Your theory sounds good to me except the part about trees causing it, much more likely row crops like corn or beans. It can be interesting to sweep the elevation on a dish with a tone alignment tool connected. I’ve seen reflections off corn so strong we gave up and had to point at the corn and figure we’d be back at harvest time. I’ve seen a reflection that is stronger over an elevation range of 10-15 degrees than the main path. Worst situation seems to be if there’s a very shallow valley between the 2 points, so that it’s not just a single reflection point.
It takes a very narrow beam to separate the main path from the ground reflections, it probably helps that you are 160 ft AGL, usually at a customer site it’s not possible unless it’s a very short link. From: George Skorup (Cyber Broadcasting) via Af Sent: Monday, September 22, 2014 10:53 PM To: [email protected] Subject: [AFMUG] That ain't right, part 2 I lost the original thread for some reason. Anyway... we encountered the same problem with a different radio. Was a KP reflector, but we used a connectorized SM on a 2' Laird HD dish as a replacement since the link needed some more power anyway. Got it up, started final alignment and bam! like a lightswitch, H pol power level dropped to -89, V SNR low, H SNR higher just like before. Changed elevation a little bit and it came back to normal. I had the guys move elevation again just so I could believe what I was seeing. Somehow we have a reflection that is now apparently just outside of the beamwidth of the 2' dish. Hopefully. At least that's my theory. It's up 160' on a grain leg about 4 miles to the main site. I wonder if the reflection point is the tops of the trees at some mid point. Maybe MIMO-A will help if this starts happening again. Here's the new SM link status. It's been stable since. Really strange how the multipath was swinging back and forth on the reflector. I guess you get to learn/hate RF more and more every day.
