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Low frequency
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Low frequency (LF) is the ITU designation for radio frequencies (RF) in the range of 30–300 kHz. Since its wavelengths range from 10–1 km, respectively, it is also known as the kilometre band or kilometre waves.
An LF radio clock
An LF radio clock
Low cost LF time signal crystal receiver using ferrite loop antenna.
Low cost LF time signal crystal receiver using ferrite loop antenna.
Monopole antenna
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A monopole antenna is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane. The driving signal from the transmitter is applied, or for receiving antennas the output signal to the receiver is taken, between the lower end of the monopole and the ground plane. One side of the antenna feedline is attached to the lower end of the monopole, and the other side is attached to the ground plane, which is often the Earth. This contrasts with a dipole antenna which consists of two identical rod conductors, with the signal from the transmitter applied between the two halves of the antenna.
A typical mast radiator monopole antenna of an AM radio station in Chapel Hill, North Carolina. The mast itself is connected to the transmitter and ra
Marconi's first monopole transmitter
Marconi's first monopole transmitter
One of Marconi's early monopole antennas at his Poldhu, Cornwall transmitting station, 1900, consisting of a small metal plate suspended from a wooden
One of Marconi's early monopole antennas at his Poldhu, Cornwall transmitting station, 1900, consisting of a small metal plate suspended from a wooden arm with a long wire running down to the transmitter in the building.
Multi-lobed radiation pattern of a 3/ 2 wavelength monopole. Monopole antennas up to 1/ 2 wavelength long have a single "lobe", with field strength de
Multi-lobed radiation pattern of a 3/ 2 wavelength monopole. Monopole antennas up to 1/ 2 wavelength long have a single "lobe", with field strength declining monotonically from a maximum in the horizontal direction, but longer monopoles have more complicated patterns with several conical "lobes" (radiation maxima) directed at angles into the sky.