[TowerTalk] Actual LP Performance vs Tribanders

[Jim Lux]

Perhaps an inexpensive approach (instead of something like SRI's RELEDOP),
albeit time consuming, would be to hook up something that monitors the NCDXF
beacons around the world.  Monitor for quite some time (a week?)
continuously, with the antenna in various positions.  One would want to
think about the sequence for rotating the antenna.  You might want to rotate
to a position, get a complete cycle or two of the beacons, rotate to the
next, get a few cycles, etc.   In the long run, you might get something with
statistical validity (i.e. averaging out the short term variations in
ionosphere)


----- Original Message -----
From: "Tom Rauch" <w8ji at contesting.com>
To: "w3frg" <w3frg at comcast.net>; <towertalk at contesting.com>; "Pete Smith"
<n4zr at contesting.com>
Sent: Friday, June 25, 2004 8:06 PM
Subject: Re: [TowerTalk] Actual LP Performance vs Tribanders


> > But let's ask a practical question.  If you are trying to
> evaluate a
> > horizontally polarized antenna, either versus another or
> more generally,
> > won't the relative signal to a station a mile or two away.
> as you rotate
> > the antenna, give you some indication?
>
> Ground effects are attenuating or nulling ANY horizontal
> signal following the earth. The worse possible way to
> measure anything is in the null, because small changes in
> the system which includes everything between and around the
> antennas can cause big changes in FS.
>
> The slightest amount of feedline radiation or polarization
> tilt of a horizontal wave caused by reflections from other
> structures can cause huge changes in FS over groundwave,
> because path attenuation is significantly less for vertical
> polarization at HF frequencies and lower.
>
> With that in mind, what would a groundwave measurement tell
> us?
>
> This is exactly what mislead a certain fellow into thinking
> his stub-matched all band dipole was several S-units louder
> than a tuner matched but otherwise *identical* dipole. Poor
> measurement methods are at the root of much misinformation
> we see. Measuring a horizontally polarized antenna over a
> large distance (more than a few wavelengths) is definitely a
> very poor method.
>
> It would be much more reliable to measure skywave in an A/B
> test than groundwave of a horizontal antenna.
>
> 73 Tom
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk