Weired stuff regarding signal quality

hi, just got my equipment up and running. 2 x 25dbi dp flat panel 5 GHz antennas with 20m antenna cable lmr-400 on both sides, rb600a and r52h on both sides. Distance between antennas is 1.6km with almost no obstructions in LOS apart from a few branches of some trees nearby. Height of antennas on one side is 4m mounted on a wall and on the other side 10m mounted on a wooden tree pole, height difference between sites ia approx. 40m…so to the weired stuff:

Initially setup as transparent bridge using static WDS.

When i using frequency 5180 MHz the signal strength was between -80 to -84 with quality 50-70% both sides…i think that was very bad considering distance and high power radios…then i switched to frequency 5800 MHz and the signal dropped to -90 to -92 and quality to 20-30%…hmmm extremly bad and dissappointing…then i switched frequency to 5300 and voila signal strength -70 to -74 with quality 85-95%…weired since there are no interference on those frequencies, im all alone , so whats going on here?? The polarization used on antenna is Vertical, havent tested horizontal yet due to lack of 1 radio, next week will get it and then ill try nstreme dual.

Anyone else experienced such fluctuations in quality by just changing the frequency?

maybe your antennas dont do that full range of 5.1 - 5.8. get the specs on the antenna and see where the sweet spot is.

Here is the antenna specs:


5.47 - 5.875 GHz
GAIN V-Pol:
H-Pol:
25.5 ± 1 dBi
24.5± 1 dBi

As mentioned im on 5.300 GHz now and its working great, but when i tested with 5.800 GHz the signal was very bad.