This is a three part question -
First of all, what does the ‘dial’ do on the old style ‘rabbit ear’ antennaes?
Second, if I were to hook my radio or TV antennae up to, say, a 5 acre (square, connected) chain link fence, would I be able to pick-up all kinds of foreign stations?
lastly, If part #2 wouldn’t work, is there any way to make a ‘Super-Duper’ antennae out of common objects?
You fence would be grounded by the fact that it is in the ground so it wouldn’t work.
A super duper directional antenna can be made fairly easily with the right length of wire.
I don’t know about the rest.
The knob is mainly to give the owner something to twiddle with. It is supposed to affect the relative balance of signal between the two ears and/or to adjust for a given freq. but you probably couldn’t get an noticable improvement in practice.
Large hunks of metal make terrible antennas. Not just a complete waste of time and materials, but an actual negative. Note that those “whole house”, make your power wiring an antenna gadgets are an outright fraud.
The only common household items that can be used to make decent antennas are wire and something to support the wire. E.g., plastic tubing &c.
Also, forget “dish shaped” antennas for standard TV and radio wavelengths.
Changes the relative phasing of the two ‘ears’, and/or the antenna impedance seen by the output line.
Nope. Probably wouldn’t work as well as the rabbit ears.
Sure, coat hangers cut to the right lengths and arranged correctly. If you look at those rooftop antennas, they’re just hollow aluminum tubes. Coat hangers cut to the same lengths, and attached together the same way will work just about as well.
I use rabbit ears to get a Lansing channel not available on cable here. There are a few dial positions that work best, and a lot that work really poorly. It does only affect the VHF stations, however. The UHF loop isn’t run through the dial, and UHF reception doesn’t seem to be affected.
It adjusts capacitance and or inductance,
your antenna has to be high to get long distance broadcasts as these radio waves follow a straight line and ordinarily dont bend, also you are dealing with wavelengths, this determines the length of the arms and spacing between driven and reflector elements of the antenna a good reference is Radio Relay League Handbook
you can make a decent dipole antenna out of ordinary copper wire, just has to be cut to a definate length
#1) The dial is to change the inductance value between the 2 “ears” This phase variation can also be attained by moving the ears.
#2) Chain link fence is gounded. Bad antenna design. If you ungrounded the fence, its still a bad antenna design. Bad material (aluminum links too thick), bad configuration (cross linking, banded at both ends, too skinny and too long), Bad position (too low to the ground)
#3) Yes, you can make antennas out of common objects but an antenna doesnt suck all signals out of the air. Antennas are designed to interact with magnetic waves of a specific frequency. They collect the magnetic waves out of the air and it is translated by the receiver. Certain frequencies act differrently than others. Thats why you can use a coat hanger for UHF but it sucks on VHF and it would be totally useless in the Gigahertz range. Antenna design is not based on just material surface area. Theres a whole lot of mathematics involved. If you wanna try to get signals from all over the world, try HAM radio
The 5 acre fence has already been shown to be a non-starter. However, even if you did build a super-duper antenna you’d still be able to only tune certain frequencies. Short wave you can get stuff from around the world. AM radio you can get from pretty far away. I once got a Boise, Idaho AM station one night in Phoenix, Arizona. I tried several otehr times but never got it again…must’ve been some fluke although a super-duper antenna might work. FM radio you can forget as it travels off into space rather than follow the curve of the world around (you’ll notice you always lose FM radio roughly 70 miles or so from the source unless your antenna sticks high into the air).
For a big antenna check out the one near Clam Lake in Wisconsin. It is an Extremely Low Frequency (ELF) transmitter used to communicate with nuclear subs around the world. All told the entire antenna is something like 80+ miles long.
Human beings are common enough, and they make excellent antennas 
Antenna behavior depends on wavelength of the radio waves. You want the wire to be roughly half as long as the distance between two peaks of the radio wave. Making a wire antenna longer than this doesn’t improve your reception. However, you CAN improve reception by holding extra wires near the main antenna wire (this is why those old yagi TV ariels from the days before cable TV are shaped that way.)
A really long piece of wire makes a great antenna for AM radio. The middle of the AM band is 1000KHz, wire kilometers is then 300,000/1,000,000/2 = 150 meters long. A metal tower 150M tall, supported by insulators, is ideal.
But for TV and FM, the frequency is 100 times higher, so the best antenna wire length will be 100 times shorter than the one for AM, or 1.5 meters long.
“ENERGY SUCKING” ANTENNAS
If the wavelength is far longer than the largest convenient antenna size, then you can get away with something weird. You can add a tuned circuit to a fairly small antenna, and this will greatly increase the EA “Effective Aperture” or virtual size of the antenna. This lets the antenna absorb radio waves from a murch larger area around itself. The tuned circuit creates intense fields around the small antenna which convert it into a sort of “energy funnel” for incoming radio waves. Devices which do this have long been sold, but they’re only worthwhile in situations where you want to receive weak signals at long wavelengths but can’t put up a longwire antenna.
Examples:
http://www.selectatenna.com/
http://www.terk.com/radio/product/amadv.html
Energy received by capacitive antennas
http://amasci.com/tesla/nearfld1.html
Active Antennas
http://www.tfcbooks.com/articles/tws5.htm
VHF can reflect off the atmosphere, but generally doesn’t (metor showers can ionize the air, google sporadic E)
VHF/UHF can also be bounced off the moon, but you need special equipment http://www.qsl.net/kl6m (and YOU can have a UHF dish)
Brian
… old style?
cries
For the record, the knob on my rabbit ears has a large effect on some stations, almost none on others. It does depend on the frequency… tuning to UPN on channel 100 (to get the Simpsons, of course), the knob can turn the distortion from green to red (choices, choices). It even occasionally makes the signal clearer… on other stations (say, channel 2), it makes some minor changes to where the fuzz is pointing.