If it is broadcast onto your property, do you not have the right to use it?
If it is truly a broadcast, yes. However, DirecTV is not "broadcast."
Are you asserting that you have an absolute right to listen to your neighbor's encrypted wireless phone because you can detect the signal on your property?
That argument has been used before with varying degrees of unsuccessful-ness, IIRC. One of its biggest proponents was a guy out of San Diego with the handle Dr. Rigormortis. Bill Cheek (Cheeks?) was his name.
He was heavily into 11-meter (CB) dx work and had a newsletter once called the 11 meter times and journal. He died of lung cancer a few years back.
He had a string of running battles with the FCC and others for years. He was ultimately pressured into stopping his newsletter because he covered illegal modifications of CBs.
He switched to scanners and scanner modifications. He was further hassled because of illegal scanner mods like which diodes to clip to open up cell freqs that were locked out, etc. He wrote a couple of books on scanner mods too.
His argument was that he had a legal right to examine any radiated signal that passed through his property (and person) for medical reasons. I seem to recall that it got him nowhere.
He was an interesting guy too bad hes gone.