Dan Marshall

US Patent:

41018940, Jul 18, 1978

Filed:

Sep 17, 1976

Appl. No.:

5/724348

Inventors:

Dan H. Marshall - Sunnyvale CA

International Classification:

G01S 504
H04B 1034

US Classification:

343112R

Abstract:

A radio beacon for a nautical emergency rescue system includes a flotation housing containing an antenna in an upper portion, a ground plane and a transmitter in a central portion, and batteries in a lower portion. When placed in the water, the lower section is submerged and the central section is at surface level, enabling contact between the ground plane and the water via conductors that pass through the housing. The upper portion projects above the water to permit efficient radiation from the antenna, which consists of a vertical rod and a coaxial cylindrical can that is open at the bottom end. The upper end of the rod is attached to the center of the can closed end. The radio transmitter is frequency modulated in a distinctive pattern, and operates with a duty cycle that permits detection and direction finding of multiple such beacons.