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A ground plane antenna for 2m or 70cm is one of the simplest antennas to build and get working, and it can work quite well for repeater or simplex operation. It is easy to build for other bands as well. I’ll show you several different construction methods that you can use, based on the materials you have available.
The antenna consists of a 22 foot long 2X2 mast, or two 12 foot pieces may be bolted together, and the radiators are #12 or #14 copper house wire with plastic coating. The radials may be cut from 4 or 5-conductor rotor cable or made from individual wires.
It can be built with very predictable results, even near trees or buildings, due to it’s low feed impedance. They are easy to build, especially for the UHF bands as you can simply use a SO-239 or N-Type chassis mount. For VHF and below however, they require some more heavy duty construction.
A vertical antenna with radials bent down at approximately 45 degrees will have a natural impedance around 50 Ohms making it a good match to the radio in use. To attach the radials to the flange of the SO-239 I use small bolt/nut/lockwasher sets in 4-40 size about 1/2" long.
The Quarter Wave Ground Plane is a very common, simple, and effective antenna. Generally it consists of a quarter wave vertical radiator connected to the center of the coax feeder, and 4 radials, often sloping downwards, that are also about a quarter wave long.
When properly built, it should act as a 1/4 wave ground mounted "ground plane" type antenna on most of the design bands. It consists of 3 sections of thick wall PVC connected together and may be self supporting, but guying is recommended due to its 33 feet + overall height!
In this article you will find a basic drawing of a J Pole antenna and the lengths, spacings, and other details to build one for the 17, 15, 12, or 10 meter bands. The J Pole antenna is a simple antenna to build for most builders and requires little skill or tools to make it work properly.
