Is it possible to make a passive element that doesn't reemit EM

[Christofer Br]

Is it possible (and if so how practical) to overdamp a conductor wire that is many times longer than the wavelength of the incident radiation so that it doesn't reradiate any detectable amount, turning practically all incident radiation into heat?

 

[anorlunda]

How would you define the difference between radiate and re-raditate? It sounds like you're asking for a black hole.

Would a wire that didn't reflect light be invisible?

When the wire converts radiation to heat and gets hot, it will start glowing red then white. Do you count that as reradiate?

It sounds like you might be working on an idea for a SF story.

Edit: Would a wire that didn't reflect light be invisible? I guess not invisible, but rather a black body. But we know that black bodies emit blackbody radiation.

 

[Christofer Br]

How would you define the difference between radiate and re-raditate? It sounds like you're asking for a black hole.

Would a wire that didn't reflect light be invisible?

When the wire converts radiation to heat and gets hot, it will start glowing red then white. Do you count that as reradiate?

It sounds like you might be working on an idea for a SF story.

Edit: Would a wire that didn't reflect light be invisible? I guess not invisible, but rather a black body. But we know that black bodies emit blackbody radiation.

I should have mentioned I was reffering to microwaves, that is, it turns ~100% of the incident microwave radiation to heat (ofc radiating heat in infrared etc.)

 

[berkeman]

I should have mentioned I was reffering to microwaves, that is, it turns ~100% of the incident microwave radiation to heat (ofc radiating heat in infrared etc.)

RAM?

 

[davenn]

Is it possible (and if so how practical) to overdamp a conductor wire that is many times longer than the wavelength of the incident radiation so that it doesn't reradiate any detectable amount, turning practically all incident radiation into heat?

that doesn't really make sense. A hot object is going to emit IR radiation ... length won't have any effect on the outcome

When the wire converts radiation to heat and gets hot, it will start glowing red then white. Do you count that as reradiate?

indeed

I should have mentioned I was reffering to microwaves, that is, it turns ~100% of the incident microwave radiation to heat (ofc radiating heat in infrared etc.)

what difference does it make what the incident radiation is ? Or more to the point ... It doesn't matter what the incident radiation is. If it heats the object, IR is going to be emitted

If you have something else in mind, that isn't SciFi, then you need to explain yourself in a much clearer way

Dave

 

[Tom.G]

I should have mentioned I was reffering to microwaves, that is, it turns ~100% of the incident microwave radiation to heat (ofc radiating heat in infrared etc.)

Not a wire, but there is material used on military aircraft for instance that essentially absorbs microwaves (I think it is applied as a paint). Also, test chambers for microwave equipment is usually lined with an absorbing material, similar to the approach used in audio anechoic chambers.

A Google search tuns up over 6 000 000 hits.
https://www.google.com/search?&q=microwave+absorbers

 

[f95toli]

I should have mentioned I was reffering to microwaves, that is, it turns ~100% of the incident microwave radiation to heat (ofc radiating heat in infrared etc.)

Any reason why you can't just terminate the conductor in a matched impedance? A standards 50 ohm terminator will do what you ask (assuming you have a 50 ohm line)

If you are talking about unguided microwaves hittign a surface you could use product like. Ecosorb or even make your own coating (radio astronomers use e.g. stycast mixed with SiC granules)

 

[tech99]

Is it possible (and if so how practical) to overdamp a conductor wire that is many times longer than the wavelength of the incident radiation so that it doesn't reradiate any detectable amount, turning practically all incident radiation into heat?

For a simple antenna we say that half the incident power is re-radiated. This is because the incident wave induces a current in the antenna, and even when it is provided with a matched load, the current will cause radiation.
If we extend this idea to a surface having a resistivity of 377 Ohms per square, the same occurs - half the energy is re-radiated.
If you compare the situation to a 100 Ohm parallel wire transmission line which is conveying power from a generator to a distant matched load, if we place a 100 Ohm resistor across the line at a position part way along it, the resistor absorbs part of the power but not all.
To make the resistor absorb all the power we can place a short circuit on the line a quarter of a wavelength behind the resistor. This reflects the energy back to resistor is such phase as to deliver all the power to it.
For the antenna case, if we place our 377 Ohm sheet a quarter of a wavelength above a metal surface, it will, by a similar mechanism, absorb all the incident power.

 

[sophiecentaur]

For the antenna case, if we place our 377 Ohm sheet a quarter of a wavelength above a metal surface, it will, by a similar mechanism, absorb all the incident power.

Blooming a lens is the same principle.