Antanna with narrow radiation pattern ...

Can we design an antanna which has very narrow radiation pattern.... for example just like a lazor .... The basic application where it has to be used is tracking an object ....
Is there any such antenna which is already available .... Other than the frequency which all parameters come into play ..... ?

Not like a razor but multi-element Long Yagi antenna is one of the most directive antenna for frequencies up to 2.5GHz.
http://www.antennex.com/Sshack/long-boom/lbyagi.html

Also for high frequencies Helix antenna is an option with narrow antenna pattern.
http://entropy.brneurosci.org/helix-antenna.html

As you know nerrow BW means bigger area (lambda wise), so first of all
you will need space, you can use the basic rules to know how much:
D~30000/(BW1*BW2) and D~4*pi*A/lambda^2
for example, an 8ft parabolic dish at 2.5GHz will give you about 2.5deg of BW.
the most efective way for BW is an array (that can also give you beam forming).
I will go with a patch antenna array, and not a Yagi one because it's samller.

phased array using printed elements is best method

you need a spiral helical beam antenna

to colubate the helical beam use a set of trapped crossed directors

biased with some rf outputs via some cross director elements at the end of the spiral
using the harmonics to direct the main carrier

spiral helical for this is best as its very narrow band

and extreamly directional with a very high front to back ratio
even with no refelctors

can i get a very compact directional antenna for frequency range 144-146 Mhz? may not be exact range but the range should include these frequencies

if u need a very narrow BW you must increase the direction of your antenna especialy your parabolic antenna.

For example in SAR (synthetic aperture radar)

the antenna of SAR is placed on a satellite or plane
so with the movement of stallite we can get a large antenna dimenson from a small antenna(also need signal processing)

We can get high resolutions from SAR with narrow beamwidth even from satellites

increase dimension of your antenna

sorry