John A Hoover

US Patent:

46971580, Sep 29, 1987

Filed:

Apr 15, 1986

Appl. No.:

6/852146

Inventors:

John C. Hoover - Roswell GA
David E. Giese - Duluth GA

Assignee:

Electromagnetic Sciences, Inc. - Norcross GA

International Classification:

H01P 139

US Classification:

333 11

Abstract:

A conductive waveguide structure has a central cavity of full height and input/output ports of a second reduced height emanating therefrom. A smaller ferrite circulator element is centrally disposed within the cavity and has outer extremities spaced from the inner edges of the reduced height input/output ports by a predetermined gap dimension "G" which is chosen to achieve an appropriate impedance match between the impedance of the ferrite element and the higher impedance of the wavguide without the necessity for the usual quarter-wave dielectric impedance matching transformer sections.

US Patent:

48019020, Jan 31, 1989

Filed:

Sep 28, 1987

Appl. No.:

7/103782

Inventors:

John C. Hoover - Roswell GA
David E. Giese - Duluth GA

Assignee:

Electromagnetic Sciences, Inc. - Norcross GA

International Classification:

H01P 139

US Classification:

333 11

Abstract:

Impedance matching between a waveguide circulator and its input/output ports is achieved by properly dimensioning a gap formed between a ferrite circulator element inside the waveguide circulator and at least a portion of the input/output port aperture itself. Typically, the I/O port aperture has at least a portion which is of lesser height dimension than the internal waveguide circulator cavity. Ridge waveguide or ridge-to-rectangular waveguide adaptor blocks, or the like, may emanate from such input/output circulator apertures.

US Patent:

57266662, Mar 10, 1998

Filed:

Apr 2, 1996

Appl. No.:

8/626475

Inventors:

John C. Hoover - Roswell GA
David J. Kiesling - Atlanta GA

Assignee:

EMS Technologies, Inc. - Norcross GA

International Classification:

H01Q 1310

US Classification:

343770

Abstract:

An antenna comprising a waveguide component and a probe assembly, coupled to the antenna assembly, for distributing radio frequency (RF) energy to slots positioned on at least one of the broad walls of the waveguide component. The probe assembly can be positioned at the approximate center point of the waveguide component to present a desired impedance to the waveguide cavity and to distribute RF energy of substantially equal amplitude and phase to each section of the waveguide cavity. The probe assembly includes a post, connected to one or both of the rear and front walls, and a probe pin. The post, which is typically positioned within the center of the waveguide cavity, comprises (1) a post cavity located within and extending along at least a portion of the post, and (2) a post slot having an opening located along the post and traversing the post cavity. A probe pin, which is inserted within one end of the post cavity and connected to the opposite end of the post cavity, couples the RF energy to the waveguide cavity via the post slot.

US Patent:

57573298, May 26, 1998

Filed:

Dec 29, 1995

Appl. No.:

8/580802

Inventors:

John C. Hoover - Roswell GA
Steven F. Hering - Lawrenceville GA

Assignee:

EMS Technologies, Inc. - Norcross GA

International Classification:

H01Q 1318

US Classification:

343770

Abstract:

The antenna includes an antenna body, comprising a conductive material, having a cavity surrounded by intersecting wall segments. The wall segments include a rear plate and a face plate having a planar array of longitudinal slots, and both plates are positioned in spaced-apart parallel planes. The antenna further includes a center wall, centrally placed between the face plate and the rear plate, to form within the cavity a parallel pair of waveguide channels. The center bar has a center bar opening extending longitudinally along a portion of the center bar, thereby separating the center bar portion into first and second center bar segments. A guidance hole is aligned with an edge of the center bar and extends through the first center bar segment and at least a portion of the second center bar segment. A probe distributes radio frequency (RF) energy in substantially equal phase and amplitude to the waveguide channels via the center bar opening. The probe includes a probe pin, which is inserted within the guidance hole and passes through both the first center bar segment and the center bar opening and into the portion of the second center bar segment.

US Patent:

46739467, Jun 16, 1987

Filed:

Dec 16, 1985

Appl. No.:

6/809175

Inventors:

John C. Hoover - Roswell GA

Assignee:

Electromagnetic Sciences, Inc. - Norcross GA

International Classification:

H01Q 1300
H01P 1165

US Classification:

343776

Abstract:

A compact adaptor is provided for making transition from ridged waveguide to rectangular waveguide while simultaneously imparting spatial reorientation of associated electric and magnetic fields. The adaptor is especially useful for feeding a phased array of radiating slots (or other structures) where adjacent radiating structures are preferably spaced from one another on the order of a half wavelength and fed with the magnetic field vectors oriented parallel to such inter-element array spacing dimensions. In the exemplary embodiment, a transition from double-ridged waveguide to rectangular waveguide is effected through an electrically short (e. g. , 1/8th to 1/4th wavelength) non-resonant cavity using oppositely tapered continuations of the ridged waveguide walls (acting as a TEM parallel transmission line) to opposing walls of a rectangular waveguide port which is spatially oriented transverse to the ridged waveguide.