I seem to have a recollection that a cheap DIY system is to get two RCA 18" dishes (or larger) and remove the LNB from the dish (or whatever the horn part is ca

I seem to have a recollection that a cheap DIY system is to get two RCA 18" dishes (or larger) and remove the LNB from the dish (or whatever the horn part is called) and affix a "cantenna" or other waveguide to the arm, then, using the shortest, largest coax you can manage, connect the two cantenna/waveguides together, and aim them 180 degrees apart. I also seem to remember that putting this "halfway", even if halfway happened to be the highest point, wasn't ideal, it was something like 60/40 or 70/30. Now-a-days, mikrotik or ubnt make doodads you can replace the LNB with that instead provides some wifi band, with PoE, so two of those up on a tower means you have active repeating, and you can probably push that solution out a lot further than 43km. For the record, i put a USB wifi stick inside of a pirouette cookie can and it was a phenomenal "war driving" antenna. I use folded-dipole-fed yagi antennas now for doing wifi surveys, but in a pinch 802.11B 1000mW+ wifi cards are stacked up in a filing cabinet...