In this paper, we quantify the temporal opportunities for secondary access to radar spectrum. Secondary users are assumed to be WLANs which opportunistically share the radar frequency band under the constraint that the aggregate interference does not harm radar operation. Each WLAN device employs dynamic frequency selection (DFS) as a mechanis m to protect the radar from the interference. We al...

Due to insufficient Radio Navigation Satellite Service (RNSS) portion of Radio Frequency (RF) spectrum for many services that are being planned for the future on L band where has come up a frequency overlapping situation, C band as an alternative spectral allocation has already been proposed in the previous years. The future C band signals could make use of the frequency band between 5010MHz an...

In this Modernistic World folks want everything compact and mobile. As the wireless devices dominate the market, the necessity of wireless network and wireless communication has been increased. The Regulations of FCC (Federal Communications Commission) allocates 2.4 GHz to ISM band. It is used by major part of the population because technologies like Zigbee, Bluetooth, Wi-Fi/802.11 and etc use ...

Anharmonic effects of the absorption and fluorescence spectra of pyridine molecule are studied and analyzed for the two-low lying singlet excited states S(1)((1)B(1)) and S(2)((1)B(2)). The complete active space self-consistent field (CASSCF) method is utilized to compute equilibrium geometries and all 27 vibrational normal-mode frequencies for the ground state and the two excited states. The p...

In Cognitive Radio Networks (CRNs); the unlicensed users named Secondary Users (SUs) are allowed to share the licensed wireless spectrum band with its licensed users name Primary Users (PUs) but without degradation in the PU's Quality of Service (QoS). As all the SUs have the same priority to access the licensed spectrum band; a spectrum sharing protocol is needed to fairly divide the available...

L-band active microwave remote sensing is one of the most important technical methods of ocean environmental monitoring and dynamic parameter retrieval. Recently, a unique negative upwind-crosswind (NUC) asymmetry of L-band ocean backscatter over a low wind speed range was observed. To study the directional features of L-band ocean surface backscattering, a new directional spectrum model is pro...

We present what is to our knowledge the first dual-band negative index metamaterial that operates in the visible spectrum. The optimized four-functional-layer metamaterial structure exhibits the first double-negative (i.e., simultaneously negative permittivity and permeability) band in the red region of the visible spectrum with a figure of merit of 1.7 and the second double-negative band in th...

An important problem in processing multispectral / hyperspectral imagery consists in the design of methods for the detection of targets. In this paper we investigate a class of detection filters based on band and spectral selection. Band selection (band screening) refers to searching for the spectral bands that would yield the largest separation between target and background. Spectral selection...

Waves in periodic media undergo multiple scattering and interference. As a result, their frequency spectrum is divided into bands in which waves pass freely, and gaps in which waves cannot propagate. This band diagram depends on the physical and geometrical properties of the periodic cell, through a dispersion relation. Using a new representation of the dispersion relation of laminates, we show...