Optimization of the exchange of energy between a free space wave and current flowing in the conductive helix of an axial mode, helical antenna is achieved by varying the pitch angle of successive turns of the antenna along the axis of the antenna, from a relatively small pitch angle at the base, feed location of the antenna, to a relatively large value at the distal end of the antenna. Pitch angles of successive turns of the antenna are varied in a non-linear manner to correspond to the non-linear manner in which the phase velocity of a wave propagating through the antenna varies relative to the phase velocity of a free space electromagnetic wave. For the case of an axial mode, helical antenna operating at C-band, the pitch angle of said antenna may be varied between 3-8 degrees at the antenna feed point to a 20-30 degrees at its free space-interfacing distal end. The variable pitch angle antenna has a gain versus bandwidth characteristic that contains a plurality of spaced apart peak regions, one of which has a peak gain slightly less than the other. This dual peak gain behavior permits application design trade off between a smaller sized antenna with slightly reduced performance versus a larger sized antenna with slightly higher performance.

Variable pitch angle, axial mode helical antenna

In a helical antenna where a helical conductor is spirally wound on a coaxial cable, spacings between turns of the helical conductor are changed in accordance with the positions of the turns.

Broad conical-mode helical antenna

A retractable antenna assembly is disclosed for tuning an antenna having a helical section to frequency by selectively positioning an appropriate tuning core within the helix. The antenna frequency can either be raised or lowered through the use of conductive or permeable tuning core compositions. The core positioning mechanism is implemented by affixing the tuning core to a portion of the antenna supporting rod slideably located within the helix. This helical antenna/tuning core configuration is readily adaptable to miniature portable radios by providing a helical antenna assembly which is retractable within the radio housing in the receive-only or standby mode, and which is outwardly extendible from the radio housing for use in the active transmit/receive mode. A unique barrel-cam latching mechanism is also described.

Retractable helical antenna

A connector coaxial cable connector comprising a connector body having an outer ramped surface, a post, engageable with the connector body, a coupling member, axially rotatable with respect to the post, and a compression portion structurally integral with the connector body, the compression portion having a ramped inner surface, wherein the inner ramped surface is configured to cooperate with the outer ramped surface during compression of the compression portion onto a portion of the connector body. Furthermore, an associated method is also provided.

Coaxial cable connector

A length of somewhat resilient yet deformable conductor wire is wound into a tight coil on a generally frustoconical mandrel. The coil is stretched axially inside the bore of an elongated, generally frustoconical antenna blank or casing such that the convolutions of the coil consecutively engage the inner periphery of the casing and are held against further movement. Liquid adhesive injected into one end of the casing in upright position sets to secure the coil to the casing. The resulting conical spiral antenna requires no inner core and is particularly adapted to mobile use such as on a car or a boat.

Method of making a conical spiral antenna

A spring tunable antenna for mounting to the frame of a vehicle. The antenna includes a base adapted to be mounted on the vehicle, a flexible rod supported at its lower end in the base, and a low-resistance wire conductor wound helically around the rod. The conductor windings in the tip region of the rod are selectively movable, whereby the antenna may be tuned.

Thomas J. Wilson

Papers

Spring tunable helical whip antenna