You can get a telescopic antenna for your scanner from Maplins. Connectors on scanners tend to be BNC, although a few newer radios use SMA.
BNC connectors on a radio are cylindrical with two diametrically opposed pegs stuck out about 1mm from the top.
SMA connectors are threaded and about 5mm in diameter.
The manual will tell you which your scanner accepts.
Good luck with the flying, I wish I could get down to a weight where I wouldnt move the CofG outside limits hehehe then I would give it a go.
Cheers n beers
Ian