[TowerTalk] terminated vee beam

[corneliuspaul@gmx.net]

Hello

Thanks to  - Al and the others -  for the fast responses. I think his answer
(see below) pretty much sums up the post received so far...

Well, I should have thought of it myself, that the resistors cannot add gain
in the wanted directions, just cancl out "unwanted gain" in the other
direction.
...wishful thinking... well OK, it improves F/B ratio.

Dont know whether your suggestions on a need for a ground screen
apply to the unterminated version as well..?

I have done some modeling on a so called v-star array already (several vee
legs covering all directions) the patterns i came up with were not sooo 
promising, at least if one wants to use it as an all band antenna or 
at least for 4 harmonic bands.

the apex angle is too narrow for the one band and too wide for the other band.
the higher bands get higher forward gain but very narrow lobes..

well... please keep your comments coming, i am looking for a directional 
allband wire antenna for traveling. 
(will probably look into an all band _inverted_ vee construction once again).

73s, Con DF4SA


k7puc wrote:
>I have been using (and some studying) of vee beams for several years now.
>Currently have a 500' long (each leg) with the apex at 100' high and the
>400' points  at about 50' then sloping down to about 20' high.  The apex
>angle is about 50 degrees estimated as I haven't been able to figure an
>accurate and easy way to measure.  The beam works pretty well on the higher
>bands.
>
>My study has concluded several things:
>1. If gain is the main consideration, then there is no need to terminate to
>get unidirectional power because the power lost in the undesired direction
>is used up in the terminating resistor.
>2. The apex angle is quite critical i.e. my 50 degree angle is much to
>narrow for 80 and probably also for 40 ( It has been a while since I modeled
>this vee using EZNEC and am relying on my memory!)
>3. I have not been able to resolve the statements "that the takeoff angle
>can not be any higher than
>the apex angle in degrees.  For this reason, I don't know if having the vee
>high is good or doesn't make much difference.


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