Mailbox Sensor - Too Hot for 2-Sided Tape

Purchased the mailbox sensor a few months back and it has worked great until now. Unfortunately, the metal mailbox combined with the summer heat of the southwest, has seen the antenna constantly fall off the box. I have changed the tape several times at this point and it always ends the same way. For the time being, I have a bungee cord wrapped around the mailbox, to keep the antenna in place, but that's not very appealing to the eye. Any solutions would be appreciated.