Non-peaky signals in wideband fading channels: achievable bit rates and optimal bandwidth

In the context of fading channels it is well established that, with a constrained transmit power, the bit rates achievable by signals that are not peaky vanish as the bandwidth grows without bound. Stepping back from the limit, we characterize the highest bit rate achievable by such non-peaky signals and the approximate bandwidth where that apex occurs. As it turns out, the gap between the highest rate achievable without peakedness and the infinite-bandwidth capacity (with unconstrained peakedness) is small for virtually all settings of interest to wireless communications. Thus, although strictly achieving capacity in wideband fading channels does require signal peakedness, bit rates not far from capacity can be achieved with conventional signaling formats that do not exhibit the serious practical drawbacks associated with peakedness. In addition, we show that the asymptotic decay of bit rate in the absence of peakedness usually takes hold at bandwidths so large that wideband fading models are called into question. Rather, ultrawideband models ought to be used.

Wideband dual sphere detector of gravitational waves

We present the concept of a sensitive and broadband resonant mass gravitational wave detector. A massive sphere is suspended inside a second hollow one. Short, high-finesse Fabry-Perot optical cavities read out the differential displacements of the two spheres as their quadrupole modes are excited. At cryogenic temperatures, one approaches the standard quantum limit for broadband operation with reasonable choices for the cavity finesses and the intracavity light power. A molybdenum detector, of overall size of 2 m, would reach spectral strain sensitivities of 2x10-23Hz-1/2 between 1000 and 3000 Hz.

On wideband deconvolution using wavelet transform

A discussion on the expression proposed in [1]–[3]for deconvolving the wideband density function is presented. Weprove here that such an expression reduces to be proportionalto the wideband correlation receiver output, or continuous wavelettransform of the received signal with respect to the transmittedone. Moreover, we show that the same result has been implicitlyassumed in [1], when the deconvolution equation is derived. Westress the fact that the analyzed approach is just the orthogonalprojection of the density function onto the image of the wavelettransform with respect to the transmitted signal. Consequently,the approach can be considered a good representation of thedensity function only under the prior knowledge that the densityfunction belongs to such a subspace. The choice of the transmittedsignal is thus crucial to this approach.

Suitability of Ultra Wideband for Mobile Devices

Mobiililaitteet ovat kehittyneet merkittävästi viimeisen vuosikymmenen aikana. Ne eivät enää ole pelkästään puhelimia tai kämmentietokoneita, vaan multimediatietokoneita, jotka pystyvät tuottamaan korkealaatuisia elämyksiä käyttäjälleen.Sisällön laadun paraneminen johtaa väistämättä myös siirrettävän tietomäärän kasvamiseen. Siksi uusia, nopeampia tiedonsiirtomenetelmiä on otettava käyttöön. Ultra Wideband (UWB) on uusi radioaaltotekniikka, jokamahdollistaa korkeat tiedonsiirtonopeudet lyhyillä etäisyyksillä. Tekniikka operoi erittäin leveällä 3.1 - 10.6 gigahertsin taajuuskaistalla.UWB on suunnattu nopeaan, langattomaan tiedonsiirtoon personal area networkin (PAN) laitteiden välillä. Tämän diplomityön tarkoituksena on arvioida UWBn soveltuvuutta mobiililaitteisiin. Arviointi tehdään teoreettiselta pohjalta, sillä UWBtä ei vielä ole implementoitu kaupallisiin laitteisiin. Ensin esitellään UWBn tekniikka ja ominaisuudet, jonka jälkeen sen soveltuvuutta arvioidaan esimerkkikäyttötapausten valossa. Esimerkkikäyttötapauksiksi on valittu kolme tyypillistä mutta erilaista toimintoa, jotka mahdollisimman hyvin kuvaavat mobiililaitteiden käyttöä.

Wideband trapezoidal strip grating for elimination of specular reflection

A trapezoidal strip grating surface that eliminates specular reflections almost over the entire X -band frequency range for TM polarization is reported This new grating structure overcomes the bandwidth limitation of conventional rectangular strip grating surfaces

Compact Wideband Antenna for 2.4 GHz WLAN Applications

A novel compact wideband antenna for wireless local area network (WLAN) applications in the 2.4 GHz band are presented. The proposed low profile antenna of dimensions 15 x 14.5 x 1.6 mm offers 18.6% bandwidth and an average gain of~5 dBi. The antenna can be excited directly using a 50 coaxial probe

A Wideband Rectangular Microstrip Antenna Using an Asymmetric t-shaped Feed

An electromagnetically coupled T-shaped microstrip feed used to enhance the impedance bandwidth of a rectangular microstrip antenna is reported. The proposed antenna offers a 2:1 VSWR bandwidth of -36% with an increase in gain of 0.8 dB

FDTD analysis of a symmetric T-strip fed wideband rectangular microstrip antenna

A theoretical analysis of a symmetric T-shaped rnicrostripfed rectangular microstrip antenna using the finite-difference titnedoniain (FDTD) method is presented in this paper. The resonant frequency, return loss, impedance bandwidth, and radiation patterns are predicted and are in good agreement with the measured results

L-strip excited wideband rectangular microstrip antenna

This paper presents the outcome of the experimental studies performed on L-strip fed compact rectangular microstrip antenna. The effect of the feed parameters upon the characteristics of the antenna is studied in detail. The antenna offers an impedance bandwidth of nearly 20% and is suitable for broadband applications

Wideband Oylindrioal Dielectric Resonator Antenna Excited Using an L-strip Feed

A broadband cylindrical dielectric resonator antenna (DRA) energized with an L-strip feed is presented The novel exciting technique achieves a 2:1 VSWR bandwidth of 18%. The variation of bandwidth for different feed parameters is also studied

Wideband Microstrip Antenna Using Hook-Shaped Feed

In this paper, we introduce a novel feeding technique for bandwidth enhancement of a rectangular microstrip antenna This antenna offers an impedance bandwidth of 22% without degrading the effciencv. The effect of the feed parameters upon patch characteristics such as resonant frequency, impedance bandwidth, and radiation pattern are studied in detail. The experimental results are verified using the FDTD results

L-strip-fed Wideband Rectangular Dielectric Resonator Antenna

In this paper, the advantages of using L-shaped microviij) feed to e.tcite a rectangular dielectric resonator cuuenna (DRA) by elemanagnetic coupling are presented. This feeding technique enhances the hardsvidth and gain of the antenna without affecting its size. The experimental re srdts are validated using Fidelity software based on the finitedifference tine-domain (FDTD) method

Compact Wideband Antenna for 2.4 GHz WLAN Applications

A novel compact wideband antenna for wireless local area network (WLAN) applications in the 2.4 GHz band is presented. The proposed low profile antenna of dimensions 15 x 14.5 x 1.6 mm offers 18.6% bandwidth and an average gain of -5 dBi. The antenna can be excited directly using a 50 coaxial probe

Compact asymmetric coplanar strip-fed antenna for wideband applications

An asymmetric coplanar strip-fed uniplanar antenna for wideband applications is presented. The resulting antenna offers a 2:1 VSWR bandwidth greater than 100% from 1.58 to 5.48 GHz covering the DCS/PCS/IEEE 802.11a/WiMAX bands. The antenna has an overall dimension of 44 × 35 mm2 when printed on a substrate of dielectric constant 4.4 and height 1.6 mm. The design equation is also presented in this article. The antenna exhibits good radiation characteristics and moderate gain in the entire operating band.