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Author Topic: G5RV vs Rotatable 10m Dipole  (Read 5034 times)
KE4VVF
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Posts: 61




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« on: January 12, 2012, 07:05:51 PM »

I have been using a 102' flat top G5RV @ 50' for 10 meters.  I'm contemplating building a 10 meter rotatable dipole and mounting it at 23'.  Other than the advantage of rotation, will the 10 meter dipole perform better than the G5RV in a fair test? 

I've heard good and bad comments about using a G5RV on 10 meters. Everything from "I'd be better off transmitting on an underground sewer line" to "It has excellent gain where there are no nulls in the pattern". 

Thanks,
Tony KE4VVF

Edited to add " 102' "
« Last Edit: January 12, 2012, 07:42:07 PM by KE4VVF » Logged
KE4YOG
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Posts: 182




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« Reply #1 on: January 12, 2012, 07:35:52 PM »

I can only speak about the double length G5RV. I have worked many stations since October on my antenna. I am not a contest like operator. I listen more than I transmit. Any way if I can get all of my QSO verified I have made DXCC with about 110. I have made several contacts with 5 to 10 watts all over the world. I normally run 100 but at times when conditions are good I try QRP. The biggest problem I have is I have trouble getting to Southeast Asia. Vietnam, Hong Kong and so forth. I have worked India and I have heard China, Hong Kong, S. Korea but I could not work them. The rotable dipole would help with that. That is just my experience. What little I have. Now anoter question are you a Tech or General. If you are a Tech I think the dipole may help you more. If you are a General and can only have on antenna then the G5RV. Mine works wonderful from 80 up. I can work 160 but my antenna tuner does not like it.
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KE4VVF
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Posts: 61




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« Reply #2 on: January 12, 2012, 07:52:17 PM »

@ KE4YOG, Ray

I'm still a Tech but will be a General soon.  I run 100 watts on an IC-746 (not Pro).  I have only one space left for a rotatable dipole, all my other masts are filled with VHF antennas.
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W7ETA
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Posts: 2528




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« Reply #3 on: January 12, 2012, 08:36:52 PM »

A ten meter antenna at 50 feet will have a different pattern than one at 25 feet.  At various times, one will be better than the other.

Making one rotatable will have that one better for signals that the other antennas receive along the axis of the wire.  One wave length for 10 meters is around 33 feet.  In theory there is an advantage to having your rotatable dipole at 33 feet.

For me, one of the great things about ham radio is that we can experiment building simple antennas.

Check out W4RNL's site for a great run through antennas; verticals with out vertigo is a great read, as is the section on self contained antennas.

73
Bob
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K0MF
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Posts: 14




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« Reply #4 on: January 14, 2012, 09:08:58 AM »

You didn't mention what type of operating you wanted to focus on, and what the G5RV orientation is..

Without firing up my EZNEC, I'm guessing that the majority of the 10M radiation will be towards off the ends of the wire.

If you want to work stateside, the dipole at 23 feet will work very nicely.  Not sure you even need to rotate it, just make it broadside east-west.

If you want to work DX. I suggest you consider something like a ground plane or halfwave vertical standing off by itself (as opposed to a 1/4 wave monopole).  You will get omnidirectional coverage and a low radiation angle, important for DX.  Many years ago my first 10M antenna was a CB groundplane with shortened elements, worked like a champ. 

The ability to switch between the G5RV and the vertical with opposite polarization will provide a good "fill in" capability.  Also, you'll learn a lot about the G5RV pattern too.

Today I still use this approach, a yagi on tower for most QSO's, but also a HyGain AV640.  There's certain times of day and directions that the vertical works as well as the yagi.

You can build a nice multiband groundplane for 40,20,15, and 10M with a Moseley 4BTV (about $125 from DX Engineering) on a 10-20' pipe and some resonant radials ( as few as 2 will work).  I really like the HyGain AV620/640 series, but more $.  Or you can build a single band version for 10 with some copper tubing, there's lot's of articles on this method.


Good luck with whatever you choose!

Mike K0MF
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K0MF
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Posts: 14




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« Reply #5 on: January 14, 2012, 09:25:14 AM »

That 4BTV is built by Hustler, not Moseley, sorry...

K0MF
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EI4GMB
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Posts: 166




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« Reply #6 on: January 14, 2012, 03:01:46 PM »

Hi Tony,

A Standard 102ft G5RV is designed for 80m,40m,20m & 12m. It displays significant losses on all other bands including 10m. I think you would be better off making a dedicated 10m dipole and switching between the two antennas.

73,

Fred EI4GMB
« Last Edit: January 14, 2012, 03:05:27 PM by EI4GMB » Logged

'You can never plan the future by the past'

'Those who don't know history are destined to repeat it.'

Edmund Burke (1729-1797)
WB6BYU
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Posts: 13113




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« Reply #7 on: January 14, 2012, 07:09:46 PM »

As far as radiation patterns go, the G5RV at 50' has about 6dB gain at 10 degrees
vertical angle compared to a half-wave dipole at 23 feet, both antennas being measured
in their optimum direction.  For a half wave dipole at 50' the difference is about 3dB.

But at a 20 degree vertical angle the half wave dipole at 23' has about a 10dB advantage.

That's because an antenna at 50' has a null at about 20 degrees due to ground reflection,
with a peak at 10 degrees.  An antenna at 23 feet has its main lobe around 20 degrees.

In other directions, the ratios will be different.

So the question of which is better is highly dependent on the relative directions of the
two antennas compared to the station you want to work, as well as the desired distance
(which determines the optimum angle of radiation.)

The maximum radiation from the G5RV at 50' is at about 45 degrees to the wire, with a
smaller lobe broadside to the wire.  If those lobes point in the DX directions of interest,
then the higher antenna is likely to be the best.  But in the inbetween directions, a
dipole may well be better (even if it isn't rotatable.)


My suggestion would be a fixed dipole at 50 feet.
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NA4IT
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« Reply #8 on: January 15, 2012, 04:59:52 AM »

I use the driven element from a TA-33 as a 10/15/20M rotatable dipole and love it. I have never used (or wanted) a G5RV type antenna, as most of them I have heard on air radiate equally poorly in all directions....

de NA4IT
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EI4GMB
Member

Posts: 166




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« Reply #9 on: January 15, 2012, 01:32:11 PM »

I have never used (or wanted) a G5RV type antenna, as most of them I have heard on air radiate equally poorly in all directions....

de NA4IT

A properly installed G5RV is a good antenna on its design frequencies. I even reached phone DXCC using the JR. version and 100W during sunspot minimum. See eHam reviews.

Kind Regards

Fred EI4GMB
« Last Edit: January 15, 2012, 01:49:20 PM by EI4GMB » Logged

'You can never plan the future by the past'

'Those who don't know history are destined to repeat it.'

Edmund Burke (1729-1797)
KE4YOG
Member

Posts: 182




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« Reply #10 on: January 15, 2012, 01:46:53 PM »

I am enjoying my G5RV. It may be just because I am ignorant of anything else. Right now G5RV and other wire HF antennas are my only choice. It has done good for me from 40 up. I just need to get my extra ticket so I get more band and I feel that would drastically help me on 80, 40, 20, and 15. I am using the double length so that may play into things I am not sure. I have 1 or 2 contacts on 160. If I can get back all qsl cards to verify things I will have earned DXCC since Oct.
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STAYVERTICAL
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Posts: 854




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« Reply #11 on: January 28, 2012, 11:20:42 PM »

Having used both types of antennas, I can advise you to build the rotary dipole.
The G5RV is fine as an antenna, but its radiation pattern on 10m is going to be multi-lobed and you may be lucky or not to get a lobe where you want one.
Remember, there is nothing magical about the G5RV as a radiating antenna, it is just an attempt to get a combination of wire length, feedline lengths and feedline types which will combine to give a reasonable match over a number of bands.
Other than matching, the antenna simply radiates the same as the length of wire comprising the antenna.
On some bands it will have few lobes, on others many. It is not designed for DX, just a good wideband radiating solution.
A dipole on the other hand is very "well behaved", with its characteristics well known at different heights, and a simple radiation pattern.
I found when I rotated mine, the peaks were quite broad, but the nulls were very sharp.
Useful if you have some source of qrm you want to minimise.

Hope this helps,
73s
« Last Edit: January 28, 2012, 11:23:01 PM by STAYVERTICAL » Logged
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