hi,
I will try to help you, according to what you listed you need to know what parameter in the list needs to be changed, In order to give a correct dipole antenna.
I recall the code that you are currently using is a tutorial I have seen but can not find at the moment. according to my memory the only parameter needs to be changed is Lambda, the rest is taken care of. you need to know your frequency of transmission (F) and then calculate Lambda = 3*10^8/F. and then simulate to see the result.
and also according to my memory
Lambda = is the wave length
Dip_rad = the dipole radius which is very small compared to the length of the dipole.
Radiation_rad = this is the radiation boundary condition around the dipole needed for the simulation.
Radation_height = this is also the related to the boundary condition above the dipole.
Res_lenght = this is the total length of the dipole.
Dip_lenght = one conductor of the dipole length.
Gap_src= this is not very sure about, but I believe the gap between the conductors for the source to be inserted.
if things not very clear please reply.