Editing Ground (electricity) (section)

=== Electrically short antennas ===
At lower frequencies the resistance of the ground system is a more critical factor because of the small radiation resistance of the antenna. In the [[low frequency|LF]] and [[very low frequency|VLF]] bands, construction height limitations require that [[electrical length|electrically short]] antennas be used, shorter than the fundamental [[resonant]] length of one quarter of a [[wavelength]] (<math>\ \tfrac{ 1 }{ 4 } \lambda\ </math>). A quarter wave monopole has a [[radiation resistance]] of around 25~36&nbsp;[[ohm (unit)|ohms]], but below <math>\ \tfrac{ 1 }{ 4 } \lambda\ </math> the resistance decreases with the square of the ratio of height to wavelength.  The power fed to an antenna is split between the radiation resistance, which represents power emitted as radio waves, the desired function of the antenna, and the ohmic resistance of the ground system, which results in power wasted as heat. As the wavelength gets longer in relation to antenna height, the radiation resistance of the antenna decreases so the ground resistance constitutes a larger proportion of the input resistance of the antenna and consumes more of the transmitter power. Antennas in the VLF band often have a resistance of less than 1&nbsp;[[ohm]], and even with extremely low resistance ground systems 50% to 90% of the transmitter power may be wasted in the ground system.<ref name=Carr-2001/>