The reality is what you have already done is about all you can do. Eliminating the temptation for a would-be vandal is pretty much always the best thing to do. If you could conclusively prove who was doing it and catch them in the act then there is a chance that he could be charged and convicted of property damage and trespassing. Would a prosecutor issue charges for that? Who knows! Regardless both charges are misdemeanors and the person wouldn't see any jail time, and probably not any probation time either. Worst case for the suspect is pay a fine to the city/state and pay you restitution for the damage.
If you had to buy an adapter to fix the cable then you would get the cost of the adapter.
And did I mention the aggravation of testifying in court, the reality that most court cases don't go to trial for 6+ months, and the high probability of the prosecuting attorney in your city/county just flat out refusing to prosecute him.
Beyond that, there may be federal laws in regards to tampering with radio towers but unless you are talking about state-owned or priority radio towers I doubt they would apply(i.e. tornado sirens, public safety radio towers, etc.). IF you knew who it was you could always sue them in civil court for the damage, if your damage is substantial enough. Good luck!
On the bright-side, your coax is shielded from the weather(and vandals) now which should prolong its life!
Or a large scream if he "pins" it--
