Hey, I am probably too late for you - and I am slightly confused if all the elements can be driven (a feedpoint on both elements for say a 2-element phased yagi).
However, draw say 2 x dipole elements on the ground (Z=0)
Feed one of them.
Make height = 15m (half a wavelength)
Calculate > Start
View far field plot
The three main variables that will affect your plot will be a) heights above ground b) different element lengths and c) distance between elements
Height will change the angle (you are aiming for 30 degrees)
The element sizes will change the gain, SWR
Distance between elements will mostly change SWR and F/B ratio
Anyway, I am probably too late - but good luck.
Callum
DX Commander