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Topic: Dipole

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  Search Results for "dipole"
Not characterized by a dipole: a nonpolar covalent bond.
...An arrangement of dipoles on a radar antenna, in which the phase of each dipole is controlled by a computer so that the beam can scan very rapidly....
Chemistry Relating to or characterized by a dipole: a polar molecule.
www.bartleby.com /cgi-bin/texis/webinator/sitesearch?FILTER=col61&x=10&y=12&query=dipole   (285 words)

  Dipole antenna :: Radio-Electronics.Com
The length of a dipole is the main determining factor for the operating frequency of the dipole antenna.
For a half wave dipole the length for a wave travelling in free space is calculated and this is multiplied by a factor "A".
Typically it is between 0.96 and 0.98 and is mainly dependent upon the ratio of the length of the antenna to the thickness of the wire or tube used as the element.
www.radio-electronics.com /info/antennas/dipole/dipole.php   (893 words)

A dipole is a pair of electric charges or magnetic poles of equal magnitude but opposite polarity, separated by some (usually small) distance.
Dipoles can be characterized by their dipole moment, a vector quantity with a magnitude equal to the product of the charge or magnetic strength of one of the poles and the distance separating the two poles.
The direction of the dipole moment corresponds to the direction from the negative to the positive charge or from the south to the north pole.
www.ebroadcast.com.au /lookup/encyclopedia/di/Dipole.html   (479 words)

 MRSEC | A Permanent Dipole Moment in Nanocrystals:
Dipole moments in crystals are more complicated than those found in diatomic molecules, but the concept is the same.
If the oscillation is slow, the dipoles (imagine a + and - charge on opposite sides of the nanocrystal) line up with + charge towards the - plate and the - charge towards the positive plate.
The dipole moment of all of the nanocrystals is measured as the magnitude of the change of voltage.
mrsec.uchicago.edu /research/nuggets/dipole   (1105 words)

 Dipole impedances
The results are presented in the form of three red impedance curves plotted on a Smith chart, which is centred on the 200 ohms transmission line impedance formed from transforming the 50 ohm coaxial feeder impedance with a balun.
In a single lambda/4 rod (one rod of the two forming the dipole) the current is maximum at the feed point, then decays co-sinusoidally to zero at the end.
In the case of the folded dipole, with a conductor bridge at the fold end, the two parallel conductors (closely spaced) form a parallel wire transmission line, of length lambda/4, and shorted at the fold.
www.ee.surrey.ac.uk /Personal/D.Jefferies/rodres.html   (855 words)

 Dipole Bound Anions   (Site not responding. Last check: 2007-11-07)
Dipole bound anions, formed by electron addition to closed-shell neutral polar molecules, are unstable relative to autodetachment unless the dipole moment strength is sufficiently large.
In this case, Dc depends on the dipole length, the rotational state and the moments of inertia of the polar molecules.
Formation of a dipole bound anion has been difficult to observe experimentally for the very diffuse and loosely bound electrons are easily stripped away by thermal collisional processes and/or by the electric fields to which they are exposed in mass analyzers.
www.sc.ehu.es /powgep99/dcytp/teoricos/research/dipole.htm   (351 words)

 dipole antenna - a definition from Whatis.com
A dipole antenna is a straight electrical conductor measuring 1/2 wavelength from end to end and connected at the center to a radio-frequency (RF) feed line.
The polarization of the electromagnetic field (EM) radiated by a dipole transmitting antenna corresponds to the orientation of the element.
The RF current in a dipole is maximum at the center (the point where the feed line joins the element), and is minimum at the ends of the element.
whatis.techtarget.com /definition/0,,sid9_gci214149,00.html   (319 words)

 Halfwave Dipole - N2UHC's Radio Stuff
A dipole basically consists of two lengths of wire connected end-to-end with a connection to a feedline in the middle.
The dipole is fed with either twinlead feedline or coaxial cable.
One last thing to note is that a dipole cut for the 80 meter ham band can, with a tuner, operate on the 40, 20, and 10 meter ham bands with good results.
www.geocities.com /n2uhc/dipole.html   (635 words)

 The Subwoofer DIY Page v1.1 - Dipole Bass Systems   (Site not responding. Last check: 2007-11-07)
However, for dipole bass systems, the rear radiation is left untreated, and instead the overall response of the system is adjusted by varying the size of the baffle and the "Q" of the system to achieve the best overall response characteristics.
This response characteristic is said to be one of the major advantages of a dipole bass system, as the restricted dispersion results in fewer boundary reflections, which in turn is supposed to result in a smoother in-room response.
Dipole bass systems tend to be rather large, employing multiple drivers, primarily to make up for the output reduction due to the 6dB/oct baffle loss.
www.diysubwoofers.org /dipole   (740 words)

 The Tom Bearden Website
In other words, the charges of the dipole continually absorb virtual photons from the seething vacuum (that is proven and well-known, and one does not have to prove it again).
The dipoles in the original matter in the universe have been doing that for some 14 billion years or so.
In solving the dipole and source charge problems, it was found that the energy input comes from the time domain into 3-space via the negative charge, and exits 3-space back to the time domain via the positive charge.
www.cheniere.org /correspondence/022502.htm   (1090 words)

 Using cryo-EM to measure the dipole potential of a lipid membrane -- Wang et al. 103 (49): 18528 Data Supplement - HTML ...
Using cryo-EM to measure the dipole potential of a lipid membrane -- Wang et al.
The resulting mean dipole potential is shown as a function of the perturbation.
In the simulations the peak dipole potentials were underestimated by 30 and 80 mV, respectively, in these two cases.
www.pnas.org /cgi/content/full/0608714103/DC1   (466 words)

 Dipole Approximation
Within the dipole approximation, the differential cross section (cross section per unit solid angle) for angle-resolved photoemission with linearly polarized x rays is described by three quantities: the partial cross section, s(hn), the angular-distribution parameter, b(hn), and the angle (q) of the photoelectron trajectory relative to the polarization vector.
In the dipole approximation, a single term describes electron angular distributions as a function of the angle q relative to the polarization, E, of the radiation.
The complex angular dependence of the differential cross section means that which corrections to the dipole approximation are needed depends on the experimental geometry, but the new results demonstrate that researchers need to be ready to include nondipole effects through at least the second order in analyzing their results.
www-als.lbl.gov /als/science/sci_archive/dipole_approx.html   (976 words)

 Dipole Summary   (Site not responding. Last check: 2007-11-07)
The dipole moment is equal to the magnitude of the equal and opposite charges multiplied by the distance between the centers of the charge distributions.
For magnetic dipoles, the dipole moment points from the magnetic south to the magnetic north pole — confusingly, the "north" and "south" convention for magnetic dipoles is the opposite of that used to describe the Earth's geographic and magnetic poles, so that the Earth's geomagnetic north pole is the south pole of its dipole moment.
Although there are no known magnetic monopoles in nature, there are magnetic dipoles in the form of the quantum-mechanical spin associated with particles such as electrons (although the accurate description of such effects falls outside of classical electromagnetism).
www.bookrags.com /Dipole   (2186 words)

 Welcome to the Folded Dipole Page
Having a folded dipole does not mean that you have an antenna that is folded in half and so you obtain an antenna that now takes up half the space of a regular dipole.
If the power to a regular dipole antenna was 100 watts and the current was 1.2 amps, we'd solve for R as R = 100 / (1.2*1.2), which is the same as R = 100 / 1.44, which is 69.44 ohms.
In the folded dipole the wires are in parallel, the current must be divided between the two wires.
www.qsl.net /w4sat/fdipole.htm   (696 words)

 Molecules test electron dipole - Physics World - physicsworld.com
The electron’s electric dipole moment is a measure of the average distance of charge from the electron’s centre of mass.
The dipole moment is parallel to the direction in which the electron spins because any other component of charge distribution would be averaged to zero by the motion of the spin.
Measurements of the electric dipole moment exploit the tendency of the dipole moment to align itself with an applied electric field and cause the spin of the electron to precess like a gyroscope.
www.physicsweb.org /article/news/6/2/13   (572 words)

 Levitated Dipole Experiment
LDX is a novel experimental device designed to explore the physics of plasma confinement in a magnetic dipole field.
LDX is a collaboration between Columbia University's Dept. of Applied Physics and the MIT Plasma Science and Fusion Center and is funded by the Department of Energy's Office of Fusion Energy.
Explore a the workings of the Levitated Dipole Experiment through this presentation of the planned daily operation of the experiment.
www.psfc.mit.edu /ldx   (251 words)

 Dipole Height
One may argue that 560 feet is ridiculous for a 40 meter dipole, but keep in mind that the data can be scaled down to a 10 meter dipole with similar results.
Once the dipole is lowered to 0.3 wavelengths, most of the radiation goes in a vertical direction.
One frequently sees a dipole azimuth pattern depicting a very sharp null off of the ends of a dipole.
www.qsl.net /aa3rl/ant2.html   (1285 words)

 Atom Voyages | Making a Dipole Antenna   (Site not responding. Last check: 2007-11-07)
The final limitation of the dipole is that its overall length, and therefore its frequency range, is restricted by the height of your mast.
Tie the mainsail halyard or boom topping lift to the end of the dipole wire that is connected to the coax core and hoist the dipole temporarily into position.
If you want to use the dipole on frequency bands other than the one it was cut for, you can connect the center pin of the dipole's coax connector to the tuner, leave the shield disconnected, and run it as you would a standard backstay antenna.
www.atomvoyages.com /projects/dipole.htm   (2958 words)

 Background: Dipole approximations of the geomagnetic field
Because of the displacement of the eccentric pole away from the Earth's centre the eccentric dipole axis and associated magnetic field, in particular, are not perpendicular to the surface at the axial poles.
The axis of the eccentric dipole is parallel to the centred dipole axis.
They are separated from their corresponding eccentric dipole axial poles by small angular distances along the great circle, with the direction of the separition being away from the local centric dipole pole (All centred and eccentric poles lie on the same great circle).
www.spenvis.oma.be /spenvis/help/background/magfield/cd.html   (1953 words)

 Molecular Dipole Moments
Even if there is no permanent dipole moment, it is possible to induce a dipole moment by the application of an external electric field.
This is called polarization and the magnitude of the dipole moment induced is a measure of the polarizability of the molecular species.
The dipole moment of water provides a "handle" for interaction with microwave electric fields in a microwave oven.
hyperphysics.phy-astr.gsu.edu /hbase/electric/diph2o.html   (386 words)

 Why is the sky blue?   (Site not responding. Last check: 2007-11-07)
If the dipole is not changing, then at large distances, the scalar potential due to one end of the dipole and the scalar potential due to the other end will tend to cancel each other out, since the distance to the two charges is almost the same.
If the dipole is much smaller than the wavelength of the light (and air molecules are thousands of times smaller than the wavelengths of visible light), the cancellation becomes linearly less complete as the frequency of the oscillation increases.
If the dipole is a molecular dipole created by an electromagnetic wave from the sun impinging on an air molecule, then it is the higher frequencies that will be primarily scattered in different directions, and removed from the incoming wave.
world.std.com /~mmcirvin/bluesky.html   (2093 words)

 Dipole Woofer
The 16" cabinet width is the result of the driver dimensions and an effort to minimize the overall size of the dipole woofer.
The direction of cone movement is such that mechanical forces cancel and only a minimum of vibration is transferred to the cabinet's outside surfaces for possible re-radiation.
Force cancellation is important because of the large cone excursions necessary for dipole operation and the associated large reaction forces.
www.linkwitzlab.com /woofer.htm   (630 words)

Additional conductors are mounted parallel to the dipole elements at a distance
folded dipole, the increase of impedance is the square of the number of conductors used in the radiator.
radii, as shown in view B. The directional characteristics of a folded dipole are the same as those of a simple dipole.
www.tpub.com /content/neets/14182/css/14182_190.htm   (264 words)

Each half of each dipole will be connected to the coax center pigtail and the shield separately.
All dipole ends at center insulator are connected together.
Since the resonant length of a given element in the presence of the others is not the same as a dipole by itself, tuning can be a tedious and difficult procedure.
www.hamuniverse.com /multidipole.html   (1152 words)

 Fan Dipole
One used five separate dipoles all cut to the same length and spread apart in a fan, and another with five dipoles all cut to slightly different lengths and arranged in a fan.
An issue or two before that Art Collins' version of the fan dipole was published with two pairs of dipoles connected at the feedpoint, with graduated spreaders leading to around 12 feet of separation at the closed ends.
Calling one dipole a fan because its elements are all within one amateur band, and another something else because its are not, is just trying to elevate one's own preference to the level of linguistic law.
www.eham.net /articles/7154   (4435 words)

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