Since your signal goes up and down, I would suggest buying a large ham radio antenna, about 15 foot, and mounting it on a seesaw. On one end put a large automotive spring, and on the other end put your antenna. Then attach a very long copper stereo wire from the ham antenna directly to the mifi unit.
When you signal starts to go up and down, you can counter it by going out and starting the seesaw. Once it hits the spring, it will go back up and then return and so on. Your signal will still go up and down, but the seesaw action will counter the up and down motion.
That should improve your signal and be steady year round unless you get a large snow storm and your seesaw is weighted down by lots of snow. In that case, you will need to shovel the snow periodically, but you will have your mifi signal back to normal.
×