Entries from March 2014 ↓

G5RV ANTENNA

Not a week goes by that I hear someone on 75 meter SSB proudly announce he is using a G5RV antenna. I resist the urge to ask if he really knows what a G5RV antenna is because if he knew he would not be so proud of using it on 75 meters. The G5RV is a 20 meter antenna!! If you really have a G5RV you would be better off trying to load your triband beam on 75 metres!

G5RV invented his antenna because he wanted a simple and cheap wire antenna for 20 meters that also had some gain. You can increase the gain of a half wave dipole by making the legs longer. In the case of the G5RV each leg is 3/4 wavelength long on 20 meters and provides about 3db gain. It also provides a high input impedance.

The high input impedance is handled by a 1/4 wave section of open wire line. It is about 33 feet long, 1/4 wave on 20 meters and transforms the high antenna impedance to close to 50 ohms for a match to normal coax.

All this trickery only works on 20 meters making this a single band antenna.

This did not prevent hams from trying the antenna on other bands. When they discovered it did not work well on other bands, they extended the ladder line to an antenna tuner and tuned the antenna system to allow it to work on other bands. Only now it is no longer a G5RV. It has become a non-resonant dipole with 50 foot legs.