GB1588228A

GB1588228A - Waveguide switches

Info

Publication number: GB1588228A
Application number: GB3649676A
Authority: GB
Original assignee: Decca Ltd
Current assignee: Decca Ltd
Priority date: 1977-08-26
Filing date: 1977-08-26
Publication date: 1981-04-15

Description

(54) IMPROVEMENTS IN OR RELATING TO WAVEGUIDE SWITCHES (71) We, DECCA LIMITED, a British Company, of Decca House, 9 Albert Embankment, London, SE1 7SW, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to multiport waveguide switches.

According to the invention there is provided a multiport waveguide switch comprising a stator in which is formed a plurality of outlet ports which face inwardly of the stator toward, and are circumferentially spaced around an axis, a rotor arm, disposed to project radially from said axis, the arm constituting a section of waveguide and being connected by a rotary waveguide joint to an input port of the switch for rotation about said axis relative to the stator, and means for rotating said rotor arm about said axis accurately to align a radially outwardly facing outlet aperture of the rotor arm with any one of the outlet ports selectively, thereby to permit the transmission of electromagnetic power between the input port and the selected output port through said waveguide section.

The rotary joint may be of the type known as an in-line rotary joint in which input and output waveguide sections to the joint are axially aligned and relatively rotatable about their common axis. The output section may either connect with the radial rotor waveguide arm through a right-angle coupling or alternatively may include a right-angle bend, the portion on the side of the bend remote from the rotary joint forming the radial rotor arm. In this arrangement, the axis about which the radial arm rotates is coincident with the common axis of the input and output sections, or at least the portions thereof adjacent the rotary joint.

Alternatively, the rotary joint may be of the type known as a cross-coupled rotary joint in which input and output wave guide sections are axially non-aligned, and extend at right angles to their axis of relative rotation. In this arrangement the output section itself constitutes the radial waveguide arm.

With both in-line and cross-coupled rotary joints, the input waveguide section is preferably fixed relative to the stator.

The outer end of the radial arm is preferably formed with a flange having an outer face surrounding an outlet aperture lying on an imaginary cylinder whose axis lies on the said axis of rotation. This outer face is preferably formed with choke grooves (which may be of the configuration disclosed in our British Patent No. 9,021,28) to reduce the insertion loss of power between the outlet aperture and the selected output port.

The radial arm is preferably rotated about the said axis to align selectively with the output ports by means of a Geneva star pin wheel mechanism.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a part-sectional schematic side view illustrating a single pole multiway waveguide switch according to the invention; Figure 2 is a view similar to Figure 1, illustrating another single pole multiway waveguide switch according to the invention; Figure 3 is a part-sectional plan illustrating in further detail certain elements of the switch shown in Figure 1, and Figure 4A and 4B show the outer end of the radial rotor arm, in elevation and section on line A-A respectively.

With reference first to Figures 1 and 3, the switch 10 illustrated includes an input waveguide section 11 extending from a connecting flange 12, provided for coupling the switch to other waveguide elements, to a first part 13 of an in-line rotary waveguide joint 14. The switch includes a stator 15 which has a base 16 and projecting therefrom a peripheral wall 17. The inner surface 17a of the wall is cylindrical and has a central axis shown as X-X in Figure 1. A ring of outlet ports 18 is provided in the stator wall, all spaced axially from the base 16 by the same distance. In the embodiment illustrated, six such ports 18 are provided, and the outer surface of the wall 17 is hexagonal in cross-section, each port open ing at the centre of a side of the hexagon, as secn in Figure 3. The stator is also provided with coupling elements (not shown) for connecting further waveguide elements to the outlet ports 18 as required.

The first part 13 of the in-line rotary joint 14 is fixed relative to the base 16 of the stator, and a second part 19 is rotatable relative to the first part 13 about the axis X-X to alter the position of a radially extending waveguide rotor arm 20, and selectively to bring an aperture 21 at the outer end thereof into alignment with the outlet ports 18. The rotor arm is a section of rectangular waveguide arranged, in this Figure 1 embodiment with its longer cross-sectional dimension or "H plane" parallel to the axis X-X, and is joined, by way of a right angle bend 22 to the second part 19 of the rotary joint. A right-angle waveguide coupling element could be employed in place of the bend 22.

As best seen in Figures 4A and 4B the outer end of the rotor arm 2C is provided with a flange 23 surrounding the aperture 21. The outer surface of the flange lies on an imaginary cylinder coaxial with the inner surface 17a of the stator wall 17 and spaced radially therefrom by a small gap 24 to permit free rotation of the rotor arm without sliding contact between the flange 23 and the stator wall 17.

In order to inhibit the leakage of microwave energy through the gap 24, otherwise known as insertion loss, the outer flange surface is formed with choke grooves 25 in known manner, for instance as disclosed in our British Patent No. 9,021,28. Figure 4A illustrates a preferred configuration of choke grooves, this configuration comprising a continuous rectangular peripheral groove 26, two grooves 27 parallel to and spaced from the longer sides of the rectangular aperture 21, and two grooves 28 parallel to and aligned with the shorter sides of the aperture 21, the whole configuration being symmetrical about the aperture.

The rotor is driven and accurately indexed by means of a Geneva drive mechanism 29 including a motor 30 whose output shaft carries a pin wheel 31 arranged to co-operate with a Geneva star 32 mounted on axis X-X and coupled to rotate the rotor arm therewith.

The Geneva drive provides the necessary accuracy in positioning the rotor arm, and can impart to this arm the high acceleration necessary for rapid switching between successive selected outlet ports 18.

Figure 2 illustrates the use of a crosscoupled rotary joint 33 in which the input waveguide section 11 and the waveguide rotor arm 20 are axially non-aligned and extend at right angles to their axis X-X of relative rotation with their shorter cross-sectional dimension, or "E plane" parallel to this axis X-X. The first part 13 of the rotary joint 33 is again fixed relative to the stator base 16, and a Geneva drive mechanism 29 is employed to rotate the rotor arm.

The choice of rotary joint between the in-line type of Figure 1 and the cross-coupled type of Figure 2 depends largely upon the particular application of the switch, on the power used, the bandwidth required, and which provides the most suitable waveguide configuration.

The switches described herein can achieve the selective coupling of an input waveguide port to a number, for instance six, or eight of output waveguide ports, while employing only a single moving element, the rotor arm.

WHAT WE CLAIM IS: 1. A multiport waveguide switch comprising a stator in which is formed a plurality of outlet ports which face inwardly of the stator toward, and are circumferentially spaced around an axis, a rotor arm, disposed to pro ject radially from said axis, the arm constituting a section of waveguide and being connected by a rotary waveguide joint to an input port of the switch for rotation about said axis relative to the stator, and means for rotating said rotor arm about said axis accurately to align a radially outwardly facing outlet aperture of the rotor arm with any one of the outlet ports selectively, thereby to permit the transmission of electromagnetic power between the input port and the selected output port through said waveguide section.

2. A waveguide switch according to claim 1 wherein the rotary joint is in an in-line rotary joint in which input and output waveguide sections to the joint are axially aligned and relatively rotatable about their common axis.

3. A waveguide switch according to claim 2 when dependent on claim 2 wherein the output section connects with the rotor arm through a right-angle coupling.

4. A waveguide switch according to claim 3 wherein the output section includes a rightangle bend, the portion on the side of the bend remote from the rotary joint forming the rotor arm.

5. A waveguide switch according to claim 1 wherein the rotary joint is a cross-coupled rotary joint in which input and output waveguide sections are axially non-aligned, and extend at right angles to their axis of relative rotation.

6. A waveguide switch according to claim 5 wherein the output section constitutes the said arm.

7. A waveguide switch according to any of claims 2 to 6 wherein the input waveguide section is fixed relative to the stator.

8. A waveguide switch according to any preceding claim wherein the outer end of the rotor arm is formed with a flange having an outer face surrounding said outlet aperture

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ing at the centre of a side of the hexagon, as secn in Figure 3. The stator is also provided with coupling elements (not shown) for connecting further waveguide elements to the outlet ports 18 as required. The first part 13 of the in-line rotary joint 14 is fixed relative to the base 16 of the stator, and a second part 19 is rotatable relative to the first part 13 about the axis X-X to alter the position of a radially extending waveguide rotor arm 20, and selectively to bring an aperture 21 at the outer end thereof into alignment with the outlet ports 18. The rotor arm is a section of rectangular waveguide arranged, in this Figure 1 embodiment with its longer cross-sectional dimension or "H plane" parallel to the axis X-X, and is joined, by way of a right angle bend 22 to the second part 19 of the rotary joint. A right-angle waveguide coupling element could be employed in place of the bend 22. As best seen in Figures 4A and 4B the outer end of the rotor arm 2C is provided with a flange 23 surrounding the aperture 21. The outer surface of the flange lies on an imaginary cylinder coaxial with the inner surface 17a of the stator wall 17 and spaced radially therefrom by a small gap 24 to permit free rotation of the rotor arm without sliding contact between the flange 23 and the stator wall 17. In order to inhibit the leakage of microwave energy through the gap 24, otherwise known as insertion loss, the outer flange surface is formed with choke grooves 25 in known manner, for instance as disclosed in our British Patent No. 9,021,28. Figure 4A illustrates a preferred configuration of choke grooves, this configuration comprising a continuous rectangular peripheral groove 26, two grooves 27 parallel to and spaced from the longer sides of the rectangular aperture 21, and two grooves 28 parallel to and aligned with the shorter sides of the aperture 21, the whole configuration being symmetrical about the aperture. The rotor is driven and accurately indexed by means of a Geneva drive mechanism 29 including a motor 30 whose output shaft carries a pin wheel 31 arranged to co-operate with a Geneva star 32 mounted on axis X-X and coupled to rotate the rotor arm therewith. The Geneva drive provides the necessary accuracy in positioning the rotor arm, and can impart to this arm the high acceleration necessary for rapid switching between successive selected outlet ports 18. Figure 2 illustrates the use of a crosscoupled rotary joint 33 in which the input waveguide section 11 and the waveguide rotor arm 20 are axially non-aligned and extend at right angles to their axis X-X of relative rotation with their shorter cross-sectional dimension, or "E plane" parallel to this axis X-X. The first part 13 of the rotary joint 33 is again fixed relative to the stator base 16, and a Geneva drive mechanism 29 is employed to rotate the rotor arm. The choice of rotary joint between the in-line type of Figure 1 and the cross-coupled type of Figure 2 depends largely upon the particular application of the switch, on the power used, the bandwidth required, and which provides the most suitable waveguide configuration. The switches described herein can achieve the selective coupling of an input waveguide port to a number, for instance six, or eight of output waveguide ports, while employing only a single moving element, the rotor arm. WHAT WE CLAIM IS:

1. A multiport waveguide switch comprising a stator in which is formed a plurality of outlet ports which face inwardly of the stator toward, and are circumferentially spaced around an axis, a rotor arm, disposed to pro ject radially from said axis, the arm constituting a section of waveguide and being connected by a rotary waveguide joint to an input port of the switch for rotation about said axis relative to the stator, and means for rotating said rotor arm about said axis accurately to align a radially outwardly facing outlet aperture of the rotor arm with any one of the outlet ports selectively, thereby to permit the transmission of electromagnetic power between the input port and the selected output port through said waveguide section.

lying on an imaginary cylinder whose axis lies on the axis of rotation of said rotor arm.

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9. A waveguide which according to claim 8 wherein the outer face is formed with choke grooves to reduce the insertion loss of power between the outlet aperture and the selected output port.

10. A waveguide switch according to any preceding claim wherein said means for rotating the rotor arm comprise a Geneva start pin wheel mechanism.

11. A multiport waveguide switch substantially as hereinbefore described with reference to and as shown in Figures 1, 3 and 4 or Figures 2, 3 and 4 of the accompanying drawings.