[VHFcontesting] Ionosphere Scatter

Keith Morehouse w9rm at calmesapartners.com
Mon Oct 24 11:34:48 EDT 2016

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

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
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting at contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting

More information about the VHFcontesting mailing list