G5RV antenna
The G5RV antenna is a dipole with a symmetric resonant[1] feeder line, which serves as impedance matcher for a 50 Ohm coax cable to the transceiver.[2][3]
Origin
Louis Varney (G5RV) invented this antenna in 1946.[4] It is very popular in the United States.[5] The antenna can be erected as horizontal dipole, as sloper, or an inverted-V antenna. It can operate on all amateur radio bands within 3.5–30 MHz.[5][6]
Impedance
While the widely used 50 Ohm coax cable is often used to directly feed this symmetric antenna,[7] this is not good practice and should be avoided, since it can result in RF interference due to high current flow on the outer surface of the coax braid. A 1:1 current balun should be used between coax and ladder line.[8] The balun not only prevents RF interference but reduces receive noise and increases performance [9]
The dipole elements are 15.55 metres (51.0 ft) and the impedance-matching symmetric feedline (ladder-line or twin-lead) can be either 300 Ohm (8.84 metres or 29.0 feet) or 450 Ohm (10.36 metres or 34.0 feet).[10] As is in general the case for all electric antennas, the height of the G5RV above the ground should be at least half of the longest wavelength to be used.[1] The ends of the symmetric feedline are soldered directly onto a 50 Ohm coax cable to the transceiver.[2] A length of at least 20 metres (66 ft) of 50 Ohm cable is recommended.[11] An antenna tuner is necessary for this antenna.[10]
There are many variants of the G5RV antenna.[12]
References
- 1 2 HF Antennas for all locations (L. Moxon, G6XN)
- 1 2 G5RV multi-band antenna (Louis Varney, G5RV) http://www.astrosurf.com/luxorion/qsl-g5rv.htm
- ↑ The G5RV Multiband Antenna ... Up-to-Date (L. Varney, G5RV in The ARRL Antenna Compendium Vol. 1)
- ↑ (Heys, J. (G3BDQ). Practical Wire Antennas - Effective HF Designs for the Radio Amateur
- 1 2 American Radio Relay League. ARRL Antenna Book, 21st ed. Chapter 7
- ↑ de Maw, D. (W1FB). Novice Antenna Notebook
- ↑ Rüegger, M. (HB9ACC). (2008-05-24). Rund um die Antenne http://www.wreiner.at/2008/05/24/rund-um-die-antenne-von-hb9acc/
- ↑ Maxwell, W. (2010). Reflections III: Transmission Lines & Antennas
- ↑ VK4MDX. What I learned from building my own G5RV / ZS6BKW Antenna http://vk4mdx.wordpress.com/2009/02/15/what-i-learned-from-building-my-own-g5rv-zs6bkw-antenna-part-1/
- 1 2 Carr, J. Practical Antenna Handbook, 4th Edition.
- ↑ Haerle, J. M. HF Antenna Systems: The Easy Way.
- ↑ Vincent, M. (G3UKV). The ZS6BKW Multiband HF Antenna Revisited http://www.ab4oj.com/dl/sprat_zs6bkw.pdf