U.S. patent number 3,731,236 [Application Number 05/281,522] was granted by the patent office on 1973-05-01 for independently adjustable dual polarized diplexer.
This patent grant is currently assigned to GTE Sylvania Incorporated. Invention is credited to Joseph G. Di Tullio, Donald J. Sommers, Windsor D. Wright.
United States Patent |
3,731,236 |
Di Tullio , et al. |
May 1, 1973 |
INDEPENDENTLY ADJUSTABLE DUAL POLARIZED DIPLEXER
Abstract
Microwave diplexer apparatus for handling two independent
polarized transmitted signals at one frequency and two independent
received signals at a lower frequency. The two transmitted signals
are introduced separately into a first two-port orthomode
transducer so as to be mutually orthogonal. From the orthomode
transducer they pass through a polarization rotator, which can be
rotated to adjust their angle of polarization, to a first four-port
orthomode transducer. The transmitted signals pass through an
antenna port of the four-port orthomode transducer to the antenna.
Received orthogonally polarized signals from the antenna pass into
the four-port orthomode transducer. They are blocked from entering
the first two-port orthomode transducer since they are below the
cutoff frequency of that transmission path. They pass through four
ports which are positioned orthogonally in the four-port orthomode
transducer. Filters at these ports prevent the high frequency
transmitted signal from passing through. The received signals are
conducted by four sections of rectangular waveguide to a second
four-port orthomode transducer. The orthogonally polarized received
signals pass through a polarization rotator to a second two-port
orthomode transducer. When the rotator is properly oriented, the
two polarized received signals are separately and independently
coupled to two ports of the two-port orthomode transducer which are
mutually orthogonal. By separately adjusting the angles of
polarization by means of the two polarization rotators, the
polarizations of the transmitted and received signals can be
changed independently of each other without changing the physical
orientation of the apparatus.
Inventors: |
Di Tullio; Joseph G. (Woburn,
MA), Sommers; Donald J. (Brookline, NH), Wright; Windsor
D. (Cambridge, MA) |
Assignee: |
GTE Sylvania Incorporated
(N/A)
|
Family
ID: |
23077657 |
Appl.
No.: |
05/281,522 |
Filed: |
August 17, 1972 |
Current U.S.
Class: |
333/126; 333/21A;
343/756 |
Current CPC
Class: |
H01P
1/2131 (20130101); H01P 1/161 (20130101) |
Current International
Class: |
H01P
1/213 (20060101); H01P 1/16 (20060101); H01P
1/161 (20060101); H01P 1/20 (20060101); H01p
005/12 () |
Field of
Search: |
;333/6,1,9,21R,21A,98R,98TN ;343/756 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rolinec; Rudolph V.
Assistant Examiner: Nussbaum; Marvin
Claims
What is claimed is:
1. Diplexer apparatus comprising
electromagnetic wave conducting means having first, second, third,
and fourth signal ports, said electromagnetic wave conducting means
being adapted to permit passage through said first port of first
and second signals in a first frequency band which are orthogonally
polarized with respect to each other and third and fourth signals
in a second frequency band which are orthogonally polarized with
respect to each other, being adapted to permit passage through said
second port of said first and second signals and to block passage
through said second port of said third and fourth signals, being
adapted to permit passage through said third port of said third
signal and to block passage through said third port of said first,
second, and fourth signals, and being adapted to permit passage
through said fourth port of said fourth signal and to block passage
through said fourth port of said first, second, and third
signals;
first transducer means having first, second, and third ports, said
first port being adapted to pass signals of said first frequency,
said second and third ports being adapted to pass two signals of
said first frequency which are orthogonally polarized with respect
to each other, one of the signals passing through each of the
ports;
second transducer means having first, second, and third ports, said
first port being adapted to pass signals of said second frequency,
said second and third ports being adapted to pass two signals of
said second frequency which are orthogonally polarized with respect
to each other, one of the signals passing through each of the
ports;
first polarization adjusting means coupled between the second port
of the electromagnetic wave conducting means and the first port of
the first transducer means and operable to adjust the polarization
of signals passing therethrough; and
second polarization adjusting means coupled between the third and
fourth ports of the electromagnetic wave conducting means and the
first port of the second transducer means and operable to adjust
the polarization of signals passing therethrough.
2. Diplexer apparatus in accordance with claim 1 wherein
said electromagnetic wave conducting means includes a first section
of circular waveguide having an opening at one end corresponding to
said first port, an opening at the other end corresponding to said
second port, a first rectangular opening in the wall thereof
corresponding to said third port, and a second rectangular opening
in the wall thereof corresponding to said fourth port, said
rectangular openings being located at orthogonal positions in the
circular waveguide.
3. Diplexer apparatus in accordance with claim 2 wherein
said first transducer means includes a second section of circular
waveguide of smaller diameter than said first section having an
opening at one end corresponding to said first port and having
first and second rectangular openings arranged to pass two signals
which are orthogonally polarized with respect to each other, said
second section of circular waveguide being adapted to cut off
signals having a frequency below that of signals in the first
frequency band;
said first polarization adjusting means includes a polarization
rotator having one end connected to the opening at the one end of
said second section of circular waveguide;
and including
impedance matching means coupled between the opening at the other
end of said first section of circular waveguide and the other end
of said first polarization adjusting means and being adapted to
match the impedance between the first and second sections of
circular waveguide.
4. Diplexer apparatus in accordance with claim 3 including
a third section of circular waveguide of the same diameter as said
first section and having an opening at one end, first and second
rectangular openings in the walls thereof located at orthogonal
positions in the circular waveguide;
a first section of rectangular waveguide coupling the first
rectangular opening in the first section of circular waveguide and
the first rectangular opening in the third section of circular
waveguide;
a second section of rectangular waveguide coupling the second
rectangular opening in the first section of circular waveguide and
the second rectangular opening in the third section of circular
waveguide;
and wherein
said second transducer means includes a fourth section of circular
waveguide of the same diameter as said first and third sections and
having an opening at one end corresponding to said first port and
having first and second rectangular openings arranged to pass two
signals which are orthogonally polarized with respect to each
other; and
said second polarization adjusting means includes a polarization
rotator having one end connected to the opening at the one end of
said fourth section of circular waveguide and the other end
connected to the opening at the one end of said third section of
circular waveguide.
5. Diplexer apparatus in accordance with claim 4 wherein
said first section of circular waveguide has a third rectangular
opening in the wall thereof located diametrically opposite said
first rectangular opening and a fourth rectangular opening in the
wall thereof located diametrically opposite said second rectangular
opening;
said third section of circular waveguide has a third rectangular
opening in the wall thereof located diametrically opposite said
first rectangular opening and a fourth rectangular opening in the
wall thereof located diametrically opposite said second rectangular
opening;
and including
a third section of rectangular waveguide coupling the third
rectangular opening in the first section of circular waveguide and
the third rectangular opening in the third section of circular
waveguide; and
a fourth section of rectangular waveguide coupling the fourth
rectangular opening in the first section of circular waveguide and
the fourth rectangular opening in the third section of circular
waveguide.
6. Diplexer apparatus in accordance with claim 5 including
four filters, one coupled between each of the four rectangular
openings in said first section of circular waveguide and the
associated section of rectangular waveguide, each filter being
adapted to present a short circuit across its corresponding opening
to signals in the first frequency band and to present a matched
impedance between its corresponding opening and the associated
section of rectangular waveguide to signals in the second frequency
band.
Description
BACKGROUND OF THE INVENTION
This invention relates to microwave diplexers. More particularly,
it is concerned with diplexer apparatus for handling simultaneously
two transmitted signals and two received signals from a single
antenna.
One type of communication system includes a master station and a
remote station each having a transmitter and a receiver to form a
two-way communication link. Typically, the information capacity of
the link is governed by the amount of available bandwidth. By
employing two signals which are mutually orthogonally polarized for
each frequency, it is possible to double the number of
communication channels available. A diplexer apparatus for handling
two orthogonally polarized transmitted signals at one frequency and
two orthogonally polarized received signals at another frequency is
described and claimed in application Ser. No. 195,413, filed Nov.
3, 1971, by Joseph G. DiTullio, Leonard I. Parad, and Kenneth E.
Story entitled "Dual Polarized Diplexer" and assigned to the
assignee of the present application.
Although the apparatus as described in the aforementioned
application is satisfactory in many communication systems, under
certain conditions it is desirable to be able to adjust the
polarization of the transmitted and received signals independently
in order to change the orientation of either or both with respect
to the apparatus. This capability is particularly important in
situations where signal propagation effects such as Faraday
rotation disturb the polarization of signals in the receive
frequency band to a different extent than that of signals in the
transmit frequency band. Fixed orthogonal polarization diplexers of
the type previously available cannot accommodate the variations of
polarization angles caused by the effects of Faraday rotation.
SUMMARY OF THE INVENTION
A polarized signal communication system having the capability of
permitting independent adjustment of the polarization angles of the
transmit and receive signals is provided by employing diplexer
apparatus in accordance with the present invention. The diplexer
apparatus comprises electromagnetic wave conducting means having
first, second, third, and fourth signal ports. The electromagnetic
wave conducting means permits passage through the first port of the
first and second signals in a first frequency band which are
orthogonally polarized with respect to each other, and third and
fourth signals in a second frequency band which are orthogonally
polarized with respect to each other. It also permits passage of
the first and second signals through the second port, and blocks
passage of the third and fourth signals through the second port.
The electromagnetic wave conducting means permits passage through
its third port of the third signal and blocks passage through the
third port of the first, second, and fourth signals. It also
permits passage through the fourth port of the fourth signal and
blocks passage through the fourth port of the first, second, and
third signals.
The diplexer apparatus also includes a first transducer means which
has first, second, and third ports. The first port passes signals
of the first frequency, and the second and third ports pass two
signals of the first frequency which are orthogonally polarized
with respect to each other, one of the signals passing through each
of the two ports. A second transducer means has first, second, and
third ports. The first port passes signals of the second frequency,
and the second and third ports pass two signals of the second
frequency which are orthogonally polarized with respect to each
other, one of the signals passing through each of the ports.
The diplexer apparatus also includes a first polarization adjusting
means which is coupled between the second port of the
electromagnetic wave conducting means and the first port of the
first transducer means. The first polarization adjusting means may
be employed to adjust the polarization of signals which pass
through it. A second polarization adjusting means is coupled
between the third and fourth ports of the electromagnetic wave
conducting means and the first port of the second transducer means.
The second polarization adjusting means may be employed to adjust
the polarization of signals which pass through it.
BRIEF DESCRIPTION OF THE DRAWING
Additional objects, features, and advantages of diplexer apparatus
in accordance with the present invention will be apparent from the
following detailed discussion together with the accompanying
drawing wherein the single FIGURE is a pictorial representation of
a diplexer apparatus in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Diplexer apparatus in accordance with the present invention as
illustrated in the drawing handles two mutually orthogonally
polarized transmitted signals at a first frequency and two mutually
orthogonally polarized received signals at a second frequency in
conjunction with a single antenna. For purposes of discussion in
the present example, the transmitted signals are in the higher
frequency band and the received signals are in the lower frequency
band. As is well understood, the diplexer apparatus operates on the
principal of reciprocity and the transmit and receive functions may
be reversed without necessitating changes in the diplexer apparatus
itself.
The transmitted signals originate from two separate independent
transmitters (not shown) and are applied to a two-port orthomode
transducer 10 through two separate sections of rectangular
waveguide 11 and 12. The two sections of rectangular waveguide 11
and 12 direct the transmitted signals into the section of circular
waveguide of the transducer 10 where their electric fields are
established at right angles to each other as is well-known in the
art. The polarized transmitted signals pass from the two-port
orthomode transducer 10 through a polarization rotator 15 and an
impedance matching transformer 16 to one port at one end of a
four-port orthomode transducer 13. The signals pass through an
antenna port at the opposite ends of the four-port orthomode
transducer 12 and through an impedance matching transformer 14 to
the antenna (not shown).
A pair of polarized received signals having their electric fields
orthogonally related are received at the antenna and pass through
the transformer 14 to enter the four-port orthomode transducer 13
at the antenna port. The received signals are independently coupled
from the orthomode transducer 13 through four sections of
rectangular waveguide 21, 22, 23, and 24. One vectoral component of
each signal divides equally into the first and third sections of
rectangular waveguide 21 and 23, and the orthogonal vector
component of each signal similarly divides equally into the second
and fourth sections of rectangular waveguide 22 and 24. The
orthogonal vector components of each of the two signals are
recombined in a second four-port orthomode transducer 26, and pass
from there through an adjustable polarization rotator 27 to a
second two-port orthomode transducer 28. When the polarization
rotator 27 is properly oriented, the received signals are
independently coupled from the second two-port orthomode transducer
28 through sections of rectangular waveguide 29 and 30, which are
orthogonal to each other, to their respective receivers (not
shown).
As illustrated in the FIGURE, the first four-port orthomode
transducer 13 includes a section of circular waveguide having an
antenna port or opening at one end coupled to the antenna by way of
the impedance matching transformer 14. The opening at the other end
is connected to the impedance matching transformer 16. Located in
the wall of the section of circular waveguide 13 are four ports to
which the four sections of rectangular waveguide 21, 22, 23, and 24
are connected. The four ports are rectangular openings located at
orthogonal positions in the waveguide. The long dimensions of the
openings as shown in the FIGURE are parallel to the axis of the
circular waveguide.
The four rectangular openings are arranged to couple the received
signals to the sections of rectangular waveguide. One pair of
vectoral components of the two received signals pass through one
pair of diametrically opposed openings into the first and third
sections of rectangular waveguide 21 and 23, and the other pair of
vectoral components pass through the other pair of openings into
the second and fourth sections of rectangular waveguide 22 and 24.
A pair of diametrically opposed openings rather than a single
opening are employed for coupling each signal from the circular
waveguide in order to maintain symmetry in the circular waveguide
and thereby reduce the excitation of higher order modes. A portion
21a, 22a, 23a, and 24a of each section of rectangular waveguide 21,
22, 23, and 24 connected to the four-port orthomode transducer 13
is a low pass filter. Each filter produces a short circuit for the
higher frequency transmitted signals so that they do not pass into
the rectangular waveguide and produces an open circuit or matched
impedance for the lower frequency received signals so that they are
efficiently coupled to the rectangular waveguide. Details of these
low pass filters are described in the aforementioned application of
DiTullio et al.
The impedance matching transformer 16 is coupled between an opening
in the end of the large diameter section of circular waveguide of
the four-port orthomode transducer 13 and the smaller diameter
circular waveguide of the polarizer 15 and the two-port orthomode
transducer 10. The diameter of the section of circular waveguide of
the four-port orthomode transducer 13 is such as to pass both the
higher frequency transmitted signals and the lower frequency
received signals. The smaller diameter of the circular waveguide of
the polarization rotator 15 and two-port orthomode transducer 10 is
such as to pass only the higher frequency signals and cut off the
lower frequency signals.
The two-port orthomode transducer 10 includes a section of circular
waveguide having first and second sections of rectangular waveguide
11 and 12 connected to it at rectangular openings or ports. The
openings are oriented with the E planes of the two sections of
rectangular waveguide orthogonal to each other thereby establishing
the relative polarity of the two independent transmitted signals
introduced into the circular section of the two-port orthomode
transducer 10 by way of the rectangular waveguide sections 11 and
12.
The polarization rotator 15 is coupled between the transformer 16
and an opening in the end of the orthomode transducer 10.
Components of this general type for rotating the polarization of
signals within selected frequency ranges over a complete angular
range of 360.degree. are commercially available components. By
rotational adjustment, as indicated by the arrow, the orientation
of the polarization of the transmitted signals may be adjusted with
respect to the elements of structure of the diplexer without
changing their position.
The first and third sections of rectangular waveguide 21 and 23 and
the second and fourth sections 22 and 24 pass orthogonal vectoral
components of each of the two received signals to the second
four-port orthomode transducer 26. The filters 21a, 22a, 23a, and
24a block the higher frequency transmitted signals. The pair of
orthogonal vectoral components of each received signal are coupled
into a large diameter section of circular waveguide of the second
four-port orthomode transducer 26 through two pairs of
diametrically opposed openings. Each pair of openings is physically
orthogonal to the other pair, thus maintaining the polarity of the
signals introduced into the circular waveguide.
The polarized signals are passed through an opening at the end of
the four-port orthomode transducer 26 to the polarization rotator
27. The polarization rotator 27 is similar to the first
polarization rotator 15 except that it operates at the lower
frequency. The angular orientation of the signals passing through
the rotator 27 is adjusted by rotation of the rotator with respect
to the remainder of the apparatus as indicated by the arrow in the
FIGURE.
The orthogonally polarized received signals pass through the
rotator 27 to the second two-port orthomode transducer 28. The
two-port orthomode transducer 28 includes a section of circular
waveguide of large diameter. The two sections of rectangular
waveguide 29 and 30 are connected to the circular waveguide at
rectangular openings. The E planes of the two sections of
rectangular waveguide 29 and 30 are at right angles so that one of
the received signals passes through each section.
The diplexer apparatus as described operates in the following
manner in the transmit mode. A first transmitter output signal at
the higher frequency is fed into the rectangular waveguide 11 and a
second transmitter output signal at the same frequency is fed into
the rectangular waveguide 12. These signals are conducted into the
section of circular waveguide of the two-port orthomode transducer
10. Because of the symmetry of the circular waveguide portion of
the orthomode transducer and the propagation properties of the
rectangular waveguide sections, the two transmitter openings are
isolated from each other. Exciting the first section of rectangular
waveguide 11 causes an electric field in the circular waveguide
which is polarized perpendicular to the broad wall of the first
section of rectangular waveguide 11. Similarly, exciting the second
section of rectangular waveguide 12 causes an electric field in the
circular waveguide which is polarized perpendicular to the broad
wall of the second section of waveguide 12. Since the broad walls
of these two waveguides are perpendicular, the transmitters remain
isolated from one another while producing orthogonal fields in the
circular section of waveguide of the two-port orthomode transducer
10.
The two orthogonal transmitted signals pass into the polarization
rotator 15. The rotator 15 may be rotated so as to adjust the
angular orientation of the combined pair of mutually orthogonally
polarized signals as desired. The transmitted signals pass from the
rotator 15 through the transformer section 16 and into the circular
waveguide of the four-port orthomode transducer 13. At the
frequency of the transmitted signals, the filters 21a, 22a, 23a,
and 24a short circuit the openings to the for sections of
rectangular waveguide blocking the transmitted signals from the
rectangular waveguide. The transmitted signals thus pass from the
antenna port in the orthomode transducer 13 to the antenna. The
angular orientation of the orthogonally polarized transmitted
signals launched from the antenna is controlled by adjusting the
polarization rotator 15.
On reception, a pair of orthogonally related signals at the lower
frequency are directed from the antenna through the transformer 14
to the antenna port of the four-port orthomode transducer 13. The
lower frequency signals are isolated from the transmitter by virtue
of the smaller diameter circular waveguide of the polarization
rotator 15 and the two-port orthomode transducer 10 which is below
cutoff at the received frequency. Thus, when the signals are
received in the circular waveguide of the orthomode transducer 13,
they leave only through the openings coupling them to the four
sections of rectangular waveguide by way of the isolation filters.
Vectoral components of the pair of received signals are conducted
by combined action of the first and third sections of rectangular
waveguide 21 and 23 to the section of circular waveguide of the
second four-port orthomode transducer 26. Orthogonal vectoral
components of the pair of received signals are connected by the
combined action of the second and fourth sections of rectangular
waveguide 22 and 24 to the orthomode transducer 26. The signals
pass from the orthomode transducer 26 through the polarization
rotator 27 to the two-port orthomode transducer 28. Since the E
planes of the two sections of rectangular waveguide 29 and 30 are
at right angles, when the rotator 27 is properly oriented, each
section of rectangular waveguide propagates a different one of the
received signals.
The field orientation for signals in the lower frequency band are
identical in the two four-port orthomode transducers 13 and 26.
Therefore adjustment of the angles of polarization of the lower
frequency band signals at every point throughout the circular
waveguide portions of the apparatus between the transformer 14 and
the four-port orthomode transducer 26 is accomplished by rotation
of the polarization rotator 27. This capability permits adjustment
of the apparatus to compensate for any orientation of the polarized
signals received at the antenna without the necessity for making
physical adjustment to the diplexer apparatus.
As a specific example, apparatus in accordance with the present
invention may be employed with transmitted signals in the frequency
range of 5.925 to 6.425 GHz and received signals in the range of
3.7 to 4.2 GHz. The diameter of the small diameter circular
waveguide is 1.375 inches and that of the larger diameter circular
waveguide is 2.125 inches. As mentioned previously, the higher
frequency signals can be the received signals and the lower
frequency signals the transmitted signals with no change in the
diplexer apparatus as shown and described.
Diplexer apparatus in accordance with the present invention thus
provides for continuously variable independent adjustment of the
senses of polarization of the transmitted signals and the received
signals. The rotational adjustment of polarization over a complete
angular range of 360.degree. is accomplished independently for each
frequency band solely by the rotational adjustment of the
appropriate polarization rotator. The rotators are conventional
well-known devices for altering the angle of polarization of
signals, and each operates over a relatively narrow band of
frequencies. Effects such as Faraday rotation which change the
polarization angles of signals at one frequency more than of those
at another frequency can therefore be compensated for without any
physical changes in the arrangement of the transmitting and
receiving equipment.
While there has been shown and described what is considered a
preferred embodiment of the present invention, it will be obvious
to those skilled in the art that various changes and modifications
may be made therein without departing from the invention as defined
in the appended claims.
* * * * *