Naichang Yuan

RCS Reduction of Ridged Waveguide Slot Antenna Array Using EBG Radar Absorbing Material

This letter investigates the application of EBG radar absorbing material (RAM) to asymmetric ridged waveguide slot antenna array to reduce its backward RCS. The EBG RAM is based on the mushroom-like EBG structure loaded with lumped resistances. A ridged waveguide slot antenna array with 4 times 10 slot elements was designed and built, part of the metal ground plane of the array is replaced with this EBG RAM. The measured results show that performance of the antenna array is preserved when EBG RAM is used. At working frequency the backward RCS of antenna array with EBG RAM has dramatically reduced than that of the common antenna array.

A Novel Compact Spiral Electromagnetic Band-Gap (EBG) Structure

A novel compact electromagnetic band-gap (EBG) structure in a spiral shape is presented and investigated. This structure significantly enlarges the capacitance between neighboring elements. The simulations and experimental results have proved that the size of the spiral structure is only 30.9% of the conventional EBG structure. Two applications have been shown, including patch antenna with the spiral EBG structure and a double-element microstrip antenna array with low mutual coupling. The measured results show that a gain improvement over 3 dB and a significant reduction of cross polarization in H-plane are obtained. A 6 dB reduction of mutual coupling is achieved in a double-element EBG microstrip antenna array.

Design of Circular/Dual-Frequency Linear Polarization Antennas Based on the Anisotropic Complementary Split Ring Resonator

A novel kind of circular polarization and dual-frequency linear polarization microstrip antennas is proposed. The designs are based on the anisotropic property of the complementary split ring resonator. When the complementary split ring resonator is etched on the patch of the probe-fed microstrip antenna, the gap orientation asymmetric or symmetric to the current propagating direction will render the antenna to radiate circular polarization waves or dual-frequency linear polarization waves. Details of the experimental results compared with the simulated results are presented and discussed.

Elimination of scan blindness in phased array of microstrip patches using electromagnetic bandgap materials

Electromagnetic bandgap (EBG) material is applied in the design of a phased array of rectangular microstrip patches. The surface-waves could be suppressed by the frequency bandgap and, therefore, the scan blindness could be eliminated. A high-impedance surface is chosen as EBG structure, and the numerical simulation is performed by periodic Greens functions plus the moment method. Both the bandgap curve of the EBG structure and the scan characteristics of the phased arrays have been calculated. The elimination of scan blindness is observed.

A novel PBG coplanar waveguide

A novel coplanar waveguide with photonic bandgap structure is proposed and is implemented by etching holes in the ground plane with an open connected with the gap between strip line and ground plane. Simulation and measurement results show the existence of a bandgap.

FDTD Formulations for Scattering From 3-D Anisotropic Magnetized Plasma Objects

The JE convolution finite-difference-time-domain (JEC-FDTD) method is developed to study the scattering from the anisotropic magnetized plasma which incorporates both anisotropy and frequency dispersion at the same time, enabling the transient solution of the electromagnetic wave propagation in anisotropic magnetized plasmas. Three dimensional JEC-FDTD formulations for magnetized plasma are derived. The bistatic radar cross section (RCS) of three-dimensional conducting targets coated by anisotropic magnetized plasmas is calculated

A circular waveguide antenna using high-impedance ground plane

A high-impedance ground plane (HIGP) is used for a circular waveguide antenna. The benefits of using such a HIGP are related to the suppression of surface waves excited by the circular waveguide mouth, because the HIGP has a very obvious surface wave bandgap. Suppression or reduction of surface waves is expected to improve antenna efficiency and to bring a reduction of sidelobe level due to diffraction of the surface waves. In agreement with the expected result, the measured radiation patterns show that a 2 dB addition in the antenna gain and a 10 dB reduction in the back lobes, if the circular waveguide antenna working frequency is in the HIGP surface wave bandgap.

Design and analysis of lumped resistor loaded metamaterial absorber with transmission band

A new type of multi-layer metamaterial (MM) absorber is represented in this paper, which behave as a dielectric slab in transmission band and act as an absorber in another lower band. The equivalent circuit model of each layer in this MM absorber has been established. The transmission line (TL) model is introduced to analysis the mechanism of electromagnetic wave traveling through this MM absorber. Both theoretical and experimental results indicate this MM absorber has a transmission band at 21GHz and an absorptive band from 5GHz to 13GHz. A good match of TL model results and measurement results verified the validity of TL model in analyzing and optimizing the performances of this kind of absorber.

A novel polarization convert surface based on artificial magnetic conductor

A novel polarization convert surface based on AMC structure is presented. For a linear polarized incident wave, a perpendicular linear polarized reflected wave, right-handed and left-handed circular polarized reflected wave can be achieved individually at different frequency. The surface can be applied to satellite communications to convert polarization state of transmitted and received wave, it can be used to stealth design, and can be used to achieve double circular polarization antenna.

Novel Compact Inter-Embedded AMC Structure for Suppressing Surface Wave

In this paper, a novel very compact inter-embedded artificial magnetic conductor (IE-AMC) structure is presented. Compared with conventional Sievenpiper AMC structure, for a desired band-gap frequency, the cell size of this novel IE-AMC structure is reduced about 70% with the same substrate used. Therefore, in practical application to microwave integrated circuits and antenna arrays for suppressing surface, for a given available space, more AMC structure cells can be used, and the performance of circuits and antennas can be improved more. On the other hand, low frequency surface wave band-gap which is applied to wireless communication band (GSM, PCS and ISM) can be obtained using IE-AMC structure.