The current distribution and the radiation pattern of dipoles of different lengths are shown in Fig.
Since the electric field is independent of , the H-plane radiation pattern is a circle which is same as that of the Hertz dipole.
The three dimensional radiation patterns for the dipole antennas of length are shown in Figs.
In general a dipole antenna has multiple beams and multiple nulls. Generally, finding the directions of the nulls is easier compared to finding the directions of the maximum radiation. We therefore obtain the directions of the nulls and place one maximum approximately half way between two adjacent nulls.
The directions of the nulls can be obtained by equating to zero. The directions of the nulls are
, the H-plane radiation pattern is a circle which is same as that of the Hertz dipole. 
are shown in Figs. 
to zero. The directions of the nulls are 
