EP0263242B1 - Microwave junction-circulator - Google Patents

Description

The present invention relates to a branching circulator for microwaves which has a waveguide branching zone penetrated by a static magnetic field, in which a ferromagnetic resonator is arranged which consists of different dielectrics, at least one of which has ferromagnetic properties.

Such a circulator, which is specially designed for very large high-frequency outputs, is known from the publications IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-26, No. 5, May 1978, pp. 364-369 and IEEE Transactions on Magnetics, Vol. MAG-17, No. 6, Nov. 1981 pp. 2957-2960. In the circulators described here, the ferrite structure consists of a plurality of ferrite disks, separated from one another by air gaps and arranged perpendicular to the static magnetic field, which are attached to metal carriers through which a cooling liquid flows.

The invention has for its object to provide a circulator of the type mentioned, which is particularly suitable for operation with very high radio frequency power.

This object is solved by the features of claim 1.

Appropriate embodiments of the invention emerge from the subclaims.

In the known high-performance circulators, the stratification of the ferromagnetic dielectric in the branching zone perpendicular to the static magnetic field has a very disadvantageous effect on the performance compatibility. In the usual H-level branching circulator, the E-field lines of the high-frequency field run parallel to the static magnetic field in the ferromagnetic resonator, so that the interfaces of the ferrite layers intersect the E-field vertically, which leads to very strong field strength increases in the air gaps between the ferrite layers . Increasing the air gaps by expanding the resonator height in order to counteract the increase in field strength is only conditionally possible, since otherwise the static magnetic field can no longer be applied with tolerable effort. The circulator according to the invention, on the other hand, has a resonator in its branching zone, the ferromagnetic dielectric of which extends over the entire height of the waveguide branching zone and the non-ferromagnetic dielectric which serves for heat dissipation is also extended over the full height of the branching zone. In this case, the static magnetic field and the high-frequency electrical field are oriented tangentially to the interfaces between the ferromagnetic and the non-ferromagnetic dielectrics. This avoids excessive field strengths in the ferromagnetic dielectric, so that the dielectric strength of the circulator becomes very high and it is therefore suitable for operation with extremely high powers.

The resonator structure designed according to the invention also enables large amounts of heat to be dissipated, which protects the ferromagnetic dielectric from thermal destruction. This applies especially to a finely structured one Configuration of the ferromagnetic dielectric, because then a particularly good heat transfer to the heat-dissipating dielectric is guaranteed. With the measures of the invention, branching circulators can advantageously be implemented both in waveguide technology and in L (Lecher) waveguide technology (for example stripline).

Figur 1

zeigt einen Querschnitt durch die mit einer Resonatorstruktur versehene Verzweigungszone eines Hohlleiterzirkulators,

Figur 2

zeigt einen Querschnitt durch die mit einer Resonatorstruktur versehene Verzweigungszone eines Zirkulators in Streifenleitungstechnik

Figur 3

zeigt eine weitere Resonatorstruktur.

The invention will now be explained in more detail with reference to exemplary embodiments shown in the drawings.

Figure 1

shows a cross section through the branching zone of a waveguide circulator provided with a resonator structure,

Figure 2

shows a cross section through the branching zone of a circulator provided with a resonator structure in stripline technology

Figure 3

shows another resonator structure.

The section of a waveguide circulator shown in FIG. 1 shows two mutually opposite waveguide walls 1 and 2 of the circulator branching zone, a resonator structure arranged therein and a magnet system which generates a static magnetic field passing through the branching zone.

The magnet system in the embodiment shown in Fig. 1 has two pole shoes 3 and 4 arranged above and below the waveguide branch, a permanent magnet 5 and a yoke 6 which forms the magnetic yoke outside the circulator branching zone and which is on the one hand on the pole shoe 3 and on the other hand on the permanent magnet 5 rests.

The resonator structure contains a ferromagnetic dielectric in the form of a plurality of ferrite rods 7, which are located between the two opposite waveguide walls 1, 2 extend parallel to the E-field of the circulator. In these ferrite rods 7, which run parallel to the E-field and extend from a waveguide wall to the opposite one without cross-sectional changes, the E-field is as large as in a non-ferromagnetic dielectric that immediately surrounds the ferrite rods. There is therefore no increase in field strength at any point in the ferrite rods, unlike in conventional resonator structures with air gaps running transversely to the E field.

The consequence of this is that a resonator structure designed according to the invention has an extremely high dielectric strength, which is why a circulator with such a resonator structure is suitable for the transmission of very high powers.

The division of the ferromagnetic dielectric into many individual rods 7 arranged at a distance from one another creates a large cooling surface, which provides extremely favorable conditions for dissipating the heat generated in the ferrite rods 7. With the aid of a coolant flowing around the ferrite rods 7, for example air or another suitable gas or a dielectric liquid, very large amounts of heat can be dissipated in a simple manner. For this purpose, all ferrite rods 7 are surrounded by a dielectric cylinder 8, which is inserted into the branching zone and sealed on the inner sides of the waveguide walls and delimits the resonator. In this dielectric cylinder 8, a liquid or gaseous coolant is introduced through an influence channel 9 in the pole piece 4 and several holes 10 in the waveguide wall 2 and discharged through holes 11 in the opposite waveguide wall 1 and an outflow channel 12 in the other pole piece 3. The two pole pieces 3 and 4 are sealed on the outer sides of the waveguide walls 1 and 2 against leakage of the coolant.

The through holes 10 and 11 in the waveguide walls 1 and 2 are dimensioned such that they are impermeable to the high-frequency field in the circulator.

Instead of the cooling device shown in FIG. 1, each individual ferrite rod 7 can also be accommodated in a dielectric tube and the coolant can be passed through each tube.

The temperature gradient in the ferrite rods is very small in both the longitudinal and transverse directions, so that mechanical destruction of the ferrite rods is not to be feared due to thermal stresses.

As FIG. 1 shows, the ferrite rods 7 are guided through openings 13, 14 in the two waveguide walls 1, 2 that are impermeable to the high-frequency field. On the one hand, this provides a simple holder for the ferrite rods 7. On the other hand, the magnetic resistance for the magnetic circuit is advantageously reduced due to the passage of the ferrite rods 7 through the waveguide walls 1, 2 up to the pole shoes 3, 4. As a result, only a smaller magnetic field strength needs to be applied, which is why a less complex magnet system is required. The reduction in the magnetic resistance between the magnet system and the ferrite rods also has the advantage that the magnetization of the ferrite rods can be increased to such an extent that the circulator can also operate above the previous frequency limit of approximately 2.5 GHz in the above resonance mode. can work. Then there are hardly any spin wave losses in the ferrite rods, which could cause non-linear effects.

2 shows a section through a planar branching circulator. This circulator has a symmetrical line structure, consisting of two planar outer conductors 15, 16 and an inner conductor 17 arranged therebetween. Here too, as with the waveguide circulator (FIG. 1), the resonator structure in the branching zone consists of several spaced apart and parallel to the E field Ferrite rods 17 aligned in the branching zone. The ferrite rods 7 are guided through bores 18, 19 and 20 in the outer conductors 15, 16 and the inner conductor 17, so that the ferrite rods 7 reach as far as the pole shoes 3, 4 of the magnet system. The magnet system corresponds to that described above and is therefore provided with the same reference numerals as in FIG. 1.

So that a liquid or gaseous coolant can flow through the ferromagnetic resonator, openings 21, 22 and 23 are provided in the outer conductors 15, 16 and the inner conductor 17.

Instead of cooling the ferromagnetic resonators in both circulator designs shown in FIGS. 1 and 2 by means of a liquid or gaseous dielectric, a solid dielectric (e.g. beryllium oxide ceramic) with good thermal conductivity can also be used, in which the ferrite rods 7 are embedded.

Any cross-sectional shape (e.g. round, square, star-shaped, hexagonal or the like) can be selected for the ferrite rods 7 mentioned in the exemplary embodiments described above. It should only be noted that the cross-section of the rods does not change in the direction of the static magnetic field.

Another form of the ferromagnetic resonator is shown in FIG. 3. Here the resonator consists of one Ferrite body 24, which extends for example in a waveguide circulator from a waveguide wall 25 to the opposite 26. Holes 27 which run parallel to the static magnetic field and which are filled with a non-ferromagnetic, heat-dissipating dielectric are embedded in this ferrite body 24. The holes 27 in the ferrite body 24 continue into the bores 28 and 29 passing through the waveguide walls 25 and 26, so that a gaseous or liquid dielectric can flow through the resonator.

An advantageous operating mode of the circulator according to the exemplary embodiment according to FIG. 1 or 2 results if the pole shoes 3, 4 and the magnetic yoke 6 are made of ferrite material and the magnet 5 is replaced by a coil wound on the yoke 6. Current surges in the coil can then very quickly reorient the magnetic field and thus the direction of rotation of the circulator, which can be attributed to direct contact of the ferrite rods 7 with the pole shoes 3, 4. In the de-energized state of the coil, the remanent field strength in the yoke 6, the pole pieces 3, 4 and in the ferrite rods 7 maintains the static magnetic field in the resonator.

Claims (12)

1. A microwave junction circulator provided with a waveguide junction zone penetrated by a static magnetic field, with a ferromagnetic resonator composed of different dielectric media being disposed in said junction zone, at least one of said media having ferromagnetic characteristics, characterized in that the interfaces between the various dielectric media form three-dimensional bodies (7, 27) which extend over the entire height of the junction zone and whose cross sections do not change in the direction of the static magnetic field.
2. A junction circulator according to claim 1, characterised in that the ferromagnetic dielectric medium is provided in the form of a plurality of rods (7) which are oriented parallel to the static magnetic field and are embedded in another dielectric medium.
3. A junction circulator according to claim 2, characterised in that the ferromagnetic rods (7) in a waveguide circulator are brought through openings (13, 14) the in oppositely disposed waveguide walls (1, 2) and said openings (13, 14) have such dimensions that they are impermeable to the high frequency field in the circulator.
4. A junction circulator according to claim 2, characterised in that, in a circulator whose waveguide junction is configured as a planar conductor structure (15, 16, 17), the ferromagnetic rods (7) are brought through bores (18, 19, 20) which pass through the conductor structure (15, 16, 17).
5. A junction circulator according to claim 1, characterised in that passage bores (27) extending parallel to the static magnetic field are provided in a ferromagnetic body (24) which fills the junction zone, said passage bores being filled with a different dielectric medium.
6. A junction circulator according to one of the preceding claims, characterised in that one of the dielectric media is a ceramic having good heat conducting properties.
7. A junction circulator according to one of the preceding claims, characterised in that one of the dielectric media is a liquid which flows through the ferromagnetic resonator to transport away the waste heat.
8. A junction circulator according to one of the preceding claims, characterised in that one of the dielectric media is a gas which flows through the ferromagnetic resonator to transport away the waste heat.
9. A junction circulator according to one of claims 2, 3 and 4, 7 or 8, characterised in that all ferromagnetic rods (7) are disposed in a dielectric cylinder (8) through which flows a liquid or a gas.
10. A junction circulator according to one of claims 2, 3 and 4, 7 or 8, characterised in that each individual ferromagnetic rod is disposed in a dielectric tube through which flows a liquid or a gas.
11. A junction circulator according to one of the preceding claims, characterised in that it is used as a circulator whose direction of rotation can be changed, with the static magnetic field in the resonator being reoriented by means of a current carrying coil disposed outside the waveguide junction zone.
12. A junction circulator according to one of the preceding claims, characterised in that the coil is wound on a ferromagnetic yoke (6) disposed outside the junction zone, said yoke forming a magnetic circuit with the ferromagnetic dielectric medium (7) in the junction zone and, in the case where the coil is without current, the residual field strength in the yoke (6) and in the dielectric medium (7) maintains the static magnetic field in the resonator.

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