Allen T Davidson

US Patent:

41386817, Feb 6, 1979

Filed:

Aug 29, 1977

Appl. No.:

5/828565

Inventors:

Allen L. Davidson - Crystal Lake IL
James M. Durante - Elgin IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H01Q 124
H01Q 904
H01Q 938
H01Q 2100

US Classification:

343702

Abstract:

An antenna for a hand-held radio transceiver includes first and second elements extending from the radio's case. The first element is comprised of a pair of series coupled members having electrical lengths of one-half and one-quarter wavelength, respectively, with the free end of the second member being coupled to the transmitter output. The second element couples to the radio's electrical ground and is configured to form a transmission line with the second member. The effective electrical length of the second element, including the influence of the elements parasitic coupling to the radio, is adjusted to be one-quarter wavelength. The resulting antenna structure minimizes surface currents across the radio's body, thereby substantially eliminating power loss caused by absorption in the user's body.

US Patent:

51207052, Jun 9, 1992

Filed:

Aug 22, 1990

Appl. No.:

7/571390

Inventors:

Allen L. Davidson - Crystal Lake IL
Marc K. Chason - Schaumburg IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H01P 104
H01B 1212

US Classification:

505 1

Abstract:

A transmission line using superconductors instead of conventional conductors substantially reduces ohmic losses compared to conventional conductors. The superconductors are cooled by refrigerant flowing through a hollow superconducting inner conductor. The refrigerant is transported to the inner conductor using a novel connector.

US Patent:

42131324, Jul 15, 1980

Filed:

Jul 19, 1978

Appl. No.:

5/926043

Inventors:

Allen R. Davidson - Crystal Lake IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H01Q 2100

US Classification:

343854

Abstract:

An improved antenna system is disclosed in which a single antenna array is simultaneously used in conjunction with several independent radio devices. Isolated and independent radio transmitters are coupled, without any signal cancellation, to each and every one of a plurality of isolated independent antenna elements by a combining network which maintains the isolation between each of the radio transmitters and each of the antenna elements. The combining network comprises an array of hybrid networks and creates a predetermined electrical phase difference between each signal received by an individual antenna element. The antenna elements form a single antenna array consisting of circularly disposed corner reflector antennas. Each reflector independently creates an individual radiation pattern and these patterns combine to form a single desired composite radiation pattern. By maintaining isolation between each of a number of radio transmitters, a plurality of these transmitters may be used simultaneously in conjunction with a single antenna array.

US Patent:

60185147, Jan 25, 2000

Filed:

Jun 29, 1998

Appl. No.:

9/106401

Inventors:

Richard S. Bickham - Cary IL
Allen L. Davidson - Crystal Lake IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04L 100

US Classification:

370217

Abstract:

A desirable operating condition is maintained in a communication device (100) that is operating in an undesirable environment by reducing the number of radio frequency signals being amplified and subsequently transmitted by the communication device (100). The remaining radio frequency signals transmitted will be transmitted at full power, so that coverage area is maintained in a tradeoff for reduced capacity.

US Patent:

53456009, Sep 6, 1994

Filed:

Aug 31, 1993

Appl. No.:

8/114526

Inventors:

Allen L. Davidson - Crystal Lake IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 110

US Classification:

455 501

Abstract:

In a radio communications system, a selectively enabled time- and/or frequency-diverse signaling scheme is employed to improve signal quality. In particular, a method of exchanging a message between communication devices using a communications resource might include the step of transmitting a first portion of the message on a first frequency within the communications resource. After determining the quality of the communications resource to be unfavorable, a second portion of the message might be transmitted on the first frequency, and also re-transmitted on a second frequency and/or at a separate time.

US Patent:

43172172, Feb 23, 1982

Filed:

Aug 11, 1980

Appl. No.:

6/176895

Inventors:

Allen L. Davidson - Crystal Lake IL
Jona Cohn - Morton Grove IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 714

US Classification:

455 24

Abstract:

Spillover of RF signal from the output of a same-frequency repeater to the input is reduced by attaching a tag to the output signal. The tag is double-sideband, suppressed carrier to place two spectral spikes, one above and one below the carrier. The tag is applied to the signal in the IF. A tagged signal of variable amplitude and phase is added to the received signal so as to cancel the tag and hence the spillover signal, leaving only the desired signal. A feedback system controls the amplitude and phase of the cancelling signal.

US Patent:

58024840, Sep 1, 1998

Filed:

Jul 12, 1996

Appl. No.:

8/678899

Inventors:

Douglas M. Hamilton - Elgin IL
Allen L. Davidson - Crystal Lake IL
Mark A. Gannon - Sleepy Hollow IL
Leigh M. Chinitz - Palatine IL
Roger J. B. Jellicoe - Woodstock IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 138

US Classification:

455558

Abstract:

An antenna structure (108) operates in the presence of narrow or wide band interference and yet is able to enjoy high receiver sensitivity. This is done by steering the antenna structure (108) radiation pattern null in its near field at the noise source.

US Patent:

42233100, Sep 16, 1980

Filed:

Oct 2, 1978

Appl. No.:

5/947383

Inventors:

Allen L. Davidson - Crystal Lake IL
Pitt W. Arnold - Crystal Lake IL
Morton Stern - Skokie IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 700
H01Q 324

US Classification:

343100CS

Abstract:

The inventive antenna coupling system is capable of simultaneously radiating an omnidirectional signal pattern for a plurality of transmitters as well as providing a directive pattern to a receiver. An antenna array is coupled to the transmitters and receiver via a plurality of antenna couplers. Each coupler includes an antenna terminal, coupled to a corresponding antenna, a transmitter input terminal and a receiver output terminal. Multiple transmitters are coupled to the transmitter input terminals through a hybrid network array. The receiver is coupled to the receiver output terminal via a logic controlled antenna switch. The antenna couplers, which may be comprised of either high pass-low pass filters or circulators provide isolation between the transmit and receiver signals.