US3670267A - Microwave switch utilizing latched ferrimagnetic material in coupling aperture of waveguide coupler - Google Patents

Abstract

Two rectangular waveguides are interconnected by a coupling aperture in which a ferrimagnetic body is disposed. At least one latching conductor extends through the body in the axial direction of the waveguides or in a direction perpendicular thereto. A pulse current flowing through the conductor causes a change in direction or magnitude of the magnetization of the ferrimagnetic body. This permits an electromagnetic wave, applied to either one of the input waveguide ends, to appear at that output end at which the wave did not previously appear.

Description

United States Patent Nakahara et a].

[54] MICROWAVE SWITCH UTILIZING LATCI-IED FERRIMAGNETIC MATERIAL IN COUPLING APERTURE OF WAVEGUIDE COUPLER [72] Inventors: Shojiro Nakahara; I-Iidetoshi Kurebayshi,

both of Kamakura, Japan [73] Assignee: Mitsubishi Denki Kabushlki Kaisha,

Tokyo, Japan 22 Filed: Feb. 17,1970

21 Appl.No.: 11,939

[1 1 3,670,267 [451 June 13, 1972 3,525,952 8/1970 Siekanowicz et al... ....333/24.l X

2,848,688 8/1958 Fraser ..333/l .l X 3,017,585 l/l962 Luke ..333/l0 X OTHER PUBLICATIONS Trwehaft et al, Use of Microwave Ferrite Toroids to Eliminate External Magnets and Reduce Twitching Power Proc. of IRE. Aug. 1958, Pg. 1538 Wright, Diodes or Ferrites- Which Switch? Microwaves, Dec. 1962 Primary Examiner-Paul L. Gensler Attorney-Robert E. Burns and Emmanuel J. Lobato 57] ABSTRACT Two rectangular waveguides are interconnected by a coupling aperture in which a ferrimagnetic body is disposed. At least one latching conductor extends through the body in the axial direction of the waveguides or in a direction perpendicular thereto. A pulse current flowing through the conductor causes a change in direction or magnitude of the magnetization of the ferrimagnetic body. This permits an electromagnetic wave, applied to either one of the input waveguide ends, to appear at that output end at which the wave did not previously appear.

6 Clainu, 11 Drawing Figures 20 SOURCE PA'TENTEDJun 1 3 m2 3.670.267

FIG. I (PRIOR ART) FIG, 2 (PRIOR ART) PHASE CIR um I j T SHIFTER FARADAY 4 3 POLARIZATION "3' 3- eflmcums --9 PHASE FILTER SHIFTER T FIG. a FIG. 40 FIG. 4

" M ULE Z0 souRcE. A 4- .FI,6 .5' c A 44 nae c MICROWAVE SWITCH UTILIZING LATCI-IED FERRIMAGNETIC MATERIAL IN COUPLING APERTURE OF WAVEGUIDE COUPLER BACKGROUND OF THE INVENTION referred to involve an arrangement including a pair of 90 phase shifters having coupled to the input and output ends hybrid circuits respectively, an arrangement including a Faraday rotator operatively associated with a waveguide polarization branching filter etc. Such known arrangements have been disadvantageous in that they are composed of a relatively large number of components and therefore are inevitably increased not only in dimension but also in costs.

SUMMARY OF THE INVENTION Accordingly it is an object of the invention to provide a new and improved microwave switching device which is relatively small in dimension and capable of continuously switching microwaves and operating on a low driving power.

It is another object of the invention to provide a microwave switching device of the type as described in the preceding paragraph including a plurality of conductors operatively associated with a body of ferrimagnetic material involved and selectively used to be operative in reciprocal mode.

It is a further object of the invention to provide a new and improved microwave switching device not only acting as a switch for completely switching one to the other of the associated circuits but also capable of switching from one to the other of the circuits such that the associated electrical energy is applied in any desired proportion to both the circuits.

The invention accomplishes the aforesaid objects by the provision of a microwave switching device for use with a waveguide multi-port comprising a pair of coupling sections of waveguide interconnected on the adjacent side walls and having respective input and output ends, and a body of ferrimagnetic material loaded at the junction of the sections of waveguide, characterized in that the body of ferrimagnetic material has a hole extending therethrough in a selected one of the axial directions of the waveguide sections, and in a direction perpendicular thereto, a latching conductor extending through the hole, and means for causing a current to flow through the latching conductor to change the magnitude or direction of magnetization of the body of ferrimagnetic material thereby either to switch one to the other of the output ends for delivering the associated electromagnetic wave or to change a magnitude of an output from the particular output end.

In order to provide a reciprocal switch, the body of ferrimagnetic material may have a plurality of holes extending through in a selected one of the axial direction of the waveguide sections and a direction perpendicular thereto and one latching conductor extends through each of the holes, a current being caused to selectively flow through the latching conductors.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a schematic circuit diagram of a microwave switching device constructed in accordance with the principles of the prior art;

FIG. 2 is a schematic view of another microwave switching device constructed in accordance with the principles of the prior art;

FIG. 3 is a perspective view of a microwave switching device constructed in accordance with the principles of the invention with parts broken away for the purpose of illustrating the internal structure;

FIG. 4a and b are sectional views of a body of ferrimagnetic material used in the device shown in FIG. 3, and in its differently magnetized states;

FIG. 5 is a schematic plan view of the device shown in FIG. 3 useful in explaining the operation of the invention;

FIG. 6 is a sectional plan view, of the most generic form of the invention; and

FIGS. 7a and b andFIGS. 8a and b are fragmental views of modifications of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS hybrid circuits 1 and a pair of variable phase shifters 2 connected in parallel circuit relationship between the hybrid circuits l with one of the hybrid circuits, in this case, the lefthand circuit, terminated by a matched dummy load 3. The phase shifters 2 each are adapted to impart to its output a phase angle of from 0 to or 90 to 0 with respect to its input. In FIG. 2 a Faraday rotator 4 is operatively associated with a waveguide polarization branching filter 5. The arrangements as shown in FIGS. 1 and 2 are the conventional microwave switching devices for continuously switching microwaves applied thereto. The details of construction and operations thereof are well known in the art and need not be further described. It is sufficient to note that such microwave switching devices have been disadvantageous in that they are large in dimension, expensive to manufacture and inconvenient for practical use due to the relatively large number of components forming the device.

The invention contemplates to eliminate those disadvantages of the conventional microwave switching devices and will now be described in detail with reference to FIGS. 3, 4 and 5.

FIG. 3 is a perspective view of a device constructed in accordance with the principles of the invention. The arrangement illustrated comprises a pair of similarly oriented rectangular waveguide sections generally designated by the reference numeral 10 and interconnected in side-to-side relationship by having the adjacent side walls connected together to form a common side wall portion. The interconnected side walls are partly removed to form a coupling aperture 12 resembling in structure a short slot type directional coupler well known in the art. A body 14 composed of ferrimagnetic material, shown in FIG. 4 as being of rectangular cross section, is loaded or disposed in the coupling aperture 12 such that its longitudinal axis substantially coincides with the interface of the connected side walls of the waveguide sections 10. A bore or hole 16 extends centrally through the body 14 of ferrimagnetic material in the longitudinal axial direction of the waveguide sections 10 and has a latching conductor 18 threaded therethrough. The latching conductor 18 has both end portions insulatingly extending through the outer side wall of one of the waveguide sections 10 and connected across a source 20 of current pulses. A current pulse from the source 20 is adapted to flow through the latching conductor 18 to magnetize the ferrimagnetic body 14 or to invert it from one to the other of its magnetized states. For example with the ferrimagnetic body 14 put in its magnetized state as illustrated in FIG. 4a, a current pulse flowing from the source 20 through the conductor 18 can change the body 14 to its other magnetized state as illustrated in F IG. 4b.

In FIG. 4a, a current is shown as flowing from the source 20 through the latching conductor 18 in a direction directed to the plane of FIG. 4a from the rear side thereof, as shown by the conventional symbol dot in circle, to provide a magnetic flux flowing within the ferrimagnetic material 14 in the counter clockwise direction as viewed in FIG. 4a. In FIG. 4b, a current is shown as flowing through the conductor 18 in the opposite direction, as shown by the conventional symbol, cross in circle," and therefore the resulting magnetic flux is in the opposite direction or the clockwise direction as viewed in FIG. 4b.

The operation of the arrangement as illustrated in FIG. 3 will now be described with reference to FIG. 5 wherein the device is shown in top plan view as including terminal pairs labelled with the reference characters A, B, C and D at the input and output ends. An electromagnetic wave entered into the terminal pair A reaches the coupling aperture 12 in which it is in the TE and TE modes as will readily be understood. More specifically, the electromagnetic wave from the terminal pair A reaches the coupling aperture 12 and therefore that end face 22 near to the tenninal pair A of the ferrimagnetic body 14 on which the wave is divided into the TE and TE modes of transmission. Then the waves in the TE and TE modes travel in that portion loaded by the ferrimagnetic body 14 of the coupling aperture 12 to the other end face 24 of the body 14. Thus it will be appreciated that the phase relationship between the TE, and T15 modes of the wave as having reached the end face 24 of the ferrimagnetic body 14 determines the amount of power emerging from the terminal pairs C and D.

It is apparent that the TE and TE modes of transmission existing in the body 14 of ferrimagnetic material are different from those existing in an empty waveguide, but what corresponds to each of the transmission modes in an empty waveguide portion is present in the ferrimagnetic material. Therefore, for purposes of simplicity, the termsTE and TE modes" are used with respect to that portion loaded by the ferrimagnetic material of the coupling aperture.

It is now assumed that the fem'magnetic material 14 is in its magnetized state as shown in FIG. 4a. Also it is assumed that the coupling aperture 12 is loaded by the ferrimagnetic body 14 substantially throughout the length thereof along the axial direction of the waveguide sections as shown in FIG. 5. Under the assumed conditions the electromagnetic wave incident upon the terminal pair A will be transmitted only to the terminal pair D provided that the following equation is held:

B phase constant of TE mode on ferrimagnetic material loaded portion,

B phase constant of TE mode on ferrimagnetic material loaded portion,

If length of coupling aperture and therefore of ferrimagnetic body. Then if a current flows through the latching conductor 18 in a direction as symbolically shown in FIG. 4b the ferrimagnetic body 14 changes from its magnetized state as illustrated in FIG. 4a to its magnetizes state as illustrated in FIG. 4b. It is assumed that this change in magnetized state causes the phase constants B and B to vary by the amounts of AB and A13 respectively and that the following equation is held:

form= 1,2,.

Then the power is transmitted to the terminal pair C alone. Subtracting the equation 2 from the equation 1 yields (AB -AB lf=i{2(nm)1}1'r 3. Therefore if the equations 1 and 3 are simultaneously held then switching is possible between the terminal pairs C and D. It is noted that, with the coupling aperture 12 loaded by the ferrimagnetic body 14 almost throughout the length thereof as shown in FIG. 5, both equations 1 and 3 are not always and simultaneously held. However, if the equation 3 is held, the equation I is possible to be held by increasing the length of the unloaded portion of the coupling aperture 12 or by loading a body of dielectric material on the coupling aperture 12.

Actually, an impedance matching means is required to be operatively associated with the ferrimagnetic body 14 or the abovementioned dielectric body for adjusting the electrical length in order to minimize reflection from the end face of either body. While any one of various matching means may be used, the use of a dielectric material will now be described in conjunction with FIG. 6 wherein like reference numerals designate the components corresponding to those shown in FIGS. 3 and 5.

In FIG. 6, the coupling aperture 12 includes an unloaded portion 26 or 28 formed at either end. The body 14 of ferrimagnetic material loading the coupling aperture 12 is provided on one end face, in this case, the lefthand face as viewed in FIG. 6 with a matching body 30 of dielectric material and on the other end face with a matching body 32 of dielectric material. Also an adjusting body 34 of dielectric material is integrally attached to the matching dielectric body. It is now assumed that the T5 and T5 modes on the unloaded portions 26 or 28 and those parts loaded with the matching dielectric bodies 30 and 32, the adjusting dielectric body 34 and ferrimagnetic body 14 of the coupling aperture 12 have their phase constants of B10! B20 Bldm Bid!!! Bid B2dr B1! and B?! respectively and lengths of la, Idm, Id and If respectively as shown in FIG. 6. Then the equation 1 can be replaced by the equation {(Bla (Bldm BMm) dm (Bld Id +(BU B2I') f 4 for n 1,2, Therefore only what is required is to determine the lengths la, ldm, Id and If so as to hold the equation 4.

Then a question rises as to whether or not the arrangement as shown in FIG. 6 will be possible to hold the equation 3. The ferrimagnetic body 14 effects changes in the phase constants AB and A3 for the respective modes in the similar manner as does the conventional type of latching phase shifters. These changes in phase constants are caused from a change in effective permeability occur-ing by changing from one to the other of the polarities of magnetization as shown in FIGS. 4a and b. If A3,, is equal to Afi then the equation (3) is not held. However with the coupling aperture 12 loaded as shown in FIG. 3 or 6 it is resulted that the ferrimagnetic body 14 is disposed at its position where the transverse field is high for the TE mode and low for the TE mode whereby it is differently affected by the individual modes. Therefore, AB is generally different from AB y. Furthermore, for the TE and TE modes traveling in a common direction the circularly polarized wave components of such modes in the portion loaded with ferrimagnetic material are opposite in direction of rotation from each other with the result that if Afl is greater than zero A13 is smaller than zero and vice versa. Thus the AB and A3,, are effectively added to each other in the equation (3.) This means that the equation 3) can be held with a particular length of the ferrimagnetic body 14.

Here it is to be noted that the switching device as above described is not reciprocal for the following reasons: That portion loaded with the ferrimagnetic body 14 of the coupling aperture 12 has its phase constant dependent upon the direction in which an electromagnetic wave is incident thereupon. For example, assuming that the phase constants for the respective modes are of B and B for a electromagnetic wave incident upon the terminal pair B, their values change to fi -l- AB and B Afi for an electromagnetic wave incident upon the terminal pair D. (If the ferrimagnetic material is inversed in polarity of magnetization the above relationship is also reversed.) Thus when an electromagnetic wave has been applied to the terminal pair D such that the electromagnetic wave falling upon the terminal pair A emerges from the terminal pair D, the wave emerges from the terminal pair B rather than from the tenninal pair A. In other words, the fixing of the polarity of magnetization of the ferrimagnetic material provides one kind of circulator.

In the arrangement as above described, an electromagnetic wave scarcely emerges from that terminal pair disposed adjacent the particular terminal pair to which the wave is applied. For example, with the wave applied to the terminal pair A, it scarcely emerges from the terminal pair B. However under these circumstances the wave will actually emerge from the terminal pair B due to some leakage between the adjacent terminal pairs. Therefore if the arrangement is utilized as a single throw double pole switch, the particular terminal pair not required is terminated by a matched dummy load.

While the invention has been illustrated and described in conjunction with a switch having a non-reciprocal characteristic, is to be understood that it is equally applicable to reciprocal switches. To this end, the ferrimagnetic body 14 as shown in FIG. 3 or 6 can be replaced by a body of ferrimagnetic material capable of realizing any one of its magnetized states such as shown in FIG. 7. The ferrimagnetic members or bodies 14 each are shown in FIG. 7 as including a plurality of cross holes 16 in this case, three, extending therethrough in a direction perpendicular to the longitudinal axial direction of the associated waveguide sections (not shown) and a pair of parallel holes 16 extendingtherethrough in thelongitudinal axial direction of the waveguide section (not shown). Then one latching conductor 18 is threaded through each of the holes 16. If desired, a single cross conductor 18 may be used. Pulse currents can flow through the respective latching conductors 18 in the direction symbolically shown in FIG. 7 to put the associated ferrimagnetic body 14 in the magnetized state reversed from that shown at the arrow in FIG. 7a or 7b. The ferrimagnetic body 14 may be put in its magnetized state of opposite polarity in the cross sectional plane as shown in FIG., 7a and it may be put in its magnetized state of one or the other polarity in the longitudinal sectional plane as shown in FIG. 7b. The ferrimagnetic body 14 as shown in FIG. 7 can replace the ferrimagnetic body 14 in the arrangement as shown in FIG. 3 or 6 to provide a reciprocal switch.

While the device is in any one of the magnetized state of the ferrimagnetic body 14 as shown in FIG. 7, a pulse current can flow through the latching conductors in a direction opposite to that symbolically shown in FIG. 7 to change the ferrimagnetic body 14 to its magnetized state reversed from that illustrated. Since the ferrimagnetic material has its effective permeabilities for TE and TE modes dependent upon its magnetized state, changing one to the other of its magnetized state causes a change in phase constant for each mode. Thus it will be appreciated that such a reciprocal switching device is operative in the substantially identical manner as previously described in conjunction with the non-reciprocal devices.

The dimension of the ferrimagnetic body 14 can be properly chosen to hold the equations (3) and (4) providing a reciprocal switch. In the reciprocal switches it is noted that unlike the non-reciprocal switches a change in magnetized state does not cause AB and A13 to vary in sign. In other words, the efiective permeability is not affected by the direction of rotation of the circularly polarized wave. Therefore a difference between A3,, and Afl is caused only from a difference in distribution of the electromagnetic field between the TE and T modes. This result in the necessity of increasing the required length of the ferrimagnetic body as compared with the non-reciprocal arrangements.

While the invention has been illustrated and described in terms of the case complete switching is efiected between the terminal pairs C and D it is to be understood that the invention is equally applicable to the case partial switching is effected to cause an electromagnetic wave to appear in both the adjacent terminal pairs with any desired proportion of its energies. Such partial switching is accomplished by properly selecting the values of the righthand sides of the equations 3 and 4. For example, the dimension of the ferrimagnetic body 14 may be selected to render the righthand side of the equation '3 equal to 1r/4 while the equation 4 is left intact. Under these circumstances, that electromagnetic wave emerging only from the terminal pair D in the magnetized state of the ferrimagnetic body 14 as shown in FIG. 4a responds to a change to the magnetized state of the body as shown in FIG. 4b to be divided into two equal portions emerging from both the terminal pairs C and D respectively.

Also the invention has been described in conjunction with a change in direction of a pulse current flowing through the latching conductor or conductors to change the ferrimagnetic body from one to the other of its magnetized states. However his to be understood that according to the principles of the inamount of power emerging from the particular terminal pair. This is because a change in magnitude of the current causes a variation in magnitude of magnetization of the ferrimagnetic material leading to changes in the AB and Afi thereof.

The invention has several advantages. For example, it is simple in construction and small-sized. Also, a pulse current is required only when the ferrimagnetic body is to be changed from one to the other magnetized state and no power is required to maintain the ferrimagnetic body in either of its magnetized states thereby resulting in a low driving power.

What we claim is:

l. A microwave switching device for use with a waveguide multi-port comprising, in combination: a pair of coupling sections of waveguide interconnected along a common side wall and having respective input and output ends, means defining a coupling aperture in said common side wall, a body of ferrimagnetic material disposed within said coupling aperture, said body of ferrimagnetic material having means therein defining a plurality of holes extending therethrough in the longitudinal axial direction of the waveguide sections and means therein defining a plurality of holes extending therethrough in a direction perpendicular to said longitudinal axial direction, a latching conductor extending through each of said holes, and means for causing a current to flow through said latching conductor to selectively change the direction of magnetization of said body of ferrimagnetic material to thereby switch one to the other of said output ends for delivering therethrough an electromagnetic wave received at one of said input ends.

2. A microwave switching device as claimed in claim 1 wherein saidcoupling aperture contains therein a matching body of dielectric material.

3. A microwave switching device for use with a waveguide multi-port comprising, in combination: a pair of coupling sections of waveguide interconnected along a common side wall and having respective input and output ends, means defining a coupling aperture in said common side wall, a body of ferrimagnetic material disposedwithin said coupling aperture, said body of ferrimagnetic material having means therein defining a plurality of holes extending therethrough in the longitudinal axial direction of the waveguide sections and means therein defining a plurality of holes extending therethrough in a direction perpendicular to said longitudinal axial direction, a latching conductor extending through each of said holes, and means for causing suflicient current to flow through said latching conductor to change the magnitude of magnetization of said body of ferrimagnetic material to thereby change the magnitude of an output from the particular output end.

4. A microwave switching device as claimed in claim 3 wherein said coupling aperture contains therein a matching body of dielectric material.

5. A microwave switch comprising: a pair of similarly orientated waveguide sections each having an input end and an output end axially spaced apart from each other along a longitudinal axis of the waveguide section; means connecting together said pair of waveguide sections in side-by-side relationship including'a common side wall portion common to both said waveguide sections; means defining only a single coupling aperture in said common side wall portion coupling together said pair of waveguide sections; a ferrimagnetic member disposed within said single coupling aperture; and means coacting with said ferrimagnetic member for selectively developing a magnetic field of sufficient strength and polarity to effectively switch the path of travel of an electromagnetic wave received at one input end of one waveguide section between each output end of said pair of waveguide sections, said last-mentioned means comprising means defining at least one hole extending through said ferrimagnetic member in a direction parallel to the longitudinal axis of said waveguide sections, means defining at least one other hole extending said ferrimagnetic member in a direction perpendicular to said longitudinal axis, a latching conductor threaded through each of said holes, and means for selectively flowing current through vention a pulse current may vary in magnitude to change 11 said latching conductor to develop said magnetic field.

6. A switch according to claim 5; wherein said ferrimagnetic member has planar side walls and planar end faces and is symmetrically disposed in said coupling aperture with respect to said pair of waveguide sections.

Claims (6)

1. A microwave switching device for use with a waveguide multiport comprising, in combination: a pair of coupling sections of waveguide interconnected along a common side wall and having respective input and output ends, means defining a coupling aperture in said common side wall, a body of ferrimagnetic material disposed within said coupling aperture, said body of ferrimagnetic material having means therein defining a plurality of holes extending therethrough in the longitudinal axial direction of the waveguide sections and means therein defining a plurality of holes extending therethrough in a direction perpendicular to said longitudinal axial direction, a latching conductor extending through each of said holes, and means for causing a current to flow through said latching conductor to selectively change the direction of magnetization of said body of ferrimagnetic material to thereby switch one to the other of said output ends for delivering therethrough an electromagnetic wave received at one of said input ends.

2. A microwave switching device as claimed in claim 1 wherein said coupling aperture contains therein a matching body of dielectric material.

3. A microwave switching device for use with a waveguide multi-port comprising, in combination: a pair of coupling sections of waveguide interconnected along a common side wall and having respective input and output ends, means defining a coupling aperture in said common side wall, a body of ferrimagnetic material disposed within said coupling aperture, said body of ferrimagnetic material having means therein defining a plurality of holes extending therethrough in the longitudinal axial direction of the waveguide sections and means therein defining a plurality of holes extending therethrough in a direction perpendicular to said longitudinal axial direction, a latching conductor extending through each of said holes, and means for causing sufficient current to flow through said latching conductor to change the magnitude of magnetization of said body of ferrimagnetic material to thereby change the magnitude of an output from the particular output end.

4. A microwave switching device as claimed in claim 3 wherein said coupling aperture contains therein a matching body of dielectric material.

5. A microwave switch comprising: a pair of similarly orientated waveguide sections each having an input end and an output end axially spaced apart from each other along a longitudinal axis of the waveguide section; means connecting together said pair of waveguide sections in side-by-side relationship including a common side wall portion common to both said waveguide sections; means defining only a single coupling aperture in said common side wall portion coupling together said pair of waveguide sections; a ferrimagnetic member disposed within said single coupling aperture; and means coacting with said ferrimagnetic member for selectively developing a magnetic field of sufficient strength and polarity to effectively switch the path of travel of an electromagnetic wave received at one input end of one waveguide section between each output end of said pair of waveguide sections, said last-mentioned means comprising means defining at least one hole extending through said ferrimagnetic member in a direction parallel to the longitudinal axis of said waveguide sections, means defining at least one other hole extending said ferrimagnetic member in a direction perpendicular to said longitudinal axis, a latching conductor threaded through each of said holes, and means for selectively flowing current through said latching conductor to develop said magnetic field.

6. A switch according to claim 5; wherein said ferrimagnetic member has planar side walls and planar end faces and is symmetricalLy disposed in said coupling aperture with respect to said pair of waveguide sections.

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