Backscattering enhancement phenomenon has attracted considerable attention from radar engineering and remote sensing fields. This paper investigates the phenomenon by analyzing numerically the bistatic radar cross-section (RCS) of a conducting circular cylinder embedded in a continuous random medium. The RCSs of different size cylinders are depicted by changing the fluctuation intensity and thickness of the random medium. As a result, strong backscattering-enhancement and oscillation in the neighborhood of the backward direction are observed for a wavelength-size cylinder embedded in a strong random medium.
This letter introduces a lossless reversible data hiding method. The original image is recovered without any distortion from the marked image following the extraction of the hidden data. The main algorithm is based on the relocation of zeros (or minima) and peaks of the histograms of the blocks of the original image to embed the data. It leads to the modification of the grey values of some pixels. It can embed more data than many of the existing reversible data hiding algorithms. The PSNR of the proposed method is better than many of the existing reversible data hiding techniques. Some of the huge experimental results are presented to prove its validity.
This paper presents a compact planar lowpass filter with super ultra-wideband (sUWB) passband and stopband for future possible sUWB radio system. The filter employs radial stubs to realize such sUWB passband and stopband and a sharp filter skirt performance. Design of the filter was based on electromagnetic simulation. The measured results of a 4-stage filter demonstrated the excellent filter performance: sUWB passband from DC to 22GHz with low insertion loss about 0.5dB at central frequency; sUWB stopband from 23 to 50GHz with attenuation larger than 35dB, which is the widest lowpass filter with widest stopband in the world, to the authors' best knowledge. The group delay over the passband is about 0.20ns and very flat. An sUWB bandpass filter with excellent bandpass and bandstop performance was also achieved and presented by integrating the developed sUWB losspass filter and an sUWB bandpass filter using broadside-coupled structure.
The diversity performance of the modurated scattering array antenna (MSAA) with various array spacing is measured in Rayleigh fading environment to investigate experimentally the relation between the array spacing and the diversity performance of the MSAA. A 2-element modulated scattering monopole array antenna with various array spacing which is supposed to be used for mobile handset applications is used as the measurement model. It is found that the diversity performance of the MSAA can be improved by reducing the array spacing as small as about 0.2 wavelength.
This letter proposes a method for active noise control (ANC) systems with online acoustic feedback neutralization. The proposed method is a modified version of authors' previous work, and the objective here is to reduce the computational complexity. This is achieved by combining the role of feedback path modeling and neutralization filters. The computer simulations are carried out which demonstrate that the proposed method achieves better performance than the existing methods and at somewhat reduced computational cost.
This article presents an ultra-wideband(UWB) bandpass filter which used shunt stub with lumped capacitor. Results from transmission line theory and experiments confirmed that a shunt stub with a capacitor can realize a large separation between the first and second resonant frequencies, which then results in a wide passband and compactness. The developed filter has excellent performance: insertion loss of 0.26dB at the central frequency; group delay about 0.13ns; and almost meet the requirement of FCC's UWB spectrum mask except for the band below 2GHz; and compact size of 2cm × 2.5cm.