Transmitting antenna employing end-fire elements

Claim 2

An antenna assembly for transmitting signals of a given wavelength, comprising an elongated electrically conductive supporting structure having a major transverse dimension greater than a quarter wavelength, at least one bay including a driven antenna carried by said supporting structure and defining a radiation axis extending therefrom, means for feeding electrical energy to said driven antenna, and at least one end-fire parasitic director having a longitudinal axis and comprising a plurality of discrete planar conductive plates disposed in spaced parallel relation along said longitudinal axis and being normal thereto, said discrete conductive plates having their respective major dimensions in the plane of the electric field vector of the transmitted signal at least a quarter wavelength, said end-fire parasitic director being so positioned relative to said driven antenna and supporting structure as to alter the shape of the antenna pattern produced by the combined effects of said driven antenna and supporting structure, while not intersecting the radiation axis of said driven antenna, to provide a selected pattern for said antenna assembly.

Claim 3

The antenna assembly of claim 1 wherein the respective major dimensions of said conductive plates are between one-fourth and one-half wavelength.

Claim 4

The antenna assembly of claim 2 wherein the major dimension of at least one of said conductive plates is one-third wavelength.

Claim 5

The antenna assembly of claim 1 wherein the distance between said spaced parallel conductive plates is less than about one-half wavelength.

Claim 6

The antenna assembly of claim 4 wherein said distance is between one-eighth and one-half wavelength.

Claim 7

The antenna assembly of claim 1 wherein said end-fire parasitic director extends generally away from said supporting structure and includes one of said conductive plates positioned farther from said supporting structure than another of said conductive plates, said one conductive plate having a larger major dimension than said another conductive plate.

Claim 8

The antenna assembly of claim 1 wherein said discrete planar conductive plates are in the form of a disc.

Claim 9

The antenna assembly of claim 1 wherein said discrete planar conductive plates are in the form of a screen.

Claim 10

The antenna assembly of claim 1 wherein said discrete planar conductive plates are in the form of rods.

Claim 11

The antenna assembly of claim 1 wherein said discrete planar conductive plates have a supporting rod extending along the longitudinal axis of said parasitic director.

Claim 12

The antenna assembly of claim 1 wherein the axis of said parasitic director lies in a plane which is approximately normal to the longitudinal axis of said supporting structure, said plane intersecting said supporting structure within a half wavelength of the center of the driven antenna, measured along the longitudinal axis of said supporting structure.

Claim 13

The antenna assembly of claim 1 wherein said one bay includes another end-fire parasitic director like said one director, each of said directors being pOsitioned on generally opposite sides of said driven antenna.

Claim 14

The antenna assembly of claim 12 wherein said bay includes a further pair of directors like said first pair, said further pair of directors being positioned in spaced relation to said first pair along the longitudinal axis of said supporting structure.

Claim 15

The antenna assembly of claim 12 wherein a further parasitic director generally extends from said supporting structure at a position approximately 180* from said driven antenna.

Claim 16

The antenna assembly of claim 1 further comprising a plurality of bays like said one bay disposed along said elongated supporting structure, the elementary antennas of each successive bay being spaced a distance between nine-tenths wavelength and one wavelength.

Claim 17

The antenna assembly of claim 15 wherein each of said bays includes a plurality of said end-fire parasitic directors like said one director.

Claim 18

The antenna assembly of claim 1 wherein the longitudinal axis of said supporting structure is vertical and wherein said driven antenna transmits a horizontally polarized wave, the axis of said end-fire director lying in an approximately horizontal plane and said discrete conductive plates having each said major dimension in said approximately horizontal plane.

Claim 19

The antenna assembly of claim 17 wherein the plane formed by each of said conductive plates is generally vertically disposed.

Claim 20

The antenna assembly of claim 18 wherein said planar conductive plates are circular discs, said major dimension of each being equal to the diameter of the disc.

Claim 21

The antenna assembly of claim 17 wherein said bay further includes another driven antenna which transmits a vertically polarized wave.

Claim 22

The antenna assembly of claim 17 wherein said supporting structure is generally tubular and has a solid wall, said driven antenna comprising a slot formed on the wall of said tubular structure.

Claim 23

The antenna assembly of claim 1 wherein the longitudinal axis of said supporting structure is vertical, said assembly comprising a plurality of bays like said one bay spaced approximately a wavelength apart vertically along said supporting structure, the driven antenna of each bay comprising a slot-type antenna element, and each bay including three end-fire directors like said one director, one of said directors being mounted on said supporting structure in alignment with the radiation axis of said driven antenna, but positioned on the opposite side of said supporting member, and a further pair of said directors each positioned on either side of said first director and between said first director and said driven antenna, said plurality of conductive plates of each director having a major dimension of from one-fourth to one-half wavelength.

Claim 24

An antenna assembly for signals of a given wavelength, comprising a supporting structure, a driven antenna carried by said supporting structure and defining a radiation axis extending therefrom, at least one end-fire parasitic director carried by said supporting structure and comprising a plurality of discrete planar conductive plates disposed in spaced parallel relation along an axis normal to said conductive plates, said planar conductive plates having their respective major dimensions one-fourth wavelength and one-half wavelength, the distance between said planar conductive plates being less than about one-half wavelength, the axis of said parasitic director lying in a plane parallel to and within one-half wavelength of a plane passing through the center of said driven antenna and containing the radiation axis thereof, and said end-fire parasitic director being so positioned relative to said driven antenna and supporting structure as to alter the shape of the antenna pattern produced by the combined effects of said driven antenna and supporting structure, while not intersecting the radiation axis of said driven antenna, to provide a selected antenna pattern for said antenna assembly.

Claim 25

An antenna assembly for signals of a given wavelength, comprising a supporting structure, a driven antenna carried by said supporting structure and defining a radiation axis extending therefrom, at least one end-fire parasitic director carried by said supporting structure and comprising a plurality of discrete planar conductive plates disposed in spaced parallel relation along an axis normal to said conductive plates, said planar conductive plates having their respective major dimensions one-fourth wavelength and one-half wavelength, the distance between said planar conductive plates being less than about one-half wavelength, the axis of said parasitic director lying in a plane parallel to and within one-half wavelength of a plane passing through the center of said driven antenna and containing the radiation axis thereof, and said end-fire parasitic director being so positioned relative to said driven antenna and supporting structure as to alter the shape of the antenna pattern produced by the combined effects of said driven antenna and supporting structure, while not intersecting the radiation axis of said driven antenna, to provide a selected antenna pattern for said antenna assembly.

Claim 26

The antenna assembly of claim 23 wherein said discrete planar conductive plates are in the form of a disc, said assembly comprising a rod extending along the axis of the parasitic director and supporting said discs in said spaced parallel relation.

Claim 27

The antenna assembly of claim 23 comprising a pair of said end-fire parasitic directors, each being positioned on generally opposite sides of said driven antenna.

Claim 28

The antenna assembly of claim 25 wherein each of said directors extends generally from said supporting structure at angles of about 120* to said driven antenna on each side thereof to provide an omnidirectional antenna pattern.

Claim 29

The antenna assembly of claim 25 wherein each of said directors extends generally from said supporting structure at angles of about 45* to said driven antenna on each side thereof to provide an antenna pattern containing two large lobes generally centered on the respective axis of each director and a deep null directly in front of said driven antenna.

Claim 30

The antenna assembly of claim 25 wherein each of said directors extends radially outward from said supporting structure at approximately 30* on each side of said driven antenna, and a further driven antenna is disposed on the radiation axis of said driven antenna to provide an antenna pattern covering a span of approximately 120* about said radiation axis.

Claim 31

The antenna assembly of claim 25 wherein each of said directors extends generally backwards and inwards from said supporting structure relative to said radiation axis to provide a generally semicircular antenna pattern.

Claim 32

The antenna assembly of claim 25 wherein each of said directors extends radially outward from said supporting structure at approximately 15* on each side of said driven antenna to provide an antenna pattern having a single large lobe centered about said radiation axis with a beamwidth of approximately 90*.

Claim 33

The antenna assembly of claim 25 comprising a further one of said end-fire directors extending generally parallel to said radiation axis.