US 5,708,445 AGranted

Antenna assembly for radio circuit and method therefor

AssigneeMotorola, Inc.

InventorsPaul J. Moller, Patrick A. Schwinghammer, Mark W. Schwartz

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Abstract

An antenna assembly, and associated method, for a radio, such as a portable radiotelephone, which is of minimal physical dimensions and which is operable over a wide range of frequencies. A length of wire is helically-shaped and includes at least a portion of a winding. A capacitive top-hat is positioned at an end portion of the wire. By increasing the number of windings of the wire, the height of the antenna assembly is reduced, but such reduction also reduces the size of the bandwidth of frequencies over which the antenna assembly is operable. Increase in the size of the surface area of the capacitive top-hat increases the size of the bandwidth over which the antenna assembly is operable. Selection of the top-hat size and the number of windings permits beth physical dimensions of the antenna assembly and the size of the bandwidth to be selected.

Claims19

Dependent claims

An antenna assembly of selected antenna characteristics for a radio having radio circuitry housed within a radio housing body, the antenna assembly comprising:

an electrically-conductive wire positioned in the radio housing body and having at least a portion of a winding formed therein to configure the electrically-conductive wire into a coiled shape, the electrically-conductive wire having a proximal end portion and a distal end portion wherein the proximal end portion is coupled to the radio circuitry;
a top-hat positioned in the radio housing body, the top hat including a first electrical coupling portion coupled to the distal end portion of the wire, wherein the top-hat is of a surface area of a magnitude related to numbers of windings formed in the electrically-conductive wire and is selected such that the number of windings of the wire and the magnitude of the surface area of the top-hat are together determinative of the antenna characteristics, and the top hat including a second electrical coupling portion for electrically coupling the top hat to an antenna associated with a projecting rod, the first and second electrical coupling portions spaced from one another;
and
a rod including a rod coil carried thereon, the rod and coil extending through the top hat and out of the radio housing body in an extended position, the rod coil coupled to the top hat at the second electrical coupling portion when the rod is in the extended position, whereby the rod coil is coupled to the radio circuitry via the top hat and the electrically conductive wire when the rod is in the extended position.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 08/024,545Filed 1 Mar 1993 · continuation in part
Priority: 29 Jan 1993
Granted: 13 Jan 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H01Q 1/362
Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith: for broadside radiating helical antennas
H01Q 1/244
With built-in antennas: extendable from a housing along a given path
H01Q 9/36
Vertical arrangement of element: with top loading
H01Q 9/40
With feed to end of elongated active element, e.g. unipole: element having extended radiating surface

Family

Serial11,016Parent of this continuation · filed 29 Jan 1993
Serial425,694Parent of this continuation-in-part · filed 19 Apr 1995
US 5,572,224 AParent of this continuation-in-part
US 5,708,445 AThis patent

From the US filing history. Foreign family members aren’t listed.

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