[NLRS] The Twin Cities - Milwaukee VHF path

[Gerald]

On Sat, 2005-06-18 at 12:19 -0500, Bruce Richardson wrote:
> 
> For the benefit of newcomers and to further my understanding, I hope many
> of you will chirp in with your observations over the years.
> 
> The Twin Cities to Milwaukee path is known to be difficult for VHF.
> Stations in both cities have CQ'd in the proper direction for many hours
> during contests hearing nothing.  Once or twice per contest, conditions
> will lift somewhat and a "few" Q's are made between 34/35 and 53/63/52/62
> in the Milwaukee area.  The land masses of Knapp Hill, Jackson Ridge (just
> west of Tomah), and the Kettle Moraine all make VHF hookups difficult.
> Interestingly,  from the Twin Cities end, changing azimuth north or south
> just a bit yields much further successful distances to Green Bay and
> eastward and Chicago and southeastward.  Yes, Chicago to TC is often easier
> than Milwaukee to TC.
> 
> Thoughts?  Anecdotes? Memories?
> 
> What would be the prime hours for likely success?  Can we cultivate a way
> to increase the contest linkups?
> 
> Bruce Richardson - W9FZ

Early morning usually gets the best summer minor inversions.
Historically early morning around here sans rovers has been the quietest
operating period of a VHF/UHF contest. It helps for the weather to be
quiet (such as under a high pressure dome which can drastically extend
the time and area under an inversion). What happens is that during a
quiet night, the earth surface radiates to space and cools below the air
and cools a thin layer of air. Maybe only 1000 feet thick. With warm air
above there's that weak inversion that gives a longer path over
obstacles. I've run a 65 mile packet link for several years, the 4/3
earth radius path is 200 feet below my horizon, but the path worked most
mornings without a strong wind. Strong winds prevent the layering
necessary for extra propagation by mixing the layers

Many a Sunday morning of a contest, I've sat calling CQ in all
directions and hearing NOTHING, not because its windy, but because there
has been pathetically little activity. And I think the best possible
propagation period has been wasted.
-- 
73, Jerry, K0CQ
Dr. Gerald N. Johnson, electrical engineer
All content copyright, Dr. Gerald N. Johnson