I drew this up to help out a local railfan who tomorrow is going to install a new ATCS Monitor receive site at Winslow AZ. Since the BNSF is long and skinny there, no value in omni antenna, better to use a pair of high-gain directional antennas (like 12-14 dBi) and suffer the 3 dB loss in combining. A whole lot better than finding a 10 dBi omni. The amplifier is one of those super-inexpensive satellite-grade rooftop in-line amps, the kind Summit Source sells for $5. Two splitters, one on the roof at the antennas, the other in the room where the radios are, and a power injector to provide power for the amp. The DC block is there to prevent any power from going beyond the amp to a possibly DC-grounded antenna. Whole thing is maybe $25 in junkbox parts, and outperforms nearly any other setup.