Hi,
The half-wave dipole is always a half-wave dipole, no matter the frequency since the real length is normalized to the wavelength. So, the radiation properties of a dipole 3 mm long at 50 GHz will be the same as the radiation properties of a dipole 3 m long at 50 MHz. Both dipoles are half-wave dipoles at each frequency. However, conductor losses are not scalable with frequency, so a greater loss resistance will appear at 50 GHz, which affects the radiation resistance of the dipole.