Definitely a job for one (or several) good distribution amplifiers...
A (sort of) related question: do the little in-line "barrel" F connectors cause a significant signal loss? I'm updating an old house for HDTV and it would be a lot easier if I could put a few "breaks" in the cable.
Don't need to get too personal, but why do you need to split 18 times? Are you wiring some sort of control room to mastermind your evil plot to rule the world?
Thanks, Patrick I'm aware of the 3dB (I've heard numbers as high as 4 dB) for a split, but I'm just talking about joining two cables to make one longer cable. How much loss is there in the coupling?
That's a function of the total length of the run of cable (the resistance of the cable gets higher as the run gets longer, which would cause signal loss). But unless we are having to consider super-long runs, you should be okay.
Using an in-line "barrel" connector to make a longer run should not have any effect on signal strength. The ones I have seen are listed as "0 db insertion loss" which means that there should not be any signal change. This is different from a splitter where there will be 3 db (i.e. half the signal) loss for each split.
Matt, I would recommend some good distribution amplifiers for what you are planning to do. If you decide to use multiple antennas, make sure that they are not right next to each other. I don't remember the minimum, but I believe they should be 20 or 30 feet from each other to prevent problems with multipath.