G5RV ANTENNA

[K3ZW]

Hi all.  I live on a city lot. I have about 80 feet between trees and 35 feet of height. I want to put up a full size G5RV ( 102 feet). So to put this up I will have to let an end or ends droop. The question is....... Should I have 11 feet droop at each end or run one leg full lenght straight and droop 22 feet at one end

[Steve - K4HX]

Make it balanced - 11 feet on each end.

[ke7trp]

Agreed.  I ran this way for several years.  I had about 15 ft drooping down. 

C

[aa5wg]

You could put up a center fed "Zepp" and use it with a link antenna coupler.

The antenna would be good for the lowest band it is cut for and all above bands plus full coverage of these bands.  

Chuck

[WA2ROC]

How about 130 feet of wire, with 25 feet at each end going down a tree trunk (high enough so nobody's hands could reach it) with a center insulator. 

Use open wire, ladder line, window line, etc to a balanced tuner. 

All bands down to 75/80 meters and MAYBE 160 0n a good day with a good tuner.

[ke7trp]

Thats exactly what I ran Dick.  Worked FB for years on all bands.  160 only when I fed as a marconi. 

BTW, Nice to work you on 20 meters!

C

[W2VW]

There's a lot of good posts on this site concerning using less than resonant lengths of doublets.

I can't seem to make the search engine work for this.

Droop works and I've used it myself. One wire for all bands is a situation where one may want to consider the drooping portion's effect on radiation patterns on the higher bands.

You certainly do not need a full 125 -135 feet of doublet to get good performance on 75/80.

Consider open wire line all the way to a coupler. Coax after a coupler can work but can also land up lossy in some situations. If the installation is in a neighborhood full of consumer electronics pay special attention to reducing any common mode currents in the feed.

[w3kmp]

Try using goggle with this:   site:amfone.net zepp

This will search amfone.net for zepp

For G5VR  site:amfone.net G5RV


Ken
w3kmp

[W4EWH]

I want to put up a full size G5RV ( 102 feet). So to put this up I will have to let an end or ends droop. The question is....... Should I have 11 feet droop at each end or run one leg full lenght straight and droop 22 feet at one end

I've never had any luck with G5RV's. No disrespect to the designer, but I think the G5RV is a compromise antenna, designed to allow pi-network output transmitters to achieve some emission on all HF bands. In other words, it's more about providing a "Less than 3 to 1" match than it is about efficiency.

I'll vote with other readers who recommend a different antenna design. Tuners are cheap.

My 2 cents.

Bill, W1AC

[Tim WA1HnyLR]

In the usual form I have never heard a strapping signal  from a G5RV antenna..The best policy is to put up a length of wire between the two highest points that are the farthest apart and feed it with open wire line to an appropriate tuner. NO  ferrite BALUNS ,especially if the antenna length is significantly shorter than a half wave. You can make a short antenna into a reasonably efficient radiator if certain conditions are met. The open wire line MUST use a heavy gauge wire at least#10 . This is to keep losses low. Antenna insulators with low leakage are most important ,being that the voltages involved will be higher than they would be if the antenna was 1/2 wavelength long. The standard methodology of feed to a G5RV is a joke. The impedance that the antenna system presents the coax feed at the transition point from the open wire line must be in the order of 50 ohms and not too reactive. A G5RV does not measure up. There is nothing magic in the 102' length of the G5 RV other than it is a 1-1/2 wavelength antenna on 20 meters with a half wave length of balanced feed line to the coass cable. This provides a 2:1 impedance mismatch to the coass assuming 50 ohm line used. I have developed a G5RV antenna that works parts of 5 bands that does not require a tuner 3680-3710(80)  7200-7300(40)  all of 17 meters. 28.9-29.2 (10) and 50.4-50.8(6) The antenna is in the developmental stage so I am not going to release specific at this point in time. De Tim WA1HnyLR

[Steve - K4HX]

Usually those running G5RVs have them at rather low heights. Put one at 70-80 feet and no one will be able to tell it from a full-sized dipole.

I've never had any luck with G5RV's. No disrespect to the designer, but I think the G5RV is a compromise antenna, designed to allow pi-network output transmitters to achieve some emission on all HF bands. In other words, it's more about providing a "Less than 3 to 1" match than it is about efficiency.

All antennas make a comprise in one area or another. G5RV most certainly was not making any major compromises for his orignal purpose. The antenna is 3 half-wavelengths on 20 meters. This creates some gain in a cloverleaf pattern - just the geographical coverage he wanted on that band. It was later discovered the length provided reasonable impedances on many other bands, making the matching easier. Crappy implementations (lower quality ladder line and baluns), and as I said above, commonly finding installations at low heights have unfairly given this antenna a bad rap.

[ke7trp]

I agree Steve.  I have heard these antennas many many times.  Some are piss weak and some are strong. Alot of factors I guess.  Tim, I agree with you when you say the best way is to put up as much wire as you can with the open line to a balanced tuner. Thats what I run and have run for years. 

I am intersted in your new design,  I have a 4 element mosely beam up as you know, I only use the Wire for 80 and 40.  I wish to get rid of all the tuners, switches and OWL runing around the property

C

[Steve - K4HX]

It pretty much boils down to the right length of wire and feedline.

http://www.w5dxp.com/notuner.htm

And lots of info here.

http://vk1od.net/antenna/G5RV/

And here.

http://vk1od.net/antenna/G5RV/optimising.htm


And here.

http://www.w8ji.com/g5rv_facts.htm

And finally there is the ZS6BKW that yields less than a 2:1 SWR (w/o a tuner) on 40, 20, 12, 10 and 6 meters! A tuner is needed on 30 and 15 meters. The SWR (w/o tuner) is 7:1 on 80 meters but should still do reasonably well with a low loss tuner. The flat-top length is just over 90 feet, so it can fit in tight spaces. The 450 Ohm feeder length is 40 feet.

www.nonstopsystems.com/radio/ZS6BKW.pdf

The link has a graph the allows for a wide range of options in flat-top length and 450 Ohm feeder length.

[K1JJ]

This is vely, bery interesting Steve.  A stroke of genius to use swicthed-in variable lengths of open wire (1/2/4/8/16' lengths)  to match any band with no tuners. Remote controlled wud be cool.

http://www.w5dxp.com/notuner.htm


For the last 15 years I've used hardline and coax only - and love the ease of use. This ant is a natural.  I'd like to try it stretched between two towers at 190'.  

Even on 75M there would be plenty of high angle for local use - and would be a killer farther out.  Using remote relays to tap in the proper matching feedline would make it quite the complement to my SDR radio. All bands with a mouse click. But I would use better quality, heavier, homebrew open wire.

The only downside is on 20M where the pattern becomes a cloverleaf and then an octopus on 10M.   40M will be a sharp figure 8, but WTF - it's a multiband antenna.

Another multi-band idea would be to have a 160M dipole fed with coax - with vacuuuum relays for each band at the proper points along the flat top. The control wires (lamp zip cord) would come down directly to the ground at right angles and terminate at a central point on the ground for remote control activation. This would give a true 1/2 wave dipole for each band.  The vac relays wud have to handle some series voltage if QRO were run.


About the G5RV.... W8JI hit it right. Many G5RV's are a newbie's first choice and they usually get zig-zagged around the backyard at 20' high. Bad rap.  I've often threatened to put one up FLAT at 90' and do an A/B. On 75M anyway, we'd never see any difference compared to a dipole. W8JI's test results were amusing, especially when he switched labels and called the G5RV a standard dipole and vice versa. It's the antenna we all love to kick in the gawd-dam BA's when we're in Jersey. As far as coax-fed multi-band antennas go, at a decent height and flat, it's probably better than most gimmick ants - certainly better than a Gotham vertical.

T

[K5UJ]

There are bands where the G5RV has a high vswr on the line and with coax that results in high loss.

I read W8JI's webpage.  I've never used this antenna.  He reports A/B testing but the testing he reports is "on-air" with ham stations via skywave.   If you want to get serious about A/B testing and provide valid results you have to measure the antennas locally from several points using a FIM and eliminate variables except for the two antennas.

Anyone can design any kind of multi-band antenna they want and it may in fact work well but there is never any free lunch--the more matching components you put out there--baluns, stubs, relays, capacitors, traps....the more junk there is outside waiting to fail during your 300+ watt 100% d/c 10 or 20 minute transmission.

This is why center fed 1/2 w. dipoles fed with ladder or open wire line and a robust tuner (KW matchbox or better) are favored to cover all of 80 and a few other bands.  Efficiency could be the same but they are simple, if built right, not much outside to go wrong.

Rob

[Steve - K4HX]

The only downside is on 20M where the pattern becomes a cloverleaf and then an octopus on 10M.   40M will be a sharp figure 8, but WTF - it's a multiband antenna.

A neat way to avoid pattern break up is to use a DJ4VM-type quad for the higher bands (20-10 meters). I suppose you could even make one for the lower bands in inverted-v fashion off a single support or mount is horizontally like the "sky hook" loops.