This isn’t corn blocking LOS, it is multipath due to reflections. We get peaks and valleys >20dB variation and unfortunately they move as the crops grow. I used to think going higher was the answer, our typical install height is 15 feet AGL, but even at 25+ feet we see this. In many cases we get better results going lower, if we can get below the last null. At the point marked “A” on the graph we lowered the dish at the customer end, but there was another null below it and as the corn grew the null moved up.
Best situation is a hill, ridge, or line of trees in the distance so there is no reflected path. We’ve had a lot of rain this June so there’s a lot of moisture in the crops. Usually things get a little better when the soybeans turn brown or the corn tassels out and starts to dry up. From: Work Sent: Saturday, July 04, 2015 3:15 PM To: af@afmug.com Cc: af@afmug.com Subject: Re: [AFMUG] see crops grow on signal graph If install by farm scope 9ft or higher if it only works lower then that don't install it — Sent from Mailbox On Sat, Jul 4, 2015 at 3:41 PM, Ken Hohhof <af...@kwisp.com> wrote: I would almost say the #1 problem we face is reflections off cropland, primarily on 5 GHz customer links. One set of problems occur at sundown with no wind. Another occurs as the crops grow. And with crop rotation, we might have problems at a customer location where we had none the year before. Here is an example where you can literally watch the crops grow day by day on the signal graph. Notice the nice roller coaster shaped graph. There are a couple other things going on at this location. At point A we moved the customer's antenna 1-2 feet lower, and changed the mount to a pipe with one of the KPP brackets that lets us slide it up and down on the pipe. Less than a month later, we're in trouble again. At point B a storm damaged the AP omni and the top was open to rain and hornets, it was replaced a couple days later. Strange I don't hear much discussion about this problem, we probably have it at 5% of our customers. Maybe most of you don't have flat land and row crops. <crops_growing.png> <crops_growing.png>
