Topband: insulated vs:bare radial wires

[Richard (Rick) Karlquist]

There is a study on skywave signals on verticals that is on my web
site.  I listened to actual received signals off the air and A/B'ed
two antennas.  In one sense, this is not as precise as you couldn't
detect a 1 dB advantage.  OTOH, these are the real signals you want
to receive, at the actual angle and of the actual polarization.
You could do a "scientific" study with a helicopter, but then you
still have make a judgment as to what arrival angle you want to
assume, not to mention random polarization.

Broadcasters worry a lot about skywave in a negative sense, so
there may be studies of skywave vs ground wave.  Skywave is bad
for them because it causes fading of the ground wave.  Successful 
skywave that causes propagation to great distances has no monetary value
for advertising purposes.  I have never seen any evidence that the 
loudest vertical for ground wave purposes is not also the loudest 
vertical for sky wave purposes.  If there were a way to selectively 
favor ground wave, the broadcasters would have found it by now.


Rick N6RK

Guy Olinger K2AV wrote:
>> N6LF established that a few elevated radials, which do not shield the
>> ground, can be as effective as the traditional on-ground radial field.  He
>> also warns that the implementation is far more critical.
>>
>> Rick N6RK
> 
> As far as I can tell with this and other such reports, including the
> benchmark 1937 work, all the measurements were made at ground level,
> and would therefore not measure skywave. The ground level measurements
> do NOT extrapolate to skywave unless one makes certain ASSUMPTIONS.
> These assumptions have not been challenged, since they have no
> essential bearing (read worthy of spending money) on commercial MF
> broadcasting, which requires signal strength readings at the ground
> for certification.
> 
> Since amateur communications consists almost entirely of SKY WAVE
> considerations we will have to provide our own SKY WAVE research.
> 
> 73, Guy.
> 
>