Standard Antenna Polar Diagram And External Antenna Polar Diagram

[Johnn]

Hi, I have recently had a external antenna put up on a 12ft pole, the aerial people said a 18ft would be to high for the house!
I now have a semi decent 360 degrees view at around 55 - 60 miles all round, I think this range is okay for my area,
would 'going higher' be the only option to have the polar diagram bigger?
I am using a Radar 100 Antenna.
Thanks John