For an outdoor installation we have a MR76-HW AP. As we can't place the AP near the antenna's I would like to know what the max lenght of COAX-cable and prefered antenna is to cover a area of +/- 35 metres arround the antenna Area is mainly open.
It depends....Not all coax is equal. You must perform the calculations. I would use nothing less than LMR400 and you will most likely need lightning arrestors and you must account for signal loss for each connector and make sure your coax runs/legs are exactly the same length for each element. You may want to hire a professional. https://www.qsl.net/co8tw/Coax_Calculator.htm