U.S. patent number 3,854,140 [Application Number 05/382,619] was granted by the patent office on 1974-12-10 for circularly polarized phased antenna array.
This patent grant is currently assigned to International Telephone and Telegraph Corporation. Invention is credited to Emmanuel J. Perrotti, Joseph C. Ranghelli.
United States Patent |
3,854,140 |
Ranghelli , et al. |
December 10, 1974 |
CIRCULARLY POLARIZED PHASED ANTENNA ARRAY
Abstract
This relates to a mat-strip dual circularly polarized phased
antenna array with independent steering of both right hand
circularly polarized and left hand circularly polarized antenna
beams. This is obtained by superimposing in a common aperture two
linearly polarized phased arrays with their dipole element axis in
space quadrature and by setting one polarizer over both linearly
polarized arrays. The two circularly polarized antenna beams can be
independently and simultaneously scanned, operated in transmit or
receive, operated at different frequency and be designed for
different bandwidth, gain and slidelobe characteristics. The beams
are oppositely polarized through the use of a single polarization
device interposed over orthogonal linear arrays. The linearly
polarized arrays are phased by a separate phase shifter coupled to
the mat-strip power division distribution network of each of the
arrays, by providing one or more mat-strip phase shifter which can
be controllably connected into the distribution network and/or by
controlling the manner in which the distribution network is
connected to the mat-strip dipole elements of the array.
Inventors: |
Ranghelli; Joseph C. (Brooklyn,
NY), Perrotti; Emmanuel J. (Ramsey, NJ) |
Assignee: |
International Telephone and
Telegraph Corporation (Nutley, NJ)
|
Family
ID: |
23509756 |
Appl.
No.: |
05/382,619 |
Filed: |
July 25, 1973 |
Current U.S.
Class: |
343/756; 342/365;
342/371; 343/814 |
Current CPC
Class: |
H01Q
25/001 (20130101); H01Q 21/0075 (20130101); H01Q
21/24 (20130101); H01Q 21/062 (20130101); H01Q
3/38 (20130101) |
Current International
Class: |
H01Q
21/24 (20060101); H01Q 3/30 (20060101); H01Q
25/00 (20060101); H01Q 3/38 (20060101); H01Q
21/00 (20060101); H01Q 21/06 (20060101); H01q
019/00 () |
Field of
Search: |
;343/756,814,816,854 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lieberman; Eli
Attorney, Agent or Firm: O'Halloran; John T. Lombardi, Jr.;
Menotti J. Hill; Alfred C.
Claims
We claim:
1. An antenna array comprising:
N linearly polarized dipole elements each having a given
orientation, where N is an integer greater than one;
a ground plane superimposed relative to, disposed below and
associated with said N elements;
a power distribution network coupled to said N elements;
a polarizer disposed in a superimposed relation to, disposed above
and associated with said N elements to provide a circularly
polarized antenna beam having a predetermined one of left handed
circular polarization and right handed circular polarization;
and
a phase shifting arrangement selectively coupled to said
distribution network to control said antenna beam to have different
selected angular directions;
said N elements including
N mat-strip dipole elements printed on a first printed circuit
board;
said distribution network including
a mat-strip power distribution network printed on said first
printed circuit board; and
said polarizer is printed on a second printed circuit board spaced
from said first printed circuit board;
said polarizer including
a plurality of spaced meander lines printed on said second printed
circuit board, each of said printed meander lines having a
longitudinal axis disposed at an angle of 45.degree. with respect
to the longitudinal axis of said N mat-strip elements.
2. An antenna array according to claim 1, wherein
each of said N mat-strip elements includes
a first dipole wing printed with said given orientation on one
surface of said first board spaced from and extending outwardly in
one direction from an end of one conductor of said mat-strip
distribution network,
a first normally non-conducting switching diode interconnecting
adjacent ends of said first wing and said one conductor of said
mat-strip distribution network,
a second dipole wing printed with said given orientation on said
one surface of said first board spaced from and extending outwardly
in a direction opposite to said one direction from said end of said
one conductor of said mat-strip distribution network,
a second normally non-conducting switching diode interconnecting
adjacent ends of said second wing and said one conductor of said
mat-strip distribution network,
a third dipole wing printed on the other surface of said first
board in a superimposed relation with said first wing,
a third normally non-conducting switching diode interconnecting
adjacent ends of said third wing and the other conductor of said
mat-strip distribution network,
a fourth dipole wing printed on said other surface of said first
board in a superimposed relation with said second wing, and
a fourth normally non-conducting switching diode interconnecting
adjacent ends of said fourth wing and said other conductor of said
mat-strip distribution network; and
said phase shifting arrangement includes
a source of switching voltage,
a first switching arrangement connected between said source and
each of said first and fourth wings to render each of said first
and fourth diodes conductive to connect said first and fourth wings
to said mat-strip distribution network to provide energy flow in
said N mat-strip elements in a first direction, and
a second switching arrangement connected between said source and
each of said second and third wings to render each of said second
and third diodes conductive to connect said second and third wings
to said mat-strip distribution network to provide energy flow in
said N mat-strip elements in a second direction opposite to said
first direction,
said first and second switching arrangements being noncoincidently
operated.
3. An antenna array according to claim 2, wherein
each of said first, second, third and fourth diodes is a PIN
diode.
4. An antenna array according to claim 2, wherein
said phase shifting arrangement further includes
at least one mat-strip phase shifter having
a quarter wavelength mat-strip impedance transformer disposed in
said mat-strip distribution network,
a first shunt mat-strip transmission line extending perpendicular
from one end of said transformer,
a second shunt mat-strip transmission line extending perpendicular
from the other end of said transformer parallel to said first shunt
transmission line,
four normally non-conducting switching diodes, each of said four
diodes being connected to an end of a different one of the
conductors of said first and second shunt transmission lines,
four radio frequency ground terminating and direct current biasing
printed circuit pads, each of said four pads being connected to a
different one of said four diodes, and
a third switching arrangement connected between said source and
each of said four pads to render each of said four diodes
conductive to radio frequency ground said first and second shunt
transmission lines by said four pads to provide a predetermined
amount of radio frequency phase shift in said mat-strip
distribution network.
5. An antenna array according to claim 4, wherein
each of said four diodes are PIN diodes.
6. An antenna array according to claim 1, wherein
said phase shifting arrangement includes
at least one mat-strip phase shifter having
a quarter wavelength mat-strip impedance transformer disposed in
said mat-strip distribution network,
a first shunt mat-strip transmission line extending perpendicular
from one end of said transformer,
a second shunt mat-strip transmission line extending perpendicular
from the other end of said transformer parallel to said first shunt
transmission line,
four normally non-conducting switching diodes, each of said four
diodes being connected to an end of a different one of the
conductors of said first and second shunt transmission lines,
four radio frequency ground terminating and direct current biasing
printed circuit pads, each of said four pads being connected to a
different one of said four diodes,
a source of switching voltage, and
a switching arrangement connected between said source and each of
said four pads to render each of said four diodes conductive to
radio frequency ground said first and second shunt transmission
lines by said four pads to provide a predetermined amount of radio
frequency phase shift in said mat-strip distribution network.
7. An antenna array according to claim 6, wherein
each of said four diodes is a PIN diode.
8. An antenna array according to claim 6, wherein
said N mat-strip elements are equal to an even integer
symmetrically disposed on said first printed circuit board; and
said mat-strip distribution network is disposed on said first
printed circuit board extending radially in two directions from a
predetermined point and connected to said N mat-strip elements;
and
further including
a combined balun and power divider coupled to said mat-strip
distribution network including
a coaxial transmission line disposed perpendicular to said first
printed circuit board adjacent said predetermined point, said
coaxial line having an outer conductor and a center conductor
extending through said first printed circuit board to one surface
thereof,
a first strip conductor disposed on said one surface of said first
printed circuit board connected directly to and extending radially
in two directions from said center conductor for connection to the
inputs of said mat-strip distribution network, said first conductor
having a given width, and
a second strip conductor disposed on the other surface of said
first printed circuit board in a superimposed relation with said
first conductor and connected between said outer conductor and said
inputs of said mat-strip distribution network, said second
conductor having a width greater than said given width.
9. An antenna array according to claim 8, wherein
said phase shifting arrangement further includes
an adjustable phase shifter coupled to said coaxial transmission
line.
10. An antenna array according to claim 1, wherein
said N mat-strip elements are equal to an even integer
symmetrically disposed on said first printed circuit board; and
said mat-strip distribution network is disposed on said first
printed circuit board extending radially in two directions from a
predetermined point and connected to said N mat-strip elements;
and
further including
a combined balun and power divider coupled to said mat-strip
distribution network including
a coaxial transmission line disposed perpendicular to said first
printed circuit board adjacent said predetermined point, said
coaxial line having an outer conductor and a center conductor
extending through said first printed circuit board to one surface
thereof,
a first strip conductor disposed on said one surface of said first
printed circuit board connected directly to and extending radially
in two directions from said center conductor for connection for the
inputs of said mat-strip distribution network, said first conductor
having a given width, and
a second strip conductor disposed on the other surface of said
first printed circuit board in a superimposed relation with said
first conductor and connected between said outer conductor and said
inputs of said mat-strip distribution network, said second
conductor having a width greater than said given width.
11. An antenna array according to claim 10, wherein
said phase shifting arrangement includes
an adjustable phase shifter coupled to said coaxial transmission
line.
12. An antenna array comprising:
a first printed circuit board including thereon N linearly
polarized mat-strip dipole elements each having a given
orientation, where N is an integer including one;
a second printed circuit board including thereon M linearly
polarized mat-strip dipole elements each having an orientation
orthogonal to said given orientation, where M is an integer
including one, said second board being coextensive with and
disposed in spaced, parallel relation to said first board;
a first ground plane coextensive with, parallel to and spaced a
predetermined amount from one surface of one of said first and
second boards;
a second ground plane coextensive with, parallel to and spaced said
predetermined amount from one surface of the other of said first
and second boards, said second ground plane being transparent to
the radiation to or from said dipole elements of said one of said
first and second boards;
a first mat-strip power distribution network carried by said first
board coupled to each of said N dipole elements;
a second mat-strip power distribution network carried by said
second board coupled to each of said M dipole elements;
a polarizer disposed coextensive with, parallel to and spaced above
said first and second boards to provide a first circularly
polarized antenna beam having a predetermined one of left handed
circular polarization and right handed circular polarization and a
second circularly polarized antenna beam having the other of left
handed circular polarization and right handed circular polarization
independent of said first antenna beam;
a first phase shifting arrangement selectively coupled to one of
said first and second distribution networks to control one of said
first and second beams to have different selected angular
directions; and
a second phase shifting arrangement selectively coupled to the
other of said first and second distribution networks to control the
other of said first and second beams to have different selected
angular directions.
13. An antenna array according to claim 12, wherein
said polarizer includes
a third printed circuit board including thereon a plurality of
spaced meander lines, each of said meander lines having a
longitudinal axis disposed at an angle of 45.degree. with respect
to the longitudinal axis of both said M and N dipole elements.
14. An antenna array according to claim 12, wherein
said first ground plane includes
a conductive body.
15. An antenna array according to claim 14, wherein
said second ground plane includes
spaced, parallel conductive members each having an orientation
parallel to and in a superimposed relation with different one of
said M dipole elements.
16. An antenna array according to claim 15, wherein
said conductive members are printed on a third printed circuit
board disposed between said first and second boards.
17. An antenna array according to claim 15, wherein
said conductive members are printed on a third printed circuit
board disposed between said conductive body and one of said first
and second boards.
18. An antenna array according to claim 15, wherein
said conductive members are spaced, parallel conductive ridges
extending from one surface of said conductive body towards said
other of said first and second boards.
19. An antenna array according to claim 14, wherein
said second ground plane includes
said one of siad first printed circuit board.
20. An antenna array according to claim 14, wherein
said second ground plane includes
said conductive body.
21. An antenna array according to claim 12, wherein
said N dipole elements are equal to an even integer symmetrically
disposed on said first board;
said M dipole elements are equal to an even integer symmetrically
disposed on said second board;
said first distribution network is disposed on said first board
extending radially in two directions from adjacent a predetermined
point and connected to said N dipole elements; and
said second distribution network is disposed on said second board
extending radially in two directions from adjacent said
predetermined point and connected to said M dipole elements;
and
further including
a combined balun and power divider independently coupled to each of
said first and second distribution networks, each of said combined
balun and power divider
including
a coaxial transmission line disposed perpendicular to the
associated one of said first and second boards adjacent said
predetermined point, said coaxial line having an outer conductor
and a center conductor extending through said associated one of
said first and second boards to one surface thereof,
a first strip conductor disposed on said one surface of said
associated one of said first and second boards connected directly
to and extending radially in two directions from said center
conductor for connection to the inputs of an associated one of said
first and second distribution networks, said first strip conductor
having a given width, and
a second strip conductor disposed on the other surface of said
associated one of said first and second boards in a superimposed
relation with said first strip conductor and connected between said
outer conductor and said inputs of said associated one of said
first and second distribution networks, said second conductor
having a width greater than said given width.
22. An antenna array according to claim 21, wherein
each of said first and second phase shifting arrangements
includes
an adjustable phase shifter coupled to an associated one of said
coaxial transmission lines.
23. An antenna array according to claim 22, wherein
each of said first and second phase shifting arrangements further
includes
at least one mat-strip phase shifter having
a quarter wavelength mat-strip impedance transformer disposed in an
associated one of said first and second distribution networks,
a first shunt mat-strip transmission line extending perpendicular
from one end of said transformer,
a second shunt mat-strip transmission line extending perpendicular
from the other end of said transformer parallel to said first shunt
transmission line,
four normally non-conducting switching diodes, each of said four
diodes being connected to an end of a different one of the
conductors of said first and second shunt transmission lines,
four radio frequency ground terminating and direct current biasing
printed circuit pads, each of said four pads being connected to a
different one of said four diodes,
a source of switching voltage, and
a first switching arrangement connected between said source and
each of said four pads to render each of said four diodes
conductive to radio frequency ground said first and second shunt
transmission lines by said four pads to provide a predetermined
amount of radio frequency phase shift in said mat-strip
distribution network.
24. An antenna array according to claim 23, wherein
each of said four diodes is a PIN diode.
25. An antenna array according to claim 23, wherein
each of said M and N dipole elements includes
a first dipole wing printed with an associated one of said given
and orthogonal orientation on one surface of an associated one of
said first and second boards spaced from and extending outwardly in
one direction from an end of one conductor of an associated one of
said first and second distribution networks,
a first normally non-conducting switching diode interconnecting
adjacent ends of said first wing and said one conductor,
a second dipole wing printed with said associated one of said given
and orthogonal orientation on said one surface of said associated
one of said first and second boards spaced from and extending
outwardly in a direction opposite to said one direction from said
end of said one conductor of said associated one of said first and
second distribution networks,
a second normally non-conducting switching diode interconnecting
adjacent ends of said second wing and said one conductor of said
associated one of said first and second distribution networks,
a third dipole wing printed on the other surface of said associated
one of said first and second boards in a superimposed relation with
said first wing,
a third normally non-conducting switching diode interconnecting
adjacent ends of said third wing and the other conductor of said
associated one of said first and second distribution networks,
a fourth dipole wing printed on said other surface of said
associated one of said first and second boards in a superimposed
relation with said second wing, and
a fourth normally non-conducting switching diode interconnecting
adjacent ends of said fourth wing and said other conductor of said
associated one of said first and second distribution networks;
and
each of said first and second phase shifting arrangements further
includes
a second switching arrangement connected between said source and
each of said first and fourth wings to render each of said first
and fourth diodes conductive to connect said first and fourth wings
to said associated one of said first and second distribution
networks to provide energy flow in associated ones of said M and N
dipole elements in a first direction, and
a third switch arrangement connected between said source and each
of said second and third wings to render each of said second and
third diodes conductive to connect said second and third wings to
said associated one of said first and second distribution networks
to provide energy flow in associated ones of said M and N dipole
elements in a second direction opposite to said first
direction,
said second and third switching arrangements of each of said first
and second phase shifting arrangements being noncoincidently
operated.
26. An antenna array according to claim 25, wherein
each of said first, second, third and fourth diodes is a PIN
diode.
27. An antenna array according to claim 12, wherein
each of said first and second phase shifting arrangement
includes
at least one mat-strip phase shifter having
a quarter wavelength mat-strip impedance transformer disposed in an
associated one of said first and second distribution networks,
a first shunt mat-strip transmission line extending perpendicular
from one end of said transformer,
a second shunt mat-strip transmission line extending perpendicular
from the other end of said transformer parallel to said first shunt
transmission line,
four normally non-conducting switching diodes, each of said four
diodes being connected to an end of a different one of the
conductors of said first and second shunt transmission lines,
four radio frequency ground terminating and direct current biasing
printed circuit pads, each of said four pads being connected to a
different one of said four diodes,
a source of switching voltage, and
a first switching arrangement connected between said source and
each of said four pads to render each of said four diodes
conductive to radio frequency ground said first and second shunt
transmission lines by said four pads to provide a predetermined
amount of radio frequency phase shift in said mat-strip
distribution network.
28. An antenna array according to claim 27, wherein
each of said four diodes is a PIN diode.
29. An antenna array according to claim 27, wherein
each of said M and N dipole elements includes
a first dipole wing printed with an associated one of said given
and orthogonal orientation on one surface of an associated one of
said first and second boards spaced from and extending outwardly in
one direction from an end of one conductor of an associated one of
said first and second distribution networks,
a first normally non-conducting switching diode interconnecting
adjacent ends of said first wing and said one conductor,
a second dipole wing printed with said associated one of said given
and orthogonal orientation on said one surface of said associated
one of said first and second boards spaced from and extending
outwardly in a direction opposite to said one direction from said
end of said one conductor of said associated one of said first and
second distribution networks,
a second normally non-conducting switching diode interconnecting
adjacent ends of said second wing and said one conductor of said
associated one of said first and second distribution networks,
a third dipole wing printed on the other surface of said associated
one of said first and second boards in a superimposed relation with
said first wing,
a third normally non-conducting switching diode interconnecting
adjacent ends of said third wing and the other conductor of said
associated one of said first and second distribution networks,
a fourth dipole wing printed on said other surface of said
associated one of said first and second boards in a superimposed
relation with said second wing, and
a fourth normally non-conducting switching diode interconnecting
adjacent ends of said fourth wing and said other conductor of said
associated one of said first and second distribution networks;
and
each of said first and second phase shifting arrangements further
includes
a second switching arrangement connected between said source and
each of said first and fourth wings to render each of said first
and fourth diodes conductive to connect said first and fourth wings
to said associated one of said first and second distribution
networks to provide energy flow in associated ones of said M and N
dipole elements in a first direction, and
a third switch arrangement connected between said source and each
of said second and third wings to render each of said second and
third diodes conductive to connect said second and third wings to
said associated one of said first and second distribution networks
to provide energy flow in associated ones of said M and N dipole
elements in a second direction opposite to said first
direction,
said second and third switching arrangements of each of said first
and second phase shifting arrangements being non-coincidently
operated.
30. An antenna array according to claim 29, wherein
each of said first, second, third and fourth diodes is a PIN
diode.
31. An antenna array according to claim 12, wherein
each of said M and N dipole elements includes
a first dipole wing printed with an associated one of said given
and orthogonal orientation on one surface of an associated one of
said first and second boards spaced from and extending outwardly in
one direction from an end of one conductor of an associated one of
said first and second distribution networks,
a first normally non-conducting switching diode interconnecting
adjacent ends of said first wing and said one conductor,
a second dipole wing printed with said associated one of said given
and orthogonal orientation on said one surface of said associated
one of said first and second boards spaced from and extending
outwardly in a direction opposite to said one direction from said
end of said one conductor of said associated one of said first and
second distribution networks,
a second normally non-conducting switching diode interconnecting
adjacent ends of said second wing and said one conductor of said
associated one of said first and second distribution networks,
a third dipole wing printed on the other surface of said associated
one of said first and second boards in a superimposed relation with
said first wing,
a third normally non-conducting switching diode interconnecting
adjacent ends of said third wing and the other conductor of said
associated one of said first and second distribution networks,
a fourth dipole wing printed on said other surface of said
associated one of said first and second boards in a superimposed
relation with said second wing, and
a fourth normally non-conducting switching diode interconnecting
adjacent ends of said fourth wing and said other conductor of said
associated one of said first and second distribution networks;
and
each of said first and second phase shifting arrangements
including
a source of switching voltage,
a first switching arrangement connected between said source and
each of said first and fourth wings to render each of said first
and fourth diodes conductive to connect said first and fourth wings
to said associated one of said first and second distribution
networks to provide energy flow in associated ones of said M and N
dipole elements in a first direction, and
a second switch arrangement connected between said source and each
of said second and third wings to render each of said second and
third diodes conductive to connect said second and third wings to
said associated ones of said first and second distribution networks
to provide energy flow in associated ones of said M and N dipole
elements in a second direction opposite to said first
direction,
said first and second switching arrangements of each of said first
and second phase shifting arrangements being non-coincidently
operated.
Description
BACKGROUND OF THE INVENTION
This invention relates to antenna arrays and more particularly to
antenna arrays employing mat-strip and printed circuit techniques
to achieve a circularly polarized phased antenna array.
The term "mat-strip" as employed herein is defined as a photo
etched or printed balanced transmission line printed on opposite
surface of a printed circuit (PC) board in such a manner that both
conductors are superimposed, are equal in width and are equal in
length. This is in contrast to a stripline transmission line which
is an unbalanced transmission line requiring two ground planes one
above and one below a single conductive strip and to a microstrip
transmission line which consists of a conductive strip above a
ground plane having a much greater width than the conductive strip.
A microstrip transmission line is analogous to a two wire line in
which one of the wires is represented by the image in the ground
plane of the wire that is physically present. Another way of
expressing what a mat-strip transmission line is is to state that
it is a balanced transmission line in which the image wire of a
microstrip transmission line has materialized and the ground plane
of a microstrip transmission line has been removed.
An antenna dipole element in mat-strip technique consists of one
half of the dipole element (one wing) being disposed on one surface
of a PC board having one end thereof connected to one conductor of
a mat-strip transmission line and the other half of the dipole
element (other wing) being disposed on the other surface of the PC
board having one end thereof connected to the other conductor of
the same mat-strip transmission line. A ground plane is associated
with the dipole elements (it has no function in the mat-strip
transmission line) to ensure that the radiation from the dipole
element is from one surface of the PC board, namely, the surface of
the PC board removed from the ground plane.
In current practice, circularly polarized phased antenna arrays are
realized in several ways. One such antenna array uses array
elements which directly generate circularly polarized energy, such
as spiral antennas, and where phase scanning is achieved by adding
a phase shifter to each element. The disadvantages of this type
antenna are the availability of only one handedness of circular
polarization and the multiplicity of components which result in
added losses and costs.
A second type of circularly polarized phased antenna array uses an
array consisting of two linearly polarized antennas in spatial
quadrature which are driven by a polarizer to phase the linearly
polarized antenna in time so as to generate circular polarization
from the two linearly polarized antennas. By the addition of a mode
transducer both left hand and right hand circular polarization are
simultaneously generated. A typical sample is a crossed dipole pair
fed from a quadrature hybrid. The disadvantages of this type of
array include limitation of two circularly polarized antenna beams
to the same frequency band because they share a common set of
components, namely, the polarizer and the mode transducer. Also,
the multiplicity of components increases the losses and cost of the
antenna.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a circularly
polarized antenna array employing the techniques disclosed in U.S.
Pat. No. 3,681,769 issued to E. J. Perrotti, J. C. Ranghelli and R.
A. Felsenheld and the copending application of J. C. Ranghelli and
E. J. Perrotti, Ser. No. 384,188, filed July 31, 1973 both of which
are assigned to International Telephone and Telegraph Corporation
which overcomes the disadvantages of the above-mentioned prior art
circularly polarized antennas. The disclosure of both U.S. Pat. No.
3,681,769 and copending application, Ser. No. 384,188 is
incorporated herein by reference.
Another object of the present invention is to provide a circularly
polarized antenna array wherein the antenna beam is either left
hand or right hand circularly polarized.
Still another object of the present invention is to provide a
circularly polarized antenna array which provides in a single
aperture two completely separate and independent antenna beams
having completely separate and independent beam forming and
scanning arrangements where each of the antenna beams have a
particular handedness of circular polarization.
A further object of the present invention is to provide a
circularly polarized antenna array capable of producing two
circularly polarized antenna beams, one of which is right hand
polarized and other of which is left hand polarized, wherein the
separate antenna beams are operated independently of each other
relative to frequency of operation, scanning angle, beam shaped,
and/or transmit-receive mode.
A feature of the present invention is the provision of an antenna
array comprising: N linearly polarized dipole elements each having
a given orientation, where N is an integer greater than one; a
ground plane superimposed relative to, disposed below and
associated with the N elements; a power distribution network
coupled to the N elements; a polarizer disposed in a superimposed
relation to, disposed above and associated with the N elements to
provide a circularly polarized antenna beam having a predetermined
one of left handed circular polarization and right handed circular
polarization; and a phase shifting arrangement selectively coupled
to the distribution network to control the antenna beam to have
different selected angular directions.
Another feature of the present invention is the provision of an
antenna array comprising: a first printed circuit board including
thereon N linearly polarized mat-strip dipole elements each having
a given orientation, where N is an integer greater than one; a
second printed circuit board including thereon M linearly polarized
mat-strip dipole elements each having an orientation orthogonal to
the given orientation, where M is an integer greater than one, the
second board being coextensive with and disposed in spaced,
parallel relation to the first board; a first ground plane
coextensive with, parallel to and spaced a predetermined amount
from one surface of one of the first and second boards; a second
ground plane coextensive with, parallel to and spaced the
predetermined amount from one surface of the other of the first and
second boards, the second ground plane being transparent to the
radiations to or from the dipole elements of the one of the first
and second boards; a first mat-strip power distribution network
carried by the first board coupled to each of the N dipole
elements; a second mat-strip power distribution network carried by
the second board coupled to each of the M dipole elements; a
polarizer disposed coextensive with, parallel to and spaced above
the first and second boards to provide a first circularly polarized
antenna beam having a predetermined one of left handed circular
polarization and right handed circular polarization and a second
circularly polarized antenna beam having the other of left handed
circular polarization and right handed circular polarization
independent of the first antenna beam; a first phase shifting
arrangement selectively coupled to one of the first and second
distribution networks to control one of the first and second beams
to have different selected angular directions; and a second phase
shifting arrangement selectively coupled to the other of the first
and second distribution networks to control the other of the first
and second beams to have different selected angular directions.
Although the antenna array described herein was originally
conceived for use as a communications antenna, this antenna is also
applicable for radar and other systems where multi-beam antennas
with polarization diversity and frequency diversity are
required.
BRIEF DESCRIPTION OF THE DRAWING
Above-mentioned and other features and objects of this invention
will become more apparent by reference to the following description
taken in conjunction with the accompanying drawing, in which:
FIG. 1 is a top plan view of the polarizer having certain portions
thereof removed to expose (1) the lower most mat-strip linearly
polarized phased antenna array, (2) the top most mat-strip linearly
polarized phased antenna array, and (3) the parallel ground planes
for the dipole elements of the top most antenna array in accordance
with the principles of this invention;
FIG. 2 is a cross sectional view of FIG. 1 taken along line
2--2;
FIG. 3 is a cross sectional view of FIG. 2 taken along line
3--3;
FIG. 4 is a cross sectional view of the lower most mat-strip
linearly polarized phased antenna array taken along line 4--4 of
FIG. 1;
FIG. 5 is a plan view of an alternative dipole element that may be
employed for the dipole elements of both the mat-strip linearly
polarized phased antenna arrays of FIG. 1;
FIG. 6 is a cross sectional view of FIG. 5 taken along line
6--6;
FIG. 7 is a cross sectional view of FIG. 1 taken along line 2--2
illustrating an alternative relative location of the three PC
boards in accordance with the principles of the present
invention;
FIG. 8 is a cross sectional view of FIG. 1 taken along line 2--2
illustrating an alternative ground plane for the upper most of the
PC board arrays in accordance with the principles of this
invention;
FIG. 9 is a cross sectional view of FIG. 1 taken along line 2--2
illustrating another alternative ground plane for the upper most of
the PC board arrays in accordance with the principles of this
invention;
FIG. 10 is a schematic illustration of the relationship between the
axis of the dipole element of the upper most PC board array and the
axis of the polarizer to generate right handed circular
polarization; and
FIG. 11 is a schematic illustration of the axis of the dipole
elements of the lower most PC board array and the axis of the
polarizer to generate left handed circular polarization.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-4 there is illustrated therein a stacked or
sandwich type arrangement of PC type linearly polarized phased
antenna arrays, associated ground planes and a common polarizer to
enable the production of two independent antenna beams, one beam
having right handed circular polarization and the other beam having
left handed circular polarization in accordance with the principles
of this invention. The antenna array includes a dielectric sheet 1
having disposed thereon by PC technique dipole antenna elements 2
in the form of two sections (dipole wings) 3 and 4, wing 3 being
disposed on the upper surface 5 of sheet 1 and wing 4 being
disposed on the lower surface 6 of sheet 1. As illustrated, this
linearly polarized phased antenna array includes a plurality of
pairs of dipole elements 2 interconnected by symmetrical parallel
power fed by a mat-strip type balanced power division transmission
line distribution network 7 including various balanced mat-strip
type conductors 8 and 9 to provide power division and parallel
feeding of the groups of dipole elements. The linearly polarized
dipole element array on sheet 1 is symmetrical in all quadrants as
are their transmission line networks 7.
It should be noted that as in the cited patent the mat-strip
conductors of balanced transmission line distribution network 7 are
formed by two strip conductors, such as strip conductor 10 disposed
on surface 5 of sheet 1 and strip conductor 11 disposed on surface
6 of sheet 1 superimposed with respect to conductor 10.
The lower most linearly polarized antenna array is disposed by PC
techniques on dielectric sheet 12. While the dipole antenna
elements 2' have symmetry in each quadrant of sheet 12 it is not
required in the antenna array of this invention that dipole
elements 2' be symmetrical with respect to dipole elements 2. As
noted in FIG. 1 dipole elements 2' are oriented 90.degree. with
respect to dipole elements 2. This lower array on sheet 12 is
parallel fed by a mat-strip type balanced power division
transmission line distribution network 7' which is identical to
network 7 on sheet 1, but also oriented at a 90.degree.
relationship with respect thereto.
The ground plane for the linearly polarized antenna array on sheet
12 is provided by the bottom of metallic housing 13 while the
ground plane for the antenna array on sheet 1 is provided by a
third PC board including dielectric sheet 14 having disposed
thereon metallic strips 15 which are oriented and disposed thereon
to be parallel to and in a superimposed relationship with the
dipole elements of the top most linearly polarized phase antenna
array on sheet 1. In the embodiment illustrated in FIG. 2, this
ground plane is disposed between the linearly polarized arrays on
PC boards 1 and 12.
The array on sheet 12 must be spaced from the ground plane 13 by
one quarter wavelength. Likewise, the spacing between the array on
sheet 1 and the ground plane provided by parallel conductor 15 is
also equal to one quarter wavelength. The one quarter wavelength
spacing for these two linearly polarized phased antenna arrays are
nominal values for the operating frequency range of the individual
ones of the linearly polarized phased antenna arrays. It should be
noted that spacing is not critical between arrays since the
velocity in free space and the coax sections is almost equal.
To convert the linearly polarized antenna beam from the array on
sheet 1 to right hand circular polarization and to also convert the
linearly polarized beam from the antenna array on sheet 12 to left
hand circular polarization a common polarizer is provided
superimposed with respect to these two linear arrays. This common
polarizer includes a dielectric sheet 16 having disposed thereon by
PC techniques a plurality of spaced conductive polarizers 17 shown
for purposes of explanation as meander lines. The polarizer is a
spatial filter having prescribed width of conductors proportioned
to give the desired characteristics for both of the circularly
polarized antenna beams each of which has a predetermined one of
right handed and left handed circular polarization. Polarizer 17
can take many different forms other than the meander type polarizer
illustrated, such as a system of bars, a system of printed straight
conductors, and variable dielectric constant stubs.
It will be noted that networks 7 and 7' include in each of the
strip conductors thereof decreased width portion and increased
width portions at the branching positions or locations thereof. The
decreased width portions and the increased width portions are each
one quarter wavelength at the operating frequency of the associated
linearly polarized phased antenna array to provide a reflectionless
power transformation between the transmission line sections
themselves and from the transmission line sections to the dipole
elements 2 and 2'.
The spacing between sheets 1, 12 and 16 and ground plane 14 are
maintained at the appropriate predetermined value by the employment
of bolts 18 extending through ground plane 14 and sheets 1, 12 and
16 with appropriate length spacers or stand-offs 19, 20, 21 and 22
disposed thereon to maintain the desired spacing of the stacked
arrangement. In addition to these bolts and separators, the coaxial
transmission line portion of the combined balun and power dividing
arrangements, to be described hereinbelow, also cooperate in
maintaining the desired separation of the stacked members. These
separations can also be maintained by frame structures made of low
density foam. This would lend itself to a bonded sandwich
construction.
The transmission networks 7 and 7' are fed from a combined balun
and power divider and is of the double ended balun type. Energy is
coupled to or from each of the arrays by similar waveguides 23 and
23a coupled to separate and independent transmitter or receiver
illustrated at 25 and 25a. The unbalanced to balanced
transformation is obtained by the combined balun and power divider
in accordance with the above cited U.S. patent which includes
similar coaxial transmission lines 26 and 26a having inner
conductors 27 and 27a, respectively, extending through sheets 1 and
12, respectively, for electrical contact with strip conductors 28
and 28a, respectively. Conductors 28 and 28a each extend radially
in two directions from center conductors 27 and 27a with the ends
thereof being respectively connected to the inputs of networks 7
and 7'. The outer conductors 29 and 29a of coaxial transmission
lines 26 and 26a are physically supporting and in electrical
contact with strip conductors 30 and 30a, respectively, having the
configuration as shown in FIG. 1 which is obviously wider than the
conductors 28 and 28a and the conductors forming networks 7 and 7'.
Thus, the combined balun and power divider of this invention
provides a direct transition from waveguides 23 and 23a to the
balanced mat-strip distribution networks 7 and 7'. It also provides
a positive mechanical connection to the balanced line of networks 7
and 7' of the printed array without the use of solder joints and,
in addition, and more importantly provides an immediate power
divider with a relatively large heat sink formed by conductors 30
and 30a thereby enabling the feeding of greater power into networks
7 and 7'.
The conductors of networks 7 and 7' and dipole elements are
composed of conductive material, such as copper, copper clad
material or the like. The dielectric sheets 1 and 12 and 16 are
composed of a low loss dielectric, such as Tellite, Rexilite,
Z-Tron and Duroid. The latter two low loss dielectric materials are
also high temperature materials and, of course, would be
particularly applicable to the present invention under high
temperature conditions.
Due to the orientation of the dipole element arrays on sheets 1 and
12 and the orientation of the ground strip conductors 15, the
dipole elements 2 and the balanced transmission lines of network 7
and the strip ground conductors 15 are invisible or transparent to
radiation to and from dipole elements 2' on sheet 12.
A phase shifting arrangement is provided for each of the arrays of
sheets 1 and 12 so that the resultant circularly polarized
independent antenna beams produced by the array of this invention
may have their angle or direction independently scanned or moved.
The antenna beams of the two linearly polarized phased antenna
arrays may be independently scanned in accordance with the
principles of this invention. Each of the linearly polarized arrays
includes one or more mat-strip loaded line type phase shifter which
includes an impedance matching transformer 31 and 31a, two shunt
mat-strip transmission lines 32 and 32a coupled at opposite ends of
the one quarter wavelength impedance transformer 31 and 31a,
respectively. There is provided associated with each of the shunt
transmission lines 32 and 32a a radio frequency ground terminating
and direct current bias mat-strip pads 33 and 33a connected to the
adjacent ends of the shunt transmission lines 32 and 32a by
normally non-conductive switching diodes, such as a PIN diodes 34
and 34a. Diodes 34 and 34a are parallel to the PC boards. When it
is desired to shift the phase of the radio frequency energy fed to
or from one of the dipole elements 2 or 2', diodes 34 or 34a are
rendered conductive by means of switching voltage from source 35
through switching arrangements 36. Once the diodes 34 or 34a have
been rendered conductive by connecting the switching voltage
through switching arrangements 36 to pads 33 or 33a, pads 33 or 33a
will provide the desired radio frequency ground termination for
shunt lines 32 or 32a and thereby provide in one step a 45.degree.
phase shift. The radio frequency ground for pads 33 or 33a is
provided by by-pass capacitors disposed in housing 13 through which
the direct current voltage is coupled from source 35 to pads 33 or
33a. This mat-strip phase shifter arrangement just described will
provide a retarded 45.degree. phase shift of the energy fed to an
appropriate one of the dipole elements 2 or 2'. In accordance with
the teachings of the above cited copending application Ser. No.
384,188 it would be possible to provide a plurality of similar
mat-strip loadline type phase shifters so as to provide discrete
strips of 45.degree. of radio frequency phase shift in networks 7
and 7a. It should be kept in mind that the phase shifter
selectively switched into the distribution network 7 or 7' can be
used by itself or in conjunction with phase shifters 24 and
24a.
Referring to FIGS. 5 and 6 there is illustrated an alternative
arrangement for the dipole elements 2 or 2' that can be substituted
for those dipole elements illustrated in FIG. 1. The dipole
elements of FIGS. 5 and 6 will also cooperate in providing a
180.degree. step of phase shift and, thus, is considered as a
portion of the phase shifting arrangement either operating
separately or in conjunction with phase shifters 24 and 24a and the
mat-strip loaded line type phase shifter described hereinabove. In
the arrangement of FIGS. 5 and 6 there is provided a first dipole
wing 37 and a second dipole wing 38 disposed by PC techniques on an
upper surface of a dielectric sheet 39. These dipole wings 37 and
38 are connected to the upper strip conductor of network 7 or 7' by
switching diodes, such as PIN diodes 40 and 41, respectively. In a
superimposed relationship to wings 37 and 38 are provided wings 42
and 43 on the lower surface of sheet 39 connected to the lower
conductor of networks 7 or 7' by switching diodes, such as PIN
diodes 44 and 45. Diodes 40, 41, 44 and 45 are parallel to sheet
39. Also diodes 40, 41, 44 and 45 are normally non-conductive and
switching arrangement 36 (FIG. 2) is coupled to the low impedance
point of wings 37, 38, 42 and 43 through by-pass capacitors 50'
disposed in housing 13'. By selecting the switching voltage to be
coupled to wings 38 and 42 diodes 41 and 44 will be rendered
conductive to thereby connect wings 38 and 42 to the distribution
network 7 or 7'. With this connection and thereby the position of
the dipole wings 38 and 42 on the upper and lower surface,
respectively, of sheet 39 electric energy will pass through the
dipole wings 38 and 42 in a given direction. To achieve a
180.degree. phase shift the switching voltage applied to wings 38
and 42 is removed and a switching voltage is coupled to wings 37
and 43 so as to render diodes 40 and 45 conductive to thereby
connect wings 37 and 43 to networks 7 or 7'. With this orientation
of the dipole wings with respect to the upper and lower surface of
dielectric sheet 39 electric energy will pass through wings 37 and
43 which is opposite to direction of the electric energy passing
wings 38 and 42 when they were actively coupled to networks 7 and
7' thereby achieving the desired 180.degree. phase shift.
As mentioned hereinabove the ground plane for the array disposed on
sheet 1 as illustrated in FIG. 2 is provided by conductive strips
15 disposed on sheet 14 which is positioned between sheets 1 and 12
carrying the two linearly polarized arrays. This is not a critical
location for the ground plane carried by sheet 14. In fact, as
illustrated in FIG. 7 sheet 14 may be disposed between housing 13
and sheet 12.
In addition, there is available still another embodiment for the
ground plane of the linearly polarized phased antenna array
disposed on sheet 1. This embodiment is illustrated in FIG. 8 and
eliminates the third sheet 14. In the embodiment of FIG. 8 the
ground plane for the dipole elements disposed on sheet 1 is
provided by parallel, spaced ridges 15a disposed on housing 13
which are parallel to and in a superimposed relation with dipole
elements 2 on sheet 1.
Still another embodiment for the ground plane of the array on sheet
1 is provided by the conductive material of the linearly polarized
antenna array carried by sheet 12 when the array carried by sheet
12 operates at a relatively high frequency, such as eight
gigahertz, and the array carried by sheet 1 operates at a
relatively low frequency, such as 200 megahertz. This is
illustrated in FIG. 9. This arrangement of having the lower most
array on sheet 12 be the ground plane for the array on sheet 1 is
possible if the conductive material disposed by PC techniques on
sheet 12 is very dense for the relatively high frequency involved
in the lower array and the relatively low frequency involved in the
higher array. However, if this is not the case metallic housing 13
will provide the ground plane for the array on sheet 1 as well as
the array on sheet 12. This is possible since a one quarter
wavelength at 8 gigahertz is approximately 3/8 inch which places
the array of sheet 12 very close to metallic housing 13. This 3/8
inch separation at 200 megahertz, at which the array of sheet 1, is
operating is not even recognized as being present by the array of
sheet 1, therefore, housing 13 will also provide the ground plane
for the array of sheet 1. Of course, when there is a large
separation of operating frequency for the two linearly polarized
phased antenna arrays disposed on sheets 1 and 12 metallic housing
13 and the conductive art work on sheet 12 could also cooperate to
provide the ground plane for the array on sheet 1.
FIG. 10 illustrates schematically the generation of a right hand
circularly polarized or clockwise polarized antenna beam
incorporating a polarizer 17 as illustrated in FIG. 1. Polarizer 17
has a relationship with dipole elements 2 of FIG. 1 where its
longitudinal axis 51 is 45.degree. retarded with respect to
longitudinal axis 52 of dipole element 2. In this relationship a
vector V.sub.t is propagated from dipole element 2 and is
intercepted by polarizer 17 which produces therein a vector V.sub.c
which results in a vector V.sub.L for propagation. Vector V.sub.c
appears on the z axis in the direction indicated and after
90.degree. the vector V.sub.L is rotated 90.degree. to the right or
clockwise and after another 90.degree. is rotated again clockwise.
This 90.degree. rotation of vector V.sub.L, which is seen by an
observer, will continue to rotate as illustrated in FIG. 10 and
thus produces right hand circular polarization.
Referring to FIG. 11 there is illustrated therein schematically the
production of a left hand circularly polarized or a counter
clockwise circularly polarized beam wherein the longitudinal axis
52' of dipole element 2' is 45.degree. ahead of the longitudinal
axis 51 of polarizer 17. When vector V.sub.t of the electric field
in dipole element 2' is produced as illustrated and intercepts the
polarizer 17 a vector V.sub.c is produced therein which results in
a propagation vector V.sub.L. Vector V.sub.L will be rotated every
90.degree. along axis z 90.degree. in a counter clockwise or left
hand rotation as observed by an observer.
While we have described above the principles of our invention in
connection with specific apparatus it is to be clearly understood
that this description is made only by way of example and not as a
limitation to the scope of our invention as set forth in the
objects thereof and in the accompanying claims.
* * * * *