WO2003026061A1

WO2003026061A1 - Electromagnetic control devices

Info

Publication number: WO2003026061A1
Application number: PCT/GB2002/004173
Authority: WO
Inventors: Tasman Simkins; Joe Pollock; Barry George Morton Helme
Original assignee: Quasar Microwave Technology Limited
Priority date: 2001-09-14
Filing date: 2002-09-12
Publication date: 2003-03-27
Also published as: GB0122172D0; EP1425816A1; ATE518274T1; EP1425816B1

Abstract

A hollow metal component for use in a waveguide system includes pre-assembled electromagnetic control devices (14, 15) (circulators or isolators) which are mounted in apertures in the component. The control devices include a plate (20) having an external magnetic element (24) coupled to ferrite core (29) mounted in the waveguide cavity. The core is carried on a multi-faceted metal matching element (28) with dielectric tuning elements (30). A plurality of mutually spaced adjusters (33) are also inserted through the plate for fine tuning in-situ.

Description

ELECTROMAGNETIC CONTROL DEVICES

TECHNICAL FIELD OF THE INVENTION

This invention relates to electromagnetic control devices of the kind which are used as isolators and circulators in waveguide systems.

BACKGROUND

In an electromagnetic waveguide system which interconnects a number of ports a magnetic control device may be used to determine the path which signals are permitted to take between the ports. In some cases the control device may be arranged to isolate a particular port with respect to signals travelling in a certain direction, and the device is therefore called an isolator. In another example the device may be arranged to permit signals to pass between adjacent ports, such a device being commonly referred to as a circulator.

In such equipment it is necessary to accurately set up the control device during manufacture and prior to use to ensure that it operates to the required specification. Adjustments are often made in situ, which requires the attendance on site of skilled personnel and often entails a considerable delay before the equipment is finally approved and put into operation. Furthermore, if it is found that the equipment does not meet the required performance standard it must be removed and replaced, repeating the whole adjustment process again.

The present invention seeks to provide a new and inventive arrangement which simplifies and speeds up the manufacture, fitting and maintenance of such installations.

SUMMARY OF THE INVENTION

The present invention proposes that in a component having a hollow metal structure which provides an electromagnetic waveguide arrangement connecting two or more ports, with a magnetic control device for determining the path which signals may take between the ports, the control device is provided in the form of a pre-assembled unit which is mounted in an aperture in the component.

The units which incorporate the control device can thus be accurately assembled, pre-adjusted and tested prior to use. Any units which do not meet the required specification can be identified and readjusted at an early stage. Since a standard pre-assembled unit with a known performance can be fitted to any component manufacturing costs are reduced. In addition, it is possible to incorporate a control device of known properties directly into any desired component, thereby simplifying the installation and reducing costs. The adjustments which may be required in situ are reduced or even eliminated. In a preferred form of the invention the pre-assembled unit has a plate and a magnetic element. The magnetic element is preferably mounted in a central region of the plate. The plate may form part of the waveguide wall, with an internal surface exposed to the internal cavity of the waveguide and an opposite external surface. The internal surface may have a multi-faceted metal matching element which projects into the cavity of the waveguide. The matching element may carry a ferrite core which is magnetically coupled to the magnetic element. A plurality of dielectric adjustment elements may be mounted about the ferrite core.

Fine adjustments may be made in situ by means of a plurality of mutually spaced adjusters which are inserted through the plate to project from the inner surface by a variable distance. The adjusters may be arranged in rows extending along the various limbs of the waveguide.

The control device can be accurately set up and tested prior to use by placing the unit into a suitable test jig.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:

Figure 1 is a general view of a diplexer component incorporating a pair of electromagnetic control units in accordance with the invention; Figures 2 and 3 are inner and outer views of one of the control units prior to installation in the diplexer;

Figure 4 is a general view of the control unit which is mounted in a test jig for adjustment purposes; and

Figures 5 and 6 are an inner views of two forms of dummy control unit which may be used in testing the diplexer.

DETAILED DESCRIPTION OF THE DRAWINGS

Fig. 1 shows, way of example, a typical component in the form of a diplexer which is used with a pair of isolators. Normally, the isolators would be provided as separate items connected to the relevant ports. In the drawing the diplexer has a T-shaped metal body 10 containing an arrangement of waveguide cavities which interconnect with three ports 11 , 12 and 13. The path of the internal waveguide is indicated by the dashed line W, but the internal configuration of the diplexer will not be described in detail, being well known in the art. The two isolator units 14 and 15 are secured to the body by screws 16, covering apertures in the waveguide wall.

As shown in Flg.s 2 and 3, each of the isolator units includes a substantially rectangular metal plate 20 having an inner face 21 and an opposite outer face 22. The outer face contains a T-shaped channel 23 containing a discshaped isolator magnet 24 which is mounted in a correspondingly-shaped recess in the central region of the plate. The inner surface of the plate is surrounded by a continuous peripheral step 25 to ensure a good electromagnetic seal, accurate registration within the aperture being achieved by dowels 31. A three-sided metal matching element 28 (for a three-port device) is mounted on the centre of the inner face 21 to project into the waveguide cavity. The size and height of this matching element determines the return loss of the three ports, which must be optimised for the required performance. The matching element 28 carries a cylindrical ferrite core 29 which is closely coupled to the magnet 24 through the plate 20 to create the necessary magnetic field in the ferrite core, the choice of the ferrite material and the associated magnet 24 being determined by the design operating frequency of the device. The diameter and height of the ferrite core 29 can be adjusted to improve the isolation value and tuning of the unit. Three dielectric matching blocks 30 may be mounted on the matching element 28. Each matching block may be mounted in the area between the ferrite core 29 and the corner of the matching element. These blocks are used to fine tune the isolation of the ports during manufacture of the isolation unit. In addition, the channel 23 contains aligned rows of tuning screws 33 which are inserted through the plate 20 to project for a variable distance from the inner face 21 into the cavity of the waveguide.

During manufacture, the isolator unit is mounted in a test jig 50, as shown in Fig. 4. As in the diplexer, the jig has a T-shaped waveguide 51 with two straight arms extending between ports 52 and 53 and a branch arm 54 which contains an electromagnetic terminator of known form. By feeding radio frequency energy through the straight section between the ports 52 and 53 and monitoring the reflected signal it is possible to adjust the dielectric matching blocks for optimum performance, as explained above.

When the isolator unit is mounted in the diplexer it will immediately perform to a high standard without requiring further adjustment. If desired however, further fine tuning adjustments can be made in situ using the screws 33, e.g. to correct for small manufacturing tolerances in the diplexer unit and differences between the electromagnetic terminators in the jig and the diplexer component.

Although a diplexer component with two isolator units has been described it should be apparent that the isolators can be used in various configurations. Furthermore, similar control units can be used as circulators in other applications.

An additional advantage of the invention is that the microwave, radio frequency, mechanical and environmental properties of the component (in this case a diplexer) can all be tested independently of the magnetic control unit. For this purpose a dummy control unit can be fitted, as shown in Fig. 5. The tuning screws, triangular matching element, ferrite core and dielectric matching blocks are replaced by a flange 40 which closes off the third arm of the waveguide in which (in the case of an isolator) the electromagnetic terminator is installed. Alternatively a matched load element can be placed in the main line prior to the waveguide T where the isolator will be. This would only test the component up to the isolator, but the other part of the component can be tested by placing the load element on the other side of the space where the isolator would be and testing from the second port. When the control unit is used as a circulator additional dummy units will be required as shown in Fig. 6, with angular walls 42 (left or right handed) which can be used to block off either of the two straight branches of the waveguide. It will be appreciated that the features disclosed herein may be present in any feasible combination. Whilst the above description lays emphasis on those areas which, in combination, are believed to be new, protection is claimed for any inventive combination of the features disclosed herein.

Claims

1. A component having a hollow metal structure which provides an electromagnetic waveguide arrangement connecting two or more ports (11 , 12 and 13), with a magnetic control device (14, 15) for determining the path which signals may take between the ports, characterised in thatt e control device is provided in the form of a pre-assembled unit which is mounted in an aperture in the component.

2. A component according to Claim 1 , in which the pre- assembled unit includes a multi-faceted metal matching element (28) which projects into the cavity of the waveguide.

3. A component according to Claim 2, in which the matching element carries a ferrite core (29) which is magnetically coupled to a magnetic element (24).

4. A component according to Claim 2, in which a plurality of dielectric adjustment elements (30) are mounted on the matching element about the ferrite core.

5. A component according to Claim 1, in which the pre- assembled unit includes a mounting plate (20).

6. A component according to Claim 5, in which the plate is part of the hollow metal structure and forms part of the waveguide wall with an inner surface (21) exposed to an internal cavity of the waveguide and an opposite external surface (22).

7. A component according to Claim 6, in which a magnetic element (24) is mounted on the external surface of the plate and a ferrite core (29) is mounted on the inner surface of the plate coupled to the magnetic element through the plate.

8. A component according to Claim 7, in which the ferrite core is mounted on a multi-faceted metal matching element (28).

9. A component according to Claim 5, in which a plurality of mutually spaced adjusters (33) are inserted through the plate to project from its inner surface by a variable distance.

10. A component according to Claim 9, in which the adjusters are arranged in rows extending along limbs of the waveguide.