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Distribution by Scientific Domains


Selected Abstracts


A band-notched CPW fed antenna with ring ground for ultra-wideband applications

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2010
Qingxin Guo
Abstract A new CPW-fed antenna with band-notched is proposed for ultra-wideband antenna applications. It consists of a ring strip connecting with two triangle patches as the ground and a rectangular patch connecting with a strip as the radiator and feeding line. A narrow slot is embedded in the radiator to obtain notched-band characteristics within bandwidth of 5,6 GHz. Simulated results gotten by FDTD method are given and compared with the experimental results. Measured results show that the antenna can cover a bandwidth from 2.5 to 10.7 GHz for VSWR < 2 except the notched-band. 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1691,1694, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25333 [source]


Ultra-wideband slot antenna with band-notch characteristics for wireless USB dongle applications

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2009
Deepti Das Krishna
Abstract A compact ultra-wideband (UWB) printed slot antenna is described, suitable for integration with the printed circuit board (PCB) of a wireless, universal, serial-bus dongle. The design comprises of a near-rectangular slot fed by a coplanar waveguide (CPW) printed on a PCB of size 20 30 mm2. It has a large bandwidth covering the 3.1,10.6 GHz UWB band, with omnidirectional radiation patterns. Further, a notched band centered at 5.45 GHz wireless local area network bands is obtained within the wide bandwidth by inserting a narrow slot inside the tuning stub. Details of the antenna design are described, and the experimental results of the constructed prototype are presented. The time domain studies on the antenna shows a linear phase response throughout the band except at the notched frequency. The transient analysis of the antenna indicates very little pulse distortion confirming its suitability for high speed wireless connectivity. 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1500,1504, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24385 [source]


Solving inverse electromagnetic problems using FDTD and gradient-based minimization

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2006
Erik Abenius
Abstract We address time-domain inverse electromagnetic scattering for determining unknown characteristics of an object from observations of the scattered field. Applications include non-destructive characterization of media and optimization of material properties, for example, the design of radar absorbing materials. Another application is model reduction where a detailed model of a complex geometry is reduced to a simplified model. The inverse problem is formulated as an optimal control problem where the cost function to be minimized is the difference between the estimated and observed fields, and the control parameters are the unknown object characteristics. The problem is solved in a deterministic gradient-based optimization algorithm using a parallel 2D FDTD scheme. Highly accurate analytical gradients are computed from the adjoint formulation. The inverse method is applied to the characterization of layered dispersive media and the determination of parameters in subcell models for thin sheets and narrow slots. Copyright 2006 John Wiley & Sons, Ltd. [source]


Compact microstrip low-pass filter using complementary split ring resonators with ultra-wide stopband and high selectivity

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2010
Hui-Yong Zeng
Abstract The transmission characteristic of the microstrip with complementary split ring resonator (CSRR) is researched. Compared with the conventional structure, this filter can achieve a wider bandgap by shifting the gap of CSRR from the side of the microstrip to the underside. And then, a lower transmission zero can be realized by loading a pair of narrow slots in the gap of the ring. The equivalent circuit model of the structure is provided. By cascading CSRR cells with different transmission zeros, a ultra-wide bandgap low-pass filter (LPF), which has a cutoff frequency at 4.3 GHz is designed. The designed LPF has a high performance with an insertion loss lower than 0.3 dB in pass band, a high out-band suppression more than 20 dB (4.55,25 GHz), and a very sharp transition band about 0.25 GHz (4.3,4.55 GHz). 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 430,433, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24942 [source]