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Topic: Dielectric constant

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Dielectric

Dielectric strength

Dielectric waveguide

Permittivity

Capacitor

Capacitance

PWB

Dipole

Free will

Insulator

Arrhenius equation

Jordan curve

Adsorption

Plastic

Wavelength

	Dielectric constant - Wikipedia, the free encyclopedia
		Electrically, the dielectric constant is a measure of the extent to which a substance concentrates the electrostatic lines of flux.
		For time-varying electromagnetic fields, the dielectric constant of materials becomes frequency dependent and in general is called permittivity.
		The dielectric constant is an essential piece of information when designing capacitors, and in other circumstances where a material might be expected to introduce capacitance into a circuit.
	en.wikipedia.org /wiki/Dielectric_constant (533 words)

	Dielectric - Wikipedia, the free encyclopedia
		A dielectric, or electrical insulator, is a substance that is highly resistant to flow of electric current.
		Dielectrics are more resistant to ionization than air, so a capacitor containing a dielectric can be subjected to a higher voltage.
		Layers of dielectric are commonly incorporated in manufactured capacitors to improve their performance above that of capacitors with only air or a vacuum between their plates, and the term dielectric refers to this application as well as the insulation used in power and RF cables.
	en.wikipedia.org /wiki/Dielectric (401 words)

	Dielectric constant -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-20)
		Dielectrics are usually (A material such as glass or porcelain with negligible electrical or thermal conductivity) insulators.
		The dielectric constant is an essential piece of information when designing (An electrical device characterized by its capacity to store an electric charge) capacitors, and in other circumstances where a material might be expected to introduce (An electrical phenomenon whereby an electric charge is stored) capacitance into a circuit.
		Dielectric waveguides are seldom used because the dielectric losses for all known dielectric materials are too great to transfer the electric and magnetic fields efficiently, however they can have specialty applications such as forming filters.
	www.absoluteastronomy.com /encyclopedia/d/di/dielectric_constant.htm (673 words)

	Dielectrics (Site not responding. Last check: 2007-10-20)
		The dielectric is characterized by a dielectric constant k, and the capacitance is multiplied by that factor.
		When a dielectric is placed between charged plates, the polarization of the medium produces an electric field opposing the field of the charges on the plate.
		The permittivity is a characteristic of space, and the relative permittivity or "dielectric constant" is a way to characterize the reduction in effective field because of the polarization of the dielectric.
	hyperphysics.phy-astr.gsu.edu /hbase/electric/dielec.html (219 words)

	Untitled Document
		Dielectric constant is often indicated by the symbol K and always has a value greater than 1.0.
		Metalized dielectrics however have a higher K due to the air that is eliminated on one side of the film by the bond of the metalized layer and the film.
		Dielectric films are classed as being either polar, where the molecular dipoles rotate and align themselves with the applied field, or as non-polar, where the materials do not rotate and align themselves.
	www.bishopelectronics.com /gi_general_terms.html (707 words)

	Emerson Process Management - CSI (Site not responding. Last check: 2007-10-20)
		A dielectric constant is a measure of the interaction of an oscillating electric field (an electric field that oscillates between positive and negative at a certain AC frequency) with a molecule.
		The dielectric constant is (partly) a measure of the forces between molecules that must be overcome by heat.
		Thus the dielectric constant is a direct result of the polarizability and dipole moment of a molecule.
	www.compsys.com /DRKNOW/APLPAPR.NSF/19fcc759cbee3c3c8525659800528caa/e6a75239e808a779852565a200646913?OpenDocument (1223 words)

	On Capacitor Dielectric Materials (Site not responding. Last check: 2007-10-20)
		The proportionality constant relating each material's capacitance enhancement over that of a vacuum is known as its "dielectric constant." The dielectric constant is a measure of the extent to which the insulating material's surface interacts with the electric field set up between the charged plates.
		The constant is dependent on two molecular level properties: the permanent "dipole moment" and the "polarizability" or the induced change in dipole moment due to the presence of an electric field.
		The residual charge from dielectric relaxation is known as the "dielectric absorption." When an audio signal is passed through a capacitor the dielectric absorption prevents full charging and discharging of the capacitor at the frequency of the alternating current signal.
	www.audience-av.com /on_capacitor_dielectric_material.htm (1551 words)

	dielectric on Encyclopedia.com
		Generally, the dielectric constant of air is defined as 1 and other dielectric constants are determined with reference to it.
		Other properties of interest in a dielectric are dielectric strength, a measure of the maximum voltage it can sustain without significant conduction, and the degree to which it is free from power losses.
		Dielectric constant of Turkish timbers in the longitudinal direction at a 9.8-GHz frequency.
	www.encyclopedia.com /html/d1/dielectr.asp (523 words)

	MTI-Measuring Thickness of Nonconductive,Dielectric Materials (Site not responding. Last check: 2007-10-20)
		If the dielectric constant of the material to be measured is unknown, or cannot be determined by contacting the manufacturer or referring to handbook references, then there are two methods to measure it using the Accumeasure equipment.
		If the dielectric constant is unknown or uncertain, then it can be measured with the Accumeasure equipment by placing a sample of the material in the operating gap and then adjusting the gap until the test material completely fills the gap.
		Most gases have a dielectric constant very close to 1.000 and therefore have little effect on the output signal of a capacitance probe when operated as a displacement sensor relative to a conductive target.
	www.mtiinstruments.com /gaging/appnotes-aci_doc.html (1598 words)

	Dielectric Loss Tangents
		The dielectric loss tangent is about 0.01 (although it isn't constant with frequency so manufacturers typically specify a worst-case value of 0.02), and the dielectric constant deteriorates from about 4.7 at 1KHz, to 4.5 at 1 MHz, to 4.3 at 1 GHz.
		Because, for good dielectrics, the dielectric constant is such a slowly moving function of frequency we generally assume it's just constant over the band of interest.
		Dielectric losses are discussed in a general way on page 159 of "High-Speed Digital Design", but not incorporated into any of the models in the back of the book.
	www.sigcon.com /Pubs/news/4_5.htm (972 words)

	dielectric material - a Whatis.com definition - see also: dielectric (Site not responding. Last check: 2007-10-20)
		A dielectric material is a substance that is a poor conductor of electricity, but an efficient supporter of electrostatic fields.
		An important property of a dielectric is its ability to support an electrostatic field while dissipating minimal energy in the form of heat.
		Another consideration is the dielectric constant, the extent to which a substance concentrates the electrostatic lines of flux.
	whatis.techtarget.com /definition/0,,sid9_gci211945,00.html (381 words)

	Dielectric constant (from industrial glass) -- Encyclopædia Britannica
		The dielectric, or nonconducting, property of glass is important for its use either as a medium separating the plates of a capacitor or as a substrate in integrated circuits.
		For capacitor usage, the dielectric constant must be high, whereas for substrates it must be low enough to allow high signal speeds between semiconductor chips.
		When dielectrics are placed in an electric field, practically no current flows in them because, unlike metals, they have no loosely bound, or free, electrons that may drift through the material.
	www.britannica.com /eb/article?tocId=76328 (844 words)

	Dielectric Constant and Relaxation Time of Asphalt Pavement Materials (Site not responding. Last check: 2007-10-20)
		The static dielectric constant and relaxation time of two asphalt aggregate mixes commonly used as the bearing and wearing courses of asphalt pavements are measured in the frequency range of 0.1 MHz to 1.5 GHz.
		The results in the frequency range of 10 MHz and 1.5 GHz indicate that, under dry conditions, the static dielectric constant of the asphalt pavement materials tested is in the range of 5 – 6, whereas the relaxation time is in the range of 100 – 400 picoseconds.
		The results show that within the range of field applications the static dielectric constant and relaxation time of asphalt pavement materials are independent of the mix type, density, and asphalt cement content.
	www.pubs.asce.org /WWWdisplay.cgi?9904553 (213 words)

	Encyclopedia: Dielectric constant (Site not responding. Last check: 2007-10-20)
		When an electromagnetic wave travels through a dielectric, the velocity of the wave will be slowed down and behave as if it had a shorter wavelength.
		In fiber optics, an optical amplifier is a device that amplifies an optical signal directly, without the need to first convert it to an electrical signal, then amplify it electrically, and finally reconvert it to an optical signal.
		Dielectrics are also used in Printed Wiring Boards (PWBs), in the layers beneath etched conductors.
	www.nationmaster.com /encyclopedia/Dielectric-constant (999 words)

	Dielectric Constant / Dissipation Factor ASTM D150 IEC 60250
		Dielectric Constant is used to determine the ability of an insulator to store electrical energy.
		The dielectric constant is the ratio of the capacitance induced by two metallic plates with an insulator between them to the capacitance of the same plates with air or a vacuum between them.
		Dissipation factor is defined as the reciprocal of the ratio between the insulating materials capacitive reactance to its resistance at a specified frequency.
	www.ptli.com /testlopedia/tests/D150Dielectric.asp (281 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		From the estimation of the dielectric constant at each frequency using CV measurement, Kramers-Kronig relation and the square of the refractive index, we suggest that the dielectric constant due to ionic and electronic polarization is not the dominant factor in decreasing the dielectric constant.
		This study demonstated a general relationship between bond-polarity and dielectric properties that carries over to organic materials as well: the more polar a bond in the classical bonding picture as defined by electronegativity differences, the smaller the contribution of the IR active vibrational modes of that bond to the static dielectric constant.
		Low dielectric constant polymers are being investigated for application as interlayer dielectrics with copper as the metal in a multilevel interconnect scheme.
	www.mrs.org /meetings/spring98/absbook/AbstractBookE.html (11933 words)

	Dielectric Constant (Site not responding. Last check: 2007-10-20)
		In measuring the dielectric constant, a basic understanding of capacitance theory is beneficial.
		Thus the dielectric constant, or relative permittivity, is the ratio of the permittivity of the material to the permittivity of free space.
		The dielectric constant is directly proportional to the capacitance, which is also proportional to the leakage current.
	www.mse.vt.edu /faculty/hendricks/mse4206/projects97/group01/solidstate/dielect.htm (450 words)

	The Influence of Dielectric Constant
		The influence of dielectric constant upon the aggregation behavior of protein solutions has been calculated taking into account the dielectric constant of mixtures between water and ethanol or polyethyleneglycols.
		It is the first time that the effect of the dielectric constant has been evaluated stepwise by using a new method to crystallize proteins in capillary tubes.
		In order to study the "in situ" influence of the dielectric constant on protein crystallization, a new device for crystallization has been recently developed (9), and is shown in Figure 1.
	www.abrf.org /JBT/Articles/JBT0005/JBT0005.html (2186 words)

	Dielectric Constant
		A collection of different dielectrics was assembled; the dielectric constants were determined at low frequencies (10kHz) by measuring the capacitance of parallel-plate dielectric sandwiches.
		Other measurements made included varying the position of the dielectric loading sheets within and around the antenna structure, investigating the effect of encasing the antenna in a graded dielectric constant by assembling sheets of different dielectric into a matrix, and investigating the effect on the azimuth radiation pattern (essentially there was no detectable effect).
		The effect of doubling the plate area for 3mm thick plates, and using a range of dielectric material, showed also that there was a measurable and consistent reduction in the resonant frequency of the ADR antennas for the larger area plates.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/antennexarticles/diecon.htm (1284 words)

	dielectric constant - a Whatis.com definition (Site not responding. Last check: 2007-10-20)
		The dielectric constant is the ratio of the permittivity of a substance to the permittivity of free space.
		Materials with high dielectric constants are useful in the manufacture of high-value capacitors.
		A high dielectric constant, in and of itself, is not necessarily desirable.
	whatis.techtarget.com /gDefinition/0,294236,sid44_gci548179,00.html (261 words)

	World Intellectual Property Organization (Site not responding. Last check: 2007-10-20)
		The first category of dielectrics has a relatively temperature-independent dielectric constant but the value of the dielectric constant is low, e.
		Since the capacitance is proportional to the dielectric constant, high dielectric constant materials are desired.
		with the perovskite structure and a lattice constant of 0.7393 nm.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/84572.011108&ELEMENT_SET=DECL (915 words)

	Journal of Electronic Materials: Synthesis and characterization of porous polymeric low dielectric constant films
		A dielectric constant kappa of 1.8 was achieved for a porous film with an estimated porosity of 40% and average pore size of 3 nm.
		The dielectric constant decreased from 2.7 to 1.8 with an estimated porosity of 40%.
		In addition, the dielectric dissipation of the porous films is lower than that of the dense film because of the very low dissipation of the gas phase in the film.
	www.findarticles.com /p/articles/mi_qa3776/is_200104/ai_n8929192 (1097 words)

	[No title]
		How effective a dielectric is at allowing a capacitor to store more charge depends on the material the dielectric is made from.
		The capacitance is maximized if the dielectric constant is maximized, and the capacitor plates have large area and are placed as close together as possible.
		If a metal was used for the dielectric instead of an insulator the field inside the metal would be zero, corresponding to an infinite dielectric constant.
	webphysics.davidson.edu /physlet_resources/bu_semester2/c08_dielectric_constant.html (205 words)

	World Intellectual Property Organization (Site not responding. Last check: 2007-10-20)
		In order to perform acceptably in tuning or resonance circuits the dielectric must have a dielectric constant that exhibits minimal temperature dependence ; otherwise small changes in ambient temperature throw the circuit out of resonance.
		provides good dielectric tunability and low loss over a frequency range of from 10 kHz to 10 MHz and is especially useful in tunable devices such as phase shifters, matching networks, oscillators, filters, resonators, and antennas comprising interdigital and trilayer capacitors, coplanar waveguides and microstrips.
		Voltages were applied across the flat electroded faces of the disks and tunability was calculated by measuring the change in dielectric constant with applied voltage.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/84561.011108&ELEMENT_SET=DECL (835 words)

	RF Cafe - Dielectric Constant, Strength, & Loss Tangent
		Values presented here are relative dielectric constants (relative permittivities).
		Dielectric loss tangent is the imaginary part of the dielectric constant, and determines the lossiness of the medium.
		Similar to dielectric constant, low loss tangents result in a "fast" substrate while large loss tangents result in a "slow" substrate.
	www.rfcafe.com /references/electrical/dielectric_constants_strengths.htm (138 words)

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