blue tooth receiver antena

I have been using the tomtom blue tooth reciever had for two years but have been told need to get an anttena as signal is being blocked because of having a tinted windscreen and sometimes blocking signal not sure what to get as have only seen ones advertised for tomtom go. I am using tomtom blue tooth with dell axim on tomtom 5 also if anyone know the cost thanks

[Charlie]

I don't think you can get them to fit that receiver anymore. Have you tried the reciever in theback window instead? I'm guessing it's not tinted.