Topband: Inverted L & radials=conclusion

[cris blak]

Hello all,

First, thanks to all who answered for suggestions.

As a conclusion, maybe to interest for further reading.

INV. L is better than an INV. Vee for TXing.
>From theory (MMANA simulation) I've notice the following:
- the longer the vertical part, the lower the vertical radiation angle;
- for a 13m vertical and 26m horizontal, the following vertical radiation angle were computed for the following radial numbers:
    - no radials = 31 degree
    - 1 radial = 31 degree
    - 2 radials = 29 degree
    - 4 radials = 28 degree
    - 8 radials = 27 degree
    - 16 radials = 25 degree
    - 32 radials = 19 degree
    - 360 radials = 9 degree
    - 720 radials = 7 degree
conclusion on this point = the more radials, the better.

>From practice with a 13m vertical and 26m horizontal, 2.5mm wire:

- I didn't verify the theory with the longer vertical part;
- with 3 radials the VSWR were 1.2:1 and the impedance where close to 50 ohm; the antenna bandwidth were about 80KHz (too large); not stable on a heavy rain (the resonance point goes downward).
- with 6 radials the VSWR goes to 1.3-1.4:1;
- with 14 radials the lowest VSWR where 1.5:1 and the badwith were about 15KHz; putting an UN-UN 2:1 toroidal transformer between the antenna and the coaxial, in about 13KHz the VSWR were 1:1:1 and become much more stable on a heavy rain.
I've notice a "good working" on DX along the radial's running. So, if you want to factorized a certain dirrection than run the radials toward it!
The radials were about 22m made of 0.5mm copper wire. 6 of theme were made of 2.5mm copper wire.

I've notice that along radials it is about 2 S-points better that the INV. Vee (made for 160m) on DX but on a short distance, the INV. Vee is better (higher angle from the INV. Vee).

Overall, is a good antenna for DX, but the vertical is better than that. Use as much vertical part as possible. Use as much radials as you can afford along the favorite directions. Radials should be 1/4WL but will do also the 1/8WL one. Is not necessary to buried theme, just laying on the ground. You can use whatever wire you have (copper, steel, etc.). Is a matter of chemical reaction that all!

Hope this will help.

73 de YO3FFF
Cristi


 
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