Transmit In Order To Receive

Cycle

Transmit In Order To Receive
«  »Last edited by Cycle
Here's something interesting:
http://www.think-aboutit.com/energy-sucking-radio-antennas/
Quote
By manipulating the EM fields, we can force an electrically-small receiving antenna to behave as if it was very, VERY large. The secret is to intentionally impress an artificial AC field upon the receiving antenna. We’ll transmit in order to receive, as it were. Conventional half-wave antennas already do exactly this because their electrons can slosh back and forth, generating their own EM fields. For example, the thin wires of a half-wave antenna are far too thin to block any incoming radio waves and absorb them. However, the current in such an antenna, as well as the voltage between the two wires, these send out large, wide, volume-filling EM fields which have a constant phase relative to the incoming waves. Because of the constant phase, these fields interact very strongly with those incoming waves. They create the lobes of an interference pattern, and this pattern has an odd characteristic: some of the incoming energy has apparently vanished. The fields produced by the antenna have cancelled out some of the energy of the impinging EM waves.

Rather than relying upon the wiggling electrons in the wires of the large half-wave antenna to generate EM fields… what if we used use a power supply instead? If an antenna is 1/10,000 wavelength across, we should be able to force it to behave as if it’s huge; perhaps 1/3 wavelength across. We simply have to drive it hard with an RF source. We must drive it at the *same* frequency as the incoming waves, then adjust the phase and amplitude of the power supply to a special value. At one particular value, our transmissions will cause the antenna to be best at absorbing the incoming waves.

Take a loop antenna as an example. If we want our little loop-antenna to receive far more radio energy than it normally would, then we need to produce a large AC current in the antenna coil, where the phase of this current is locked in synch with the waves we wish to receive, and is lagging by 90 degrees. The voltage across the antenna terminals stays about the same as when an undriven antenna receives those waves. However, since the current is much higher in the driven antenna, the energy received per second is much higher as well. This seems like engineering blasphemy, no? How can adding a larger current increase the RECEIVED power? And won’t our receiving antenna start transmitting? Yet this actually does work. Power equals volts times amps. To increase the RF power received from distant sources, we increase the antenna’s amperes intentionally.

Think like this: how large is the diameter of the antenna’s nearfield region at 10KHz? Around 10 kilometers? What if we could extract half of the incoming energy from that entire volume?!! In theory we can: half can be absorbed, and the other half scattered. In theory a tiny loop antenna sitting on your lab bench can intercept just as much energy as a longwire 1/2-wave antenna which is 10KM long. Bizarre, eh?

At resonance, the 10pF capacitance of our metal plate effectively vanishes. At resonance, an ideal parallel-resonant circuit behaves like an infinite resistor. If the LC circuit is exactly at resonance, and neglecting the resistance of the wires involved, how high will the voltage on the metal plate rise? It rises to ten megavolts!!!! The resonant circuit will continuously accumulate EM energy until the voltage at the antenna-plate rises to the same value of voltage as the transmitter. Weird!

Keep in mind that this device is a relatively small affair sitting in your back yard. It’s not a 1KHz quarter-wave dipole tower 25 miles tall. There’s no huge antenna, so we would not expect to find any huge level of electric power appearing in the circuit. If we weren’t aware of the mechanism behind this, all we’d see is a passive LC resonator which seems to burst into oscillation of its own accord, and the voltage grows higher and higher until the darned thing suffers a corona outbreak or something. Lightning bolts shoot out! The EM fields near the metal plate grow FAR STRONGER than the weak fields already present in the environment. The device in our back yard resembles an impossible “perpetual motion” machine, which might make physicists suspect a hoax.
http://amasci.com/tesla/dipole1.html

This how Tesla managed to transmit power.

If we could cause a resonant oscillation through an antenna using a joule ringer type circuit, it could conceivably receive more energy than we put into it. Size the antenna(s) to ultra-high frequency radiation, and it could conceivably receive far more energy than we put into it, while remaining compact in size.

Conversely, size (and drive) the antenna(s) to be resonant with the earth's Schumann cavity size, and pick up the ~150 V/m static fair weather charge.

Or, if we could print electrically-conductive material in a 3-D printer, print up a 3-D fractal antenna in the form of a Sierpinski Tetrahedron (pyramid), which would give you a very wide-band antenna. Then you could adjust your driving frequency to whichever frequency gives the highest energy return on energy invested.

onepower

Re: Transmit In Order To Receive
« Reply #1,  »
Amasci.com also has the best lectures i have ever read on what electricity is and how it works. As well as lectues on power and energy. His website is required reading in my opinion.

Ragnor

Re: Transmit In Order To Receive
« Reply #2,  »
 OP's concept is essentially valid. By applying the correct voltage at the correct frequency to our pie plate it becomes a 10 km wide antenna. As per Teslas words on the subject. My concern has been vaporizing my half mile of 28 awg magnet wire upon ringing the correct frequency. I can visualize the process and reactivity, but math is not my strong suit. Someone needs to work out the figures, Just winging it will inevitably result in lost equipment.

Cycle

Re: Transmit In Order To Receive
« Reply #3,  »
I was thinking... if you created such a device with a directional antenna, and its EM 'footprint' extended outside the planet's atmosphere, you'd pick up all that high-energy radiation that usually gets absorbed in the ionosphere. You'd in essence be creating a "well" into which high-energy UV and X-Ray radiation was funneled.

Much of it would then still be absorbed by the atmosphere, but you'd still have a steady infall of energy to pick up, and the resonance to do so. I wonder if doing so at a high enough rate would cause a localized auroral effect?