Anyone Know How To Shorten A Standard 9N Aerial?

[MaTTHeW]

Its already on here but the link has expired.. So ive got no idea? I got one of them small vw sharan aerials from ebay for £8.45 but the reception is not that good.
So ive put back on the original aerial. And seen you can cut it down to size. Someone explain please.

[chewy]

Take it off the car
Get a hacksaw
Cut aerial (See arrow in pic below)



Refit to car
Job done