G5RV - The Ultimate Field Antenna

Started by Scott, September 02, 2012, 12:18:16 am

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Scott

Bold title, right?

The G5RV dipole is one of the cornerstone wire antenna classics.  If you don't believe me, go read ARRL Wire Antenna Classics.  They've got just about an entire chapter dedicated to the G5RV, and for good reason.

The G5RV is essentially a 102' ladder-fed dipole, named for the callsign of the German operator who designed it to overcome the need for forward-deployed German forces to carry multiple antennas.  Through an ingenious use of the 450-ohm ladder line twin-lead feed as a variable matching section, this single dipole antenna can be tuned for use on 80m - 10m, and will run on 40m, 20m, and 15m without a tuner (*cough*mostly*cough cough*).

A rolled-up G5RV will fit in a lady's purse and weighs about 4 pounds.  Most modern commercial offerings have a 4:1 balun at the bottom of the 450-ohm ladder line so you can use familiar 50-ohm coax to feed it.  All you have to do is hang the bitch up, plug in your favorite field-friendly tuner, and you're on the air multi-band.

Best part?  These things are CHEAP.  The one I'm using came from AES for $50.

Downside:  the 10m access is a little bit of a lie unless your tuner is sweet.  Trying to tune that much wire for 10m pretty much requires God's permission, and he's strict about it.

More downside:  102' is far, y0.  If you don't have the space for it, welcome to the club.

Upside to more downside:  you can mount it in an inverted vee configuration, but don't let the interior angle pinch tighter than 120 degrees or you can forget tuning the lower bands.  Higher bands are hard enough as it is.

Super upside:  NVIS-friendly, baby!  Flat-top that bitch at 1/4 wavelength above the dirt and booyaa -- you're ready for regional / local HF.

Also, remember that for any dipole antenna, the final 1/6 of each wire is pretty much just for electrical matching.  If you have to do creative bends / tweaks to make it fit, do them here.  Impact to your signal won't be significant.

Hope this helps!  If you don't have a G5RV in your HF-equipped go-kit, you're doing it wrong.

MIA

Great review.

The G5RV is a study in compromise, but one that works surprisingly well. It was the first wire antenna that I owned, and I still keep one in the air, and one in my comms go kit. My old IC-746 has never had a problem tuning one, whether on 80m or 10. The 746 will even tune it on 6m (far from ideal, but workable). Using a G5RV I worked over 30 states and almost 100 grids during my first two months on 6 meters, before getting a small beam. They usually don't quite match up to a band specific dipole, but they do work very well.

One correction, though. Louis Varney (G5RV) was English, not German. ;?)

Scott


Paul

I think if you do a little investigating you'll find that the 'G5RV' was designed and built as a single band wire antenna with some gain.  It was not made to be multi-banded, and Mr Varney never made claims for it being more than a 20 meter antenna.  If it's constructed correctly, 20 meters is the only band where it will not need a tuner for use.  It can be usable on the non-WARC bands, 10, 15, 20, 40, and 80 meters because it is harmonically related.  It's a very good 20 meter antenna, on other bands it's a mediocre compromise at best.
- Paul

gil

So, here is my question for you guys with more practical experience: The lot my house is on is about 100' wide. I can't really use the length, which would mean a wire above the driveway and almost to the street; not very discreet. The top of the roof is at 20'. I could use a few feet of mast tube above that. I probably would have to use an inverted V antenna of some sort. Feed point would need to be in the middle. I thought about a folded terminated dipole, but is is a bit large.. The G5RV might be the solution. Maybe a doublet fed by ladder line.. What other solutions are there and which one would be best?
With an antenna that low, it would pretty much be for NVIS on 80/40. If I get bonus bands, so much the better. I have a vertical for 10/15. My K1 and K2 have built-in ATUs.

Thanks,

Gil.

Paul

I wouldn't worry much about that NVIS thingy, mostly it's just a matter or propagation.  I've used an 80 meter full wave loop that may have been 20 feet above ground in spots, mostly less though.  That loop worked well on almost all bands, didn't like 15 meters much though.  It was fed through a tuner and used ladder line.  It wasn't all that 'regular' in shape, roughly rectangular with very 'rough' corners, sort of.  Also roughly N/S oriented with the longer axis.  The short sides were something like 40 - 50 feet long, and the long sides something like 60 - 70 feet long (lots of give/take in those measurements).  That loop served well into South and Central America when there were 'problems' down there.  Also did remarkably well during Dessert Shield/Storm.  Not bad for a NVIS antenna, huh?  It was hung from trees and lasted till an ice storm 'got' the trees.
Most 'wire' antennas aren't too 'picky' about being bent a little.  Put up the longest antenna you can and play with it.  I'd rather use a balanced antenna than a 'longwire'/randomwire antenna, but that's personal preference.  I also don't much care what an antenna 'looks' like (within reason) so never worried about that aspect.
YMMV
- Paul

recon_prepper

I have a g5rvmax its 210 foot long the thing is massive. The center is about 40 feet up and the two sides angle slightly so its somewhat v shaped. Not an inverted v like it should be.
That said I have talked all over the world with it.
Im in Georgia USA and have talked to australia, ireland, croatia, spain, california, washington state, canada, new york, and more to give you an idea.
I use all the frequencies it will give me.
10 meter works fine.
160 meter is surprisingly well also as I routinely hear a net of tenn. guys on 160 chatting. needless to say I am impressed.
I have a 72 foot tower sitting on the ground right now and as soon as I get the hole dug and footing poured I will put the center of the g5rvmax on a flagpole like system where I can raise and lower it up to the top. One day I hope to get a good beam antenna up there as well.
I also have a cb, with linear amp.
Ftdx 3000 yaesu
897d yaesu
several small handhelds 2 meter and 440 dual bands
ft-7800r yaesu
2 meter antenna is a jpole but hope for a yagi soon.
and always looking for more good deals.