Xuewu Cui

The impact of introduced coupling elements on characteristic mode

This paper gives a detail discussion about the impact of introduced coupling elements on characteristic mode. Different types of inductive coupling elements (ICEs) and capacitive coupling elements (CCEs) placed on plate structure and box structure have been taken into account. The eigenvalue, mode current and far-field of the combined structure with coupling elements are evaluated. In comparison with the original body, mode current of combined structure has changed in some degrees due to the presence of the coupling elements. But eigenvalue and mode far-field are in close proximity to the original. The impact on characteristic mode provides physical explanation about how coupling elements excite the desired characteristic modes. Information provided by CM of the combined structure can be used to optimize the size and geometry of the coupling elements.

Radar cross section reduction of dipole antenna using checkerboard surface

The radar cross section (RCS) reduction technique for dipole antenna using checkerboard surface is investigated. The checkerboard surface is used as ground of dipole antenna instead of a metal ground. In the operating frequency band of the antenna, the checkerboard surface can reflect electromagnetic wave nearly in phase, thus the radiation performance of the antenna is not degraded. However, for the out of band case, the scattered fields by two types of subarrays of the checkerboard surface are out of phase, which lead to reduced RCS of the antenna when compared with that loaded with metal ground. Results show that broadband RCS reduction can be achieved with few influence on the radiation properties in terms of both S-parameter and radiation pattern.

Grating lobe reduction in phased arrays with regular subarray architecture

Phase weighting at the subarray level alone causes grating lobes (GLs) in the far field pattern. In this paper, a technique for reducing GLs in phased arrays with regular subarray architectures is proposed. Two measures are used in this method. They are: (1) integrating a power divider with phase difference among output ports for each subarray, which controls the each subarray pattern has a different beam direction; (2) switching the subarrays on or off during scanning. The optimization of the beam directions of subarrays is carried out by using particle swarm optimization (PSO) algorithm. Numerical results show that the proposed approach can successfully suppress GLs while maintain the similar beamwidth (BW) with the filled array.

Scattering and radiation simulation by discontinuous Galerkin time domain method

In this paper, the implementation of the sources for scattering and radiation of the discontinuous Galerkin time domain method (DGTD) are presented. Based on formulations of the DGTD method, the sources implementation procedure is given, including the incident plane wave generated for scattering and the modeling of a coaxial port feed for antenna radiation. Numerical examples of PEC almond scattering and a microstrip antenna radiation are demonstrated the accuracy and efficiency for the source implementation in DGTD method.

A small RFID tag antenna for metallic object using characteristic mode

A small UHF RFID tag antenna for metallic object using characteristic mode theory (CMT) is presented in this paper. The tag antenna is composed of a rectangle loop and the metallic object. The rectangle loop is used as an inductive coupler element (ICE) to excite a specified characteristic mode current of the metallic object. In this case, the metallic object itself will act as the main radiator. The loop is printed on the ceramic material with a high relative dielectric constant and placed at a current maximum of a desired mode. The satisfactory result proves that the desired characteristic mode has been partially excited by this small loop.

Physical optics method over high-order triangular element for complex source beam applications

A method that combines high-order triangular element and PO method over electrically large conducting targets illuminated by a complex source beam (CSB) is developed in this paper. High-order triangular element is used to subdivide the surface of target and PO result is obtained to investigate the scattering properties. This method has the merit of being very accurate and efficient, and its computation cost does not increase with frequency. Numerical examples are also given in this paper to demonstrate the efficiency of this method.

A Wideband Magnetoelectric Dipole Antenna With Microstrip Line Aperture-Coupled Excitation

In this communication, a novel wideband magnetoelectric (ME) dipole antenna is proposed and investigated. A microstrip line aperture-coupled feeding structure is used to excite the antenna. This simple feeding structure can significantly enhance the impedance bandwidth. An antenna prototype is fabricated and exemplified to validate the proposed concept. Measured results show that the proposed ME dipole antenna with microstrip line aperture-coupled excitation achieves an impedance bandwidth of 85% for VSWR < 2 from 2.5 to 6.2 GHz. Further, a measured maximum boresight gain up to 8 dBi is obtained and a 1 dB gain bandwidth is about 67% from 2.5 to 5 GHz. The antenna radiation patterns perform well over the 1 dB gain bandwidth range. A low cross-polarization level is obtained over the operating band.

Delaminating Quadrature Method for Physical Optics Integrals over High-Order Triangular Mesh for Complex Source Beam Applications

ABSTRACT A novel method for calculating physical optics (PO) integrals over an electrically large target illuminated by a complex source beam is presented. A high-order triangular element is used to mesh the surface of this target. The PO integrals over these elements are calculated with a delaminating quadrature method. This method is very stable, accurate, and efficient, and its computation cost remains constant as the frequency increased. The influence of critical points is taken into account by subdividing the integral intervals. Numerical results are shown in this article to demonstrate the efficiency of this approach.