Here's a reference: http://en.wikipedia.org/wiki/G5RV_Antenna
Now looking at the lengths, it is no more than a 1/2 wave antenna on 80M
with a coax feed at the center. {51' + 51' + 34 = 136'} While the math
shows the antenna overall to be long for 3.5 MHz, it does take into
effect the velocity effect, thus the reduced electrical length of the
balanced feed system. It is only about 32 ft electrically due to VF.
Threfore the effective antenna is about 134 feet or so.
It is much like a dipole with drooping ends except the drooping part is
the balanced feed or at the center and not the ends. It is also
harmonically related to the 3.5 x 2 = 7.0, 3.5 x 4 = 14.0, 3.5 x 6 =
21.0, 3.5 x 8 = 28.0 numbers based on the 5 bands available when the
antenna was developed. The general conclusion is that the antenna does
require a tuner for all band/frequency operation.
This is no difference than a 135 ft flat-top fed with open wire or
balanced feed in which a tuner is required for all band operation.
One point to the original concept, the required length of coax originally
used has a noteable amount of loss due to the original size and type and
length thus it appears to tame the SWR on different bands.
Personally should one have room to put up a 135 ft flat top or as an
inverted V type, then the better choice is a balanced feed system
terminating in a GOOD 1:1 or 4:1 {if you insist} balun. And then use a
good UNUN or common mode choke or current break between the tuner and the
radio. If the tuner is internal to the radio, then put the UNUN between
the radio output and the input to the 1:1 or 4:1 balun.
With the original G5RV design, not some of the hybrids of today, it does
work all bands with a tuner. This includes the new WARC bands.
Personally 135 ft of wire, center fed, with a balanced feed is still one
of the most efficient all band {with a good balun and tuner} antennas for
the money, space, and time.
73
Bob, K4TAX
> Let's not perpetuate the myth that the G5RV was designed as a single
band 20m antenna!
>
> It's worth reading what Varney himself said about his design
> requirements in his first article about the antenna in 1958, which he
entitled "An effective multiband aerial of simple construction":
>
> "Since only an average size back garden was available it was not deemed
worthwhile to construct a beam for the DX bands. Operation on 1.8 and
3.5 Mc/s was an important requisite, but efficient operation on 7, 14
and 28 Mc/s was also desired. The aerial to be described was evolved
and
> proved to work splendidly from 1.8 to 28 Mc/s."
>
> I don't know how the myth began that Varney set out to design a 20m
monoband antenna ????
>
> Steve G3TXQ
>
>
>
>
> On 09/07/2013 08:10, Geoffrey S. Mendelson wrote:
>> Most people don't even know what a G5RV is. It is NOT a multiband
antenna, it was a 20 meter(ish) dipole fed with coax. The dimensions
were not chosen by some radio magic, the length of the top section was
the size of Vareny's garden.
>
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