EM rad/Photon transition, How low can you go!

[YT2095]

consider an electrical oscilator at 30KHz, there will be a transmition (carrier wave) broadcast.

Photons will leave the antenna or coil as this electrical charge oscilates, basicly a Radio transmition.

 

now consider we lower the rate of this oscilation gradualy, at what point does it cease to transmit photons? DOES it cease to transmit them?

 

we lower this frequency to just over 1KHz (middle C on a piano) it`s still an electrical signal being switched through a coil, does it still transmit but just on a REALLY REALLY long wavelength?

 

now we lower this freq further to say 50Hz, our coil still has this electrical signal passing through it, does it still transmit?

 

there is a Granite bed in Scotland, it`s used as an antenna for ELF frequencies used by submarines, naturaly it would need and antenna that long for such a low freq but it works as it`s Global!

 

are photons being emitted from a speaker coil at 20khz? as they would be from a coil at say 2Mhz?

 

where is the transition (if there is one) and Why?

 

if there isn`t a transition, what happens when we get down to a 1Hz electrical pulse in our coil?

[Meir Achuz]

There is no sharp transition, but the radiated power varies like the frequency squared

and will be very small at low frequencies. Antenna efficiency also varies like frequency squared, so the observation of radiation goes like f^4.

[mmalluck]

I think the limiting factor for low frequencies transmisions is usually the antenna. Although your driving your speaker coil at a very low frequencies, very few, if any photons are created because it's a very poor antenna.

 

So why not make a better antenna? Because the antenna would be fricken huge. At 1 Hz a quarter wave dipole antenna would be 75,000 kilometers long or about twice the circumferance of the Earth.

 

if there isn`t a transition, what happens when we get down to a 1Hz electrical pulse in our coil?

 

If you're using a 1 Hz sinewave, then only photons of that fundemental frequency will be created.

 

Now if your pulsing the coil at 1 Hz (sending a square wave through our coil) photons will be emited across the entire spectrum with smaller power levels appearing at higher frequencies. This has to do with the fact that a perfect square wave is composed of a infinite combination sinewaves, not that it's a 1 Hz pulse.

 

Now the coil itself will have a natural resonating frequency and this should also be evident if you look at the output power. It'll act as a better antenna around that frequency and so more of the photons will be emitted from the antenna at that frequency.

[YT2095]

so even a 1Hz signal will transmit SOMETHING?

[mmalluck]

but the radiated power varies like the frequency squared

and will be very small at low frequencies. Antenna efficiency also varies like frequency squared' date=' so the observation of radiation goes like f^4.[/quote']

 

Assuming your using the same antenna to pick up multiple frequencies. Frequencies lower or higher than the designed operating frequency will vary as you describe.

[YT2095]

I totaly agree, a 1 Hz sine would need 300,000 kms of good wire to work, that`s not the point, all that is taken as understood and as a given.

 

so you`re saying that there IS NO transition per se?