operation in a broadband of 0.4 GHz-2GHz. The antenna is designed and simulated with the application of CST MICROWAVE STUDIO®software based on the Finite Integral Method. The simulation results show that the antenna achieves the necessary lateral size reduction to 61% of the normal log-periodic antenna, while keeping its radiation characteristics nearly constant.

Study on RFID Antenna for Railway Vehicle Identification

In this paper, a sort of RFID (radio frequency identification) system for railway vehicle identification is presented, and we design and measure the transmitting-receiving antenna of the RFID system. When the RF power is 1.34 W, the tag read range in vertical (parallel) direction of the train is 2 m (4 m). We adopt 4 units microstrip antenna array as transmitting/receiving antenna, which operates at 915 MHz. The measured VSWR (voltage standing wave ratio) is less than 1.4, and the gain is more than 9 dB. The system has advantages of hardware modularity, good applicability and high reliability. And it has taken experiments in railway

Optimized dielectric rod antenna for millimeter wave FPA imaging system

Dielectric rod antennas have a number of significant advantages over conventional waveguide, horn antennas, printed dipole or TSA when used as feed eltments in focal plane arrays (FPA). In this paper the principle of dielectric rod antenna is introduced and CST Microwave Studio is used to simulate the influence of antenna parameters, optimized dielectric rod antenna designed. The optimized dielectric rod antenna can raise the gain of the antenna by controlling the length of the antenna but not the cross-section, provide a broadband input matching, small side-lobe, coupling and cross polarization. The antenna is suitable for the arrangement of the array and and better edge illumination to realize better illumination effect to the lens.

A novel miniaturized ultra wideband log-periodic antenna

The log-periodical antenna (LPDA) is a kind of ultraw wide-band antennas. To achieve the purpose of miniaturization of the LPDA in radiate direction, this paper presents a novel structure log-periodically loaded with symmetrical meandering dipoles. The radiate direction is reduced to 46% of the conventional LDPA. The return loss is less than −10dB from 200MHz to 2GHz, according to the simulation results. A good directivity is also obtained that the gain ranges from 1.9dB to 7.2dB.

Analysis and design of novel directional ultra wide-band antennas

Ultra wide-band is one of the hottest issues in the current researches on antennas. The circular monopole antenna is a kind of ultra wide-band antennas with simple structure. Firstly a novel antenna was researched. Four circular disc monopoles were placed across each other. They were considered as the feedings, and the reflection plane was planar. It could achieve dual polarization characteristics. On this basis, further study was applied to two other novel antennas. The first was changing the planar reflector to parabolic one, and the purpose was to realize wide beam, high gain and directed radiation characteristic. The other was changing the circular disc shape, and the purpose was to realize wider lower frequency bandwidth. The novel antennas were theoretic analyzed, and the S- parameter and radiation patterns of the antennas were discussed by electromagnetism simulation software. The analytic results verify that the characteristic of the traditional monopole antenna is effective improved by the novel antennas. Dual-polarization, high gain, wide beam and directed radiation characteristics of the antenna are realized. The novel antennas are suitable for the satellite and mobile communication systems with good prospects.

Research on an axially slotted cylinder antenna coated with plasma sheath

For radiation characteristics research on antenna coated with a plasma sheath, an axially slotted cylinder antenna is presented. The proposed antenna is composed of a narrow slot cut in the wall of a hollow circular cylinder. The working band width is about 200 MHz. The plasma sheath media was simulated with laminate medium given by drude dispersion model. The electron density in layered plasma model is presented following experimental data. According to the simulation results, return loss deteriorates seriously when thickness of plasma sheath is thickened. And the radiation patterns are mainly in opposition with the plasma sheath when thickness of plasma sheath is 25 mm due to the plasma sheath reflection. The theory analysis and simulation results are presented.

Novel planar complex spiral ultra-wideband antenna

Planar equiangular spiral antenna and Archimedean spiral antenna are two kinds of ultra-wideband circular polarized antennas, which are used in various applications. However, the lower frequencies of these antennas are limited by their dimensions. In order to minimize antennas dimension, we designed an equiangular spiral-Archimedean spiral-integrated antenna. In the frequency spectra 400 MHz-2000 MHz, the measured return loss of the proposed UWB antenna is less than -10dB. This novel antennas wide band characteristic, especially the characteristic in the lower frequency, is better than that of the planar equiangular spiral antenna in the same dimension.

Design and Simulation of Novel Ultra Wideband Planar Reflector Antenna

A novel ultra wideband planar reflector antenna is presented in this paper. The proposed antenna is composed of a circular disc dipole and a finite reflector plane. The impedance matching and bandwidth for the presented antenna are mainly affected by the diameter of the disc and feeding separation. The theory of ultra wideband planar reflector antenna is discussed and simulated. By properly choosing adequate dimension and adjusting feeding distance, impedance bandwidth of S11<- 10dB is about from 1.7GHz to 19.8GHz, and relative bandwidth is greater than 160%. The antenna can get broad radiation beam in the low frequency band. The main lobe 3dB width is wider than 65deg at E-plane and H-plane in low frequency. To increase the impedance bandwidth, a changed planar reflector antenna is proposed. The simulation and analysis results are presented.

A triple-frequency circularly polarized microstrip antenna

A triple-layer patch circularly polarized microstrip antenna is proposed for triple-frequency operation. It is shown that the antenna resonates at three different frequencies of 1.207GHz, 1.268GHz and 1.561GHz with adequate values of return loss and gain. The antenna is designed and simulated with the application of CST software based on the finite integral method. The simulation results and analyses are presented.

Analysis and design of an ultra-wideband nested coaxial waveguide feed

In this paper a four-cavity 60:1 frequency bandwidth (1-60 GHz) ultra-wideband nested coaxial waveguide feed with extended center conductors is designed and analyzed. The performance of the feed is presented and discussed in detail. The feed has less than -10 dB reflection loss over its operating frequency. The excitation of the coaxial cavities is accomplished by impressing a circularly polarized TE/sub 11/ coaxial waveguide mode. The correlated parameters are rigorously carried out by experimental measurement (1-8 GHz) and a finite element method (FEM) computer simulation study (8-60 GHz).