[MAMS] [Midwest-Microwave] SPACING OF ROVER DISH ANTENNAS DURING 10up CONTEST

[Zack Widup]

I traveled with a group of 4 to 7 vehicles in the 10 GHz contest this past
weekend roving the Wisconsin side of Lake Michigan. We often parked right
next to each other down a row of parking spaces in a parking lot. It was an
organized effort - there were 6 or 7 other stations across Lake Michigan we
were trying to work. Each station at our end took a turn calling all the
stations on the other end and we generally worked them in the same order
each time. We never had any problems with that, but if you are doing some
kind of disorganized operation where different people are trying to work
different people at random, I see how it could cause a problem. It works
out really well when only one station is transmitting at a time and
everyone is listening for the same other stations. They get their turn to
work them.

73, Zack W9SZ

On Mon, Sep 19, 2022 at 1:06 PM Bill Koch via groups.io <ddikoch=
yahoo.com at groups.io> wrote:

>
>
> All:
>
> K1RZ, K3WHC and I were roving together for the 10UP contest this past
> weekend.
> We noticed that our dishes, on tripods, interacted with each other causing
> signals to attenuate or disappear..
>
> We thought about yagi and quagi antennas with their 'rules of thumb' for
> spacing as well as some WA5VJB comments on spacing.
> We are wondering whether there are some 'rules' on spacing of parabolic
> dishes
> a) between two bands, say 10 and 24?
> b) between rovers on 10ghz?
> Is there a capture area for a parabolic dish that is markedly different
> than it's diameter?
>
> We observed some 'not understood' reductions of received signal strength
> as follows.
> At Reddish Knob, FM08jl, we were lined up such that all three of us could
> aim NE and SW relatively straight on.
> All all three of us had a 'White Box' 2 foot dish that has a WG feed.
> K1RZ and I have a WG switch with Kuhne EME LNA.  K3WHC had a high quality
> coax feed to a relay and LNA..
> Due to the real estate layout, the centers of our dishes were about 6 feet
> apart.
> K1RZ was on left end, K3WHC was center and I was on right end.
> K1RZ and K3WHC worked WA4PGI right away; I could not hear WA4PGI and was
> frustrated.  I generally hear quite well.
> K3WHC moved his dish to point somewhere else and all of a sudden WA4PGI
> jumped up to a very strong signal...easily 5x7.
>
> Yesterday, at Blue Knob, FN00rg, we experienced the same impact, albeit
> that K3WHC and K1RZ did have some interaction as I experienced the day
> before.
> We were lined up about 8 feet apart.  We turned our dishes 90 degrees or
> so from the operating dish and generally made the Q, although the band was
> up and down.
>
> K1RZ and I have been at FN00rg before although not nearly as closely
> positioned.  When we worked N1DPM and co. for a 10up contest's long Q, we
> were a good 50' apart.
> On the other hand, AF1T, K1RZ and K3WHC work from a tightly sized balcony
> on Block Island (that W1GHZ uses as well on a different weekend) and they
> did not have the issue.
> I've worked all three of them from FN00rg or FM08us.
>
> Can anyone help us understand what was or may have been happening?  Are
> there some rules on spacing between dishes to protect against signal
> reduction?
> What are we missing?
>
> TNX/ 73
>
> Bill
> W2RMA
>
>
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