Hi,
don’t forget that you must enhance the DL path (increase EIRP) but also enhance the UL path equally (increase sensitivity).
– higher antenna
– higher gain antenna
– bigger feeders
– TMA (for UL gain only)
– less combiners on the Tx path (for DL gain only)
it’s not really difficult to reach 70km, as long as there are not much obstacles and line of sight (sea, high mountain, desert, open area, …).
Now, in a busy environment, you can’t even dream of reaching 20km 🙂