CST MWS - electric filed and discrete port

Hi, In CST MWS, I create dipole source by using discrete port couple to two PEC particles.After simulated, the result show that electric field is highest in the middle of 2 particles instead of at the particles as in theory. Any idea why it like that? I guess because the discrete port(the red cone) become a point source. and if I want to calculate it. Which equations I can use? Thank a lot