Antenna heights Due to the long wavelengths in the band, nearly all LF antennas are electrically short, shorter than one quarter of the radiated wavelength, so their low radiation resistance makes them inefficient, requiring very low resistance grounds and conductors to avoid dissipating transmitter power. These electrically short antennas need loading coils at the base of the antenna to bring them into resonance. Many antenna types, such as the umbrella antenna and L- and T-antenna, use capacitive top-loading (a "top hat"), in the form of a network of horizontal wires attached to the top of the vertical radiator. The capacitance improves the efficiency of the antenna by increasing the current, without increasing its height.
Antenna heights Due to the long wavelengths in the band, nearly all LF antennas are electrically short, shorter than one quarter of the radiated w?avelength, so their low radiation resistance makes them inefficient, requiring very low resistance grounds and conductors to avoid dissipating transmitter power. These electrically short antennas! need loading coils at the base of the antenna to bring them into resonance. Many antenna types, such as the umbrella antenna and L- and T-antenna, use capacitive top-loading (a "top hat"), in the form of a network of horizontal wires attached to t:he top of the vertical radiator. The capacitance improves the efficiency of the antenna by increasing the current, without increasing its height.