Experimental Measurements of UHF Antennas near an Air-Sea Interface.
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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APPLIED TO A FREQUENCY OF 250 MHz. Results indicated that an insulated half-wave dipole floating half-submerged in the sea would have a peak gain of about 8 dB below isotropic and would exhibit wide variations in gain with small changes in water level relative to the dipole center line. A half-wave slot antenna, backed by a quarter-wave rectangular cavity exhibited a peak gain of about dB above isotropic when flush with the water surface. Reducing the size of the cavity backing the slot reduced the gain and the efficiency of these antennas. A cylindrical cavity with a layer of insulation, with a diameter of about 0.1 wavelength 5 inches at 250 MHz exhibited a gain near 0 dBi when floating at any level in the water as long as not completely covered by water and for the slot on top or bottom of the cylinder. Author
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