US2867773A

US2867773A - Four terminal waveguide network

Info

Publication number: US2867773A
Application number: US45280A
Authority: US
Inventors: Nathaniel I Korman
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1948-08-20
Filing date: 1948-08-20
Publication date: 1959-01-06
Anticipated expiration: 1976-01-06

Description

Jan. 6, 1959 N, KO MAN 2,867,773

FOUR TERMINAL WAVEGUIDE NETWORK Filed Aug. 20, 1948 INVENTOR Mlluznzkllfirm BY I ATTORNEY United States Patent FOUR TERMINAL WAVEGUIDE NETWORK Nathaniel I. Korman, Merchantville, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application August 20, 1948, Serial No. 45,280

Claims. (Cl. 33311) This invention relates to a four terminal-pair network of the type sometimes known as hybrid couplers.

Four terminal-pair networks having the property that electro-magnetic energy applied to any one terminal-pair will be transferred substantially entirely to two of the other terminal-pairs with substantially no energy transference to the fourth terminal-pair are well known to the art. Such networks may he wave guide, coaxial line, or open line networks. Generally speaking, their properties, advantages, and uses are well known to the art. In particular, my invention is concerned with hybrid coupler networks employing waveguides of the hollow pipe type. It will be understood that when referring to a terminal pair with reference to a waveguide, the reference is to the waveguide termination.

Heretofore, the most common type of hybrid coupler network, sometimes known as the magic tee, is that which employs four rectangular waveguides having a common junction. Two of these four waveguides may be considered as a single waveguide which has a third waveguide making a junction therewith in the H plane and still another waveguide which makes a junction with the first pair of waveguides at the same junction point and in the E plane. The result of this arrangement is that power fed into any one of the waveguide arms extending from the junction will be transferred substantially entirely to two of the other arms and substantially no energy will be transferred to the fourth arm, if account is not taken of reflected energy. In this common arrangement, the difiiculty is encountered that the orientation of the arms extending from the junction is substantially fixed. Moreover, the division of power between the two guide arms which receive power is substantially equal. The ratio of power which is transferred to them is substantially fixed and cannot be chosen at will.

It is an object of the present invention to provide a four terminal Pair waveguide network of the hybrid coupler type which is more flexible than prior types, and more particularly which is more flexible in the arrangement and disposition of the waveguide arms.

It is further an object of the invention to provide such an improved and flexible arrangement in which the arms are rectangular waveguide arms.

It is further an object of the invention to provide a simple arrangement for a four terminal-pair waveguide network of the hybrid coupler type in which the arms may be readily located at a desired distance from each other.

It is a further object of the invention to provide such an arrangement utilizing rectangular waveguide arms,

These and other objects, advantages and novel features of the invention will be apparent from the following description taken in connection with the accompanying drawing in which:

Figure 1 is a face view of one embodiment of my invention;

Figure 2 is a cross sectional View along the lines 2--2 pt Figure 1;

ice

Figure 3 is a cross sectional view along the lines 3-3 of Figure 1;-

'Figure 4 is a face view of a second embodiment of the invention in which a pair of the waveguide terminal arms which are not directly coupled have a junction separated from the other pair and in which the angular relationship of the paired arms results in other than equal energy division between arms of the same pair;

Figure 5 is a cross sectional view of the embodiment of Figure 4 along the lines 5-5;

Figure 6 is a face view of still other embodiment of invention in which one pair of uncoupled terminal arms may be angularly related as desired with respect to the radial direction of the other pair from the junction network and a desired division of energy may still result between arms of a pair;

Figure 7 is a cross sectional view of the embodiment of Figure 6 along the line 7-7 of Figure 6.

In accordance withmy invention I provide an elliptical waveguide and two pairs of rectangular waveguide terminal arms. Each arm of one pair is oriented with respect to the other arm of the one pair so that energy incident through one arm of the one pair is not coupled to the other arm of the one pair through the elliptical waveguide, and the other pair of arms is coupled to receive substantially all the energy incident through any one of the arms of the one pair. This is accomplished by excitation of the elliptical waveguide in the TE mode through one of the arms of one pair, with the waveguide arm of the other one of this one pair being oriented with respect to the principal vector of that mode so that it is decoupled from that mode of excitation.

Referring now to the drawings, in which like numerals are used to indicate like parts, and referring more particularly to Figures 1, 2 and 3, a circular waveguide 10 has two rectangular

waveguide arms

12 and 14 extending therefrom and making a junction therewith at substantially the same point. It is understood that a circular waveguide is a special instance of an elliptical waveguide.

Waveguide arms

12 and 14 have their axes normal to each other and normal to the axis of the circular waveguide 10. A similar pair of rectangular waveguide arms 16 and '18 make a junction with the circular waveguide 10 at a point on the axis of the waveguide 10 removed from the point of junction of

waveguides

12 and 14. Waveguides 12, 14, 16 and 18 have broad and narrow walls and have their broad walls oriented parallel to the axis of the circular waveguide Ill. Circular waveguide 10 is closed at each end to completely enclose its junctions with the rectangular waveguides by

pistons

20 and 22 which may be adjusted axially of the circular waveguide for impedance matching and which may comprise choke joints as shown to minimize energy leakage between the pistons and the circular waveguide walls. Matching diaphragms may be inserted in the various rectangular waveguides for impedance matching as will be Well understood by those skilled in the art.

In operation, let it be assumed that energy enters from the terminal waveguide 12. Such energy in the TE mode in the rectangular waveguide will excite energy in the TE mode in circular waveguide 10. This mode in the circular guide is indicated in Figure 3 by the vectors there shown. The principal vector of the TE mode characterizes the orientation and magnitude of this mode. It will be clear that waveguide 14, which is oriented at right angles to waveguide 12, will not be excited by this energy. However, referring to Figure 2, it will be clear that both

waveguides

16 and 18 will be directly excited by the energy indicated by vector 26. In the example here shown, since

waveguides

16 and 18 are each oriented at a 45 angle, with respect to vector 26', each will receive half the energy and will be excited as in the comtheir axes at right angles as before.

may be made any desired angle.

3 parative phases indicated by vectors 28. Assuming that the system is substantially perfectly matched throughout, there will be no reflected energy, and the energy represented-by vector 26 will be vectorially divided between

waveguides

16 and 18 in accordance with the angles'the vector makes withthenormal.tothe axis of the rectangular-waveguidesldand18. The distance 1 maybe chosen substantially at will affording great flexibility to the arrangement, andease of connection with associatedapparatus.

Referring now to Figures 4 and 5, waveguides l2 and l-dare shown having a junction with waveguide .with Reflecting plates 30 and '32 may be used to obtain impedance match. Waveguides ldrand 18 similarly form junctions with waveguide 10, but these junctions are displaced from each other axially along waveguide 19 and in this instance, are on opposite sides ofthe junction of

waveguides

12 and 14 with waveguide 10.

Theoperation of'thedevice will be apparentfrom what has been said before. Ifany energy is incident through any of the rectangular waveguides, such energy will not be directly coupled to the rectangular waveguide paired thereto and'having'its axis'normal to the axisof the waveguide through which the incident energy enters. Such incident energy will be substantially entirely absorbed by the two rectangular waveguides of the other pair. The energy absorbed by the'other pair will be divided therebetween vectorially in accordance with the angles which they make with the principal vector of the energy advancing in the circular waveguide. In this case waveguides 16 and 18, for example, are arranged so that the former receives a major portion of energy from waveguide 14, and the latter from waveguide 12, and vice versa.

Still another example of my invention is illustrated .in Figures 6 and 7, in which again

rectangular waveguides

12, 14, 16 and 18 form junctions with waveguide 34. Waveguide 34 is circular in cross section except for a portion 36 thereof which is transformed to be eccentrically elliptical. The portion 36 is of such a length and has such major and minor axes of the elliptical crosssection that energy advancing through the circular waveguide from one side of section 36 in the TE mode and having its principal vector oriented in a given direction has its principal vector shifted through angle X, which As Well understood, this;may be accomplished because energy traveling in the elliptical section has even and odd modes, in one of which theprincipal vector is along the major axis and the other of which is along the minor axis of the ellipse. .These two modes have differing phase velocities. The

transformation may be adjusted to produce the desired result by means of a clamp (not shown) exerting pressure against the outside walls of waveguide section 36 to a desired degree. Impedance matching devices have been omitted, in Figures 4 to 7, because such devices are numerous and well known. Other means are also known to procure the angular shift of the principal vector of energy in the circular waveguide mentioned in con? nection with Figures 6 and 7.

In the device of Figures 6 and 7, the division of energy between

arms

16 and 18 incident from, say, arm 12 may be made as desired by appropriately choosing the shift in the direction of the electric vector of energy in section 36 and the angular relationship of the

arms

16 and 18 j'with respect-to arm 12. Either section 36 or the angular direction of arms 16 and 18 (the axes of which remain normal to each other) may be independently adjusted to secure this result. Hence, there is a highly desirable flexibility in .choosing the relationship of the arms to facilitate connection with apparatus'of which the waveguidenetwork forms a part.

In practice, it will be be understood that any of the rectangular waveguides shown in the drawing may be connected to extensions or to other apparatus. Any of the rectangular waveguides may have a resistive matching termination or a crystal and reflective termination, or other terminations. Such extensions and terminations I have not shown, as they are peculiar to the device in which my waveguide junction network may be employed, and do not aid in an understanding of the present invention.

I claim as my invention:

1. A four terminal-pair waveguide network comprising an elliptical waveguide having a longitudinal axis and two pairs of waveguide arms, each said arm having a longitudinal axis and having a junction with said elliptical waveguide, at each said junction the said axes of the elliptical waveguide and the waveguide arm being normal to each other.

2. The device claimed in claim 1, further comprising impedance matching apparatus to match the impedance of said waveguide arms to the impedance of said elliptical waveguide at the said junctions.

3. A four terminal-pair waveguide network comprising an elliptical hollow pipe waveguide having a longitudinal axis and two pairs of hollow pipe waveguide arms, each said arm having a longitudinal axis and having a .junction with said elliptical waveguide and being adapted for excitation by electromagnetic energy in a transverse electric mode having a single principal electric vector normal to the said axis thereof, at each said junction the said axes of the elliptical waveguide and the waveguide arm being normal to each other and said principal vector being oriented normal to the axis of said elliptical waveguide.

4. A four terminal-pair waveguide network comprising an elliptical hollow pipe waveguide having a longitudinal axis, andtwo pairsof rectangular hollow-pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrow internal walls and each having a junction with said elliptical waveguide, at each said junction the said axes of the elliptical waveguide and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide arm beingparallel to the said elliptical Waveguide axis.

5. A four terminal-pair waveguide network comprising an elliptical hollow pipe waveguide closed on each end and having a longitudinal axis, and two pairs of rectangular hollow pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrow internal walls and each having a junction with said elliptical waveguide, at each said junction the said axes of the elliptical waveguide and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide arm being parallel to the said elliptical waveguide axis, the waveguide axis of one of said rectangular waveguide pair being normal to thatofthe other of the same pair.

6. A four terminal-pair hollow pipe waveguide network comprising an elliptical hollow pipe waveguide having a longitudinal axis, andtwo pairs of rectangular hollow pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrowinternal walls and each having a junction with said elliptical waveguide, at each said junction the said axes of the elliptical waveguide and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide arm;being parallel to the said elliptical waveguide axis, the waveguide axis of each of said rectangular waveguide pair being normal to that of the other of the same pair.

7. A four terminal-pair waveguide network comprising an elliptical hollow pipe waveguide having a longitudinal axis, and two pairs of rectangular hollow pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrow internal walls and each having a junction with said elliptical waveguide, at each said junction the said axes of the elliptical waveguide and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide armbeing parallel to the said elliptical waveguide axis, the waveguide axis of each of said rectangular waveguide pair being normal to that of the other of the same pair,'the junction of one rectangular waveguide with said elliptical waveguide being displaced along the said elliptical waveguide axis with respect to the junction of the other of the same pair.

8. The network claimed in claim 7, the said junctions of said one .pair of rectangular waveguide arms with the elliptical waveguide displaced from each other along said elliptical waveguide axis being on opposite sides of the junction of the other pair of rectangular Waveguides with said elliptical waveguide.

9. A four terminal-pair waveguide network comprising a circular hollow pipe waveguide having a longitudinal axis, and two pairs of rectangular hollow pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrow internal walls and each having a junction with said circular waveguide, at each said junction the said axes of the circular waveguide and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide arm being parallel to the said circular waveguide axis, the waveguide aXisof one of said rectangular waveguide pair being normal to that of the other of the same pair.

. 10. A four terminal-pair waveguide network comprising a circular hollow pipe waveguide closed on each end and having a longitudinal axis, and two pairs of rectangular hollow pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrow internal walls and each having a junction with said circular waveguide, at each said junction the said axes of said circular waveguide and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide arm being parallel to the said circular waveguide axis, the waveguide axis of one of said rectangular waveguide pair being normal to that of the other of the same pair.

11. A four terminal-pair waveguide network comprising a circular hollow pipe waveguide closed on each end and having a longitudinal axis, and two pairs of rectangular hollow pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrow internal walls and each having a junction with said circular waveguide, at each said junction the said axes of the circular waveguide'and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide arm being parallel to the said circular waveguide axis, the waveguide axis of each of said rectangular waveguide pair being normal to that of the other of the same pair.

12. A four terminal-pair waveguide network comprising a circular hollow pipe waveguide closed on each end and having a longitudinal axis, and two pairs of rectangular hollow pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrow walls and each having a junction with said circular waveguide, at each said junction the said axes or the circular waveguide and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide arm being parallel to the said circular waveguide axis, the waveguide axis of each of said rectangular waveguide pair being normal to that of the other of the same pair, the junction of one rectangular waveguide with said circular waveguide being displaced along the said circular waveguide axis with respect to the junction of the other of the same pair.

13. A four terminal-pair waveguide network, comprising a hollow pipe waveguide having on each end circular closed portions and having a longitudinal axis, and two pairs of rectangular hollow pipe waveguide arms, each said rectangular waveguide arm having a longitudinal axis and broad and narrow internal walls and each having a junction respectively with each said cir cular waveguide end portion, at each said junction the said axes of the circular waveguide portion and the rectangular waveguide arm being normal to each other and the broad walls of each rectangular waveguide arm being parallel to the circular waveguide portion axis, the waveguide axis of each of said rectangular waveguide pair being normal to that of the other of the same pair, the junctions of each one of one pair of rectangular waveguides wtih said circular waveguide portion being at the same point along the said circular portion waveguide axis with respect to the other of the same pair and the said junctions of one pair being displaced along said hollow pipe waveguide axis with respect to the other pair.

14. The network claimed in claim 13, said hollow pipe waveguide having a section deformed to eccentric ellipticity joining the said circular waveguide portion.

15. The network claimed in claim 13, said hollow pipe waveguide between said circular waveguide portions having means to rotate the electric vector of electro-magnetic energy passing through said waveguide.

References Cited in the file of this patent UNITED STATES PATENTS 2,443,612 Fox June 22, 1948 2,445,895 Tyrrell July 27, 1948 2,458,579 'Feldman Jan. 11, 1949