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G5RV (Yet Again)
As someone who is relatively inexperienced with the hobby, I am amazed
at the confusion and mysticism surrounding the "G5RV" antenna. It appears to be nothing but a dipole, with a length of "balanced line" to transform the impedance to a better match for coax at certain frequencies. A little consideration reveals that this antenna should suffer from unwanted return currents unless a balun is used (like any coax-fed dipole), and substantial loss in the coax at certain frequencies. So why is this antenna better than two pieces of reasonably long wire driven with balanced line and a tuner? What am I missing? -JJ |
wrote: As someone who is relatively inexperienced with the hobby, I am amazed at the confusion and mysticism surrounding the "G5RV" antenna. It appears to be nothing but a dipole, with a length of "balanced line" to transform the impedance to a better match for coax at certain frequencies. A little consideration reveals that this antenna should suffer from unwanted return currents unless a balun is used (like any coax-fed dipole), and substantial loss in the coax at certain frequencies. So why is this antenna better than two pieces of reasonably long wire driven with balanced line and a tuner? What am I missing? -JJ (A) The G5RV feedpoint impedances are relatively low within some of the ham bands. (B)It's a coax-fed antenna which does not need a balanced antenna tuner which are scarce, complex and expensive. w3rv |
wrote in message oups.com... As someone who is relatively inexperienced with the hobby, I am amazed at the confusion and mysticism surrounding the "G5RV" antenna. It appears to be nothing but a dipole, with a length of "balanced line" to transform the impedance to a better match for coax at certain frequencies. A little consideration reveals that this antenna should suffer from unwanted return currents unless a balun is used (like any coax-fed dipole), and substantial loss in the coax at certain frequencies. So why is this antenna better than two pieces of reasonably long wire driven with balanced line and a tuner? What am I missing? -JJ Marketing. |
As someone who is relatively inexperienced with the hobby, I am amazed at the confusion and mysticism surrounding the "G5RV" antenna. It appears to be nothing but a dipole, with a length of "balanced line" to transform the impedance to a better match for coax at certain frequencies. A little consideration reveals that this antenna should suffer from unwanted return currents unless a balun is used (like any coax-fed dipole), and substantial loss in the coax at certain frequencies. So why is this antenna better than two pieces of reasonably long wire driven with balanced line and a tuner? What am I missing? ============================ Well done! You are correct about the G5RV in every respect. As a multi-band HF antenna it is just another dipole without any magical properties. With the coax (Zo unspecified) its loss is greater than other dipoles. Its balanced feedline impedance Zo is not specified. This important performance parameter can be anything you like and the antenna will still remain a G5RV. It has an approximate impedance match at only one frequency, 14.15 MHz. You will be very lucky to find a resonance in any other band. The impedance match to coax at 14.15 MHz is not at the desirable 50 but 75 ohms. It has a cloverleaf radiation pattern only in the 20m band, sometimes praised as desirable if you work from South America into both Europe and the USA as G5RV often did. As with other balanced line fed dipoles a current or choke balun is best when converting impedance from a balanced line to a tuner plus 50-ohm transmitter. But the biggest joke of all is the half-size G5RV. Mr R L Varney must be turning over in his grave. ---- Reg, G4FGQ |
wrote:
As someone who is relatively inexperienced with the hobby, I am amazed at the confusion and mysticism surrounding the "G5RV" antenna. It appears to be nothing but a dipole, with a length of "balanced line" to transform the impedance to a better match for coax at certain frequencies. A little consideration reveals that this antenna should suffer from unwanted return currents unless a balun is used (like any coax-fed dipole), and substantial loss in the coax at certain frequencies. So why is this antenna better than two pieces of reasonably long wire driven with balanced line and a tuner? What am I missing? It is a pretty good antenna on 80m, 40m, 20m, and 12m because the 50 ohm SWR is relatively low on those bands. A dipole fed by balanced line and a tuner may perform better or worse than a G5RV depending upon the configuration. If one knows what one is doing, the 100% balanced line approach is best and can be done without a conventional tuner as explained on my web page. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Reg Edwards wrote:
It has a cloverleaf radiation pattern only in the 20m band, sometimes praised as desirable if you work from South America into both Europe and the USA as G5RV often did. It has a multi-lobed pattern on all frequencies above 14 MHz. A 102' dipole has a beautiful clover- leaf pattern on 17m. But the biggest joke of all is the half-size G5RV. Mr R L Varney must be turning over in his grave. Antennas are scalable with frequency, Reg. The 102' G5RV is a pretty good antenna for 80m, 40m, 20m, and 12m. That makes the 51' half-sized G5RV a pretty good antenna for 40m, 20m, 10m, and 6m. When Mr. Varney designed the G5RV antenna, there were no WARC bands. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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JJ,
What you're missing is the 'mystique' the advertising department has generated. 'Doc PS - By the way, I have this bridge for sale. Built from gold bricks... |
G5RV originally designed the antenna for gain on the 20 meter band.
Over the years, various mfg. have made minor changes, but the design essentially remains unchanged. (The "double-size" for 160 is not an efficient antenna. Better to feed 260' of wire via ladder or open wire line.) |
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