All antennas, both inside and outside, should be installed 3 feet away from metal and other antennas. The two inside antennas should have a minimum of 3 feet of separation between each other and metal objects.
Typically, two inside antennas are used to provide a greater coverage area and should be placed at least 20 feet apart. When extending the inside antenna included with a PowerMax repeater system with a 2-way combiner, use Digital Antenna's PowerMax 10, 15 and 25 foot extension cables with factory attached mini-UHF female and mini-UHF male connectors.
Digital Antenna also offers a 9dB gain inside directional antenna, the 426-PW.