# wavelength

1. ### why does 1/4 wavelength have a ground plane and 1/2 wavelength needs no?

why does 1/4 wavelength have to have a ground plane and 1/2 doesn't? I know that an antenna that has half a wavelength does not need the ground plane (example a dipole antenna) and when using a wavelength of 1/4 it is usually necessary to have the ground plane (planar antennas [PCB]). My...