Thanks Bill. Lots of good data referenced, which I am now collecting,
reading, and trying to digest.
However I fear I may need the help of a few bottles of Tums or some Nexium.
Jerry, K4SAV
Bill Tippett wrote:
> K4SAV:
>
> >The only time I have verified EZNEC being different from my real world
> measurements is usually because of some error I put into the model or
> something I left out of the model. However I can't do comparisons of
> high dipoles and verticals on 160 at my station because I don't have
> them. I can look at data generated by others (who are likely to not be
> in error) and check that with EZNEC. In the case of 160 (and only 160)
> I can't get their results to agree with EZNEC. So I'm wondering if
> there is some magic on 160 that says a vertical get a special advantage,
> and what the heck is it?
>
> >EZNEC says a 300 ft high dipole on 160 beats a quarter wave vertical at
> all elevation angles under 54 degrees even if I assume zero near field
> ground loss for the vertical. Real world data disagrees.
>
> >By the way, this disagreement doesn't exist on 80 meters.
>
> This problem has to do with something called magnetic coupling
> (or polarization) loss. This primarily affects 160m which is closest to
> the gyro-electron frequency which varies from about 0.7-1.7 MHz worldwide
> depending on the intensity of the magnetic field). If you want to read
> more, search the terms " magnetic polarization polarisation coupling
> loss " in various combinations on the following Topband list archive page
> (enter the above search terms into the box at the top):
>
> http://lists.contesting.com/archives//html/Topband/2009-04/index.html
>
> I agree with all of Jerry's comments above. EZNEC does not take
> this effect into account. Here's a post with some modeling results for
> a vertical and dipole, both with and without the coupling loss effect:
>
> http://lists.contesting.com/archives//html/Topband/2002-05/msg00098.html
>
> The results including coupling loss agree with my experience on 160.
>
> 73, Bill W4ZV
>
>
>
>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|