solarwind wrote: > I've been very interested in electrical engineering and radio > recently. I've been trying to learn how radio waves tie into > electrical engineering. They don't. Radio works on magic. That's why there are people that specialize in RF (Radio Frequency). You usually see them wearing long robes, tall pointy hats, and carrying stick like things in their hands. Seriously though. These are good questions but to answer them properly is way beyond the scope and size of a PIClist post, and the time anyone can probably devote to writing one. Back when I was in high school, I found the ARRL Handbook a good source for looking up things RF. I sortof remember it had a bunch of introductory chapters on much what you're asking about. I don't know if it's still around, but if not, try to find a old copy. It used to be the size of a medium phone book. Maybe nowadays its on line. Go to your local library and see if you can find one, then maybe get pointers from there. I just entered "ARRL Handbook" into Google, and it's alive and well and can be had for $50. There are probably chunks of it on line somewhere. Follow the cookie crumbs and you'll probably find some good information, or for $50 you can have it all for sure. > How do we create them? How do we receive them? > I've read the howstuffworks article as well as some Wikipedia pages on > the matter, but still do not know exactly how they "work". Very briefly. Voltages do not end at the ends of conductors. A voltage field, called the E field permeates all space. If you have two pieces of aluminum foil 1 meter apart and connect a 12V battery between them, the E field between will have a strength of 12V/meter. Yes, it's really that simple. The not so simple part comes from when these voltages start changing. If you were a few meters away and could sense what's left of the E field at that distance you would see it change a very short time after the voltage on the plates changed. That's because the E field propagates at the speed of light. So when you switch on the two plates, you've created a disturbance in the E field that radiates out from your location at the speed of light. This effect drops off in magnitude quickly to the point where we can't measure it anymore, but it actually radiates out inifinitely and forever. A year after you did this and your aluminum foil pieces are long gone, the electric disturbance you created is still propagating outward at the surface of a sphere a light year in radius. A little bit of the energy from the 12V battery has essentially been transmitted into space. This thought experiment is only to show that any electric change not only happens in wires, but little bits of its energy leave and propagate away. Only a very very tiny fraction of the energy in the aluminum foil example was transmitted. However, once you know this can happen you can get clever and design systems to do this deliberately, you can get a good fraction of the energy or your circuit to radiate. That's exactly what a RF transmitter connected to a antenna is. To do this efficiently, we usually try to get the system to resonate at the transmitting frequency. Resonance is a whole other topic I don't have time for, but is usually important in RF transmitting and receiving systems. Again, very briefly, simple resonance requires the electric conductors to be around 1/2 wavelength in size, or multiples of 1/2 wavelength. At that size, the propagation delay from one end to the other is such that the wave sloshes back and forth. That makes bigger voltages more easily, which makes bigger E fields, which means the E field disturbance can be detected at greater distance. Radio is the art of getting all this right. I gotta go now. Maybe more later. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist