My guess is you're using a low-end system instead
of a major brand - like Futaba, JR or Spektrum.
Those systems are poorly designed and have just
enough range to work within the capacity of the
cheap model sthat come with them. Not being sarcastic
here, just real. A different antenna wouldn't be
worth the trouble. I suggest that you live with
what you have for now, and if you plan to move on
to more sophisticated models, buy a good system
- the $250 will save you a lot of heartache and
BTW I've been operating RC models
for many decades and have seen a lot of people make
the mistalke of trying to use those cheap systems
in higher end models with disasterous results.