US2788494A

US2788494A - Ridged waveguide microwave switch

Info

Publication number: US2788494A
Application number: US259914A
Authority: US
Inventors: Jr Clyde E Vogeley; Thaddeus A Osial
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1951-12-05
Filing date: 1951-12-05
Publication date: 1957-04-09
Anticipated expiration: 1974-04-09

Description

April 9, 1957 c. E. VOGELEY, JR ET AL 2,788,494

RIDGED WAVEGUIDE MICROWAVE SWITCH Filed Dec. 5, 1951 2 Sheets-5heet 1 Fig.1.

WITNESSES: INVENTORS C|ydeE.V0geley Jr. 6%77/ and Thaddeus Absio l.

- ATTORNEY April 9, .1957 c. E. VOGELEY, JR., ET AL 2,738,494

RIDGED WAVEGUIDE MICROWAVE SWITCH Filed Dec. 5, 1951 2 Sheets-Sheet 2 WITNESSES: lNVENTORS,

. 4 7 Clyde E.Voge|ey 777/ 0nd Thaddeus A.O

ATTORNEY United States RIDGED WAVEGUIDE MICROWAVE SWTTCH Clyde E. Vogeley, Jr., and Thaddeus A. Osial, Pittsburgh, Pa., assignors to Westinghouse Electric Qorporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application December S, 1951, Serial No. 259,914

9 Claims. (Cl. 3337) Our invention relates to conductors for electromagnetic oscillations, and more particularly, to apparatus for controlling the flow of oscillations in ridged waveguides.

In accordance with the prior art of which we are aware, microwave switch devices have been built which employ such types of apparatus as swinging gates, rotating discs with apertures conforming to the waveguide cross section cut therein, or plunger-s moving up and down into the guide. These devices have many disadvantages, such as the requirement of space consuming auxiliary gear which is often quite cumbersome. Also these devices are not readily employable with a ridged Waveguide in view of its complex geometry.

In situations where it is desirable to provide a Y-section having three branches, it is usually desirable that two of the branches be isolated from each other. f-sections and standard waveguides have been built in which a septum comprising a thin sheet of metal is placed at the junction of the two branches which are to be isolated from each other. However, this does not isolate the branches to the degree which is usually desired.

It is accordingly an object of our invention to provide an improved microwave switching apparatus.

Another object of our invention is to provide an improved microwave Y-section.

Still another object of our invention is to provide a new and useful apparatus for controlling the flow of electromagnetic oscillations.

The ridged waveguide which is commonly employed in the art comprises a hollow conductor having a substantially rectangular cross section. Extending into the hollow conductor is a re-entrant portion also of electrically conducting material, this re-entrant portion being generally referred to as a ridge. The re-entrant portion extends along the length of the hollow conductor and is located approximately half way between the two sides of the hollow conductor. The re-entrant portion extends up from the bottom a distance which is roughly equal to half the height of the waveguide, the exact height depending on the use to which the waveguide is to be put. The ridged waveguide has the advantage over the standard rectangular waveguide of having a lower cut-otf frequency than a standard waveguide having the same overall cross sectional dimensions.

In accordance with our invention, we provide a section of waveguide having therein over a portion of its length a re-entrant portion extending thereinto, thereby forming a ridged waveguide over a portion of the length of the waveguide and a standard waveguide over the remainder of the length of the waveguide.

Since the portion of the hollow conductor which contains the ridge has a lower cut-off frequency than the portion of the hollow conductor which does not contain the ridge, oscillations may be caused to flow freely through the region where the ridge is located, while being completely prevented from traversing that portion of the chamber where the ridge is not located. Thus, by'connecting two conductors to the chamber at differcut points along the length of the chamber and by proper adjustment of the location of the ridge, oscillations may be either caused to flow from one conductor to another or alternatively, to be prevented from flowing from the one to the other.

The novel features which we consider characteristic of our invention are set forth with more particularity in the appended claims. The invention, however, with respect to both the organization and the operation thereof, together with other objects and advantages may be best understood from the following description of specific embodiment when read in connection with the accompanying drawings, in which:

Figure 1 is a showing in section of a microwave switch built in accordance with one embodiment of our invention,

Fig. 2 is a showing in section of the apparatus shown in Fig. 1, taken along the line lIII of Fig. 1,

Fig. 3 is a showing in section of a Y-section built in accordance with another embodiment of our invention,

Fig. 4 is a showing in section of the apparatus shown in Fig. 3, taken along the line IVIV of Fig. 3.

In accordance with our invention, we provide an inner cylinder 6 and an outer cylinder 8 of electrically conducting material. The outer cylinder 8 is hollow and has an internal diameter substantially greater than the outside diameter of the inner cylinder 6. The inner cylinder 6 is located inside the outer cylinder 8 and is oriented coaxially therewith so as to form a cylindrically shaped hollow region between the inner and

outer conductors

6 and 8. At one end of the inner and

outer conductors

6 and 8 is placed a top plate 10 which fills the cylindrically shaped region between the inner and outer cylinders at that end. At the other end of the

cylinders

6 and 8 from that at which the top plate 10 is located, there is a bottom plate 12. The bottom plate 12 in conjunction with the inner cylinder 6, the outer cylinder 8, and the top plate 10 forms a cylindrical shaped chamber or cavity of rectangular cross section. The bottom plate 12 includes a rectangularly shaped projection 16 which extends into the chamber 14 so as to form, in conjunction with the walls of that chamber, a ridged waveguide over a portion of the length of the chamber. In a preferred embodiment of our invention, the projection 16 is adjustably mounted so that it may be rotated about the inner cylinder 6 by applying a torqueto a handle 18 to which the projection 16 is connected. Thus the projection may be moved to the desired position along the length of the chamber 14 by rotating it about the inner cylinder 6.

In the embodiment shown in Figs. 1 and 2, a first branch ridged waveguide 20 is coupled to the chamber 14 at a first point along the length of the chamber 14. A second branch ridged waveguide 22 is coupled to the chamber 14 at a point geometrical degrees around the chamher 114 from the point Where said first branch wave guide 25} is connected. A third branch ridged Waveguide 24 is coupled to the chamber 14 at a point equally distant from the point where the first branch 2t! is coupled to the chamber 14 and the point where the second branch 22 is coupled to the chamber 14.

In the preferred embodiment of our invention the projection 16, which extends into the chamber has a length in the direction in which the chamber 14 extends such that it extends around the chamber a distance greater than a quarter, but less than a half of the length chamber 14.

When the projection 16 is located as indicated in Fig. 1, namely so that it extends from the region of the first branch guide 29 to the region of the third branch guide 24, but does not extend into the region of the second branch guide 22, there is efiectively provided, a ridged of the l waveguide between the first branch guide 2% and the third branch guide 24. However, a standard Waveguide is provided between the first branch guide it) and the second branch guide 22 and between the second branch guide 22 and'the third branch guide 24.

Whenthe frequency of the oscillations employed in the waveguides is such that the section of the chamber which represents efiectively a standard waveguide is below the cut-ofi dimensions corresponding to that frequency while the dimensions of the section of the chamber containing the projection 16 are such to produce a ridged waveguide,- the cut olf dimensions of which are not below that corresponding to the frequency to be employed, the oscillations will be allowed: to pass from the first branch ridged guide 29 to the third branch guide 2 but not from the first branch. waveguide 23th to the second branch waveguide 22.

We have thus taken advantage of the previously explained principle thatwith the same overall cross sectional dimension the cut-off dimension for a ridged waveguide is lowerthan the cut-off dimension ot a standard waveguide. By proper adjustment of the location of the projection 16, the first branch maybe coupled to the third branch or alternatively the second branch be coupled to the third branch. Also, it is understood that by increasing the length of the projection 16 it is possible tobuild the apparatus so that the first branch could be coupled to the second branch as well as the third branch or instead of the third branch;

In accordance with another embodiment of our inventionas shown in Figs. 3 and 4, a Y-section may be constructed by properly choosing the length of the ridge member-16 and thelocation of

thebranch waveguide

2Q, 22,, 24. In accordance with this emobdiment of our invention the second branch 22 and the third branch 24 are coupled to the chamber 14 at points equally distant from thepoint' where the first branchwaveguide 2% is connected to. thechamber 14. In this embodiment of our invention, the length of theridge member 16 and its location are chosen so that it extends from the region of the second branch waveguide 22 past the first branch waveuide 26' to the region of the third branch waveguide 24, while causing a discontinuity to'exist in the ridge Waveguide between the second branch 22' and the third branch 24 on the side away from the first branch 2d. Therefore, oscillations entering the third branch 24 have topass the first branch 2% before reaching the second branch 22. Likewise, oscillations entering the second branch 22 have to pass the first branch 24 before reaching' the third branch 24. Thus by properlychoosing the a length ofthe ridge and byproperly adjusting. the location of the ridge, most of the oscillations coming in the secnd branch 22'may'be caused to pass out the-first branch while only a small percent pass out the-third branch 24.

In accordance with another embodiment of our invention the ridge member 16 may be tapered at the end thereof soas to form a tapered transition between the region capable of. supporting oscillations and the region which is beyond cutoff.

Although we have shown and described specific embodiments of our invention, we are aware that other modifications-thereof are possible. Our invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and the spirit of the invention.

We claim as, our invention:

1. A microwave switch for a given frequency, comprising. an inner cylindrical conductor and an outer cylindrical conductor, said inner cylindrical conductor having' a diameter substantially less than the inside diameter of outer cylindrical conduct-or, said inner conductor being adapted to be" inserted inside said outer conductor so as to form a toroidal cavity between said inner and said outer conductors, a bottom plate filling the region between saidinner and said outer'oonductors at one end of said toroidal cavity and a top plate filling the region between said inner and said outer conductors at the opposite end of said toroidal cavity from said bottom plate, said bottom plate including a re-entrant portion which extends into said cavity so as to form, in conjunction with the walls of said cavity, a ridged waveguide over a first part only of the length around the said cavity, said ridged waveguide having a cutoff frequency below said given frequency, a second part of the length around said cavity comprising a non-ridged waveguide, whereby electromagnetic oscillations below said cutoff frequency. of said ridged waveguide are substantailly prevented from being transmitted through said non-ridged waveguide, a plurality of connections for coupling conductors for electromagnetic oscillations to said cavity, said first part of the length being at least as great as the minimum part of said length around said cavity which separates two of said coupling conductors.

2. Apparatus as described in claim 1, characterized in that the location of said re-entrant portion is adjustable with respect to the position of said connections.

3. A microwave switch for a given frequency, comprising a toroidal chamber of substantially rectangular cross section having wallsof electrically conducting material, a re-entrant portion extending into said chamber so as to form, in conjunction with the walls ofsaid chamber, a ridged Waveguide over afirst part of the length of said chamber, said ridgedwaveguide having a cutoff frequency below said given frequency, said reentrant portion being discontinuous over a second part of the length around said toroidal chamber so asto form a non-ridged waveguide, whereby electromagnetic o'scillations below said cutofi frequency of said ridged waveguide are substantially prevented from being transmitted through said non-ridged waveguide and a plurality of hollow wave-guides for conveying electromagnetic oscilla tions to said chamber.

4. Apparatus as described in claim 3', characterized in that the location of said re-entrant portion is variable around the length of said cavity with respect to the points where said connections are coupled to said wave-guide.

5. A microwave switch for a given frequency, comprising a rectangular waveguide extending in a circular direction, said waveguide having a top; a bottom and two sides, one of said sides being on the inside of the curve of said waveguide and one of said sides being on the outside of the curve of said waveguide, a re-entrant portion extending into said rectangular waveguide over a first portion of its length so as to form, in' conjunction with the walls of said rectangular waveguide over a portion of its length, a ridged waveguide, said ridged waveguide having a cutoff frequency below said given frequency, said re-entrant portion being discontinuous over a second part of the length of said waveguide so as to form a non-ridged waveguide, whereby electromagnetic oscillations below said cutoff frequency of said ridged waveguide are substantially prevented from being transmitted through said non-ridged waveguide and a plurality of conductors for electromagnetic oscillations coupled to said wave-guide.

6. Apparatus as claimed in claim 5, characterized in that the location of said re-entrant portion is adjustable with respect to the points where said conductors are coupled to said waveguide.

7. Apparatus as described in claim 5, chara'ctriied in that said plurality of conductors comprise'a first conductor connected to said wave-guide at onejp'oint al'on'g' its length, a second conductor connected tosaid' wave guide at a point 180 geometrical degrees from said first conductor and a third conductor located. at a, point geometrical degrees from said first conductor and said second conductor;

8. In combination, a hollow chamber having Walls of electrically conducting material; said chamberextending in a circle so as to forms closed loop and having a' substantially rectangular cross section, a circular projection of rectangular cross section extending through a wall of said chamber, said projection being of electrically conducting material, a first conductor for electromagnetic oscillations connected at a first point along the length of said chamber, a second conductor for electromagnetic oscillations connected to said chamber at a second point along the length of said chamber, said projection extending around the length of said chamber a distance less than the distance around said circle but extending a distance greater than the distance between the point where said first conductor is connected to said chamber and the point where said second conductor is connected to said chamber, said projection being adjustable around the length of said chamber so that a portion of said projection is in the region of said first conductor or alternatively that none of said projection is in the region of said first conductor.

9. in combination, an outer cylinder of electrically conducting material, an inner cylinder of electrically conducting material, said inner cylinder being located inside said outer cylinder and said inner cylinder having a diameter substantially less than the diameter of said outer cylinder so that said inner cylinder and said outer cylinder form walls of a hollow cylindrical chamber located th re'oetween, a top plate filling the region between said inner cylinder and said outer cylinder at one end of said cylinders, a bottom plate filling the region between said inner cylinder and said outer cylinder at the other end of said cylinder so as to form, in conjunction with said inner cylinder, said outer cylinder and said top plate, a cavity of rectangular cross section and extending in a closed loop, a first conductor for electromagnetic oscillations connected to said cavity at a first point, a

ond conductor connected to said cavity at a second point around the length of said cavity and a third conductor connected to said cavity at a third point around the length of said cavity, the distance between said first conductor and said second conductor being equal to the distance between said first conductor and said third conductor, a ridged member extending into said cavity so as to form, in conjunction with the walls of said cavity a ridged waveguide over part of the length of said cavity, said ridged member extending from the region of said second conductor past said first conductor to the region of said third conductor, said ridged member being discontinuous over a portion of the distance between said second conductor and said third conductor over the closest path between said first conductor and said third conductor.

References Cited in the file of this patent UNITED STATES PATENTS 2,412,159 Leeds Dec. 3, 1946 2,423,396 Linder July 1, 1947 2,514,957 Larson July 11, 1950 2,520,220 Nergaard Aug. 29, 1950 2,567,748 White Sept. 11, 1951 2,573,713 Kannenberg Nov. 6, 1951 2,615,958 Phillips Oct. 28, 1952 2,639,325 Lewis May 19, 1953 OTHER REFERENCES Tunable Waveguide Filters, by Sichol: et al., Proceedings of the I. R. E., vol. 39, issue 9, pages 1055-1059, pub. September 1951.