your typical satellite modem will have an RF interface either somewhere between 70 to 140 MHz (where it's intended to be upconverted/downconverted by the LNB and BUC/SSPA at the antenna), or somewhere between 1100 to 1900 MHz, both intended for attachment to low loss coaxial cables. This works fine if you're putting the modem fairly close to the LNB and BUC/SSPA. If it needs to be a hundred meters away or something, it's a lot of RF loss, and path loss/link budgets in geostationary satellite are already hard enough without introducing any more loss at the ground side.
https://www.comtechefdata.com/products/satellite-modems