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An antenna exhibiting a very wide bandwidth with reconfigurable rejection within the band is presented. The proposed topology is versatile in terms of the number of available antenna states and location of the rejection frequencies, and also allows the ope ...
Institute of Electrical and Electronics Engineers2010
The effect of substrate permittivity on UWB antenna radiation is studied. Microstrip and CPW-fed UWB monopoles are designed using substrates with different dielectric constants. The radiation patterns are measured. The transfer function of a two identical ...
Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2009
This paper presents the design and implementation of a circularly polarized stacked patch antenna element for Ka-band applications. The printed element has been developed to be used in a LEO satellite antenna array. Two circular stacked patches, with air g ...
Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011
A theoretical approach based on coupled-mode theory is presented in order to determine the radiation pattern of LEDs incorporating a shallow photonic crystal. From this, a fundamental limit for the directionality of the diffraction of a single guided mode ...
This letter presents a Vivaldi antenna having the capability of dynamically rejecting interferers, mainly aiming at multistandard communication with dynamic frequencies allocation. Only half of the Vivaldi is used and placed over a ground plane, which is s ...
Institute of Electrical and Electronics Engineers2011
We report on the growth by metalorganic vapor phase epitaxy of a InGaN/GaN resonant-cavity light emitting diode (RCLED) emitting at 454 nm and incorporating a 12-pair Al0.82In0.18N/GaN distributed Bragg reflector as bottom mirror. A(1-x)In(x)N layers with ...
The application of the reconfigurable reflectarray structure to software-defined and cognitive radio is discussed for the first time. The main idea is that the reflectarray has the potential-in addition to dynamical beamforming-of simultaneous frequency an ...
IEEE Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, NJ 08855-1331 USA2010
Motivated by the fabrication potential of multi-walled carbon nanotube structures, we numerically investigated a paired structure consisting of two metallic spheres each grown on one end of a multi-walled nanotube. The paired two-segmented structure is cap ...
This paper is intended for teachers and students dealing with antenna engineering. Graphical tools have historically been used for illustrating many basic features of radiation patterns, such as the position and number of secondary lobes, null angles, and ...
Institute of Electrical and Electronics Engineers2011
Various practical applications of the average (A) and difference (D) of Friedel opposites are described. Techniques based on the resonant-scattering contribution to Friedel differences are applied to see whether a crystal is centrosymmetric or not, and to ...
