I don't think that it is a polarity mismatch, the Power Beam M5 400 is a dual polarity unit, and I've tested them at 20 degrees off center, and have never seen such a mismatch between signal strengths on AP and CPE. In my experience you would not see such a difference between signal strength on the CPE and and signal strength on the AP with a polarity mismatch, but rather, both signal strengths would suffer.
I think that this is an issue with orientation and/or distance and/or angle. If the receive signal strength on the CPE is good, that means that the AP is oriented correctly towards the CPE, and at a good distance for the size of the antenna of the CPE. If the receive signal strength in the AP is bad, that means that the CPE is not oriented properly towards to AP, or that the AP's antenna is too small to capture enough signal at that distance for the angle at which the signal is arriving at the antenna. It would of course be useful to know the CCQ as well, and the distances and angles.
Who oriented the client device? What are the distances and angles and ccqs? Remember that receive signal has a LOT to do with effective surface area of antenna, whereas transmission has more to do with EIRP. Also, it would be useful to know the Noise Floor of both units.
Last edited by stoser
on Mon Nov 07, 2016 4:48 pm, edited 1 time in total.