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A proximity-fed annular slot antenna for UWB applica-tions with a band rejection using different techniques is presented. The proposed antenna provides an UWB performance in the frequency range of &asyum; 2:84 to &asyum; 8:2 GHz with relatively stable radiation parame-ters. Three different techniques to construct a resonant circuit for the proposed antenna are investigated to achieve the band-notch property in the band &asyum; 5:11 to &asyum; 5:69 GHz band which include the WLAN and HIPERLAN/2 services without degrading the UWB performance of the antenna. Three resonators are considered; a single complementary split ring resonator (CSRR), a complementary spiral loop resonator (CSLR) and a spurline slot. Furthermore, the band-notched resonance frequency and the bandwidth can be easily controlled by adjusting the dimensions of the resonator. The proposed antenna is simulated, fab-ricated and measured. The measured data show very good agreements with the simulated results. The proposed antenna provides almost om-nidirectional patterns, relatively flat gain and high radiation effciency over the entire UWB frequency excluding the rejected band.

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A proximity feed ultra-wide band (UWB) patch antenna with four notched bands is presented. The proposed antenna introduces UWB performance in the frequency range of 1.9 GHz to 10.3 GHz with omnidirectional radiation pattern. Slots etching techniques are utilized to provide four bands notches at frequencies of 2.3, 2.8, 3.5, and 5.5 GHz to avoid the interference with the existing wireless networks which occupy bands at these frequencies. Furthermore a curve fitting technique is applied to synthesize an equivalent electric circuit model to the proposed antenna. The analysis and design of the proposed antenna were carried out using the commercially available Ansoft high frequency structure simulator (HFSS). The antenna is fabricated and tested. The measured data of the fabricated antenna demonstrate very good agreement with the simulated results and the equivalent circuit results.

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In this article, an ultrawideband (UWB) antenna with triple band-rejection characteristics is proposed. The antenna is compact with size of 22.5 3 24 mm2. Matching between a sector-disk shaped radiating patch and the 50-X microstrip line is manipulated through a proximity-feed technique. An elliptically-shaped aperture is etched in the ground plane to enhance the antenna bandwidth. Double shunt stubs are used to get more enhancement of the impedance bandwidth of the antenna. The band notches at WiMAX of 3.3–3.9 GHz, lower WLAN of 5.15–5.35 GHz, and upper WLAN of 5.725–5.825 GHz are realized by embedding three elements; a reversed F-shaped slot etched off in the patch, a reversed U-shaped slot etched off in the feed line, and adding a parasitic flipped C-shaped strip around the patch, respectively. The antenna is fabricated and the experimental data show that the designed antenna has an impedance bandwidth of 3.2–11.6 GHz for VSWR less than 2, except at three frequency stop-bands of 3.20–4.19, 5.02–5.32, and 5.51–6.10 GHz. Curve fitting formulations to describe the influences of the embedded structures on the corresponding notched frequencies are obtained by using a second-order polynomial. Moreover, physical lumped elements of an electrical equivalent circuit model of the proposed antenna are obtained using a rational function approximation based on the vector fitting technique. The antenna provides almost omnidirectional patterns, relatively flat gain, and high radiation efficiency over the entire UWB frequency excluding the rejected bands. VC 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:646–654, 2014; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.28149

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Power system frequency deviation is always presented result to the continuous loads variation, thus leading to build the load frequency control (LFC) systems. In this paper, HVDC systems are used to suppression such this frequency oscillations which occur result to load variation between two-area interconnected systems. A comparative evaluation between HVDC and superconducting magnetic energy storage (SMES) are introduced in this paper to make a comparative study between different controllers to improve the dynamic performances of the power system. Two-Area Power system with AC/DC parallel tie lines is simulated and then it is subjected to different disturbances. Responses of frequencies deviation, AC tie line powers deviation and area control errors have been plotted for two areas. The system Dynamic performance using HVDC FACTS Controller is superior with fast response and less overshoot/undershoot.

Power system frequency deviation is always presented result to the continuous loads variation, thus leading to build the load frequency control (LFC) systems. In this paper, HVDC systems are used to suppression such this frequency oscillations which occur result to load variation between two-area interconnected systems. A comparative evaluation between HVDC and superconducting magnetic energy storage (SMES) are introduced in this paper to make a comparative study between different controllers to improve the dynamic performances of the power system. Two-Area Power system with AC/DC parallel tie lines is simulated and then it is subjected to different disturbances. Responses of frequencies deviation, AC tie line powers deviation and area control errors have been plotted for two areas. The system Dynamic performance using HVDC FACTS Controller is superior with fast response and less overshoot/undershoot.