GB2208972A - Waveguide switching apparatus - Google Patents

Abstract

Waveguide switching apparatus includes a rotor 56 housed in a stator and having a plurality of waveguide passages 57, 58, 59 and 60 therein. The curved passages 57 and 58 are arranged such that the tangents to their centre lines 65 and 66 at their ports are non-radial, and do not intersect at the centre of the rotor 56. This has the advantage that a larger proportion of the rotor area is available for accommodation of cross-under passage 59. The rotor 56 may thus have a smaller diameter than would a conventional rotor, reducing inertia and improving switching accuracy. <IMAGE>

Description

Waveguide Switching Apparatus This invention relates to waveguide switching apparatus, and more particularly to switching apparatus used in high power microwave energy arrangements.

A simple known waveguide switch, which may be termed an "S" switch, is illustrated in Figure 1, which is a transverse section through the stator and rotor of a switch and Figure 2 which is a longitudinal section through the rotor and bearings. The switch comprises the rotor 1, which is generally cylindrical in form, and which is arranged to rotate on bearings 2 in the stator 3. Four waveguide channels 4, 5, 6 and 7 are located within the stator 3 and provide passages along which microwave energy may be transmitted. Each of the waveguide channels 4, 5, 6 and 7 terminates at a port A, B, C and D respectively, which is arranged adjacent to the rotor 1, the ports A, B, C, D lying in the same plane and being arranged at 900 intervals around the rotor 1.The rotor 1 includes two curved passages 8 and 9 located within it which are arranged such that their openings at the rotor surface are spaced at 900 intervals. In the orientation shown in Figure 1, no interconnections are made between the ports A, B, C and D in the stator 3. However, if the rotor 1 is rotated through 450 in a clockwise direction, ports A and B, and ports C and D become interconnected. If the rotor 1 were to be rotated anti-clockwise through 450 from the illustrated position, then ports A and D would be interconnected, and ports B and C interconnected.Thus, for example, energy transmitted along waveguide channel 4 may be switched into channel 5 or channel 7 depending on the orientation of the rotor 1 An arrangement in which "S" switches are used is illustrated in Figure 3, which is a schematic diagram of an amplifying stage employed in a satellite. The arrangement comprises five amplifiers 10, 11, 12, 13 and 14, which are arranged to amplify high power microwave signals applied to them on input lines 15, 16, 17, 18 and 19. Two spare amplifiers, 20 and 21, are also included in the arrangement. A plurality of "S" switches 22 are included and are arranged so that, if one of the amplifiers 10 to 14 fails, one of the spare amplifiers 20 and 21 may be switched into the circuit in its place.As can be seen, a large number of "S" switches, in this case twenty, are required to ensure that a failure in any two of the five amplifiers 10 to 14 can be compensated for by switching in the spare amplifiers 20 and 21. Failure of any two amplifiers in this configuration will require the operation of four switches to switch in the two spare amplifiers. For example, if a failure were to occur in amplifier 12, then switches 23 and 24 must be rotated through 900 to switch the applied signal on line 17 through the spare amplifier 20. If another failure occurs, for example, if the amplifier 13 were to fail, then the rotors of switches 25 and 26 must be rotated through 900 to switch the signal on line 18 to the spare amplifier 21.

Another type of waveguide switch, which may be termed an "R" switch, is illustrated in Figure 4, which is a transverse section through the stator and rotor of such a switch, and Figure 5, which is a longitudinal section through the rotor and bearings. The "R" switch is similar to the "S" switch described with reference to Figures 1 and 2, in that it includes two curved passages 27 and 28 within the rotor 29. In addition, the rotor 29 also includes a further passage 30, which is straight and is arranged between the curved passages 27 and 28, along a diameter of the rotor 29. This configuration permits a larger variety of interconnections to be made between four waveguide channels 31, 32, 33 and 34 located within the stator 35, and having ports A, B, C and D respectively, than is possible with an "S" type switch.In the position illustrated in Figure 4, ports B and D only are interconnected. If the rotor 29 is rotated through 450 clockwise from the position shown, then ports A and B are interconnected, and ports C and D interconnected, by the curved passages 27 and 28 respectively. Similarly, ports B and C may be connected, and ports A and D, if the rotor is rotated through 450 anti-clockwise from the illustrated position. Therefore, in a particular arrangement, fewer switches may need to be included if they are "R" type switches rather than "S" type switches. However, although an arrangement using "R" switches may include fewer switches, a greater number of switching operations tend to be necessary if failure occurs.The essential reliability of the switches depends on the number of switching operations which are required to effect a desired path change and it is desirable, therefore, especially in applications where failure cannot easily be rectified, that a minimum number of switching operations are employed.

Another waveguide switch, which may be termed a "T" switch, is illustrated in Figures 6 and 7, which are transverse and longitudinal sections respectively through the rotor 36 of such a switch. The "T" switch is similar to the "R" switch, in that it includes two curved passages 37 and 38 through the rotor and a straight passage 39 across a diameter of the rotor. In addition, another passage is also included to provide a connection orthogonal to that provided by the straight passage 39. The additional passage is a cross-under passage 40 which has ports in the same plane as the other passages in the rotor 36, but which passes underneath them, as shown in Figure 7. This type of switch-enables a greater variety of interconnections to be made than does either an "S" or an "R" switch.Thus, where "T" switches are included, in an amplifying section for example similar to that shown in Figure 3, the same number of switches are required as would be necessary if "R" switches were to be used and the number of switching operations necessary to include spare amplifiers in the circuit is the same as in an arrangement which uses "S" type switches. However, a "T" type switch is much larger than either an "S" or "R" type switch having similar sized channels, and requires a thicker rotor of larger diameter to accomodate the four passages. This increases the inertia of the rotor considerably, which has the disadvantage that switching accuracy may be reduced and greater torque is required for the switch to be operated. Also heating effects associated with the "T" switch dictate that a large spacing be left between the rotor and stator to allow for expansion.This may result in an unacceptable degree of leakage where the waveguide channels feed into the passages in the rotor.

This invention seeks to provide improved waveguide switching apparatus.

According to a first aspect of the invention, there is provided waveguide switching apparatus comprising a rotor and a stator arranged to undergo relative rotation, there being a waveguide passage in the rotor, the passage having a transverse dimension which is nonconstant along its length in a plane transverse to the axis of rotation of the rotor.

It is preferred that the transverse dimension of the passage is larger at its ports at the surface of the rotor than mid-way between them. This is particularly advantagecus in a switch in which it is desired to have a central through passage along a diameter of a rotor and curved passages on either side, for example, as in an "R" or "T" type switch, a curved waveguide passage being curved in the plane in which the transverse dimension is non-constant. By employing the invention, the overall diameter of the rotor may be reduced compared to that which would otherwise be necessary and hence inertia is reduced and switching accuracy of the switch may be improved. Advantageously, the curved passage is arranged such that tangents to its centreline at its ports extend non-radially, whereby it encompasses a larger area of the rotor than if said tangents were to extend radially, and preferably the curved waveguide passage is part of a circle.

Advantageously, the transverse dimension varies in steps. A second waveguide passage may be included and arranged orthogonal to the first-mentioned passage.

According to a second aspect of the invention, there is provided waveguide switching apparatus comprising a rotor arranged to rotate relative to a stator, there being included in the rotor a curved waveguide passage arranged such that tangents to its centre-line at its ports extend non-radially, whereby it encompasses a larger area of the rotor than if said tangents were to extend radially. Preferably the curved passage is part of a circle. Thus, instead of the tangents intersecting at the axis of rotation, as is conventional, they intersect beyond it.

Where such a curved passage is included, it enables a rotor of a "T" switch, for example, to have a smaller diameter than that of a conventional rotor whilst still enabling a passage to be accommodated in the area of the rotor which it encompasses.

Preferably, there are included first and second channels in the stator having respective ports at a boundary between the rotor and stator members, the arrangement and construction of the two members being such that, when in a particular position relative to one another, they define a passage between the ports which connects the channels and which is located partly in the rotor and partly in the stator member. Thus the moment of inertia may be further reduced, since one of the members which defines part of the passage is not required to rotate. Also, as the rotor may be smaller than would be possible for a previously known rotor in which the whole of a similar size passage between ports is located within it, expansion due to heating effects is correspondingly reduced and thus the spacing between the rotor and stator may be smaller.Apparatus in accordance with the invention is particularly advantageous in switching apparatus in which one passage is arranged to cross under another channel, such as in a "T" type switch for example. Although, most advantageously, the first rotor is generally cylindrical, it could be some other convenient configuration.

According to a feature of the invention, a microwave amplifying arrangement includes waveguide switching apparatus in accordance with the invention, this being particularly suitable in satellite applications, for example.

The invention is now further described by way of example with reference to Figures 8 to 10 of the accompanying drawings, in which: Figures 8 and 9 are schematic transverse sections of respective switching apparatus in accordance with the invention; Figures 10 and 11 are schematic longitudinal and transverse sections of another switching apparatus in accordance with the invention; Figure 12 is a transverse section of part of a further switching apparatus in accordance with the invention; Figure 13 is an explanatory diagram relating to Figure 12; and Figure 14 is a switching arrangement in accordance with the invention.

With reference to Figure 8, in an embodiment of the invention, a waveguide switch includes a rotor 41 having two curved passages 42 and 43 therethrough, a cross-under passage 44, and a straight passage 45 located along a diameter of the rotor 41. The straight passage 45 has a transverse dimension in a plane normal to the axis of rotation of the rotor 41, which is greater at its ports than at its centre to give a curved, "waisted" configuration. This enables the two curved passages 42 and 43 to be located closer to one another than would be possible with a conventional straight-sided passage, and thus the diameter of the rotor 41 is reduced compared to a conventional "T" type rotor. By altering the transverse dimension of the passage 45 along its length, the losses in it may also be modified such that they are made substantially equal to those of the curved passages 42 and 43.Thus, any position of the rotor 41 with respect to the stator tends to result in similar power losses in the device, enabling the design of the circuitry to be optimized.

Which reference to Figure 9, a switch includes a rotor which is similar in configuration to that shown in Figure 8 but has, along the diameter of the rotor, a straight passage 46 which has stepped sides. This enables good matching to be achieved.

With reference to Figures 10 and 11, in another embodiment of the invention a "T" type waveguide switch includes a rotor 47 arranged to rotate in bearings 48 relative to a stator 49. The rotor 47 includes two curved passages 50 and 51 to provide connections to waveguide channels in the stator 49, the ports of which are spaced apart by a 900 interval, and a first straight passage 52 across the diameter of the rotor 47. These three passages are contained entirely within the rotor 47 and the straight passage 52 is stepped to give a nonuniform dimension in a plane normal to the axis of rotation of the rotor 47. A second passage 53 also provides a straight path which is in a direction normal to that provided by the first-mentioned straight passage 52.However, in this case the passage 53 is a crossunder passage and is arranged to pass beneath the other three passages 50, 51 and 52. The passage 53 is not contained entirely within the rotor 47 but includes a portion 53a within the rotor 47 and another portion, 53b, located in the stator 49, the passage 53 being defined by the rotor 47 and stator 49 when they are in a particular position relative to one another. Thus, in the position illustrated, the cross-under passage 53 connects waveguide channels 54 and 55 in the stator 49.

As the rotor 47 rotates from the position illustrated, the ports of the cross-under passage 53 go out of alignment with channels 54 and 55 and the portion 53a becomes misaligned with the portion 53b in the stator.

Since only part 53a of the passage 53 is included in the rotor 47, this enables the moment of inertia to be greatly reduced over what would be required for a conventional "T" type switch having similar passage dimensions. This reduction in size also enables the clearance required between the rotor 47 and the stator 49 to be reduced, since expansion due to heating effects is also less.

With reference to Figure 12, switching apparatus in accordance with the invention includes a rotor 56 for a "T" type switch having a plurality of passages therein, two part-circular curved passages 57 and 58, a crossunder passage 59 and a stepped passage 60, the transverse dimension of which is smaller at its midpoint than at its ports, arranged along a diameter of the rotor 56. In the rotor 61 of a conventional "T" type switch, as illustrated in Figure 13, a curved passage is arranged such that the tangents to its centre-line 62 at its ports 63 and 64 intersect at the centre C of the rotor 58. In the embodiment of the invention shown in Figure 12, tangents to the centre lines 65 and 66 of the passages 57 and 58 respectively at their ports intersect beyond the centre C of the axis of rotation.This has the advantage that a larger proportion of the rotor area is available for accomodation of the cross-under passage 59, enabling the diameter of the rotor 56 to be reduced compared to that of a conventional rotor. There is some discontinuity between the waveguide channels in the stator portion where they connect with the curved passages 57 and 58 in the rotor 56. However, this is compensated for by the extra length of the curved passages 57 and 58.

Figure 14 illustrates a microwave amplifying arrangement for use in a satellite which includes five main amplifiers 67, 68, 69, 70 and 71, two spare amplifiers 72 and 73 and ten "T" switches 74 in accordance with the invention, each of the switches 74 including a passage arranged along a diameter of the rotor having a transverse dimension which is non-uniform along its length.

If a failure occurs in one of the main amplifiers 67 to 71 only two switching operations are required to switch a spare amplifier into the circuit to replace it.

If a further failure then occurs a maximum of four switching operations are required to include the other spare amplifier.

Claims (8)

1. Waveguide switching apparatus comprising a rotor and a stator arranged to undergo relative rotation, there being a waveguide passage in the rotor, the passage having a transverse dimension which is nonconstant along its length in a plane transverse to the axis of rotation of the rotor.

2. Apparatus as claimed in claim 1 and wherein the transverse dimension of the passage is larger at its ports at the surface of the rotor than mid-way between them.

3. Apparatus as claimed in claim 1 or a and wherein the transverse dimension varies in steps.

4. Apparatus as claimed in claim 1, 2 or 3 and including a second passage in the rotor arranged orthogonal to the first-mentioned passage.

5. Apparatus as claimed in any preceding claim and including a waveguide passage in the rotor which is curved in the plane in which the transverse dimension is non-constant.

6. Apparatus as claimed in claim 5 and wherein the curved passage is arranged such that tangents to its centre-line at its ports extend non-radially, whereby it encompasses a larger area of the rotor than if said tangents were to extend radially.

7. Apparatus as claimed in claim 5 or 6 and wherein the curved waveguide passage is part of a circle.

8. Apparatus substantially as illustrated in and described with reference to Figures 8 and 10 of the accompanying drawings.

8. Waveguide switching apparatus comprising a rotor arranged to rotate relative to a stator, there being included in the rotor a curved waveguide passage arranged such that tangents to its centre-line at its ports extend non-radially, whereby it encompasses a larger area of the rotor than if said tangents were to extend radially.

9. Apparatus as claimed in claim 8 and wherein the curved passage is part of å circle.

10. Apparatus as claimed in claim 8 or 9 and including a second waveguide passage, part of whizz is included in the area encompassed by said curved waveguide passage.

11. Apparatus as claimed in any preceding claim, including first and second channels in the stator having respective ports at a boundary between the rotor and the stator, the arrangement and construction of the rotor and stator being such that, when in a particular position relative to one another, they define a passage between the ports which connects the channels and which is located partly in the rotor and partly in the stator.

12. Apparatus as claimed in claim 11 and including a passage located entirely within the rotor and discrete from, and in a crossing relationship with, the passage located partly in the rotor and partly in the stator.

14. Apparatus as claimed in claim 13 and wherein the four channels have respective ports at the boundary spaced equidistant around the boundary.

15. A microwave amplifying arrangement including waveguide switching apparatus as claimed in any preceding claim.

16. Apparatus substantially as illustrated in and described with reference to Figures 8 to 12, and Figure 14 of the accompanying drawings.

Amendments to the claims have been filed as follows

1. Waveguide switching apparatus comprising a rotor arranged to rotate relative to a stator, there being included in the rotor a curved waveguide passage arranged such that tangents to its centre-line at its ports extend non-radially, whereby it encompasses a larger area of the rotor than if said tangents were to extend radially.

2. Apparatus as claimed in claim 1 and wherein the curved passage is part of a circle.

3. Apparatus as claimed in claim 1 or 2 and including a second waveguide passage, part of which is included in the area encompassed by said curved waveguide passage.

4. Apparatus as claimed in claim 3 and including a third waveguide passage in the rotor arranged orthogonal to the second passage.

5. Apparatus as claimed in any preceding claim and wherein four channels are included in the stator, and the stator and rotor are constructed and arranged such that connection may be made via passages at least partly located within the rotor between any two of the four channels.

6. Apparatus as claimed in claim 5 and wherein the four channels have respective ports at the boundary spaced equidistant around the boundary.

7. A microwave amplifying arrangment including waveguide switching apparatus as claimed in any preceding claim.