Topics

Elevated radials


Tadej S52X
 

Hello Group,

I am new here and I have my Butternut HFV6 on my way. Has anyone made any comparison of the elevated radial system with ground radial system? My antenna is going to be installed in the wood and just wondering what is the best solution for best performance.

73s
Tadej, S52X


Craig KC2BK
 

Hello Tadej - I installed my HF6V on the ground, and connected 24 radials of varying lengths on the ground.  Basically, if I can hear a station I can work the station (with 100 watts).  Lots of DX and always nice signal reports.  I have never had a vertical mounted above ground, and have been using various brands for more than 30 years with excellent results - all installed on the ground with radials.  Plus - a lot easier to get to the antenna for maintenance!  Happy to set up a scheduled QSO if you want to hear my station - my HF6V is only 4 months old. 

Craig
KC2BK

On Friday, September 11, 2020, 4:41:25 PM EDT, Tadej S52X <tadej.arcon@...> wrote:


Hello Group,

I am new here and I have my Butternut HFV6 on my way. Has anyone made any comparison of the elevated radial system with ground radial system? My antenna is going to be installed in the wood and just wondering what is the best solution for best performance.

73s
Tadej, S52X


Preben Larsen
 

Hello group

Elevated  radials

Not specifik Butternut Radials, but we have an 80m fullsize,

8 Elevated radials in 1,5m height, feels more efficient than 90 laying on the ground...

vy 73 de oz1fhu Preben

Den 11-09-2020 kl. 22:41 skrev Tadej S52X:

Hello Group,

I am new here and I have my Butternut HFV6 on my way. Has anyone made any comparison of the elevated radial system with ground radial system? My antenna is going to be installed in the wood and just wondering what is the best solution for best performance.

73s
Tadej, S52X


 

Tadej,
There are two schools of thought on this subject.  You say you are setting up in the woods is that correct?  If so there is not a lot of benefit one over the other.  People who are faced with a lot of surrounding objects (homes, sheds, garages and/or uneven terrain) find a benefit getting the antenna elevated.  The main lobe for most bands on this antenna is about 15 degrees above the horizon.  So it doesn't get you much to raise the antenna and radials 20-50 feet because the elevation does not get you any further on DX skip.  Some will argue that raising the antenna and radials will get you less ground reflection which is true but the main interaction between the antenna and ground is what gives you the 15 degree lobe.
The simplest installation is on the ground with as many radials as you can manage.  64 radials at 33 ft. long is a great start.  If you don't have room for 33 ft. wire length than make as many as long as you can and put down shorter radials where needed.  I have had my antenna for along time and over various radial systems.  I have the best effect now with 64 radials most at 33 ft. long and some are bent to fit around objects like my patio, property line and shed.  The antenna worked fairly well (counting QSOs) with 16 radials, half at 33 ft. and the rest shorter.  I added wire over the years and things improved a little but after I did some investigating, I realized that a low SWR did not mean anything unless the feedpoint impedance was near theoretical.  Yes you can get this antenna to tune up using a ground rod hammered into the ground with a few radials but when you truly look at the feedpoint you see that it is closer to 50 ohms than to 36 ohms where it should be.  When I had a chance to tear up the backyard and lay new sod, I had the landscaper leave the yard for a few days.  I bought some #14 THNN house wire and laid it out like spokes in every direction.  I had four reels that I put on a pipe.  I tied on end at the base of the antenna and then walked them out as far as I could stretching each one a foot or so from the next one.  Most of those wires are at least 33 ft. and some a little longer.  I staked down the ends with a DX Engineering radial install kit that has environmental dissolving stakes.  The landscaper came in and laid sod over the top and I was done.  When I checked the bandwidth had narrowed to near specification and I felt I had much high receive strength than previously.  I work mostly QRP and I am doing just fine making a lot of contacts on FT-8 and other modes.  I worked Ecuador earlier this week from outside of Chicago on 5 watts, FT-8.
--
Al
WB9UVJ


Jim Strohm
 

Hi

"High and in the clear" is a common rule of thumb for antennas, but for a Butternut ... maybe not so much.  We know from VHF and UHF quarter-wave antennas that resonant radials sloping down between 30 and 45 degrees will provide a closer match to 50 ohms than resonant radials at right angles to the radiating element -- that use case usually comes in at about 35 ohms.

In either case, any SWR mismatch causes a minimal loss of power at the antenna, but a higher SWR may make your solid-state transmitter fold back somewhat (NOT an issue with a properly tuned tube rig).

There are anecdotal, possibly apocryphal, reports from the 11 meter gang about putting their ground-plane antennas in the top of a 70-foot pine tree and getting improved performance from "high and in the clear."  Feedline losses would probably cancel this out, and ground plane antennas this high have an inferior take-off angle.  Only directional antennas can significantly benefit, and only when set at a suitable height for take-off angle.  For a multi-band ground-plane vertical like the Butternut, your installation will always be a compromise, and not just because of the take-off angle.

Consider these issues:

* Height of the antenna above ground:  If you have a raised Butternut, then you have to balance between "how high" and your personal maintenance issues.  If you have ANY traffic below the raised elements, you MUST position them high enough so that nothing gets tangled in them.  Examples:  on TV this morning, I saw elk (maximum antler height 10 feet (3 M)) and big trucks (maximum height 14 feet (4.5 M)).  I also saw a dude who was 6 foot 9, which is 2.5 M or thereabouts.  I have to mow my lawn today, but I'm more than a foot shorter than that tall dude.  Still, I need at least 6 feet (2 M) of clearance above ground everywhere.

A ground-mounted antenna has no overhead clearance issues, but ground wires have to be low enough that nobody can trip over the wires or catch the wires in a lawnmower.  Or in elks' hooves....

* Length of the ground elements:  While "more is better" for elevated radials, the point of diminishing returns is reached at 4 elements per band.  Since you've got resonance in pairs -- 80M and 30M, 40M and 15M, etc., you don't necessarily need 4 elements for EVERY band.  I'll leave it as an exercise for the student to calculate the total lengths needed for 4 resonant elevated elements per band vs. 64 ground-mounted non-resonant elements of 30 feet each.(1920 feet).  According to ARRL testing and documentation, the point of diminishing returns is 64 ground-mounting elements.

If you have room for elevated radials AND you can maintain a Butternut with its Q coil at 15 feet up, with sloping radials optional, you may consider that option as preferable.  I use 100-lb test twisted nylon fishline to string my shorter radials to my tie points.

If you can install (and can afford) a good ground-mounted radial field and cannot do overhead maintenance, then you may prefer a ground-mounted option. 

If you don't have room for either a good ground-mounted radial field or elevated radials, then you'll have to do the best you can with what you've got. 

73
Jim N6OTQ

On Fri, Sep 11, 2020 at 4:30 PM Preben Larsen <oz1fhu@...> wrote:
Hello group

Elevated  radials

Not specifik Butternut Radials, but we have an 80m fullsize,

8 Elevated radials in 1,5m height, feels more efficient than 90 laying
on the ground...

vy 73 de oz1fhu Preben

Den 11-09-2020 kl. 22:41 skrev Tadej S52X:
> Hello Group,
>
> I am new here and I have my Butternut HFV6 on my way. Has anyone made any comparison of the elevated radial system with ground radial system?


Tadej S52X
 

Hello everyone and thanks for your time. 

I am still undecided about radial system, but I achieved good results with monoband full size verticals with 4 tuned raised radials following N6BT method. I think I will try raised radials first. The space is not a problem since the installation in the woods allows plenty of space. This antenna is going to be used for contest inband operation few hundred meters away from the main yagi site. Since the ground radials doesn't need to be resonant, has anyone try with so called “chicken wire”? This should save some time in the installation and produce a good radial system!?

Thanks again
73s Tadej S52X 

On 12 Sep 2020, at 16:01, Jim Strohm <jim.strohm@...> wrote:

Hi

"High and in the clear" is a common rule of thumb for antennas, but for a Butternut ... maybe not so much.  We know from VHF and UHF quarter-wave antennas that resonant radials sloping down between 30 and 45 degrees will provide a closer match to 50 ohms than resonant radials at right angles to the radiating element -- that use case usually comes in at about 35 ohms.

In either case, any SWR mismatch causes a minimal loss of power at the antenna, but a higher SWR may make your solid-state transmitter fold back somewhat (NOT an issue with a properly tuned tube rig).

There are anecdotal, possibly apocryphal, reports from the 11 meter gang about putting their ground-plane antennas in the top of a 70-foot pine tree and getting improved performance from "high and in the clear."  Feedline losses would probably cancel this out, and ground plane antennas this high have an inferior take-off angle.  Only directional antennas can significantly benefit, and only when set at a suitable height for take-off angle.  For a multi-band ground-plane vertical like the Butternut, your installation will always be a compromise, and not just because of the take-off angle.

Consider these issues:

* Height of the antenna above ground:  If you have a raised Butternut, then you have to balance between "how high" and your personal maintenance issues.  If you have ANY traffic below the raised elements, you MUST position them high enough so that nothing gets tangled in them.  Examples:  on TV this morning, I saw elk (maximum antler height 10 feet (3 M)) and big trucks (maximum height 14 feet (4.5 M)).  I also saw a dude who was 6 foot 9, which is 2.5 M or thereabouts.  I have to mow my lawn today, but I'm more than a foot shorter than that tall dude.  Still, I need at least 6 feet (2 M) of clearance above ground everywhere.

A ground-mounted antenna has no overhead clearance issues, but ground wires have to be low enough that nobody can trip over the wires or catch the wires in a lawnmower.  Or in elks' hooves....

* Length of the ground elements:  While "more is better" for elevated radials, the point of diminishing returns is reached at 4 elements per band.  Since you've got resonance in pairs -- 80M and 30M, 40M and 15M, etc., you don't necessarily need 4 elements for EVERY band.  I'll leave it as an exercise for the student to calculate the total lengths needed for 4 resonant elevated elements per band vs. 64 ground-mounted non-resonant elements of 30 feet each.(1920 feet).  According to ARRL testing and documentation, the point of diminishing returns is 64 ground-mounting elements.

If you have room for elevated radials AND you can maintain a Butternut with its Q coil at 15 feet up, with sloping radials optional, you may consider that option as preferable.  I use 100-lb test twisted nylon fishline to string my shorter radials to my tie points.

If you can install (and can afford) a good ground-mounted radial field and cannot do overhead maintenance, then you may prefer a ground-mounted option.  

If you don't have room for either a good ground-mounted radial field or elevated radials, then you'll have to do the best you can with what you've got.  

73
Jim N6OTQ

On Fri, Sep 11, 2020 at 4:30 PM Preben Larsen <oz1fhu@...> wrote:
Hello group

Elevated  radials

Not specifik Butternut Radials, but we have an 80m fullsize,

8 Elevated radials in 1,5m height, feels more efficient than 90 laying 
on the ground...

vy 73 de oz1fhu Preben

Den 11-09-2020 kl. 22:41 skrev Tadej S52X:
> Hello Group,
>
> I am new here and I have my Butternut HFV6 on my way. Has anyone made any comparison of the elevated radial system with ground radial system? 


Ken WB8VTW
 

I do not have the data with me but I modeled both ground and elevated using EZNEC. Being elevated the models show the main lobe concentrated more towards the horizon than ground mounted. I have an HF9V at 22' using 2 multiband tuned radials from Butternut (all I have room for). It is awesome on 20m. I am located on a canal from the Gulf of Mexico so that probably helps. 


Barry <boat.anchor@...>
 

Tadej
It is my understanding that raised radials must be resonant.
Chicken wire works on the ground.
GL de Barry


Dennis W0JX
 

I have used elevated radials on many antennas including an old HF6V. I have never used the Butternut with a ground radial system. Here are my observations:

First, the most important factor is that a vertical antenna needs to be in the clear. By this I mean some distance from taller trees, especially big leafy ones. I just moved my 40M half square from my tower to a spot surrounded by tall trees and the performance dropped by at least an S unit compared to my vertical elevated radial ground plane (base up 25 feet).

I have an 80 foot shunt fed tower I use on 160M. It is really affected by the surrounding tall trees (90 to 115 feet tall) until the leaves drop in the fall. I have noticed this in each of the 20 years I have had the tower in operation.

My 40 meter vertical with four elevated radials is an excellent DX antenna, especially on long paths.

A butternut with elevated radials can work well if it is up high enough and in the clear. The base needs to be at least 10 feet off the ground for 80 meters. Tuning can be trickier with elevated radials and if the base is up high, it can get complicated. A competent antenna analyzer, connected close to the antenna, is an absolute must so you not running back and forth to the shack. 

If you use elevated radials, you should use an effective choke balun on the vertical close to the feedpoint or the antenna pattern will be distorted. This can be accomplished by winding turns of the 75 ohm matching line around one or two ferrite toroids. That's hard to do with RG-11 but can be done with RG302/U teflon coax (very spendy) or a Comtek 75 ohm bead balun from DXE. Or you could try an "ugly balun" wound as a solenoid air choke on a 4 inch form.

Lastly, Rob Sherwood, NC0B, has two good articles on the Sherwood Engineering website about using ground screens instead of wire radials. These can be extremely effective ground systems IF you use a screen that is big enough. I use WELDED fence that has 2 x 3 inch squares. Originally I used regular galvanized fence wire but that began to rust so I have changed to green vinyl covered fence wire (purchased at Menards in 4 x 50 foot rolls) I have approximately 600+ square feet of fence wire out under my 80 foot shunt fed tower and it does make a difference.

73 Dennis W0JX






Jim Strohm
 

Hi all

My Butternut installation is next to the roof with the Q coil at about 15 feet.  I had been thinking about building a little deck up there so I could tune at my leisure without having multiple trips up and down a ladder, and ruining the shingles by the antenna mount.

Then this morning I saw an ad from our local sporting goods chain for some deer stands.  In case you don't know, these are tripod structures that stand about 15 feet (3 M) high and are relatively portable.  For USD$250 carry-out, I could have one of these and it'd be the perfect height for my install. 

I had previously estimated about USD$1000 for my antenna maintenance deck.

These deer stands are made from angle iron, but it's not really an issue since it'll be below the ground elements ... or I can move it to use for hanging dipoles in the stunted trees we have around here.

73
Jim N6OTQ

P.S. We don't have any elk in Texas except in the zoo, or at the Elks Lodge.

On Sun, Sep 13, 2020 at 8:51 AM Dennis W0JX via groups.io <w0jx=yahoo.com@groups.io> wrote:
I have used elevated radials on many antennas including an old HF6V. I have never used the Butternut with a ground radial system. Here are my observations:

[snip]


 

Tadej,
To be truly accurate, resonant wires at the base of a vertical are called "counterpoise".  They serve to provide a return path for the antenna current to insure low SWR.  I think you should try a ground mounting first as it is the easiest way for you to get comfortable with the antenna.  Put down as many wires as possible.
I have read about chicken wire being an effective radial system but I should remind everyone, that it very fine steel wire that will produce a high resistance after it has been out in the weather.  A friend of mine just put down two lengths of chicken wire ( in an "X" pattern) under his Butternut at his lake property.  He saw significant improvement over the wires he had laid down previously.  The chicken wire does produce a lot of surface area for coupling into the earth near the antenna.
--
Al
WB9UVJ


Federico IK3UMT
 

Hi Tadej, how are you ???

 

Tuning/cutting elevated radials “per band” is a waste of time in HF as the ground plane is too much close to ground in wavelength terms unless you butternut is installed few hundred feet high as fo VHF-UHF happens, so ground interaction detunes your wishes….        

I had to install my 9V 10ft from ground because of vineyard below …. 😉 the results were excellent.

My experience : http://ir3ip.net/ik3umt/vertical.htm

 

73

Federico

Ik3umt

 

 

 


Markku SM5FLM
 

Don't click on the link from IK3UMT!

It contains Malware according to my anti-virus software (F-secure)


Federico IK3UMT
 

Amazing !!!

Let me check !

Federico
ik3umt


Barry <boat.anchor@...>
 

On Tue, Sep 15, 2020 at 11:09 PM, Markku SM5FLM wrote:
Don't click on the link from IK3UMT!

It contains Malware according to my anti-virus software (F-secure)
The only issue I see is it is not secure.
It is http instead of https
I have been to this site multiple times and have
not reached my demise.
cheers de Barry


Jon NN5T
 

One comment on counterpoise - 2 resonated wires have to cancel the RF current each other to stop the radiation from the counterpoise.  You may have seen articles how to tune the raised radials with RF current meter.  For VHF/UHF, it is easy to balance 2 wires.  For example on low bands like 160/80/40, wires such a length of 40/20/10 meter long over the ground probably above 6 - 8' (for the RF safety, could cause RF burn if some one touches while you TX), due to the ground conductivity change and also you cannot maintain the complete flatness (or from the object like trees or construction), RF current over 2 paired wires never been equal, that means radiation from the ground radials.  I am using HF2V in my 1/3 acre city lot.  I created 15 x 25' copper ground mesh around the feeding point in parallel to 25 - 65' x 35 ground wires under the grass level.  Took me about 3 days with 1,500' copper wires and working great from 160 - 30 meter bands.  My expectancy of Butternut on high bands is not very high, I have a separate 20/15/10/6 meter fan dipole on my roof as chimney mount (43' feeding poing - 1/2 wave on 14MHz) and works really good.  GL & 73 de Jon NN5T


Tadej S52X
 

Thanks everyone for answers. We installed the HF6V with 32 ground radials and with antenna analyzer seems fine, the 80m band has few 10 kHz of usable bandwidth.

73s
Tadej S52X 
Sent from my Iphone

On 19 Sep 2020, at 00:19, Jon NN5T <nn5t@...> wrote:

One comment on counterpoise - 2 resonated wires have to cancel the RF current each other to stop the radiation from the counterpoise.  You may have seen articles how to tune the raised radials with RF current meter.  For VHF/UHF, it is easy to balance 2 wires.  For example on low bands like 160/80/40, wires such a length of 40/20/10 meter long over the ground probably above 6 - 8' (for the RF safety, could cause RF burn if some one touches while you TX), due to the ground conductivity change and also you cannot maintain the complete flatness (or from the object like trees or construction), RF current over 2 paired wires never been equal, that means radiation from the ground radials.  I am using HF2V in my 1/3 acre city lot.  I created 15 x 25' copper ground mesh around the feeding point in parallel to 25 - 65' x 35 ground wires under the grass level.  Took me about 3 days with 1,500' copper wires and working great from 160 - 30 meter bands.  My expectancy of Butternut on high bands is not very high, I have a separate 20/15/10/6 meter fan dipole on my roof as chimney mount (43' feeding poing - 1/2 wave on 14MHz) and works really good.  GL & 73 de Jon NN5T


 

Tadej,
With the number of radials I suspect the usable bandwidth would be about 100kHz. 
--
Al
WB9UVJ