[VHFcontesting] Ionosphere Scatter

Mark Spencer mark at alignedsolutions.com
Mon Oct 24 13:32:12 EDT 2016


Hi this is interesting.   From a practical perspective I'd be curious in knowing if there is much difference in what needed to be successful using long haul tropo scatter versus iono scatter on 50 MHz ?

Presumably bigger antennas, higher power levels and a clear view of the horizon will all be useful ?

The comments about the K index and time of day for iono scatter are of particular interest to me.

73
Mark S
VE7AFZ


> On Oct 24, 2016, at 8:34 AM, Keith Morehouse <w9rm at calmesapartners.com> wrote:
> 
> On 6M, pretty much any two stations with decent power and at least 5-6
> elements at a good height can work out beyond 1000 miles frequently.  I
> think having a good low angle signal is a key to success on ionoscatter.
> I've worked many people using this mode.  Signals are not strong so CW or
> digital modes like ISCAT are helpful.  But, I've worked plenty of SSB
> ionoscatter, too.
> 
> On 2M, I've found it's quite a bit more difficult.  Whether it's a lack of
> truly well equipped stations on 144 MHz  or whether the ionoscatter mode
> does not propagate well at higher frequencies, I don't know.  I have read
> papers that speculate 144 MHz is a bit high in frequency for ionoscatter.
> I never heard much that could have been 2M ionoscatter, even when operating
> from a large multi-multi station with very large antennas, very high up.
> 
> It's a useful mode when there is no other available - which is most of the
> time on 6M.  Give it a try, but be realistic about the capabilities of the
> other station you're trying with and, YOUR station.  If you're running 100W
> and a 3 el at 25' and nobody hears you, it's probably not a failure of the
> ionoscatter mode of propagation.
> 
> Jay W9RM
> DM58 CO
> 
> Keith J Morehouse
> Managing Partner
> Calmesa Partners G.P.
> Olathe, CO
> 
>> 
>> 
>>> On 10/24/2016 10:02 AM, Sean Waite wrote:
>>> 
>>> Hi everybody,
>>> 
>>> I see that WSJT has an "ISCAT" mode for ionosphere scatter. I can't find
>>> much about how to operate in this mode, or even much about ionosphere
>>> scatter in general.
>>> 
>>> I gather that it's a daytime mode, best at noon and loves it when the K
>>> index is high. I also see things about how the military used to do it with
>>> 40kW transmitters through 20dB gain antennas. I'm a few dB short of that
>>> on
>>> most bands.
>>> 
>>> OZ1RH has an article on qsl.net (qsl.net/qz1rh/ionoscatter_lec
>>> ture_2002.htm)
>>> where he has a little info on it, but not much about what mode he was
>>> using
>>> and given the age I doubt he's using any of the JT modes. He suggests 1kW
>>> with a 12dBd antenna may be possible on 6m, but I'm hoping with the ISCAT
>>> mode a lesser station could do it, and maybe even 2m.
>>> 
>>> I can't find much about whether the antenna requires elevation.
>>> 
>>> He does suggest that it has a sweet spot of around 1000-1800km, which I
>>> think puts it beyond the reach of meteor scatter. Is this a mode that is
>>> ever used in the contests? Does anyone have any additional information
>>> about it?
>>> 
>>> Thanks and 73,
>>> Sean Waite, WA1TE
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