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| Joined: | Nov 7th, 2007 |
| Location: | Alabama USA |
| Posts: | 127 |
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. I will not bore you all with too much explanation, but a little is in order.Based on the output impedance of the RF generator, and supporting devices, I had to find a resonant circuit that would match that impedance. Yet, since the antennas will be enclosed in the Faraday cage, I had to limit their size, and the interaction between the antennas and the inside of the cage. This, as was stated before, was the first hurdle.
Think of throwing a ping pong ball into a fairly small steel box. That energy stored into the ball from the thrower, will dissipate by the ball bouncing all around inside that box, right? The result will be the same with electromagnetic energy when released inside that enclosure. The leading edge of the wave will strike an inside surface of the box, and ricochet in another angle to some other inside surface of the box. That will cause another ricochet, and another, and another.... etc., until the energy has dissipated.
You can see that as the wave leaves the transmitting antenna, the receiving antenna will receive not only the transmitted signal; but several other "phantom" signals a very short time later. This causes a great confusion of what exactly the receiving antenna was supposed to hear in the first place, resulting in a very muddy, and incoherant reception, as you can guess.
This called for the "damping" effect. Damping is the science of stopping energy. To help in understanding, your home audio entertainment amplifier that drives your speakers has what is called a "Damping Factor". This is an electronic method that forces the amplifier to stop your speakers, woofers to be exact, from loosely ringing after a low note from your audio source has been reproduced. Let's say the sound is a simple thump from a kick drum. Without the Damping Factor, your woofer would produce the 'kick' sound, but just keep vibrating until the suspension arrangement of the woofer cone stopped the cone from moving back and forth. That would be: THUMP WOWWOWWOWwowowow. Nice huh? Well, here's the good news: Because of the Damping Factor, your amplifier has the ability to stop your woofer cone from moving after the 'kick' sound immediately, so all you hear is the 'thump'. This is what I had to factor into the Faraday and antenna relationship. WHEW!!!!
That was tough enough, but when damping is added, impedance changes, so I had to recalculate how to match impedance!
Well, design is finished, now I have to build the thing. By the way friends, please be patient; this, as all things, requires money, and with Christmas rapidly approaching, I must consider my loved ones for gifts and such, so I won't be building until after the new year. Until then, we must keep in contact, and let me know if I can be of help in any other area of EVP/ITC as well.
Many blessings to all of you!
Jeff