JArthur wrote:
If a longer antenna is better then why do they sometimes have to be cut
shorter when tuning?


I guess you're getting anal about a 1:1 SWR?

Most mobile antennas have an SWR of about 1.5:1 when tuned properly.
Tune for maximum field strength, not lowest SWR. The two don't
always happen at the same place.

My CB antenna runs about 1.7:1. I talk anywhere I want to. I don't
even know what my 2 meter beam is at. It works just fine.

Shorter makes an antenna capacitive.
Longer makes an antenna inductive.

This length is frequency dependent.

May I suggest a trip to your local library to pick up some books on
RF/antenna theory? Try ARRL handbooks and others somewhere around 630.