SAFETY FIRST: When installing an antenna, be sure there are no electrical wires or equipment close enough that could possibly come into contact with the antenna. Take necessary precautions to protect yourself from falling, electrical shock, and other dangers. If you are a minor, get a knowledgeable adult to help you. If you are an adult, get a knowledgeable adult to help you. I cannot take responsibility for accidents, injuries, or worse.
SAFETY FIRST: For lighting protection, the antenna should also be left disconnected from the radio and connected to an outside ground.
It is important to understand that the crystal radio, the antenna and the ground all function together as a system. Change any one, an the radio will perform differently.
ANTENNA:The antenna can be as simple as a long horizontal wire that leads down to the radio. Make the antenna out of insulated wire as high and as long as possible. A convenient kit is available at Radio Shack for $9.99, part number 278-758. Although the wire is not insulated, the kit comes with two insulators to keep the wire out of contact with trees, houses, etc.
The best method is to suspend the antenna between two tall objects such as trees. I use the Radio Shack kit, and I tied a straightened-out coat hanger to each of the trees to connect to the insulators. To minimize the chance of windblown trees breaking the antenna wire, I installed a largish hardware store spring between one insulator and the coat hanger wire.
If you use the kit, you will have to obtain some insulated lead-in wire to connect the antenna to the radio. Any type wire will do, but stranded wire works best because it won't break like solid wire does when it gets bent too much. Any size from 18 to 26 gauge works just fine; thicker is better.
If you don't use the kit, you can use one long piece of the type of wire described in the previous paragraph. you can just tie your antenna wire to a tree, then suspend it to another tree, leaving enough slack so that if the trees move the wire won't break. Don't cut the wire to separate it from the lead in, instead, keep it intact.
Although you can just tie the wire to a tree and drape it down the branches, it is best to separate it from the trees and other objects (like your house) as in the Radio Shack kit. Don't forget to connect it to the ground when you are not using the radio. That is an alternative to buying a lighting arrestor.
Lead the wire through a window. Try not to have the antenna touch anything. Impossible, but try. Suspend it with string, not wire. Use toilet paper tubes or paper towel tubes to keep it away from other objects, especially metallic surfaces. Simply connect it under one of the antenna screws on the radio, and tighten the screw down. You will find the antenna works better on one screw than another, all depending on your system.
You can vastly improve the system's performance with an antenna tuner, which is simply another coke can capacitor and another coil. Simply stated, it matches the antenna to the radio, optimizing power transfer. I will not discuss construction and operation here, but you can check the links at the bottom of the page to get an idea how to make and use one. See "Wave Traps" at the first link.
GROUND: The simplest ground is a clean connection to a cold water pipe, such as a metal hose bib. Your ground wire to the radio should be as thick as possible stranded wire, 14 to 18 gauge. 20-22 gauge will work, and you may not be able to tell the difference.
If you use a hose bib, use sandpaper or a wire brush to clean the hose bib down to the metal. Strip the wire so that you have about two inches of bare wire. Wrap it around the cleaned portion of the hose bib. Secure it with a hose clamp. For a less permanent installation, you can use several layers of tape or rubber bands, but don't expect them to last long.
Another approach is to drive a copper grounding rod (six to eight feet long!) into the ground, and connect your ground wire to it. Grounding rods are available at places like Home Depot, but it sure is a lot of trouble.
My ground consists of two eight foot copper pipes driven into the ground most of the way AND a connection to a hose bib. It works quite well.
The lead in wire for the ground is not as critical to keep clear of objects as in the case of the antenna. Just bring the other end of the wire to the radio and screw it to the ground connection.
Congratulations! You're done. Have fun with the radio. Try it with a shorter antenna, a higher antenna, a longer antenna, another ground, and you'll find that it tunes differently in all those cases. Don't forget to try both antenna connections (but not at the same time!)
If you want to do more with antennas, antenna tuners, and crystal
radios in general,
here is one really good link: CLICK HERE.
More info for an antenna tuner.