RE: My crash
Is it possible you damaged the connection where the antenna wire attaches to the receiver board? I would suggest sending your receiver to Futaba for a checkout. I just sent in a 149DP that crashed from about 700 ft up, straight down and then sat in the creek bed for about four months before being found. They replaced two ceramic filters and the GWS crystal I had put in, and which I'm now blaming for the crash. It cost me less than $50 and the piece of mind alone was worth that.
I run my antenna through a piece of antenna tubing that I burry in the fuselage as best I can. It gives you a sort of straight wire. One of the guys at the field is an ex ham and he makes an antenna out of copper foil for leaded glass and builds it into the wing of his planes. He has a plug on it for removing the wing. That seems to work quite well also.
One thing to keep in mind is that when the plane is going straight away from you, the antenna is at it's worst for signal gathering. If you point your transmitter at the plane, you are doubling the problem. Keep the transmitter atenna vertical as best you can to reduce this problem. All that said and done, you shouldn't have lost signal anyway. Assuming a 20MPH flying speed, your 30 seconds would have put you out less than 900 ft, way less than the expected range. I'll bet though that your flight was less than 15 seconds, so that would have halfed the distance.
Get your receiver checked out.
Don