Hello,

Am a real novice when it comes to antenna theory, but am trying to learn.
if anyone could explain the following for me, even though I admit it's
really awfully basic, would be most appreciative.

Am interested in receiving only, around the Marine VHF bands of 156 MHz, or
so.

I understand that "Gain" is achieved in many antenna configurations by
making them very directional.
My understanding is that you in effect re-shape the lobes to be prominent
along one axis, and minimal at right angles.

So, how is Gain achieved in a
vertical whip (the specs usually mention 3 or even 6 db), or the
rubber-duckie, types of antennas used so often on handheld scanners (or
mounted to recreational boats) ? They are, I believe, truly omni
directional.

Also, are there vertical whip antennas that are directional, with "gain"
perhaps ?

Thanks,
Bob