A simple, low-cost, trapless short vertical antenna which amazingly works on three HF bands (20, 15 and 10 meters).
http://dt.prohosting.com/hacks/antenna/petlowany.html
Describes many different designs. Worth take a look.
http://www.qsl.net/on7yd/136ant.htm
The Radial Wire aerial is simply a length of wire laid on the ground in a straight line. Radial Wire aerials are a very simple and easy way of obtaining amazingly good radio reception on longwave, mediumwave and the lower shortwave bands.
http://radiodx.com/spdxr/Radials.htm
A hidden antenna must be just that: hidden. So don't install an antenna, but something else. Lika a bird feeder.
http://www.hard-core-dx.com/nordicdx/antenna/hidden/birdfeed.html
add external antenna connector to your AM radio which does not have it.
http://www.hard-core-dx.com/nordicdx/antenna/loop/amloop.html
A Beverage antenna is a very giid antenna type for medium wave DX use.
http://radiodx.com/spdxr/Beverages.htm
reception antennas which work close to earth.
http://www.hard-core-dx.com/nordicdx/antenna/special/swlant.html
You have a fence, add a tuner, some wire and a ground rod -- and you have a fine, hidden antenna.
http://www.hard-core-dx.com/nordicdx/antenna/hidden/fence.html