With new FCC regulations come new worries. The rules make it easier for you, the consumer, by letting you buy only complete kits, meaning that the antennas have already been chosen for you. However, this also means that you need to use those antennas as wisely as possible to make sure that you get the gain that you need.
If there’s one rule you should not break, it’s the distance between your cell booster’s outdoor and indoor antennas. You need 15 feet in most cases — either horizontally, vertically or both. If you don’t have that separation, your booster will automatically cut power so that you don’t start feeding back noise and interference into the cell towers. That also means that you won’t get your money’s worth from your booster.
If your booster is designed for mobile or small office use, it may come with shorter cables which can be used for maximum power, but most boosters come with 50′ cables which should be used to make sure that your antennas are as far away as possible.