Yay for 1.06 as an old SAR guy, but 1.82 (or 1.85) is probably garbage, if it's referring to ESM. We deleted it from NAWDC's mind on the HSM/HSC side 7 years ago. RF horizon is geometric limit, it doesn't matter if you're active or passive, one-way or round-trip. RF horizon is the same for a given frequency and path/environment.
Okay, technically I had a fourth number, but I wasn't sure if it was releasable. I was taught 1.5, though other than in the sim, there was never a practicable way to test it in the real world because there was always some sort of ducting going on.