[Antennaware] Help with Short Dipole

[Guy Olinger K2AV]

At this point in the experiment, you wind it, put it on the analyzer, read
it, use it. It will show the separate R and X.  Measure, measure, measure
and type the facts into the EZNEC loads. The more stuff in the model is
hard fact, the more accurate the model is going to be. Those values of
inductive reactance make for really big coils, like really big.

Be sure and come back with your results.

73, Guy



On Tue, Mar 5, 2019 at 6:35 PM Gedas <w8bya at mchsi.com> wrote:

> Hi Guy. ok now that I have an initial model built correctly I can
> proceed with my experimentation. You had asked "The next question, what
> are you trying to accomplish with this? You wanting to put this in the
> air? Coming up with the coils will be interesting. 1265 ohms X is a lot
> of wire turns." The simple answer is pure fun mixed with a little science.
>
> In reality I have the property to make a full sized inv-v type dipole
> for this frequency and suspend it from 85' but I realize even this would
> be a pure cloud warmer as the antenna is kissing the ground. Your
> analogy of the 40m antenna is spot on. But I could eliminate the
> inductors completely if I wanted to. I am doing this out of curiosity. I
> like to see how reality differs from different models using different
> models.
>
> Ok, so getting back to this antenna.....I already have the 160m dipole
> up in the air operating and it is purely curiosity driving me to try
> this antenna. I know with 100% certainty that I will be going with a
> vertical radiator fed against some sort of ground but given I like to
> play with antennas, in particular model them, build them, and actually
> put them on the air this is only for my personal gratification and my
> own curiosity.
>
> I should note that the values of "R" for the inductors in my model were
> 100% guesses on my part before I did any calculations. That was going to
> be my next question to you. I was wondering if a half-way accurate
> number for the resistive component could be obtained before the
> inductors built and measured. I do own a VNA (actually an ENA) from
> Agilent that may help me get an accurate number but I am wondering how
> accurate the number would be based on the predicted Q from some of the
> better Inductor Calculator programs out there.
>
> I have just run several calculations to make a large inductor using a
> 4.5" dia form and if one can trust the predicted Q at this frequency to
> be around 400 is it safe to initially use a value of 3.2 ohms for R?
>
> I will of course measure it with the VNA to see how close this number is
> but is this the value for R that I would use (R derived from XL/Q) ?
>
> Gedas, W8BYA
>
> Gallery at http://w8bya.com
> Light travels faster than sound....
> This is why some people appear bright until you hear them speak.
>
>
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