Bill,
I did a bunch of research on this subject recently; I’m no expert, but at least it’s fresh in my mind. 
You can take a look here for some starting info:
Flightaware Coaxial Cables - FlightAware / ADS-B Flight Tracking - FlightAware Discussions
There are two basic properties of a coax cable you want to know - the impedance and the attenuation (or loss per length).
Generally cables seem to tend to come in either 50 Ohm or 75 Ohm impedances - 50 Ohm seems used for radio related applications (like here), and 75 Ohm is used more in Cable TV, etc. It’s not critical that you match the impedances in a system, but any mismatch will incur some (modest) additional loss, so when given a choice try to match - which in this case means “use 50 Ohm”.
The attenuation is really the issue you want to focus on more. Cables will generally have increasing losses at higher frequencies - “loss” (usually measured in “dB per length”) tend to increase as the square-root of the frequency; so the same cable will have ~41% more loss when you double the frequency.
TV frequencies are low enough that cables which are typically used there (e.g. RG-6) will have a lot of loss in the 1000 MHz range (where ADS-B operates). For TV channel 13 (top of the VHF) RG-6 has loss of ~4dB per 100 ft - at 1090MHz (ADS-B) it’s nearly 11 dB. RG-8 is even worse (~14dB/100ft @ 1090MHz)
[per CoaxCableLossChart.pdf (kd3y.com) ]
The “good stuff” seems to be cable designed for (Ham?) radio applications, with the gold standard being “LMR” From Times Microwave.
LMR 240, LMR 400, and LMR 600 are increasingly “low loss” (and increasingly expensive!) cables intended for this sort of use. From the above link, losses per 100ft @1200 MHz are:
LMR 240: 8.8dB
LMR 400: 4.8dB
LMR 600: 3.1dB
From Times: LMR-400.pdf (timesmicrowave.com)
There are a number of “other/off brand” versions of these cables, usually with the same numbering, but a different set of letters (e.g. RFC400, KMR400, KSR400, …) Based on reviews I’ve read, some of these are basically the same (just not “Times” branded), and some are potential crappy Chinese knockoffs.
Given the total cable loss is a function of length, generally you don’t want a lot more cable than required. That said, if you are using something “good” like LMR 400, an extra 10 feet of cable is adding < 0.5dB - which is fairly low. You’ll probably get that much loss from a couple of adapters (N-to-SMA) in the system.
FWIW, after much reading, researching, and head scratching, I ended up getting this cable:
which seemed like it would be a good compromise between cost and quality. So far it seems to be working for me, although I don’t have a good way to measure its actual attenuation.
I hope there some nugget in there for you.
Regards,
–Mark