The K3MT "Grasswire Antenna"
The K3MT "Grasswire Antenna".
Accessed on 27 November 2015, 19:46 hrs, UTC.
Original author: M. Toia (K3MT).
If you're looking for the ideal stealth antenna, the "Grasswire Antenna designed by M. Toia (K3MT) may be what you're looking for. I posted a few articles on this antenna on 12 and 26 October 2013, but I didn't experiment further until moving to my new QTH in the Puna District.
The antenna is incredibly simple and easy to use. Basically, the "Grasswire Antenna" is an end-fed long wire antenna that is built either on the ground or a few inches above ground. First used by K3MT in 1988, the grasswire antenna was made from 204-feet/62.19 meters of #18 AWG magnet wire laid along Toia's property line, anywhere from 1 inch to 6 inches/2.54 cm to 15.24 cm above the ground. You can use either an 8-foot/2.43 meters ground rod or an optional counterpoise wire to complete the antenna. The only labor intensive part of the project is the winding of a trifilar 9:1 balun to match the system. Like K3MT, I used a T-200-2 core for the balun. The antenna is largely resistive, ranging from 150 to 500 ohms. According to K3MT, the grasswire antenna radiates a vertically polarized signal off the end of the wire. The antenna is lossy in all directions, but is less lossy off the far end of the wire. The antenna is very quiet on receive. I have made contact with the grass wire by pointing the far end of the antenna to the U.S. mainland. On 40 meters, the grasswire performs almost as well as my 40 meter inverted V antenna. The antenna is a compromise, but it does work. The grass wire is nearly invisible and could be used in deed-restricted housing (HOAs and CC&Rs). The grasswire antenna is suitable for portable or emergency use.
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Aloha es 73 de Russ (KH6JRM).