I suspect you’ll be just as close by trusting the model. Making measurements
of antennas in the wild, especially one with so many lossy elements, is likely
to involve a lot of approximations, too.
Curious how much TX power you’ll be using. Will you actually get close to the
legal limit on 630m? BTW, I’m waiting for you to fire up on WSPR so I can give
you a signal/noise report.
73, Terry N6RY
> On 2019 Mar 17, at 10:23 AM, Gedas <w8bya@mchsi.com> wrote:
>
> Right. I.e., in my case since we are talking about a short 600' inv-v antenna
> on 630m at 85' I get a calculated value for R(rad) of about 0.66 ohms.
>
> If I raise this perfect antenna model to approx 1/2-wave above a perfect
> ground I get ~16 ohms and at 1-wavelength above perfect ground ~17.3 ohms.
>
> My goal is to arrive at a somewhat accurate number for EIRP to ensure I am
> compliant with FCC requirements.
>
> I think I have two choices:
>
> 1. Should I trust EZNEC and return my ground type to real, add back in all my
> wire losses, and losses in my inductors etc and trust the finished dBi gain
> value provided by the program?
>
> 2. Or should I or do I need to install the finished antenna at height with
> all it's inductors and ohmic losses etc and try to make measurements of the
> antenna voltages and currents at the feedpoint in an attempt to calculate
> R(loss) ? I realize I will have to carefully take into account the impedance
> transformation due to the coax feeding the antenna since my measurements will
> be in the shack and not up on the tower top.
>
> Opinions or experiences anyone want to share?
>
> Gedas, W8BYA
>
> Gallery at http://w8bya.com
> Light travels faster than sound....
> This is why some people appear bright until you hear them speak.
>
> On 3/17/2019 12:23 PM, Edward Mccann wrote:
>> Noting that the Rr varies as a function of height above ground.
>>
>> AG6CX
>>
>> Sent from my iPhone
>>
>>> On Mar 17, 2019, at 7:38 AM, Dave Cuthbert <telegrapher9@gmail.com> wrote:
>>>
>>> Gedas,
>>>
>>> you are correct. The reported resistive part of the input impedance is the
>>> short dipole is the radiation resistance.
>>>
>>> Dave KH6AQ, formerly WX7G
>>>
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