Shu-Xi Gong

A COMPACT FOLDED PRINTED DIPOLE ANTENNA FOR UHF RFID READER

A compact printed dipole antenna for UHF RFID reader is presented. The peak gain of the printed dipole antenna is 2.07 dBi, which is higher than traditional UHF RFID antenna. The proposed antenna occupies a volume of 65 × 30 × 2m m 3 and the radiator is composed of two rectangular patches etched with folded slit. The radiation element of the dipole antenna is fed by 50 Ω coaxial line. Measured results indicate that the proposed antenna has a good impedance matching characteristic at 905-935.5 MHz (return loss less than 10 dB). In addition,the effect of some parameters on the performance of the proposed antenna is also discussed in this article. This printed dipole antenna will be applicable for future RFID systems.

SCATTERING ANALYSIS OF A PRINTED DIPOLE ANTENNA USING PBG STRUCTURES

A novel broadband design of a printed dipole antenna using PBG (photonic band-gap) structures is proposed and studied in the electromagnetic scattering. The high surface impedance and a frequency gap are used to reduce RCS (radar cross section) across needed frequency range (3.7–4.5 GHz). Because the high surface impedance restrains the surface waves, the obtained results show that RCS is reduced by 15 dB at resonance frequency and radiation characteristics of the antenna at operating frequencies are improved. The method of RCS reduction is suggested, and experimental results are presented.

A Novel Wilkinson Power Divider for Dual-Band Operation

The design and analysis of a dual-band equal-split Wilkinson power divider are presented in this paper. The structure of the power divider and the formulas used to determine the design parameters have been given. The divider has two output ports shifted away from the isolation resistor to the open stub. As a result, the bandwidth can be enhanced obviously for small band-ratios. Closed-form design equations are derived using even- and odd-mode formulation. For verification, a microwave power divider operating at 1 and 2 GHz is fabricated, the experimental results show that the designed power divider fulfills all the features of a conventional Wilkinson power divider, such as an equal power split and impedance matching at ports.

APERTURE COUPLED MICROSTRIP ANTENNA WITH LOW RCS

Research of antenna Radar Cross Section (RCS) is very important for low observable platform. Aperture coupled microstrip antenna is fit for the low RCS antenna design because the feed network produce less effect on scattering of microstrip patch. A novel aperture coupled microstrip antenna is proposed, which utilizes the chip-resistor load, ground slot and miniaturization, to realize RCS reduction. Aperture coupled antenna with rectangular patch is chosen as the reference antenna. Two antennas are simulated and measured. The measured results show that the designed antenna realizes only 0.5 dB gain loss while RCS are reduced in almost all the frequency band.

WIDE SCANNING PHASED ARRAY ANTENNA USING PRINTED DIPOLE ANTENNAS WITH PARASITIC ELEMENT

A active phased array antenna has been developed that is capable of wide scanning angle with small deviation in antenna gain using printed dipole antennas with parasitic element, which may have the capability of adjusting the influence of mutual coupling in the array element pattern. The design of the parasitic element is examined and the effect of its shape on pattern characteristics is confirmed. Beam scanning angles of 58 degrees in the φ = 0◦ plane were obtained for each array antenna pattern.

A Novel UWB Clover-Disc Monopole Antenna With RCS Reduction

Antenna Radar Cross Section (RCS) research is mainly on the microstrip antenna which is a narrow band device. Few publications on the RCS of ultrawideband (UWB) antenna have been published. A novel clover-disc monopole antenna, which simulates the trifoliolate leaves of clover, is designed to realize RCS reduction compared with a usual circular-disc monopole antenna. Both of the two antennas are UWB antennas whose RCS performances under different loads are studied and compared. The results show that RCS of clover-disc antenna is reduced compared with circular-disc antenna in the whole frequency band while maintaining the radiation performance.

A Novel Low RCS Microstrip Antenna Using Aperture Coupled Microstrip Dipoles

A microstrip antenna composed of parallel dipoles of different widths fed by rectangular slots cut in the ground plane of a microstrip line is designed for low RCS property. Based on the surface current distribution on the patch, the effects of cutting slots in the patch and the ground plane on the resonant modes which have a unique relationship with the radiation performance and RCS response of a microstrip antenna are discussed. By properly controlling resonant modes, the proposed antenna realizes good radiation performance and low RCS. Compared to the rectangular patch antenna with the same operating frequency, the proposed antenna, with only a 0.5 dB reduction of gain, has an RCS reduction of approximately 2–10 dB in the vicinity of the peaks illuminated by the plane wave from different incidence directions. Additionally, the antenna bandwidth does not decrease, which overcomes the problem that the RCS reduction techniques cause the loss of bandwidth.

ULTRA-WIDEBAND MONOPOLE ANTENNA WITH FOUR-BAND-NOTCHED CHARACTERISTICS

A compact ultra-wideband (UWB) monopole antenna with four-band-notched characteristics is introduced in this paper. The proposed antenna can achieve four-band rejection at 3.4, 5.7, 8 and 11 GHz with desired bandwidths only using one novel structure called nested complementary split-ring resonator (CSRR) which is etched inside the ground plane. This method used to obtain four-bandnotched characteristics is firstly proposed in this paper. The antenna has a small dimension of 35× 27 mm2. The VSWR and radiation patterns of the fabricated antenna are presented, which prove that the designed antenna is a good candidate for various UWB applications.

Compact Graded Central Feeder Line CPW-fed Broadband Antenna

A broadband planar antenna fed by coplanar waveguide (CPW) with gradually changed central feeder line is proposed. Central feeder line of the CPW and the ground plane are designed to be graded structure, which endow the proposed antenna with better impedance matching characteristic and broader bandwidth than microstrip line (MSL) fed antenna. Compared with antennas in previous researches, this proposed antenna has smaller size but covers wider bandwidth, which can operate from 0.7 GHz to 5.9 GHz for return loss less than –10 dB, and shows omni-directivity in azimuth plane.

Reducing Bandwidth of FSS using Substrate-Integrated Waveguide Technology

A novel method of reducing bandwidth of FSS is introduced based on Substrate-integrated Waveguide (SIW) technology. As examples of using SIW technology, the bandwidth of ring aperture FSS and Y-loop aperture FSS is evidently reduced compared with conventional array FSS. Besides, several important parameters that characterize the proposed FSS are also investigated in this article. We use CST simulation tool to analyze the proposed FSS, and its effectiveness is validated by good agreement between the simulated results and the measured results.