several antennas with BNC type connectors exist accessable worldwide
that will increase the range when compared to the short 1/4 wave whip
(supplied in the starter kit)
to name a few:
Comet RX7 BNC
Comet SH-95 BNC
BNC-24 (really long)
the Comet CH-32 can be used to shorten the range like for indoor,
or normal visual flights, only 1 inch long.
I have been looking a bit on patches but they are quite narrow band
and will move their resonant frequency alot when they are close to metals and such,
so until I find the "perfect" type I can not recomment it, but again it depends on the frequency band you use and the antenna type, they must match.
3-6 elements are small and cheap and can be made wideband enought to handle 430 to 450MHz at the same time, they improve the range a lot, when pointed to the plane, note: becareful to use same polarizing on ground and plane.
a 9dB gain antenna will make your 500mW emit like 4W !
or your 7W booster to emit like 50W !
remember to double check antenna frequency range