yagi uda antenna vertical polarization

im working on yagi uda as my project and as i see in real life there differnt types of yagi uda some are normal shape all are from dipole and directors ...some are in shape of oval dipole and directors and some has a shape of satalite reflector and then directors .... i saw also directors in vertical and horizantal shapes in differnt yagies or in same yagi ...it doesnt effect of signals when both (horizantal and vertical directors are in same antenna )
what does these types mean.... where are they use ....and how does theses effects of the paramerts of the antenna....

The source is the planar ave guidance.

any more answers with more explanation thanks

@thegame2008:
The different types of Yagi antenna exist to serve different purposes, for instance, to get a high forward gain, low front-to-back ratio, sharp beamwidth, horizontal or vertical polarization, high or low antenna input impedance,etc... Each type of director, reflector and driven element was designed to serve a specific target.
However, all of these Yagi antenna comply with the Yagi antenna principle that: Antenna elements must be arranged in the order of reflectors, driven element, directors and ony driven element is excited.
hope it helps