20 meter long wire

TX Four Square Antenna - A 220-ft tower that has five catenary lines, each about 500 feet long. Four of these lines, running NE, SE, SW, and NW support four 1/4-wavelength wire verticals used in a 160-meter four-square antenna.

W5GI Mystery Antenna  ^{updated  pop} - W5GI Mystery Antenna is a multi-band wire antenna that performs exceptionally well even though it confounds antenna modeling software. This antenna covers 80 to 6 meters with low feed point impedance and will work with most radios, with or without an antenna tuner. It is approximately 100 feet long, can handle the legal limit, and is easy and inexpensive to build. It�s similar to a G5RV but a much better performer especially on 20 meters.

QRP Antenna 80-40-20-15 End Fed Antenna - A long wire antenna that will load up on 80, 40, 20 & 15 meters without an antenna tuner and without balun coils