[신간안내] Computational Electrodynamics (the finite difference time - domain method)

This paper presents a miniaturized frequency-selective rasorber (FSR) that has a wide transmission band with low insertion loss and a wide absorption band below the transmission band. The FSR is composed of a resistive sheet and a bandpass frequency-selective surface (FSS). The unit cell of the resistive sheet is a resistor-loaded hexagonal metallic loop, each side of which is inserted with a circular spiral resonator (CSR) in the center. The CSR is equivalent to a parallel LC circuit that has a high inductance and low parasitic capacitance. At a high frequency of 10 GHz, the CSR resonates to be infinite impedance, around which a 0.5 dB transmission band of 8.68–11.34 GHz is produced. The bandpass FSS is a triple-layer FSS in which two layers of identical hexagonal patches are coupled through a layer of hexagonal aperture; it has a fast rolloff 0.5 dB transmission band of 8.2–11.33 GHz, which almost coincides with that of the resistive sheet. The 1 dB transmission band of the FSR by placing the resistive sheet on the bandpass FSS is 8.3–11.07 GHz. At low frequency, the FSR performs as an absorber, and the 10 dB absorption band is 2.4–7.1 GHz. In addition, due to its tiny physical sizes of only $1.2\,\,\text {mm}\times 1.6$ mm, the CSR can be viewed as a lumped element circuit with a high inductance, in which the parallel resonance is almost independent to the incident angle. The transmission performance of the FSR has a good independence of polarizations and incident angles. A prototype of the proposed FSR is fabricated and measured to validate the design.

Miniaturized Frequency-Selective Rasorber With a Wide Transmission Band Using Circular Spiral Resonator

Multiple input multiple output (MIMO) antenna is at core of the presently available wireless technologies. The design of MIMO antennas over a limited space requires various approaches of mutual coupling reduction, otherwise gain, efficiency, diversity gain, and radiation patterns will be severely affected. Various techniques have been reported in literature to control this degrading factor and to improve the performance of the MIMO antennas. In this review paper, we have carried out an extensive thorough investigation of diversity and mutual coupling (correlation) reduction techniques in compact MIMO antennas.

MIMO antennas with diversity and mutual coupling reduction techniques: a review

The design of a thin microwave absorber which exhibits a −10 dB reflectivity bandwidth of 108% at normal incidence and 16% for simultaneous suppression of TE and TM polarised waves over the angular range 0–45° is presented. The structure consists of a 3 mm-thick metal backed frequency selective surface (FSS) with four resistively loaded hexagonal loop elements in each unit cell. The surface resistivity and width of the loops are carefully chosen to maximise the bandwidth by merging the reflection nulls that are generated by the multi-resonant absorber. Measurement and simulation results are in good agreement over the broad frequency range 7.8–24 GHz.
Introduction:

/pdf/compact-fss-absorber-design-using-resistively-loaded-1iup48u2v6.pdf

Compact FSS absorber design using resistively loaded quadruple hexagonal loops for bandwidth enhancement

Microwave scanning antennas, vol l, apertures

Hardware acceleration of Finite-Difference Time-Domain (FDTD) algorithm has always been an important part of FDTD research. In this essay, we discussed the advantage and feasibility of accelerate FDTD algorithm using Graphics Processing Unit (GPU). With the implement of lattice-threads mapping and other techniques, we proposed a GPU FDTD programming model that is both efficient and accurate. Then we simulated two projects using proposed model, the result shows good agreement with CPU computing while simulation speedup is 20 at minimum, thus proves the efficiency and great potential of GPU accelerating in FDTD research.

Accelerating FDTD algorithm using GPU computing

In this work, an ultra-wideband FSS is designed with a hexagonal ring unit cell and a dual-FSS array structure to widen its bandwidth. The 3dB bandwidth is from 17.83 to 45.66 GHz, covering the entire K and KA band and the unit periodicity is about λ 0 /5.75 for the lowest passband. The designed FSS features low profile, flat passband, and stable performance regarding incident angle and polarization, providing a practical solution to encrypted wideband satellite communications and radome for radar cross section reduction.

Ultra-wideband frequency selective surface at K and Ka band

The spectral correlation function (SCF) is an efficient tool for analyzing cyclostationary signals In a low signal-to-noise (SNR) conditions, however, the spectral lines associated with the SCF signal chip rate may be corrupted The most general measurements of SCF are based on averaging methods to diminish the effect of noise Here, the noise contribution is discussed and a new method for the estimation of parameters of modulated signals is brought forward

http://ieeexplore.ieee.org/iel5/9738/30721/01422436.pdf

Spectral correlation function in low SNR environment

A generalized method for analysis of antenna near field is presented which relies on both additivity of radiation field of discrete antenna elements and sampling method of an aperture field. It has advantages of implementing easily and saving the computing time and storage. Some results are compared with published data, and the agreement is good. It can be widely used in EMC prediction.

A generalized algorithm for antenna near-field computation in EMC prediction

Near-field scattering measurements research has become popular in recent period. Time domain planar near field scattering measurements can obtain the wideband scattering data in one measurement. This paper concerns simulation of time domain near field scattering measurements. This time domain measuring method is based on plane wave spectrum formulas. The near-field scattering measurement data are transformed to far-field scattering data such as Radar Cross Section (RCS). The formulas of this method, derivation of the formulas, the simulation method, the simulation results and analysis will be presented in this paper.

https://ieeexplore.ieee.org/iel5/6222070/6230122/06230229.pdf

Li Wei-ming

Papers

Accelerating FDTD algorithm using GPU computing

Ultra-wideband frequency selective surface at K and Ka band

Spectral correlation function in low SNR environment

A generalized algorithm for antenna near-field computation in EMC prediction

Time domain planar near field scattering measurements