In this article, a modified circular ring shaped slot antenna is presented for dual-band wireless applications. Dual frequency bands are achieved by combining the circular ring shaped slot with U-shaped slot. Analysis of proposed radiator has been carried out on HFSS EM simulator. For experimental verification, the prototype of proposed radiator is fabricated and tested. Experimental results confirm that the proposed radiator operates over dual frequency bands, that is, 1.69 to 1.94 GHz and 3.64 to 3.88 GHz with the impedance bandwidth of 14.1% and 6.4%, respectively. Far-field features of proposed radiator are stable and confirm its better performance in between dual frequency range. The proposed antenna can be used for global system for mobile (GSM) (1.8 GHz) and Worldwide Interoperability for Microwave Access (WiMAX) (3.7 GHz) applications. K E Y W O R D S dual-band, GSM, slot antenna, U-shaped slot, WiMAX
In this article, design and analysis of a modified circular slot antenna is discussed. The proposed antenna design is attractive because of two important reasons: (i) modified circular slot creates dual operating bands; (ii) stable radiation characteristics over the operating frequency bands are observed. The complete analysis of proposed radiator has been done on Ansys HFSS simulation software. For verifying the simulated outcomes, a prototype of antenna structure is fabricated and tested. Measured results show that the proposed antenna operates over two frequency bands, i.e., 2.88-3.92 GHz and 5.26-6.28 GHz with the fractional bandwidths of 31% and 17% respectively. Experimentally measured average gain of the proposed radiator is 3 dBi and 6 dBi in lower and upper frequency bands, respectively. All these features of the proposed antenna make it appropriate for WiMAX (3.5 GHz) and WLAN (5.8 GHz) applications.
This paper presented comprehensive study with performance analysis of very recent Wavelet transform based image compression techniques. Image compression is one of the necessities for such communication. The goals of image compression are to minimize the storage requirement and communication bandwidth. Compression is achieved by the removal of redundant data. Discrete Wavelet Transform (DWT) is a recently developed compression technique in image compression. DWT image compression includes decomposition (transform of image), Detail coefficients thresholding, and entropy encoding. This paper mainly describes the transform of an image using DWT and thresholding techniques. In this paper we have taken the standard image Lena of size 256X256 of 8 bit depth and applied DWT (haar). Then two results set are obtained by applying two different techniques of thresholding and then compare the result.Keywords: Discrete Cosine Transform, Wavelet Transform, JPEG Compression and Entropy Encoding
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