eHam

eHam Forums => Antennas and Towers and more => Topic started by: K2OWK on November 02, 2012, 04:40:24 PM



Title: S9 31 FOOT VERTICAL
Post by: K2OWK on November 02, 2012, 04:40:24 PM
Hello, I just finished installing a 31 foot S9 antenna. I have the LDG radial plate with 20 radials most at the recommended 26 feet 9 inches, a few a little shorter due to room problems. I have the LDG 4 to 1 UNUN at the base of the antenna. The antenna is being fed with about 30 feet of RG 8x. At the shack I have an MFJ -914 Auto Tuner Extender. Now here is the problem (which might not be a problem). I have never used a vertical antenna before. Here is how it is working and what it is doing. It will tune 40, 15, 12 and 6 meters, and the upper portion of 80 meters (it is not supposed to work here). It will not tune 20, 17 or 10 meters. I know an S9 antenna is a non resonant vertical long wire, but I thought it would tune all the bands between 40 and 6 meters. I made my first contact on 40 meters today and got a 5 by 9 signal report from IL. He was running a kilowatt and he was hitting me with a 10+ signal. The receiving on the antenna is better by 2 S units then my 40 meter inverted "V" on 40.
So here is my question is this the way this antenna is supposed to work, or do I have a problem with the way I installed it? I was hoping to be able to use it on all bands from 40 thru 6. My antenna analyzer agrees with my auto tuner that the bands that do not work can not be adjusted with the MFJ-914 below 3 to one VSWR. The 914 has the capability to match antennas up to a 10 to 1 VSWR, but the bands indicated are greater then 10 to one and can not be brought down low enough.

Any help would be greatly appreciated.

73s

K2OWK


Title: RE: S9 31 FOOT VERTICAL
Post by: G0VKT on November 03, 2012, 06:12:49 AM
My guess that the impedance on the bands that don't work are out of the range of your auto tuner. Sorry, but I am at the early stages of EZNEC so i can't model it.

I am curious about the 4:1 on 40M. The impedance will already be quite low and the UNUN may make it too low. The antenna may be more efficient on 40M without it. Perhaps others will comment.

From their website:

For multi-band use, a 4:1 Unun is recommended at the antenna feed point for coax runs over 50 feet long. A 4:1 unun lowers the higher impedance's presented by the antenna on frequencies above 40 meters. If you are using a quality antenna tuner and have a coax run under 50 feet, a 1:1 current choke balun located outside of the radial field will suffice.

There are a couple of things here that are confusing and a little suspicious. The comments about feed line length suggests to me that the coax is part on the antenna and is radiating. And why would you have a current balun outside of the radial field (i.e 26' from the feed point if I am understanding correctly) for runs <50'. Again, it suggests to me that the coax is part of the antenna.


Title: RE: S9 31 FOOT VERTICAL
Post by: KC7YE on November 03, 2012, 06:50:35 AM
I use a home brew knock off of S9 and what ever the /portable location allows for radials. AH4 tuner at base of ant. 80 -10. Today it is set up at cabin in state park for CW SS operation, 1 radial, needed to keep this one low profile. I and several other WWA ops have had good results with set up.


Title: RE: S9 31 FOOT VERTICAL
Post by: KH6AQ on November 03, 2012, 07:10:02 AM
I assume you are using the autotuner in your transceiver along with the tuner extender. An external manual tuner will tune it but if you want to try using what you have here is what I would do:

1. Remove the 1:4 UNUN and feed it directly. See if it will tune all bands. If this is not satisfactory...
2. Increase the coax length to add loss. It may need 100' to tune.


Title: RE: S9 31 FOOT VERTICAL
Post by: W8JI on November 03, 2012, 09:15:06 AM
I don't know why people think, or are told, that a 30 foot vertical is an all band antenna. Especially one with a thin wire element.

The entire "vertical longwire" concept is strange to me.


Title: RE: S9 31 FOOT VERTICAL
Post by: W5DXP on November 03, 2012, 10:37:59 AM
I don't know why people think, or are told, that a 30 foot vertical is an all band antenna.

If it had something like an SG-230 at the base, with a good radial system, it wouldn't be all that bad of a 40m-15m antenna. It's too long on 6m for my tastes.


Title: RE: S9 31 FOOT VERTICAL
Post by: K2OWK on November 03, 2012, 05:32:27 PM
Thanks for all the information. I tried adding an additional 50 feet of RG8X to my existing 30 feet with no change in VSWR noted. The instructions on the antenna says you can use RG8X in runs less then 50 feet. I used a short run to keep losses to a minimum. I guess the 914 range is not broad enough to cover all the frequencies. I will have to get a manual tuner to use the antenna to its full capability. Just for a note, the instructions say that the use of a 1 to 1 balun is recommended for a single frequency (in the case of this antenna 40/15 meters) when used as a ground plane with 4 tuned radials at elevated height. W8JI the antenna tunes great on 6 meters. The 914 allows me to tune the complete band. I will let everyone know how a regular manual tuner works on this antenna. I believe that is what is recommended. I know an auto tuner at the base is ideal, but they are to expensive for me.

Thanks again everyone.

73s

K2OWK

PS: The receiving  side of this antenna works great on all the bands.


Title: RE: S9 31 FOOT VERTICAL
Post by: KH6AQ on November 03, 2012, 05:40:24 PM
RG-8X is too lossy for this antenna. A short run of RG-213 or better and a good manual tuner and it should tune 80-10 meters.


Title: RE: S9 31 FOOT VERTICAL
Post by: N3HAM on November 03, 2012, 08:03:58 PM
I've had mine up for almost 4 years with 40 radials with half bent on two axes to fit my yard. I use a 4:1 unun and a manual tuner, though the tuner in my FT990 will tune it. It can tune a bed spring. I use RG6 and it works 80 trough 10 fine enough for me. /http://http://vk1od.net/transmissionline/RG6/


Title: RE: S9 31 FOOT VERTICAL
Post by: W5DXP on November 03, 2012, 08:09:50 PM
W8JI the antenna tunes great on 6 meters.

With a take-off-angle of 40 degrees, who are you going to talk to?:)


Title: RE: S9 31 FOOT VERTICAL
Post by: WB6BYU on November 03, 2012, 09:08:22 PM
Actually the 31' vertical has more radiation at +5 degrees above the horizon than a quarter wave
vertical does.  (In fact, increasing the height a couple feed would add another dB or so.)

But not too many serious 6m operators use a ground mounted vertical.


Title: RE: S9 31 FOOT VERTICAL
Post by: W5DXP on November 04, 2012, 07:52:37 AM
Actually the 31' vertical has more radiation at +5 degrees above the horizon than a quarter wave vertical does.

How about from 13 degrees to 30 degrees?:)


Title: RE: S9 31 FOOT VERTICAL
Post by: K2OWK on November 04, 2012, 10:05:24 PM
I am back with one last question. The 4 to 1 UNUN I have is mounted with its bottom flush down against the aluminium radial plate. Could this cause any kind of coupling that might de-tune the UNUN? I have never used a UNUN before and I am wondering if I should move the UNUN so it is not in direct contact with the radial plate? For some reason I can not tune 40 meters today when I could yesterday. The only variation between today and yesterday was a large drop in temperature. I am going to remove the UNUN tomorrow and check for cold solder joints and bad connections. If I need to relocate the UNUN this would be a good time to know if I should.

Thank to all the answers I received all were very helpful.

73s

K2OWK


Title: RE: S9 31 FOOT VERTICAL
Post by: W5DXP on November 05, 2012, 05:45:40 AM
For some reason I can not tune 40 meters today when I could yesterday.

40m is the band where the 4:1 transformation makes things worse. According to EZNEC, it takes the SWR from 2.4:1 with a 1:1 unun up to 6.7:1 with a 4:1 unun. You would probably solve your 40m problem by using a 1:1 unun instead of a 4:1 on 40m. Of course, having to switch ununs at the feedpoint sorta defeats the purpose of that compromised vertical design, doesn't it? (There is no free lunch.):)


Title: RE: S9 31 FOOT VERTICAL
Post by: V47JA on November 05, 2012, 06:09:27 AM
W8JI the antenna tunes great on 6 meters.

With a take-off-angle of 40 degrees, who are you going to talk to?:)

And the answer is: In 2 years, 37,000+ QSO's, 223 countries, 5 Band DXCC. All with a 31' , S9 Vertical, using the metal roof as the radials, with a Balun Design 4:1 Unun, and an AT-AUTO Tuner. which tunes it better then 1.2:1 on all bands 10-80m.

73,

John V47JA  -  W5JON



Title: RE: S9 31 FOOT VERTICAL
Post by: W5DXP on November 05, 2012, 06:19:05 AM
In 2 years, 37,000+ QSO's, 223 countries, 5 Band DXCC.

That's quite an accomplishment for 6m only operation - especially the 5 band DXCC.:) Hint: The 40 degrees take-off-angle I was talking about was only in the context of 6m operation as can be seen from the posting to which I was responding. Can we hear it from hams who use a 31 ft. vertical on 6m? How does it perform on 6m? Any 6m DXCC using a 31 ft. vertical?


Title: RE: S9 31 FOOT VERTICAL
Post by: AG6WT on November 05, 2012, 06:22:59 AM
Another option is to add 10-15 feet of wire to the top and pull it out horizontally or nearly so with some light line. You'll essentially have a bent over 43' vertical which should be easier to tune on 80-10 with the unun and tuner at the rig. The optimal length will depend on such factors as the angle of the extra wire and your radial field. It will be an inverted-L but as only a small part of the wire is horizontal the radiation pattern will be more like a true vertical antenna.

Ray KJ6AMF


Title: RE: S9 31 FOOT VERTICAL
Post by: K5USF on November 05, 2012, 08:14:42 AM
At first I used a manual shack tuner and a 1:4 unun.  No problems tuning 80-10m.  I did add a shunt coil and tuned base coil for 80m to improve the Z.  Now, I use a remote, home brew tuner at the base, a 1:1 current choke and 75 feet of 1/2 inch hardline.  Continues to tune fine on 80-10m.  Wouldn't waste your time on 160m or 6m.  Jim


Title: RE: S9 31 FOOT VERTICAL
Post by: KE2TR on November 07, 2012, 09:20:46 PM
The 31' vertical is almost a full 1/4 wave for 40ty, maybe add two turns of wire at the base and you just might get it to resonate by itself on 40ty, the other bands its gonn be like a G5RV with some low angle. I tryed a 43 ft vertical, it worked real well on 20 were it was 5/8ths wave but sucked everywere else, tryed 75 and it was kinda light on that band so I did  LL job of loading and mde it a 75mtr only antenna but Sandy blew it apart so it bck to the drawing board.


Title: RE: S9 31 FOOT VERTICAL
Post by: K2OWK on November 08, 2012, 02:45:29 PM
I checked the UNUN on my 31 foot antenna and all looked well. I tightened some connections and reinstalled it at the base of my antenna. Now for some crazy reason it tunes all the bands with the exception of 40 meters using my MFJ-914 Auto Tuner Extender. I checked it with my MFJ antenna analyzer and it showed all the tunable bands can be adjusted to better then a 3 to 1 VSWR (even the upper part of 80 meters). I am still getting the MFJ-949E just in case something changes again. What a strange experience. The antenna works absolutely great on both transmit and receive. I am very pleased with the S9.

Thanks for all the great advice as this is my first vertical.

73s

K2OWK


Title: RE: S9 31 FOOT VERTICAL
Post by: W5WSS on November 11, 2012, 12:02:34 PM
I used a 31 ft vertical wire originating from the window sill that went upwards to a tree .
I connected the coax shield to tuned elevated sloping radials from the exact window sill two per band lowest frequency to highest frequency out to the farthest insulated dead end plastic stakes so when all were installed they looked like cat whiskers from the source outward or as viewed from above the lowest and longest pair first to shortest directly below.
With the use of an LDG 200 pro auto tuner at the feedpoint the system tuned from 6m to part of 75m.
This 31ft vertical with two pairs of tuned elevated radials at 5 ft base height developed the expected pattern expected means: length of vertical to Tao ratio.
Not included is the debate on how many radials are best for proper pattern modeled but rather a minimal radial set of elevated radials for getting on the air from a vacation cottage.
As a general one can expect with slightly varying results where the length of the vertical is close to a quarter wave then one can expect the lower angles to manifest for transceiving  remembering as the antenna is a fixed length and frequency is varied then the length to Tao changes thus if we press the 31 ft vertical into a tuned matched state we still follow the mandate that the length dictates the manifested Tao.

My findings with this type of system my 31 ft version with a pair of elevated tuned radials where frequency applied mandates a near quarter wave physical length will be a gratifying system pursuant to dx work for example,when used to around the area of bands that limits the length to a quarter wave to a 5/8 wave respectively.
As the antennas physical length in percentage increases beyond the 5/8 wave the Tao manifests at higher and higher angles and the antenna utility changes to transceiving sensitivity for closer and closer skywave work.


Title: RE: S9 31 FOOT VERTICAL
Post by: WB6BYU on November 11, 2012, 12:09:37 PM
Quote from: Lao Tse

The Tao that you can see is not the true Tao.



Title: RE: S9 31 FOOT VERTICAL
Post by: KO7I on November 17, 2012, 10:38:33 AM
I have a resonant 40M quarter wave vertical in my back yard. It is fed with 100 ft of RG-213 and I have 66 32ft long radials stappled down in my lawn. On 40M I drive the antenna with 900W. Using a MFJ model 929 auto tuner I can get my vertical/coax/radial system to "load" on all bands 80 thru 10 mtrs. It is noted that on the non-reasonant bands I am very careful to limit the transmit power to 100W.

While I do not advertize this as a cure all solution, it works, well sort of. Not "that bad" on 30 & 20 meters.

As already suggested, I would dump the 4:1 balun it is not helping you. I would take all extra coax and roll it up into a 6" dia coil near the entry point to your house to help de-couple stray RF on the shield of your coax.

You mentioned RG-8X, you need to carefully inspect the connector at the feed point of the antenna and make sure water had not inflitrated your coax cable.

73, Don KO7i


Title: RE: S9 31 FOOT VERTICAL
Post by: N4JTE on November 17, 2012, 06:50:20 PM
Reality check, there is no way 30 ft of wire or alum. in any configuration is gonna be a multiband efficent antenna, no matter what extensive ground system or tuner you might add.
Amazing how the advertisments try to forget the laws of physics.
Most times your feedline is your emmiter when off anything beyond 40 meters, think Tak antenna and the isotron, it is what it is, and good for limited expectations when small area for real antennas.
Bob


Title: RE: S9 31 FOOT VERTICAL
Post by: W5DXP on November 17, 2012, 07:31:10 PM
Reality check, there is no way 30 ft of wire or alum. in any configuration is gonna be a multiband efficent antenna, no matter what extensive ground system or tuner you might add.

30 ft of conductor is close to 1/4WL on 40m. 1/4WL is known to be an efficient vertical radiator.

30 ft of conductor is close to 1/2WL on 20m. 1/2WL is known to be an efficient vertical radiator.

30 ft of conductor is close to 5/8WL on 17m. 5/8WL is known to be an efficient vertical radiator.

All one needs for efficient multiband performance is a good power delivery system which includes a conjugate match and low-loss transmission line.


Title: RE: S9 31 FOOT VERTICAL
Post by: KO7I on November 17, 2012, 09:02:54 PM
Reality check, there is no way 30 ft of wire or alum. in any configuration is gonna be a multiband efficent antenna, no matter what extensive ground system or tuner you might add.
Amazing how the advertisments try to forget the laws of physics.
Most times your feedline is your emmiter when off anything beyond 40 meters, think Tak antenna and the isotron, it is what it is, and good for limited expectations when small area for real antennas.
Bob

Yupp!! Never said a non resonant ant fed with 75ft of coax works great - just said it would "load up".  :o

base loading that chunk of wire with a remote tuner would help reduce transmission line losses provided it has an efficient ground system.

73, Don KO7i


Title: RE: S9 31 FOOT VERTICAL
Post by: K2OWK on November 17, 2012, 09:10:25 PM
Hello everyone. I kind of ended this post on a second post called UNUN/Balun. The S9 antenna using a 4 to 1 UNUN with an MFJ-914 Auto-tuner extender and an MFJ-949E manual antenna tuner (for 40 meters only), will now tune the bands from 80 thru 6 meters. It is a fantastic antenna regardless what the laws of physics say. Using my Yaesu FT-450AT at 100 watts, anyone I can hear I can talk to. I have made many contacts with this set up. I am very pleased with what I have, and now see why the S9 has such an excellent review.

Talk to you on the air.

73s

K2OWK


Title: RE: S9 31 FOOT VERTICAL
Post by: KB1GMX on November 18, 2012, 10:44:06 AM
>>>30 ft of conductor is close to 1/4WL on 40m. 1/4WL is known to be an efficient vertical radiator.

30 ft of conductor is close to 1/2WL on 20m. 1/2WL is known to be an efficient vertical radiator.

30 ft of conductor is close to 5/8WL on 17m. 5/8WL is known to be an efficient vertical radiator.

All one needs for efficient multiband performance is a good power delivery system which includes a conjugate match and low-loss transmission line.<<<


Actually line loss is mostly not the real issue.  Its making the transmitter happy that is the concern.

At 40M its fine direct fed.  However at 20M its and end fed half wave vertical and the feed point is
above 2000ohms so feed point correction to get it down some is a must.   On 17M the feed point resistance is not so much the issue as the reactance is very high.

It would be very easy to put an auto tuner at the base and that would solve most problems save
for above 15M it's too long and the RF takeoff angle is up and forget 6M.  Just because a vertical
can take power at 6M that doesn't make it useful as the polarization is wrong for SSB (save for
E-season where wet noodles work).   The biggest issue with these all band verticals is the numbers
for gain and pattern make little sense as in ineffective or wrong polarization when you get too high
in frequency.  At some point say 10M a vertical dipole is only 16.5 ft tall (or long) and easily hide. 
If you need a 6M antenna make a horizontal wire dipole its only about 116 inches long and only
needs to be 20ft up to be very effective.

So for 80 through 15m a simple relay switched network of coils and caps would make the feed point
nearly 50 ohms cheaply.  With a bit more effort it's possible to make a match network that keeps the
feed point SWR under say 300ohms and above about 20 ohms making it an easy match for most transceiver tuners and if RG213 were used the losses would be trivial.

For HF the one do all antenna of any height (save trapped systems for other discussions) suffers
from far to many compromises.   That and any claim of low SWR is meaningless as an indicator of usefulness (besides making the solid state finals happy).  If you have power to burn then put a
wide range tuner on the desk and stop worrying about the cable loss.


Allison


Title: RE: S9 31 FOOT VERTICAL
Post by: W5WSS on November 18, 2012, 11:52:51 AM
Bob, I built and used one with the prior knowledge that when we design for proper delivery then the mandate of a 31ft length is exactly as I have just previously stated.

As Myself and Cecil and others have experienced in the real" that the zone of frequencies where the length in this case a 31ft monopole is specifically pressed and held from between a band where the 31 ft is equal to a 1/4 up to a 5/8 wave will perform a utility of lower angle manifested power radiation conducive to the pursuit of long range dx work.

This is always what the monopole can deliver when we design a delivery system that can stand up to the pressure when the frequency applied to the monopole and the length is a halfwave in this case 31 ft would fall on 20m service. yes the pressure is greater on the network but that does not change the power manifested TOA.

Our design parameter challenge is not only in optimizing the antenna but in providing a network that can handle the 1/2 wave pressure imposed on both the network integral Balun and auto tuner.

The Monopole and network,Balun as a system can offer excellent multi band utility when one understands what to expect.

I used 3 quick change vertical lengths 22ft,44 and 66ft and expected excellent long range dx communications and the system offers excellent service when we deliver via a network designed for the job.


Title: RE: S9 31 FOOT VERTICAL
Post by: W5DXP on November 18, 2012, 04:06:47 PM
Its making the transmitter happy that is the concern.

Actually, personification of an inanimate transmitter may be the biggest concern. :) Assuming that a transmitter is actually capable of human emotions, I guarantee that a conjugate match will make the transmitter happy. What could possibly make a transmitter happier than delivering all of its available power to the load?


Title: RE: S9 31 FOOT VERTICAL
Post by: W8JX on November 18, 2012, 05:45:43 PM
30 ft of conductor is close to 1/4WL on 40m. 1/4WL is known to be an efficient vertical radiator.

Bit short for 40 by about 3 feet so not a good match.

30 ft of conductor is close to 1/2WL on 20m. 1/2WL is known to be an efficient vertical radiator.

About 3 feet short for a 1/2 wave on 20 too

30 ft of conductor is close to 5/8WL on 17m. 5/8WL is known to be an efficient vertical radiator.

and 2.5 feet short for 17m too

All one needs for efficient multiband performance is a good power delivery system which includes a conjugate match and low-loss transmission line.

Point is it does not really do anything really well and is a compromise at best. A resonate antenna will outperform it.


Title: RE: S9 31 FOOT VERTICAL
Post by: WB6BYU on November 18, 2012, 07:28:45 PM
Quote from: W8JX

Point is it does not really do anything really well and is a compromise at best. A resonate antenna will outperform it.



You may be able to invent circumstances where it would, but simply being resonant
doesn't imply anything for antenna performance or efficiency.  If it were a resonant
half wave on 20m instead of being a bit short, it would probably work a bit WORSE
in many cases.

Here is an example:  using a 31' vertical on 20m with 75' of RG-213 to a tuner in
the shack and no balun at the feedpoint, maximum radiation is -0.05dBi at 20 degrees.
The coax loss is 5.335dB, so taking that into account the radiated signal is -5.38dB.

If we lengthen the antenna to 33.48' is is now resonant.  Radiated signal increases
to +0.19dB, an improvement of 0.24dB.  But even though the antenna is resonant
the coax losses have increased to 5.837dB, for a radiated strength of -5.64dB.
Your signal DROPPED by about 0.2dB when you made the antenna resonant.

As you increase the length further towards 5/8 wave (which isn't a resonant length)
the antenna gain increases and the angle of maximum radiation lowers a bit.  In this
situation the difference among 31', 33.5' (resonant), or 37' is a fraction of a dB, and
the resonant case does NOT give the best performance, regardless of whether or
not you include the coax losses.  If you don't care about a couple tenths of a dB,
you can say that all three of those lengths will work about the same, but it certainly
is NOT the case that the resonant antenna outperforms the others.


What makes the biggest difference is the coax loss - around 5 to 6dB in this case (about
half that with a perfect 4 : 1 transformer.)  The reason that the antenna is 31' instead
of a resonant length is to keep the voltage down somewhat so it can be matched with
a relay-switched autotuner, which is the most effective way to feed it on most bands.  
In that case, lengths that are longer than resonance will give a bit more radiation than
resonant lengths.


So, yes, the 31' vertical is a compromise, but so is any other antenna, regardless of
size:  you pick a set of properties that meet your needs, even if they are different than
those that others would pick.  The behavior is relatively predictable, rather than being
contrary to the laws of physics.


Title: RE: S9 31 FOOT VERTICAL
Post by: STAYVERTICAL on November 19, 2012, 02:14:05 AM
BYU - right on the money!

Even a dipole/yagi/quad is a compromise antenna except on its design frequency and perhaps 15m for a 40m dipole.
As soon as you go multiband - all bets are off for almost all antenna's.
Even Log-Periodic antenna's are compromises in that not all elements are involved on every frequency.
Life is daily full of compromises, and antennas which are not shape shifters have the same limitations.

I used a fixed vertical for many years with great results - now I am using a magloop.
Both are compromise antenna's, but like those of us who have to live with others, it mostly works out.
My current whacky project is getting a thin copper wire to climb up 23 feet inside a fibreglass tube.
A poor mans version of the smallIR vertical.
We will see how that turns out - and it will be educational to compare its performance with my old fixed vertical.

I subscribe to the Missouri slogan of "show me" when it comes to antenna's.
Most of the time it is me showing myself how something works, but the idea is the same.

Happy experimenting,

73 - Rob


Title: RE: S9 31 FOOT VERTICAL
Post by: W5DXP on November 19, 2012, 06:55:49 AM
Point is it does not really do anything really well and is a compromise at best. A resonate antenna will outperform it.

Why does a non-resonant 5/8WL vertical outerform a resonant 1/4WL vertical?

According to EZNEC, a non-resonant 31' vertical used on 17m, at an elevation angle of 10 degrees, has about 4dB advantage over a resonant 33' 1/4WL vertical used on 40m. All the 31' vertical needs is an auto-tuner at the base or a simple coil-matching technique as is used in 5/8WL verticals (also non-resonant).

The most amazing 10m vertical performance I have ever seen was a 22' non-resonant vertical with four 22' elevated radials slanted down at 45 degrees and fed with an SG-230. EZNEC sez it has a gain of 4.2 dBi @ 10 deg. TOA.


Title: RE: S9 31 FOOT VERTICAL
Post by: W5WSS on November 19, 2012, 08:56:31 AM
Yeah Cecil I agree. I found that when we use three lengths 22ft 44ft 66ft we can choose the better length to better serve dx pursuits on one of our allocated HF ham bands In my case I used wire and worked out the hoisting details to include a commonality for quick change rather than loading coils etc.

I for example with this revelation about three years ago designed an auto tuner and balun that would handle the 1/2 wave pressure regardless of which length chosen and frequency within the range of 1/4 to 5/8 wave radiator respectively.
 
The primary challenge was eliminating the feedline while keeping a sensitive remote tuner protected by lightning, since eliminating feedline generally places the tuner and balun network at the antenna terminals. I found a unique solution where I place the network of auto tuner and Balun on a window sill and construct radials two per band 10m pair 12m pair up to 75m tune them then press the better length radiator pushing against the pair that is pertinent and already in place. The work of improving an Miltie band radial set is our current challenge holding the three better lengths unchanged as we search for an better Miltie band radial sets of pairs of tuned elevated sets.

The construction of the radial sets simply included sloping downward to isolated from dc path to earth surface using a series of Teflon anchors.

The vertical wires can be disconnected from the system and switched to ground outside for better lightning arresting design etc.

So yes all the factors of individual specifics respective to feedpoint base height, slope angle of elevated radials  and DC isolation of the radials sets can be modeled for estimates of performance prior to design.

One of the first steps to design is considering we can get the better performances when we utilize 1/4 wave to 5/8 wave limits on frequency applied to one of the three length's. Mine cost $20 worth of wire and a rope over a tall tree as a hoist the vertical angle was almost straight up but perhaps a few degrees.The Black color insulated#14 stranded copper elevated radials were parallel to the back wall of the house and positioned opposite each other very inconspicuous from the 5ft feedpoint the network was weather proof and a wander lead was used to place the vertical wire/s to a ground rod outside.

Performance was excellent.