Multiple reflection conical microwave antenna

Claim 2

A microwave antenna comprised of a main reflector having an inside surface in the shape of a hollow frustum of a cone for reflecting incident rays into parallel rays which are parallel to the axis of said cone and which emerge from said reflector as a plane wave front, and means for irradiating said main reflector surface with microwave rays from a point source at such angles of incidence that they are reflected by said main reflector surface as rays parallel to said axis with a plane wave front, said means including a subreflector having a surface produced by rotating a segment of a parabola about said cone axis, said segment being oriented with respect to said main reflector so that initial rays reflected by said main reflector onto said subreflector are reflected by said subreflector back onto said main reflector surface to be re-reflected therefrom as parallel rays with a plane wave front.

Claim 3

A microwave antenna as defined in claim 1 wherein said means for irradiating said main reflector surface with initial rays comprises a point-source feed element on said cone axis in front of the antenna aperture defined by the edge of said main reflector surface of largest diamEter.

Claim 4

A microwave antenna as defined in claim 1 wherein said means for irradiating said main reflector surface with initial rays comprises a point-source feed element on said cone axis in back of the antenna aperture defined by the edge of said main reflector surface of largest diameter, and subreflecting means in front of said antenna aperture for reflecting rays from said element directly onto said main reflector surface for double reflection therefrom as said parallel rays with a plane wave front.

Claim 5

A microwave antenna as defined in claim 2 wherein said subreflecting means comprises a subreflector having a surface produced by rotating a segment of an ellipse about said cone, said ellipse having foci at the point of feed from said element and at a focus of said segment of said parabola as reflected from in back of said main reflector to a point in front of said main reflector.

Claim 6

A microwave antenna as defined in claim 4 including means for furling said main reflector by moving a plurality of radial sections thereof evenly spaced inwardly.

Claim 7

A multiple-reflector antenna with minimum aperture blockage of radiation emanating from a point source into parallel rays with a plane wave front, comprised of a main reflector having an inside reflecting surface in the shape of a cone the axis of which defines the axis of the multiple reflector antenna, a subreflector disposed inside of said cone, said subreflector having an outside reflecting surface facing said inside reflecting surface of said cone, said subreflector being of a form generated by revolving a segment of a parabola about said axis of said cone, where said parabola has its focus outside of said cone so positioned that rays appearing to emanate from said focus as a feed point are reflected by said subreflector onto said main reflector for reflection by said main reflector into parallel waves with a plane wave front, and means for irradiating said main reflector with rays everywhere appearing to emanate from a point corresponding to said focus reflected from outside of said cone to inside of said cone.

Claim 8

A multiple-reflector antenna with minimum aperture blockage of radiation emanating from a point source into parallel rays with a plane wave front, comprised of a main reflector having an inside reflecting surface in the shape of a cone the axis of which defines the axis of the multiple reflector antenna, a subreflector disposed inside of said cone, said subreflector having an outside reflecting surface facing said inside reflecting surface of said cone, said subreflector being of a form generated by revolving a segment of a parabola about said axis of said cone, where said parabola has its focus outside of said cone so positioned that rays appearing to emanate from said focus as a feed point are reflected by said subreflector onto said main reflector for reflection by said main reflector into parallel waves with a plane wave front, and means for irradiating said main reflector with rays everywhere appearing to emanate from a point corresponding to said focus reflected from outside of said cone to inside of said cone.

Claim 9

A multiple-reflector antenna as defined in claim 6 wherein said irradiating means comprises a point source feed element on said cone axis radiating directly back into said main reflector from a point outside and in front of said cone which is a mirror image of said focus of said parabola a segement of which is rotated the generate the form of said subreflector.

Claim 10

A multiple-reflector antenna as defined in claim 6 wherein said irradiating means comprises a point source feed element on said cone axis and inside of said main reflector, said element radiating directly out of said main reflector, and an auxiliary reflector in the direct path of radiation from said point source radiating element for reflecting radiation back into said main reflector as though emanating from an infinite number of apparent point source elements in a ring about said cone axis, each of said infinite number of point source elements being a point in front of said cone which is a mirror image of said focus of said parabola, a segment of which is rotated to generate the form of said subreflector, said main reflector functioning as a reflecting surface to form said mirror image.

Claim 11

A multiple reflector antenna as defined in claim 8 wherein said auxiliary reflector has a reflecting surface, facing into said main reflector and toward said radiating point source element, which is generated by revolving a segment of an ellipse about said axis of said cone, one of the foci of said ellipse being at said radiating point source element and the other one at one of said infinite number of apparent point source elements.

Claim 12

A multiple reflector antenna as defined in claim 9 wherein said subreflector is formed on the outside of a cylinder and said radiating point source element is mounted in a coaxial cylindrical cavity in said cylinder.