Lots of factors go into the signal strength.
The size of your antennas on either your Access Point (AP, the Mimosa A5 you are using) as well as the Client (the Mikroitk LHG))
Alignment, if the Client isn’t aligned very well you will have a weak signal. These antennas are called “dish” or “Parabolic” which basically means that they are very directional, only a few degree wide beamwidth (which is where your signal will be strongest) I would recommend looking up aligning one of these it can be quite the process especially over a longer distance link.
Speaking of distance, the further away from your AP your client is the less signal you will recieve, this is especially the case with an omni-directional antenna like the A5. (Meaning the antenna puts out signal in all directions) (Note: there is a bit of glossing over I am doing here because technology of Mimosa is really cool, but complicated and doesn’t quite fit) I would recommend playing around with the Mimosa Design Tool on cloud.mimosa.co to give yourself a good idea of how the A5 performs over distance.
Other factors include what might be blocking the signal, Buildings or (hated in this industry) Trees, both of which can effect you even if they don’t completely block your signal (look up “fresnel zones” to get a better idea). Basically anything that isn’t empty space will effect your signal, hills and extreme weather can effect you as well. (Ice buildup kills me in the winter and is a bugger to handle)
Finally, there could be issues with the actual antennas or radios, bad connectors or bent/broken parts that make them not perform optimally.