| Author | Message | ||
     Anonymous |
i was wondering how you transmit electicity over distance by radio waves or magnetic fields | ||
| Simon Quellen Field (Sfield) |
As we show in our chapter on Radio, you can measure the power received by the antenna of a radio, and capture that power to run things. That is basically what a crystal radio is doing -- capturing transmitted energy, and converting it into movement in the diaphragm of the earpiece. Radio transmitters can direct their energy in one direction using a directional antenna. Unless this is done, most of the energy is lost by being radiated in all directions. Directional antennas are easier to make for high frequencies than for lower frequencies, due to the size of the antennas required. This is why the plans for solar power satellites use microwaves to beam the power down to earth, where antenna farms collect it and convert it to 60 hertz power for the power grid. Using even higher frequencies, some researchers are using laser beams to light up solar cells on small aircraft. These solar cells convert the laser light to electricity to power the propeller. | ||
| Anonymous |
when i do a search for directional antennas all i get is antennas for communications and not power | ||
| Simon Quellen Field (Sfield) |
Why would you think there's a difference? You can't communicate without sending power to the other side. | ||
| Anonymous |
well yeah but arent those designed for low power output? im looking to be able to power something that takes a 9v battery or several AAs | ||
| Simon Quellen Field (Sfield) |
If you place the klystron tube of your microwave oven at the focal point of a large satellite dish, you can put out a kilowatt of energy in a beam. The beam will be 12 feet in diameter, so you won't cook passing pigeons, but you still wouldn't want to sit in front of it. Military radar puts out these kinds of power levels (and more). You will want another 12 foot dish to collect the energy on the other side. The beam spread will depend on the dish diameter, in wavelengths. So, to get a tighter beam, you can use a larger dish, or a higher frequency. This is why lasers are so attractive in this situation. A nine volt battery is generally considered low power. | ||
| Anon |
Note: Tesla's work on transmitting electricity thru atmosphere (rather than wires) allegedly gave inspiration to Marconi to use it for radio. In fact Tesla is 'quietly' responsible for many great inventions. AC mains was invented by him. | ||
| Troy (Pharoah) Intermediate Member Username: Pharoah Post Number: 36 Registered: 3-2006 |
However Tesla used gas discharge and induction in his experiments with high-volume energy transmission, not radio waves. |
