Many moons ago I had a dabble with RF..... 27 Mhz children's band and a few of those really olde things Valves..... 27Mhz input at about 4W... + an 807 in class C about 50W.... then add two 4CX1000A's in class AB1 with 3600V plate voltage at 900mA nearly 3Kw at 27 Mhz... That's how radio works...Big amplifier... goes anywhere and messed up 405 line tv a treat... well it was 1981... I do micros now less power hungry Steve -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of solarwind Sent: 31 March 2010 07:27 To: PICLIST Subject: [EE] How does radio work? I've been very interested in electrical engineering and radio recently. I've been trying to learn how radio waves tie into electrical engineering. 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". For example, a very simple 1 MHz AM transmitter is described here: http://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html I am referring to the image here: http://sci-toys.com/scitoys/scitoys/radio/xmitter_schematic.gif I understand that the top left pin of the crystal oscillator is the input for some voltage. So assuming that I provide a steady +5 volts on that pin, what will I see on the output pin (top right)? Will I see a 1 MHz wave with a peak voltage of +5 volts? Or will it have an RMS voltage of 5 volts? How is the radio wave generated in this case? If I stick an appropriately sized antenna on the output pin, how is the radio wave generated? Why is it generated? Is it because of the oscillating potential difference across the output pin and ground? What governs the output power of the radio wave? How do we generate a more "powerful" signal? Assuming the photon theory of electromagnetic radiation (if that is the correct theory to use here), does the output power refer to the number of photons emitted/time? If so, how do we increase the power? And why are the photons emitted in the first place? On the receiving end, assuming a properly sized antenna, how is the radio wave "received"? When a radio wave strikes the antenna, what happens? If I were to have a long, straight piece of wire and clip two terminals of a sensitive oscilloscope to each end of that wire, will I be able to see the wave (assuming a powerful enough transmitter)? If not, why not? I know bits and pieces of things but I'm still not able to see the big picture here. I can only understand this stuff if I know the fundamentals on a very low level. I'm really trying to learn this stuff, and I have searched in several books and on the Internet, but it is proving to be a difficult task to find this information. I know you guys are the best people to ask. So here I am. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist