The higher the frequency the shorter the wavelength. As frequency
doubles, wavelength halves. The ideal antenna has a direct relationship
with the wavelength - the best length for a radio transmitting antenna
being considered to be a 'half-wave dipole' ('di' meaning two elements
of one-quarter wavelength each).
The normal marine VHF antenna would be a 'half-wave dipole'
Antennas connected to marine MF IHF SSB radios consist of a quarter-
wave element above water (the whip or wire antenna connected to the
ATU) - with the sea (connected through the ship's hull or other 'ground
plane') forming the other{but non-transmitting) 'quarter'
< - - -wilvelength --->
~----~-----+------r-----;--+ time1 second
Figure App IV.7
a) I cycle-peT-second (1Hz) b) 2 cycles-peT-second (2Hz), ,
,~----~-----+------r-----;--+ time
,' 1
<I
,' 1
.... ...' I
1
1
1 second
The 2Hz frequency has a wavelength half of that of the 1Hz
frequency_
1Hz (I Hertz) - 1 cycle per second
1kHz (I kiloHertz) - 1000 cycles per second
IMHz (I MegaHertz) - 1,000,000 cycles per second
IGHz (I GigaHertz) - lots and lots and lots of HzMARINE COMMUNICATIONS 229