My lady and I were driving on the interstate recently when we noticed an unusual phenomenon. We were listening to the radio (an FM signal), and only over a couple of bridges did we entirely lose our signal. I had some ideas explaining this but I'm not sure, so I am asking for your help. What caused this?
To clear things up a bit:
- It happened over three bridges in a thirty mile stretch. Each was over a river (not sure if that matters for reasons of over-water architecture or aquatic radio effects), but we crossed several other bridges that did not cause this phenomenon.
- Our signal was excellent the whole drive except on these few bridges, when it suddenly disappeared (white noise) and reappeared immediately after crossing.
- The bridges were concrete with no supports from above, no street lights, etc. There was no difference in obstructions above the vehicle for the entire drive.
- I have spent a lot of time driving with the radio on and have never experienced such a loss of signal with no explainable obstruction. I can only assume that the construction of these few bridges is unique.