GB1566333A - High power y-junction h-plane circulator for microwave transmission - Google Patents

Description

(54) A HIGH POWER Y-JUNCTION H-PLANE CIRCULATOR FOR MICROWAVE TRANSMISSION (71) We, THOMSON-CSF, a French Body Corporate, of 173, Boulevard Haussmann 75008 Paris - France - 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: The Parent, British Patent No. 1420050 filed on the 14th November 1973, relates to an invention concerned with high-power, Y-junction, H-plane circulators for the transmission in microwave range between -40 C and +85"C.

The invention is based upon the fact that, in a circulator comprising ferrite wafers polarised by a direct magnetic field exceeding a certain value it is possible to transmit a high peak power without incurring the penalty of non-linear effects. Ferrite wafers in respect of which the spin wave spectrum line is narrow are chosen, these being polarised using permanent magnets so that it is possible to produce circulators of small weight and bulk.

In accordance with claim 1 of the Parent Patent, there is provided a high-power, Y-junction, H-plane circulator for the transmission in microwave range between tempera tures of -40 C and +85"C, comprising a H-plane waveguide junction and in said junction at least one element, having two sides parallel to the H-plane, made of a ferrimagnetic material and means for generating a direct magnetic field perpendicularly to said sides, wherein said material is of the kind which exhibits a spin-wave linewidth below 10 oersteds, said direct magnetic field being: - capable of saturating said material, - weaker than the gyromagnetic resonance field Hr - stronger than the direct magnetic field which renders the critical power in the circulator minimum, - and close to the limiting fieldstrength HL beyond which first order non-linear effects are negligible, the operating frequency being high enough to allow the following condition to be satisfied: Hr > > HL.

The Parent Patent describes an application of the invention to a waveguide-type circulator.

The present application for Patent Of Addition relates to an application of the invention to a stripline circulator.

According to the present invention, there is provided a high-power, Y-junction, H-plane circulator as claimed in claim 1 of the Parent Patent, comprising a star conductor with three arms, arranged between two ferrite discs themselves disposed between two earthing planes, said discs being surrounded by dielectric rings filling the space between the two earthing planes, and said direct magnetic field being developed by permanent magnets located in openings formed inside the earthing planes.

The application for Patent of Addition will be better understood and ather of its features rendered apparent from a consideration of the ensuing description and the accompanying drawings in which: Figure 1 is a section in a central plane parallel to the two earthing planes, through a circulator in accordance with the invention; Figure 2 is a section through the same circulator in a plane perpendicular to the earthing planes and on the line AA shown in the section plane of Figure 1.

To improve the clarity of Figure 2, the sections through the earthing planes 1 and 2 have not been hatched. In addition, only one connector 16 has been shown instead of three.

The arms, spaced at 1200, of the conductor 12, comprise two portions: - a first portion of width Wl whose length is limited to the radius of the dielectric ring 14; - a second portion of width W2 (less than W1) terminating at the point where the arm leaves the space between the earthing planes; this portion has a tongue 121 which is all that projects from the space defined between the earthing planes. This tongue is designed to be soldered to the central plug 161 of a connector 16.

The earthing planes 1 and 2 have a rectangular shape and a thickness sufficient to enable the collar 162 of the "peripheral conductor" part of the connector 16, to be attached to their section by screws. This connector will for example be the female part of a standard coaxial cable plug-in connector arrangement.

During assembly of the circulator, two ferrite discs 13 are placed at either side of the conductor 12 and then two dielectric rings 14 which surround the discs.

Finally, the discs 15, made of a material constituting a permanent magnet, are arranged in the openings 10 and 20 at the centre of the earthing planes.

In the chosen example, the following materials were used: - components 1 and 2 : aluminium alloy; - component 12 : passivated silvered brass; - component 13 : yttrium gadolinium aluminium garnet ferrite of the general formula: Y3.3x Gd3X Fe5sy Al5y 012 where x = 0.1 ; y = 0.2 whose characteristics at ambient temperature are as follows: saturation magnetic moment : 400 U.C.G.S.E.M.

gyromagnetic resonance spectrum line width at 9.5 Gc/s : oersteds effective gyromagnetic factor : 2.03 relative dielectric constant (at 9.5 Gc/s) : 14.5 tangent of the dielectric loss angle (at 9.5 Gc/s) : 2.10-4 Curie point : 1600C spinwave spectrum line width (at 9.5 Gc/s) : 6.2 oersteds.

component 14: REXOLITE (registered trade mark) synthetic resin having a relative dielectric constant of : 2.53 - component 15 : TICONAL (registered trade mark) permanent magnet type 1500 (made of alnico 8 alloy) producing an operating magnetic field of 680 to 700 oersteds in the space defined between the earthing plane and the central conductor, in the presence of the component 13.

As an example a circulator in accordance with the invention has the following characteristics measured in the temperature range from 0 to 60"C: - frequency band : 2.4 to 2.6 Gc/s; - maximum insertion losses : 0.5 dB; decoupling between channels : 20 dB; - maximum standing wave ratio : 1.15; - permissible peak power : 3.3 kW across matched load; - permissible mean power : 150 W across matched load; - size : 59.6 mm by 61.2 mm by 27.5 mm; - weight : 0.4 kg.

WHAT WE CLAIM IS: 1. A high-power. Y-junction, H-plane circulator as claimed in claim 1 of the Parent Patent comprising a star conductor with three arms, arranged between two ferrite discs themselves disposed between two earthing planes, said discs being surrounded by dielectric rings, and said direct magnetic field being developed by permanent magnets located in openings formed inside the earthing planes.

2. A circulator as claimed in claim 1, wherein said ferrite discs are made of yttrium, gadolinium, aluminium, garnet of the formula Y3-3x Gd3x Fes-sy Alsy 012 where x = 0.1 ; y = 0.2.

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

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. drawings in which: Figure 1 is a section in a central plane parallel to the two earthing planes, through a circulator in accordance with the invention; Figure 2 is a section through the same circulator in a plane perpendicular to the earthing planes and on the line AA shown in the section plane of Figure 1. To improve the clarity of Figure 2, the sections through the earthing planes 1 and 2 have not been hatched. In addition, only one connector 16 has been shown instead of three. The arms, spaced at 1200, of the conductor 12, comprise two portions: - a first portion of width Wl whose length is limited to the radius of the dielectric ring 14; - a second portion of width W2 (less than W1) terminating at the point where the arm leaves the space between the earthing planes; this portion has a tongue 121 which is all that projects from the space defined between the earthing planes. This tongue is designed to be soldered to the central plug 161 of a connector 16. The earthing planes 1 and 2 have a rectangular shape and a thickness sufficient to enable the collar 162 of the "peripheral conductor" part of the connector 16, to be attached to their section by screws. This connector will for example be the female part of a standard coaxial cable plug-in connector arrangement. During assembly of the circulator, two ferrite discs 13 are placed at either side of the conductor 12 and then two dielectric rings 14 which surround the discs. Finally, the discs 15, made of a material constituting a permanent magnet, are arranged in the openings 10 and 20 at the centre of the earthing planes. In the chosen example, the following materials were used: - components 1 and 2 : aluminium alloy; - component 12 : passivated silvered brass; - component 13 : yttrium gadolinium aluminium garnet ferrite of the general formula: Y3.3x Gd3X Fe5sy Al5y 012 where x = 0.1 ; y = 0.2 whose characteristics at ambient temperature are as follows: saturation magnetic moment : 400 U.C.G.S.E.M. gyromagnetic resonance spectrum line width at 9.5 Gc/s : oersteds effective gyromagnetic factor : 2.03 relative dielectric constant (at 9.5 Gc/s) : 14.5 tangent of the dielectric loss angle (at 9.5 Gc/s) : 2.10-4 Curie point : 1600C spinwave spectrum line width (at 9.5 Gc/s) : 6.2 oersteds. component 14: REXOLITE (registered trade mark) synthetic resin having a relative dielectric constant of : 2.53 - component 15 : TICONAL (registered trade mark) permanent magnet type 1500 (made of alnico 8 alloy) producing an operating magnetic field of 680 to 700 oersteds in the space defined between the earthing plane and the central conductor, in the presence of the component 13. As an example a circulator in accordance with the invention has the following characteristics measured in the temperature range from 0 to 60"C: - frequency band : 2.4 to 2.6 Gc/s; - maximum insertion losses : 0.5 dB; decoupling between channels : 20 dB; - maximum standing wave ratio : 1.15; - permissible peak power : 3.3 kW across matched load; - permissible mean power : 150 W across matched load; - size : 59.6 mm by 61.2 mm by 27.5 mm; - weight : 0.4 kg. WHAT WE CLAIM IS:

1. A high-power. Y-junction, H-plane circulator as claimed in claim 1 of the Parent Patent comprising a star conductor with three arms, arranged between two ferrite discs themselves disposed between two earthing planes, said discs being surrounded by dielectric rings, and said direct magnetic field being developed by permanent magnets located in openings formed inside the earthing planes.

2. A circulator as claimed in claim 1, wherein said ferrite discs are made of yttrium, gadolinium, aluminium, garnet of the formula Y3-3x Gd3x Fes-sy Alsy 012 where x = 0.1 ; y = 0.2.

3. A circulator as claimed in claim 2, wherein said permanent magnets produce a

magnetic field of 680 to 700 oersteds.