Self-Erecting, Hemispherically Directional Buoy Antenna

1. Field of the Invention

Self-erecting buoy antennas of the type described in the present application are generally useful for communication buoys and emergency equipment in conjunction with submarines and the like. In one specific use for a buoy antenna, the body of the buoy contains batteries and a miniature transmitter with some form of antenna connected thereto. The buoy is releasable from, for example, a submerged submarine which may be in distress. Upon release, the buoy floats to the surface, the antenna is erected and the transmitter is activated. Since buoys of this type are generally used in conjunction with emergencies, it is essential that the system be simple and reliable.

2. Description of the Prior Art

The prior art buoy antenna systems use quarterwave whip antennas erectable by means of explosive charges, helical springs and the like, which are relatively complicated and, therefore, unreliable. The whip antenna does not provide good radiation coverage at the zenith, which is a defininte handicap when communicating with satellites, overhead aircraft, etc. Therefore, it is desirable to supply the buoy with an antenna having substantially hemispherical radiation coverage and with an antenna which is reliable, light weight and rugged.

The present invention pertains to a self-erecting, hemispherically directional buoy antenna including a buoyant body with movable means affixed thereto for movement from a stored to an erected position, a plurality of elongated, electrically conductive spring members each connected at one end to the body and at the other end to the movable means so as to be generally equally spaced about a central axis and to bias the movable means toward the erected position, releasable means normally holding the movable means in the stored position and releasable to allow the movable means to move to the erected position and means connecting a radio within the buoy to the spring members to provide generally hemispherical radiation therefrom.

It is an object of the present invention to provide a self-erecting, hemispherically directional buoy antenna.

It is a further object of the present invention to provide a self-erecting, hemispherically directional buoy antenna wherein plurality of elongated, electrically conductive spring members provide the erecting force and also define spaced apart arcuate portions of a sphere in the erected position, which arcuate portions operate as the elements of the antenna to provide generally hemispherical radiation.

These and other objects of this invention will become apparent to those skilled in the art upon consideration of the accompanying specification, claims and drawings.

Referring to the drawings, wherein like characters indicate like parts throughout the figures:

FIG. 1 is a view in perspective, with portions thereof exploded, illustrating an embodiment of the present invention with the antenna in the stored position;

FIG. 2 is a view in perspective of the apparatus illustrated in FIG. 1, with the antenna in the erected position;

FIG. 3 is a view similar to FIG. 1 of another embodiment of the present invention; and FIG. 4 is a view in perspective of the apparatus illustrated in FIG. 3, with the antenna in the erected position.

Referring specifically to FIGS. 1 and 2, a buoyant body 10 is illustrated as having an elongated, generally cylindrical shape. A ring 11 is coaxially affixed around the body 10 for sliding movements therealong. Four elongated spring members 12 each have one end affixed to the ring 11 and the other end affixed to one end 13 of the body 10. The spring members 12 are preformed into the shape illustrated in FIG. 2, which is the erected position, and may be forced inwardly against the body 10 to assume the position illustrated in FIG. 1, which is the stored position. The spring members 12 and the ring 11 are maintaned in the stored position by a two-piece releasable housing 15 which is designed to form a cup-like cap over the end of the body 10 containing the hemispherically directional antenna. The housing 15 may be held together in sealing engagement over the body 10 by means of a burn wire, water soluable material, etc. and releases upon the proper actuation, as for example when the buoy is discharged into water or when an electrical current is applied to the burn wire. When the material holding the portions of the housing 15 together is released, the spring members 12 force the housing 15 away from the body 10 and move, with the ring 11, into the erected position illustrated in FIG. 2.

In the erected position of FIG. 2, the spring members 12 form quarterwave length semi-loop antenna elements which are, for example, fed at the end 13 of the body 10 by connections to a transmitter located within the body 10. The spring members 12, in the present embodiment, are quadrature excited to provide an omni-directional, hemispheric radiation pattern. Because of the hemispheric radiation pattern, the present antenna provides better coverage at the zenith than other prior art antennas. Further, the spring members 12 provide the bias necessary to move the assembly from the stored to the erected position to greatly simplify the present assembly and increase reliability thereof. It will of course be understood by those skilled in the art that insulating material will be utilized where necessary, such as end 13 of body 10, to provide the proper operation of the antenna.

Referring to FIGS. 3 and 4, a second embodiment of a self-erecting, hemispherically directional buoy antenna is illustrated wherein a telescopically extendable rod 20 is attached at one end of a cylindrically shaped buoyant body 22 so as to extend axially outwardly therefrom generally coaxial with the cylindrical body 22. A plurality (in this embodiment 4) of spring members 23 each have one end affixed to the end 21 of the body 22 and the other ends are affixed to a ring 24 slideable engaged over the rod 20. The spring members 23 are preformed into arcuate portions of a sphere as illustrated in FIG. 4. With the rod 20 in the stored position and the ring 24 adjacent the end 21 of the housing 22, the spring members 23 are folded inwardly so that a releasable housing 25 can be positioned thereover. The housing 25 is generally cupshaped and fits over the antenna assembly in sealing engagement with the end 21 of the housing 22 to maintain the antenna assembly in the stored position. The housing 25 is formed in a plurality of parts which are held together by means of burn wires, water soluable material, etc. which may be released when desired to allow the housing 25 to separate. The preformed spring members 23 separate the portions of the housing 25 when the material holding them together is released and telescope the rod 20 outwardly to assume the position illustrated in FIG. 4. As in the previously explained embodiment, the spring members 23 form quarterwave length antenna elements which may be fed from either end. In this embodiment the spring members 23 are quadrature excited from the end 21 of the body 22 so as to provide a generally hemispheric radiation pattern. Also, as will be understood by those skilled in the art, various portions of the structure must either be formed of insulating material or coated with insulating material to provide the proper antenna operation. In this embodiment, as in the previous embodiment, the spring members 23 provide the bias required for self-erecting the antenna and, because a minimum of components are required, the antenna is very light weight and reliable.

While we have shown and described specific embodiments of this invention, further modifications and improvements will occur to those skilled in the art. We desire it to be understood, therefore, that this invention is not limited to the particular forms shown and we intend in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.