How to determine the dielectric constant of egg tray?

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Discussion Overview

The discussion revolves around determining the dielectric constant of egg trays, particularly those made from paper, and their potential use in applications such as electromagnetic wave absorption. Participants explore various methods for measurement, the influence of additives like graphite, and the relationship between the dielectric properties of egg trays and paper.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant inquires about methods to determine the dielectric constant of egg trays beyond the dielectric probe technique and questions if it is the same as that of paper.
  • Another participant expresses skepticism about the incorporation of graphite into egg trays, suggesting it may be a thought experiment.
  • A different participant confirms they are conducting experiments with egg trays mixed with graphite for their project.
  • There is a suggestion that the dielectric constant could be determined by incorporating the material between capacitor plates, with a note on the importance of insulation if the dielectric is not a good insulator.
  • Several participants discuss the potential use of egg trays as materials for electromagnetic wave absorbers, with one participant mentioning plans to wet the egg tray and coat it with carbon or graphite.
  • One participant raises a question about the permittivity of paper egg trays, suggesting it may relate to the permittivity of recycled newsprint but expresses uncertainty due to the presence of more air in egg trays compared to paper.
  • Another participant notes that the dielectric constant may not significantly affect absorption characteristics, emphasizing the importance of conductivity and the shapes of the material used.
  • Participants discuss the design of absorbers in simulation software, highlighting the need for specific values of permittivity and permeability for egg tray material.
  • There is a mention of the potential relationship between impedance and absorption characteristics, with a suggestion to consider the optimum bulk resistivity for effective absorption.

Areas of Agreement / Disagreement

Participants express various viewpoints regarding the dielectric properties of egg trays and their applications. There is no consensus on the exact dielectric constant of egg trays compared to paper, nor on the implications of incorporating graphite. The discussion remains unresolved with multiple competing views.

Contextual Notes

Participants acknowledge limitations in their understanding of the dielectric properties of egg trays, particularly regarding the influence of air content and the effects of additives like graphite. There are also unresolved questions about the specific values needed for simulations.

opticfibering
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Hi, can i know how to get the dielectric constant of the egg tray (the one with the paper) beside using dielectric probe technique? is it have same dielectric constant of paper? or it is different? i hope someone can help me.
if the egg tray mix with the carbon or graphite, as i know the graphite dielectric constant for epsilon=12, mue=1, how to calculate the dielectric constant of if both are mix?

thanks in advance.
 
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I can't imagine a manufacturer would incorporate graphite into his egg trays. Perhaps this is a thought experiment?
 
i just do the experiment, using egg tray as material. then the egg tray will mix with graphite and fabricate shape. :)
 
I can't think of any way to determine εr apart from incorporating the material between the plates of a capacitor. If the dielectric is not a good insulator, insulate it from the plates and take this into account.
 
Thanks NascentOxygen.
here, i would like to do the EM wave absorber using egg tray as material. i need to fabricate using egg tray which i plan to put the egg tray in the water and make it wet and then mix or coated with carbon/graphite.
anyway, εr of the egg tray same with the paper or not?
thanks.
 
or what is the permittivity of paper egg tray? same as paper?
 
opticfibering said:
or what is the permittivity of paper egg tray? same as paper?
Well, it would certainly be related to the permittivity of the recycled newsprint that it is made from. But because egg tray material seems to incorporate more air than does the equivalent thickness of paper, I'm hesitant to guess how this pans out.
 
opticfibering said:
Thanks NascentOxygen.
here, i would like to do the EM wave absorber using egg tray as material. i need to fabricate using egg tray which i plan to put the egg tray in the water and make it wet and then mix or coated with carbon/graphite.
anyway, εr of the egg tray same with the paper or not?
thanks.

Interesting, you are wanting to make your own Anechoic RF Absorbent Material (RAM)?

http://en.wikipedia.org/wiki/Radar_absorbent_material

The dielectric constant will not have a big effect on the absorption characteristics. It is more dependent on the conductivity/losses and the shapes of the cones. The rounded bottoms of the paper egg containers are not a great shape for this, but I don't know of many good alternatives offhand. You might be able to figure out a way to cast some material in the shapes of the cones of typical RAM materials...

And what RF frequencies are you hoping to absorb? The depth of the cones should be on the order of the wavelength that you are trying to absorb.
 
thank you NascentOxygen.
this means that i need to quick to find the permittivity of the egg tray before i proceed
 
  • #10
berkeman said:
Interesting, you are wanting to make your own Anechoic RF Absorbent Material (RAM)?

http://en.wikipedia.org/wiki/Radar_absorbent_material

The dielectric constant will not have a big effect on the absorption characteristics. It is more dependent on the conductivity/losses and the shapes of the cones. The rounded bottoms of the paper egg containers are not a great shape for this, but I don't know of many good alternatives offhand. You might be able to figure out a way to cast some material in the shapes of the cones of typical RAM materials...

And what RF frequencies are you hoping to absorb? The depth of the cones should be on the order of the wavelength that you are trying to absorb.

my project is using egg tray as material to absorb EM wave. in my simulation software, i design the absorber in pyramidal shape then using the egg tray as material. the problem is in the library of the software don't have egg tray material, so i need to load a new material with value of epsilon,ε (permittivity) and mu,μ in there.
 
  • #11
opticfibering said:
my project is using egg tray as material to absorb EM wave. in my simulation software, i design the absorber in pyramidal shape then using the egg tray as material. the problem is in the library of the software don't have egg tray material, so i need to load a new material with value of epsilon,ε (permittivity) and mu,μ in there.

I would think that your simulations should show that the attenuation of the RF doesn't depend much on the permittivity and permeability, and would depend a lot on the lossy-ness (resistance) of the material. There is probably a sweet spot in conductivity between high and low that offers the optimum absorption. Be sure to make your cones large enough for whatever frequency you want absorbed.
 
  • #12
In fact, I wonder if the optimum impedance would match the 377 Ohms of free space. Not sure how to translate that into the volume resistivity target that you should shoot for, but your simulations should show a curve for absorption versus bulk resistivity that has a maximum at some bulk resistivity value.

And I'm referring to cones that have the same resistivity throughout their volume, not just an egg carton that has some bulk resistivity in the surface of the cups.
 
  • #13
ok, thanks. ^^
i will check and try to do regarding to your suggestion/guideline.
 
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