Rob and group
There is a ground wave, and there is a space wave. The groundwave loses its
effectiveness at about 3 MHz. due to dielectric losses. If ionospheric
propagation is not available at 14 MHz and above, communication over a
limited distance is still possible via the space wave. This component
travels at the height of the antenna, and can provide communications at a
limited distance. If the antenna is raised higher, the signal will travel
further, just as VHF signals do.Also, the groundwave is more apparent when
using a vertical antenna at low frequencies, which is one of the reasons
broadcast stations use them.
Ron
K3MIY
----- Original Message -----
From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
To: <rohre@arlut.utexas.edu>; <tentec@contesting.com>
Sent: Thursday, January 08, 2004 10:02 PM
Subject: Re: [TenTec] Off topic: Paul's wire loop antenna report ground wave
> Paul, you'd better flood your property with salt water, put up a 1/2 wave
> helical thingy, operate pactor and enjoy your 5 watt "ground wave" on 2
> meters. I'd like for someone to please explain to me why TV and FM
> broadcast stations on VHF put their antennas up 1000 feet or more if they
> have a ground wave to work with, and why they disappear into the noise
when
> I drive away over the horizon from them. Where's their ground wave?
>
> Cheers,
>
> Rob/K5UJ
>
>
> From: "Stuart Rohre" <rohre@arlut.utexas.edu>
> To: <tentec@contesting.com>
> CC: <k5uj@hotmail.com>
> Subject: Re: [TenTec] Off topic: Paul's wire loop antenna report ground
> wave
> Date: Thu, 8 Jan 2004 18:56:19 -0600
>
> Paul, Ground Wave not there above 3 MHz? It is there, in fact an antenna
we
> developed here at the research lab did Ground wave near 10m band out to
100
> miles! That was with the Folded Conical Helical invented by Dr. Robert L.
> Rogers and team, which they call the FLEX antenna. We also did it with
some
> helical 10m ham sticks, and with a half wave 10m antenna, (vertical).
This
> was done over salt water. Ground wave exists for all frequencies. It is
> what works your simplex modes at 2m, etc.
>
> There are noise issues at one frequency vs. others, but ground wave on HF
is
> very useable. Incidentally, our testing was at 5 Watts Pactor II.
> 73,
> Stuart Rohre
> K5KVH
>
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