What Is The Difference Between These "Dielectric" Terms?


by FredericChopin
Tags: dielectric, difference, terms
FredericChopin
FredericChopin is offline
#1
Nov2-13, 08:25 PM
P: 34
Can someone please explain to me what the difference between these terms are?

1. Dielectric constant
2. Relative dielectric constant
3. Dielectric loss

I came across them on this website:

http://www.lsbu.ac.uk/water/microwave.html#pen

Also, I don't really know what "δ" and "εr'" on the website are meant to represent.

All and any help would be appreciated.

Thank you.
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FredericChopin
FredericChopin is offline
#2
Nov3-13, 02:23 AM
P: 34
Also, does anyone know the derivation to the equation:

$$\alpha = \frac{2 \pi }{ \lambda } \sqrt[]{ \frac{ \varepsilon_r \sqrt[]{1 + tan^{2} \delta } - 1}{2} }$$

, which is also on the website?

Thank you.
NascentOxygen
NascentOxygen is offline
#3
Nov4-13, 04:29 AM
HW Helper
P: 4,717
An ideal capacitor has no losses, a dielectric introduced between the plates just changes the total capacitance in proportion to the relative dielectric constant.

An non-ideal dielectric also introduces a loss, which we represent by a resistance between the plates. So the real capacitor shows both capacitance and resistance; I think that leads to the angle you have there, δ.


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