Materials that absorb RF energy

[Ralf11]

we should distinguish intensive material properties from shapes that absorb, as well as the freq.s of interest...

 

there are a number of materials commercially available, including ferrite materials, rings embedded in a matrix, metametals, graphite particles in rubber,  carbonyl iron balls in epoxy, and lots more

[Ralf11]

Dark Matter, of course, cannot absorb RF energy to any appreciable degree.

[Ralf11]

9 minutes ago, jabbr said:

You mean dark matter not "Dark Matter (tm)" ?

 

I'm certain the inside of my amplifier is very dark..

 

No reason to believe that "Dark Matter (tm)" isn't made of an epoxy that contains RF absorbing substance(s) and for which a datasheet could be provided which characterizes absorption by frequency (as the Laird website provides ... I've used their products and they are a real vendor, no voodoo).

 

no voodoo implied

 

- who owns a bandsaw?

[Ralf11]

2 hours ago, jabbr said:

Dude ... you don't know what could happen ...

 

you will note that I did not volunteer to saw thru it myself...

[Ralf11]

1 hour ago, barrows said:

Considering commercial/industrial products, i have used this to good effect:

 

https://www.digikey.com/products/en?mpart=30410S&v=732

 

But I prefer not to use ferrite based absorbers around analog circuits.

 

ferrite powder - surprised that Wurth is making it

[Ralf11]

but it is more than mere absorption isn't it?  I mean in terms of the processing inside the material

 

of course, it sounds better too

 

 

[Ralf11]

Just to re-emphasize that this is a real world phenomena and not some Tice clock nonsense.

 

barrows says he is not making much profit on this and I think it is good to explore possible benefits

 

...

when used in a conscientiously applied program of double blind testing and regular professional care

[Ralf11]

4 minutes ago, jabbr said:

 

RF absorbing materials absorb RF just like black felt absorbs visible light. ...

 

I will disagree.  Felt absorbs radiation without the need for any included materials.  The photons are directly absorbed by the material itself.  RAM uses (AFAIK) something such as small balls or loops embedded in a matrix.  And the spatial properties of those 'items' are important too...

[Ralf11]

with a photon, you are bumping things around in the outer valence shell; not so for RAM

 

at any rate, absorb would be ok

[Ralf11]

yup

[Ralf11]

Let's not get all crazy here.  If the DM contains RAM, then putting it in between an RF source and X will absorb RF, preventing some of it from impacting X.  If X is ... um... invariant to RF it won't matter however.  If X is affected by RF it will, so long as the delta in effect on X make a difference in SQ of the entire system.

 

I am still trying to figure out a way for something in a box to absorb non-impinging light in a room -- a nice singularity would do it, but then there is no box, no room...

[Ralf11]

50 minutes ago, mansr said:

Good luck with that.

 

 

ok, I have it!  Eureka!

 

anything in the box will give a non-zero probability of the RF wavicles winking out of existence due to quantum fluctuations

 

QED

[Ralf11]

I'm sure the item barrows is selling is effective at preventing RF from going from area A to area B.  No idea as to difference in SQ on any given system, and DBTs are a must with spendy items, tho not with a $100 item.

 

 

My last comment is correct.  In fact, there is a non-zero P() that the entire universe could vanish in a quantum fluctuation.  Might take a while...  Is it better to quantum out than to fade away?

[Ralf11]

Maxwell was wrong

 

good approximation for the mid-range* tho

 

 

 

* spatial scales, not wavelength

[Ralf11]

59 minutes ago, jabbr said:

 

Oh dear ... 

 

"Classical theories just don't cut it with the quarks."

 

- Muster Mark

[Ralf11]

suppose I put a photon in a box and come back to find an electron and a positron ?

[Ralf11]

ok, my understanding is that they do not function well (or are not proven to) under certain conditions - not true?

 

 

and what about Feynman's concerns?

[Ralf11]

ok, last post on this - my understanding is that Maxwellian wave superposition is not consistent with some things in quantum field theory, e.g. photon scattering from another photon, or various quantum relativistic phenomena

 

no, not audio related but much of this site is not...

[Ralf11]

jabbr - concise responses:

1. No, but it is incomplete

2. No, of course not

3. Here is something on Feynman - I must have given away my paper copies (we used the Bezerkely books anyway - and it was eons ago)...

 

http://www.feynmanlectures.caltech.edu/II_28.html

[Ralf11]

https://en.wikipedia.org/wiki/Field_(physics)

 

amazingly, psychology & sociology have field theories too...

[Ralf11]

back to RF absorption inside a DAC, which I think is an interesting idea...

[Ralf11]

I'm all for a low noise WiFi receiver...

 

BTW, that civet cat coffee is $35/lb. at Amazon

 

Can we all just say that barrows was a bit imprecise in his writing about the DM block, and go on to what this $100 expenditure might do that other items do not?

[Ralf11]

ok, only $73 - "Build that Wall," Jud!

[Ralf11]

part of a post on another thread by @jabbr copied here:

 

1 hour ago, jabbr said:

3) I do strongly suspect that audible differences between USB cables has to do with radiated vs conducted EMI including EMI radiated from the USB transmitters. This has to do with common vs differential mode noise. It is well known that shielding patterns affects radiated EMI (not just external EMI).

 

 

[Ralf11]

4 hours ago, jabbr said:

I’ve talked about this above but there is often a misunderstanding of the role of the “shield” as if the shield only exists to prevent external EMI from affecting the signal.

 

The “shield” is capacitatively coupled with the signal and forms a return path for radiated EMI ie common mode noise. That’s why the “shield”is connected to the source ground plane — the “shield” is an extension of the ground plane itself!

 

In this case however, the shield is not acting simply as a faraday cage nor absorbing RF, rather providing a return path for radiated ie common mode RF.

 

 

But, could a sheath of RAM (or a plane of it normal to a USB cable run, placed next to the DAC) reduce EMI?