To follow-up on Ignacy's note....
After following this thread for some time, here are some of the questions I
have relative to a number of variables.
In looking for Halfwave Vertical solutions for max signal - ground wave (80
& 40M only) (G) versus DX (D) on all 5 bands considering the below
points. Individually,
these variables may only result in fractions of a db; however, fractions
collectively can result in whole numbers.
And, yes…soil conditions probably result in the largest variable, even
changing sometimes over the length of the radial field.
Anyhow, I invite anyone to comment.
1. End fed (A) versus middle fed (B) with feedline horizontal or
sloping for (X) distance
2. Bottom End point at (Z) distance above ground
3. Radials (R), screen (S), counterpoise wire (C), or ground rod (G)
4. Number (N1) of radials on ground versus number (N2) of radials
above ground
5. Length (X1) of radials on ground versus length (X2) of radials
above ground (Z1)
6. Screen on ground only size (S1)
7. Should radials/screen be electrically connected to shield of coax
feedline (Yes or No)?
8. Matching (M) to coax via 49:1 balun or L/C manual/auto-tuner
Please solve for G and D above, and provide data for other variables – A,
B, Z, R, S, C, G, N1, N2, X1, X2, Z1, M and S1.
Space below is provided for your answers. Attach extra pages if necessary.
Provide links to reference data.
Extra credit will be awarded for identification of other unknown variables.
73,
Henry - K4TMC
On Wed, Oct 28, 2020 at 4:56 PM Ignacy Misztal <no9e@arrl.net> wrote:
> Interesting discussion, with many points coming from simulation. I am just
> wondering how good the simulation is for vertical antennas since it seems
> to depend on zillions of factors. Much more than for horizontal antennas.
>
> With simulations, you find (just example) that having 64 radials gives
> your 1.57 db more gain than 8 radials. Also few elevated radials are doing
> pretty well. But the reality does not always match. Below are a few
> examples.
>
> A high inv L with 4 elevated radials should be perhaps 2-3 db below of a
> loaded tower with 30 radials but it is 10 db below. An EU guy on 160 who
> put 100 radials is loud with everyone else just barely copy, and the
> standard here is at least 32 radials. My 4 sq on 80 should be perhaps 10 db
> better than the high dipole for DX, but it is just 2 db better; asymmetry
> is not an issue as F/B is excellent. On the other hand, verticals over salt
> water on 160m should be 10db better by simulation, but they seem to be 20
> db better. Imagine EU stations heard well 2 hrs before the sunset, and hear
> them booming like locals half an hour before the sunset, an
> unforgettable experience.
>
> So is it an inadequate simulation problem or just a complexity of terrain?
> For instance, is the far field response of verticals dependent on trees in
> a forest?
>
> Ignacy NO9E
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