Guizhen Lu

Bio: Guizhen Lu is an academic researcher from Communication University of China. The author has contributed to research in topics: Antenna (radio) & Patch antenna. The author has an hindex of 4, co-authored 10 publications receiving 34 citations.

Directivity enhancement of fabry‐perot antenna by using a stepped‐dielectric slab superstrate

Abstract: A Fabry-Perot resonator excited by a microstrip patch antenna that has a superstrate with a stepped dielectric constant is designed to operate at 5.8 GHz. The antenna is fabricated and is shown to provide enhanced directivity over that achievable using uniform dielectric slabs, with either er = 4.4 or er = 10.2 as superstrates. The measured maximum gain of the patch antenna with a step-index dielectric constant superstrate with a dimension of 2λ0 × 2λ0 was found to be 13.44 dBi, whereas the corresponding values for the uniform dielectric superstrate are 11.25 (er = 4.4) and 12.44 dBi (er = 10.2). As shown in this article, the aperture efficiency of the step-index dielectric is also higher than those of the other two. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:711–715, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26614

Unequally spaced linear antenna arrays synthesis based on genetic algorithm

Abstract: The analysis for the assembling of non-uniform, linear arrays based on Genetic Algorithm is presented. The GA optimization techniques generate the locations of the elements for reducing the side-lobe level. Results are presented for the placement of 20 elements under the design of a 15.5 λ. linear array. The scanning properties of the designed arrays are also investigated. According to the optimized results, patch antenna arrays are simulated by Ansys HFSS software to verify the optimization technique.

Directivity Enhancement of Microstrip Patch Antennas Using a Dieletric Superstrate

Abstract: In this paper, we present a systematic design methodology for enhancing the direc- tivity of microstrip patch antennas (MPAs), by using it as an exciter of a Fabry-Perot (FP) (6) resonant cavity. The design procedure involves three steps: (i) determing the resonance fre- quency of the empty cavity, with the MPA removed, when operating in the receive mode; (ii) designing the patch antenna to operate at the same frequency in the presence of the superstrates; (iii) flnally, we operate the composite system in the transmit mode to investigate its aperture distribution that provides us a clue for enhancing the directivity. We show that the directivity can be enhanced by more than 8dB, over that of the MPA without the superstrate, by using either planar or curved superstrates as covers for the MPA.

Directivity enhancement of microstrip antennas using dielectric superstrates

Abstract: The subject of directivity enhancement of microstrip patch antennas (MPAs), using either a Frequency Selective Surface (FSS) or a double-negative (DNG) metamaterial slab, has been investigated by a number of researchers in recent years. The purpose of this paper is to show that we can also achieve the same goal by using a much simpler design for the superstrate, namely a dielectric slab, whose performance can comparable, and even be superior to those of the other two typical choices for the superstrate, namely the FSS or the DNG.

Design of high performance sleeve dipole array antenna

Abstract: A 5-element planar dipole array antenna is analyzed and successfully implemented. The proposed antenna is designed for operation at 1.9 GHz band for basic station applications with S 11 < −14 dB. The planar dipole array antenna comprises of a 1×5 dipole array and fed by a microstrip line. This structure is easily constructed by printing on both sides of a dielectric (FR4) substrate. The measured −14 dB return loss (VSWR 1.5:1) impedance bandwidth is around 7.0% (1.79–1.92 GHz). A reflector is put behind the dipole array to obtain directional radiation and high gain, and the measured maximum gain for operating frequencies across the 1.9 GHz band is about 6.9–8.6 dBi. The measured results of radiation efficiency, radiation pattern, antenna gain and return loss show that this dipole array is with a good performance.

Steering the Beam of Medium-to-High Gain Antennas Using Near-Field Phase Transformation

Abstract: A method to steer the beam of aperture-type antennas is presented in this paper. Beam steering is achieved by transforming phase of the antenna near field using a pair of totally passive metasurfaces, which are located just above and parallel to the antenna. They are rotated independently or synchronously around the antenna axis. A prototype, with a peak gain of 19.4 dBi, demonstrated experimentally that the beam of a resonant cavity antenna can be steered to any direction within a large conical region (with an apex angle of 102°), with less than 3-dB gain variation, by simply turning the two metasurfaces without moving the antenna at all. Measured gain variation within a 92° cone is only 1.9 dBi. Contrary to conventional mechanical steering methods, such as moving reflector antennas with multiaxis rotary joints, the 3-D volume occupied by this antenna system does not change during beam steering. This advantage, together with its low profile, makes it a strong contender for space-limited applications where beam steering with active devices is not desirable due to cost, nonlinear distortion, limited power handling, sensitivity to temperature variations, radio frequency losses, or associated heating. This beam steering method using near-field phase transformation can also be applied to other aperture-type antennas and arrays with medium-to-high gains.

Dielectric Phase-Correcting Structures for Electromagnetic Band Gap Resonator Antennas

Abstract: A novel technique to design a phase-correcting structure (PCS) for an electromagnetic band gap (EBG) resonator antenna (ERA) is presented. The aperture field of a classical ERA has a significantly nonuniform phase distribution, which adversely affects its radiation characteristics. An all-dielectric PCS was designed to transform such a phase distribution to a nearly uniform phase distribution. A prototype designed using proposed technique was fabricated and tested to verify proposed methodology and to validate predicted results. A very good agreement between the predicted and the measured results is noted. Significant increase in antenna performance has been achieved due to this phase correction, including 9-dB improvement in antenna directivity (from 12.3 dBi to 21.6 dBi), lower side lobes, higher gain, and better aperture efficiency. The phase-corrected antenna has a 3-dB directivity bandwidth of 8%.

Fabry–Pérot Resonator Antenna With High Aperture Efficiency Using a Double-Layer Nonuniform Superstrate

Abstract: Due to the nonuniform electromagnetic (EM) field amplitude distribution over its aperture, the Fabry–Perot resonator antenna (FPRA) suffers from relatively low aperture efficiency. In this communication, an FPRA with high aperture efficiency is proposed based on a double-layer nonuniform superstrate (DNS). The DNS is designed to have a constant reflection phase but a varying reflection magnitude, thereby obtaining a uniform EM field amplitude distribution over the FPRA’s aperture and, hence improving the directivity and the corresponding aperture efficiency. As an example, a cylindrical FPRA with an aperture diameter of $3.5~\lambda $ (where $\lambda $ is the wavelength in free space) is presented. In comparison with a uniform superstrate, the proposed DNS enhances the FPRA’s directivity from 19.6 to 20.4 dBi and correspondingly improves the aperture efficiency from 76.3% to 91.7%.

Superstrate-Based Beam Scanning of a Fabry–Perot Cavity Antenna

Abstract: Incorporating phased array technique to scan the main beam of a Fabry-Perot cavity (FPC) antenna produces sidelobes proportional to the scan angle. An alternative dielectric-ferrite superstrate-based scan mechanism with controlled sidelobe level is presented in this letter. A beam scan of 24 ° is demonstrated by axially magnetizing the ferrite part of the superstrate with ΔH = 0.25 T. Stepped dielectric part of the superstrate is optimized to reduce the sidelobe level of the FPC antenna by 4.49 dB. The fabricated antenna is tested to verify the simulated radiation patterns and reflection responses. The requirement of magnetic biasing can be considerably reduced using LTCC technology, where biasing coils are embedded within the ferrite superstrate.

3-D Printed Fabry–Pérot Resonator Antenna with Paraboloid-Shape Superstrate for Wide Gain Bandwidth

Abstract: A three-dimensional (3-D) printed Fabry–Perot resonator antenna (FPRA), which designed with a paraboloid-shape superstrate for wide gain bandwidth is proposed. In comparison with the commonly-adopted planar superstrate, the paraboloid-shape superstrate is able to provide multiple resonant heights and thus satisfy the resonant condition of the FPRA in a wide frequency band. A FPRA working at 6 GHz is designed, fabricated, and tested. Considering the fabrication difficulty caused by its complex structure, the prototype antenna was fabricated by using the 3-D printing technology, i.e., all components of the prototype antenna were printed with photopolymer resin and then treated by the surface metallization process. Measurement results agree well with the simulation results, and show the 3-D printed FPRA has a |S11| < −10 dB impedance bandwidth of 12.4%, and a gain of 16.8 dBi at its working frequency of 6 GHz. Moreover, in comparison with the planar superstrate adopted in traditional FPRAs, the paraboloid-shape superstrate of the proposed FPRA significantly improves the 3-dB gain bandwidth from 6% to 22.2%.