Image denoising method based on sparse decomposition means the useful information in the image is taken as the sparse component and noises in the image as the residuals after the removal of sparse component, which is the basis for image denoising. In this paper, a new image denoising algorithm using the gradient matching pursuit is proposed based on the study of image sparse decomposition. It firstly constructs an over complete atomic library in the image, then the optimal atom is found by the sparse decomposition method with gradient tracking. At last reconstruct the image with using the optimal atomic. The simulation results show that the convergence of the improved algorithm is fast and stable, and it can effectively eliminate the noise.

Abstract-A printed ultra-wideband (UWB) monopole antenna with both tunable and switchable band-notched characteristics is proposed. An embedded resonant slot loaded with a varactor and a pin diode controlled by DC signal through one common bias network is employed to tune and switch the notch band. In the "all-pass" state when the two diodes are partially turned on, the power consumption of this active antenna is only 2.4 µW. Measured return loss, radiation pattern, gain and group delay of the introduced antenna are presented in this paper.

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Abstract-A quarter-wavelength folded patch antenna is adopted as the passive wireless strain sensor for structural health monitoring (SHM) of bridges. It can be used for continuous surveillance and damage detection. According to theoretical formulations, strain simulation and experiments, it is found that a good linearity relationship can be achieved between normalized resonance frequency shift and the strain both in longitudinal and transverse directions. And the sensing sensitivity in longitudinal strain is better than that in transverse strain. Through conducting tensile experiments, we find that many factors can influence the strain sensitivity. To address this fundamental issue in antenna sensors for strain sensing, a new strain sensitivity experiment is proposed to take the influence of strain transfer ratio change under strain. The linear relationship of strain transfer ratio and deformation is obtained by sensitivity experiment. The corrected sensitivity in longitudinal and transverse strains is calculated based on the linearity. Furthermore, the Possion effect is taken into consideration to explain the opposite effects of experimental and simulated sensitivities in transverse strain.