The 10/11 Meter Ground Plane Antenna
Are you looking for an antenna that does not require a tall tower, mast or an acre of land? Then a simple ground plane antenna may be just what you need! Ground plane antennas have been used for many years for both amateur radio communications as well as citizen's band radio.
Although primarily mounted on a mast and used for short range base to mobile communications, ground plane antennas also make good DX antennas. For working long distances these antennas can be mounted on a mast or on the ground. A ground plane antenna mounted on the ground is often called a "ground mounted vertical" antenna.
Ground plane antennas can easily be built for most bands. In theory the vertical element is 1/4 wavelength long and so are the radials. In practice the vertical element tends to be a little taller or the radials are made slightly shorter (about 5% shorter).
Also according to theory a capacitor should be added to the feed-point of a ground mounted vertical antenna to match impedance but many antenna builders, including some commercial manufacturers, do not add a capacitor.
To match the impedance of a mast mounted ground plane antenna the radials are brought down at about a 45 degree angle. This is simple to do with smaller VHF and UHF antennas as the radials are usually made of stiff wire and are easy to bend down into position. Insulators attached to the ends of wire radials and tied off with rope are used on larger homebrew HF and CB antennas that are mounted on a mast.
The vertical element for this 10 meter antenna is made with three sections of aluminum tubing that are four feet long. The two largest sections of aluminum tubing are notched out at one end and are assembled with hose clamps. The vertical element length of the antenna shown in the video is 8' 7" (2.616 m).
A short piece of PVC pipe is used as an insulator between the vertical element and the mounting plate. U-bolts are used to mount the vertical element and the mast to the mounting plate. 14 Gauge solid copper wire was used for the radials for this antenna but you can also use stranded wire. The calculated length of the radials is 8' 3" (2.515 m) and the radials were made one inch longer for connecting to the mounting plate.
The U-bolts used for this project are slightly wider than the mast. The U-bolts that attach the vertical element to the mounting plate have to clear the mast pipe on the opposite side. On this antenna my U-bolts were slightly too large for the PVC pipe. I used a scrap piece of aluminum as a shim between the PVC pipe and the mounting plate to fasten the vertical element.
Below is an image of a simple quarter-wave ground plane antenna made with wire.
Video Instructions Watch the video below to learn how to build this antenna.
Running the Radials
For a ground mounted antenna the wire radials can be attached to the U-bolts. The mounting plate should be installed 3 to 4 inches above the ground.
If desired an additional hole can be drilled in the bottom two corners of the mounting plate so that the radials can be attached to both sides of the plate and ran equally in different directions.
Mono-band ground mounted vertical antennas work well using just four radials. The use of 120 or 360 radials is ideal but you probably will not notice a huge difference in performance when using only three or four radials. The wire radials can be installed on top of the ground or buried a few inches underground.
For an antenna mounted on a tall mast, the radials can be attached to either the mounting plate or a guy wire bracket mounted directly below the antenna. Run each radial through an eye-bolt in the guy wire bracket and secure with wire rope clips, then attach the ends of the radials to the U-bolts. Stretch the radials out at about a 45 degree angle and tie off with insulators and rope. Be sure to make the radials slightly longer to allow for the insulators and connection at the base of the antenna. By the way, you can also try using guy wire and insulators for the radials. You will need to use three or four radials spread apart equally for an omni-directional pattern.
If the antenna is to be mounted on a mast then the antenna should be grounded. Attach a ground wire to a U-bolt on the mounting plate and run it down the mast to a ground rod. Antennas mounted on the ground may already be grounded by the mast or water pipe that the antenna is mounted to. If unsure of a proper ground then install a ground rod next to the antenna and connect it to the mounting plate using a suitable ground wire.
Tuning is by either lengthening or shortening the vertical element. Often times the vertical element is a few inches longer than the calculated quarter-wave length.
Safety First! Please use caution and keep common sense safety rules in mind when installing an antenna. Never install antennas near power lines or in any location that would place people or pets within the near field radiation pattern of an antenna. All users understand and agree that the owner of this web site is not responsible for accidents or other mishaps that may have been caused directly or indirectly as a result of the information published on this web site and/or in any of the video presentations.