Steerable null antenna arrangement

Claim 2

An electronically steerable antenna arrangement capable of having patterns with a plurality of steerable nulls comprising: a. a plurality of omnidirectional antenna elements arranged to provide at least two orthogonal element pairs; b. first means coupled to said plurality of antenna elements for providing first antenna pattern signal energy; c. second means coupled to said plurality of antenna elements for providing reference antenna pattern signal energy; and d. means for continuously electronically varying the signal energy of said first means relative to said second means to provide a combined antenna pattern signal energy having a plurality of steerable nulls.

Claim 3

The arrangement according to claim 1 wherein said plurality of omnidirectional antenna elements include two orthogonally arranged pairs of omnidirectional elements, with the element separation of each pair being equal and less than 1/2 lambda .

Claim 4

The arrangement according to claim 2 wherein said first means include a first balanced hybrid having a balanced port, an in-phase port, a first port coupled via a first line to one element of one of said antenna element pairs, and a second port coupled via a second line to the other element of said one antenna element pair, said first port being responsive to first energy and said second port being responsive to said first energy having a 180* phase relationship with said first energy at said first port, said first and second ports simultaneously being responsive to in-phase second energy.

Claim 5

The arrangement according to claim 3 wherein said second means include a second balanced hybrid having a balanced port, an in-phase port, a first port coupled via a third line to the one element of the other of said antenna element pairs, and a second port coupled via a fourth line to the other element of said other antenna element pair, the first port of said second balanced hybrid being responsive to said first energy having a +90* phase relationship with said first energy at the first port of said first balanced hybrid and the second port of said second balanced hybrid being responsive to said first energy having a -90* phase relationship with said first energy at the first port of said first balanced hybrid, the first and second ports of said second balanced hybrid simultaneously being responsive to said in-phase second energy.

Claim 6

The arrangement according to claim 4 wherein said first, second, third and fourth lines are electrically the same length.

Claim 7

The arrangement according to claim 5 wherein a steerable cardioid pattern is provided and wherein said means for varying the signal energy of said first means relative to said second means comprise phase shifting means.

Claim 8

The arrangement according to claim 5 wherein a steerable cardioid pattern is provided and wherein said means for varying the signal energy of said first means relative to said second meaNs comprise signal energy resolving means.

Claim 9

The arrangement according to claim 6 wherein said first means further include a quadrature hybrid having a first port, a second port, 0* phase port coupled via a fifth line to the balanced port of said first balanced hybrid and a 90* phase port coupled via a sixth line to the balanced port of said second balanced hybrid, said fifth and sixth lines having the same electrical lengths.

Claim 10

The arrangement according to claim 8 wherein said second means further include a first power adder/divider having an in-phase port and first and second ports coupled via seventh and eighth lines respectively to the in-phase port of said first and second balanced hybrids, said seventh and eighth lines being of the same electrical length.

Claim 11

The arrangement according to claim 9 wherein said phase shifting means includes a first phase shifter having at least a first port coupled to one of the first and second ports of said quadrature hybrid.

Claim 12

The arrangement according to claim 10 further including a second power adder/divider having a first port coupled to a second port of said first phase shifter and a second port of said first phase shifter and a second port coupled to said second means.

Claim 13

The arrangement according to claim 11 wherein said first phase shifter is a dual-channel phase shifter having first and third ports respectively coupled to said first and second quadrature hybrid ports and a second port coupled to said second power adder/divider, and wherein the second port of said second power adder/divider is coupled to the in-phase port of said first power adder/divider by way of a predetermined fixed phase shift means.

Claim 14

The arrangement according to claim 12 wherein trimming means are coupled between said dual-channel phase shifter and said second power adder/divider in order to optimize the cardioid pattern characteristics.

Claim 15

The arrangement according to claim 10 wherein said second power adder/divider is coupled to the inphase port of said first power adder/divider by way of first trimming means and is coupled to said first phase shifter by way of second trimming means, said first and second trimming means being provided for trimming the relative amplitudes of the signal energy at the first and second ports of said second power adder/divider in order to optimize the null of the cardiod pattern.

Claim 16

The arrangement according to claim 11 further including a third power adder/divider having a first port coupled to the other of said first and second quadrature hybrid ports, a second port coupled to the second port of said first phase shifter and an in-phase port coupled to the first port of said second power adder/divider, and a second phase shifter coupled to said first power adder/divider in-phase port via a predetermined fixed phase shift and further coupled to the second port of said second power adder/divider, said first and second phase shifters being in a ganged relationship in order to provide a two-to-one phase shift ratio.

Claim 17

The arrangement according to claim 14 further including trimming means coupled between said second and third power adders/dividers for controlling the amplitude of the energy at the first port of said second power adder/divider relative to the energy at the second port thereof in order to optimize the cardioid pattern characteristics.

Claim 18

The arrangement according to claim 10 wherein said first phase shifter is a dual-channel phase shifter having first, second and third ports, said first and third ports respectively coupled to said first and second quadrature hybrids ports, and further including variable resolver means having a first port coupled to the second port of said dual-channel phase shifter and a second port coupled to the in-phase port of said first power adder/divider, said resolving means providing variable angular separation of the nulls of the resultant antenna pattern.

Claim 19

The arrangement according to claim 17 wherein said resolver means proVides a dual-null angular separation which varies from 0* to 360*.

Claim 20

The arrangement according to claim 7 wherein said first means further include a first variable resolving means having first and second ports coupled respectively via fifth and sixth lines to the balanced port of said first and second balanced hybrids, said fifth and sixth lines having the same electrical length.

Claim 21

The arrangement according to claim 19 wherein said second means further include a first power adder/divider having an in-phase port and first and second ports coupled via seventh and eighth lines respectively to the in-phase port of said first and second balanced hybrids, said seventh and eighth lines being of the same electrical length.

Claim 22

The arrangement according to claim 20 further including a second power adder/divider having a first port coupled via trimming means to a third port of said resolving means and a second port coupled to the in-phase port of said first power adder/divider, said trimming means controlling the amplitude of the energy at the first port of said second power adder/divider relative to the energy at the second port thereof in order to optimize pattern characteristics.

Claim 23

The arrangement according to claim 20 further including a second variable resolving means having a first port coupled to a third port of said first resolving means and a second port coupled to the inphase port of said first power adder/divider, said second resolving means providing variable angular separation of the nulls of the resultant antenna pattern.

Claim 24

An electronically steerable antenna arrangement capable of having patterns with a plurality of steerable nulls comprising: a. a plurality of omnidirectional antenna elements arranged to provide at least two orthogonal element pairs with the separation of each pair being equal and less than 1/2 lambda ; b. first means coupled to said plurality of antenna elements for providing reference antenna pattern signal energy; c. second means coupled to said plurality of antenna elements for providing a first antenna pattern signal energy; d. continuous phase shifting means coupled to said first means for varying the phase of the signal energy of said first means relative to said second means in order to provide a steering of the resultant antenna pattern; and e. continuous resolver means coupled between said phase shifting means and said second means for providing variable angular separation of the nulls in the resultant antenna pattern.

Claim 25

An electronically steerable antenna arrangement capable of having patterns with a plurality of steerable nulls comprising: a. a plurality of omnidirectional antenna elements arranged to provide at least two orthogonal element pairs with the separation of each pair being equal and less than 1/2 lambda ; b. first means coupled to said plurality of antenna elements for providing reference antenna pattern signal energy; c. second means coupled to said plurality of antenna elements for providing a first antenna pattern signal energy; d. continuous phase shifting means coupled to said first means for varying the phase of the signal energy of said first means relative to said second means in order to provide a steering of the resultant antenna pattern; and e. continuous resolver means coupled between said phase shifting means and said second means for providing variable angular separation of the nulls in the resultant antenna pattern.

Claim 26

The arrangement according to claim 23 wherein each said plurality of omnidirectional antenna elements include a pair of omnidirectional radiators of predetermined separation, said elements being arranged in pairs about a central point substantially equally spaced from each other, with the paired members being on opposite sides thereof and oriented such that the radiators comprising each element pair form a straight line which includes the center point.

Claim 27

The arrangement according to claim 24 wherein said elements are end-fired to provide individual lobes directed outward in azimuth from said central point, each loop having a phase which is independent of the others.

Claim 28

The arrangement according to claim 25 wherein said first means are coupled to said plurality of antenna elements to provide a multiphase first antenna pattern signal energy.

Claim 29

A non-physical steerable antenna arrangement capable of having patterns with a plurality of steerable nulls comprising: a. first means providing an omnidirectional omniphase reference first excitation having a predetermined initial phase; b. second means providing a substantially omnidirectional multiphase second excitation simultaneously with said first excitation, said multiphase excitation having a predetermined initial rate of change of phase per azimuth angle, said first and second excitations combining to provide a resultant pattern excitation having a plurality of nulls, the number and azimuthal position Thereof being dependent upon the phase of said reference first excitation in combination with the rate of change of phase per azimuth angle of said multiphase second excitation; c. third means for varying the phase of said reference first excitation; d. fourth means for varying the rate of change of phase per azimuth angle of said multiphase second excitation; and e. steering means causing the resultant pattern excitation to be oriented in azimuth to any predetermined direction.

Claim 30

A non-physical steerable antenna arrangement capable of having patterns with a plurality of steerable nulls comprising: a. first means providing an omnidirectional omniphase reference first excitation having a predetermined initial phase; b. second means providing a substantially omnidirectional multiphase second excitation simultaneously with said first excitation, said multiphase excitation having a predetermined initial rate of change of phase per azimuth angle, said first and second excitations combining to provide a resultant pattern excitation having a plurality of nulls, the number and azimuthal position Thereof being dependent upon the phase of said reference first excitation in combination with the rate of change of phase per azimuth angle of said multiphase second excitation; c. third means for varying the phase of said reference first excitation; d. fourth means for varying the rate of change of phase per azimuth angle of said multiphase second excitation; and e. steering means causing the resultant pattern excitation to be oriented in azimuth to any predetermined direction.