GB2129227A - Faraday rotator type reciprocal phase shifter - Google Patents
Faraday rotator type reciprocal phase shifter Download PDFInfo
- Publication number
- GB2129227A GB2129227A GB08322534A GB8322534A GB2129227A GB 2129227 A GB2129227 A GB 2129227A GB 08322534 A GB08322534 A GB 08322534A GB 8322534 A GB8322534 A GB 8322534A GB 2129227 A GB2129227 A GB 2129227A
- Authority
- GB
- United Kingdom
- Prior art keywords
- yoke
- phase shifter
- ferrimagnetic material
- reciprocal phase
- magnetic circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/18—Phase-shifters
- H01P1/19—Phase-shifters using a ferromagnetic device
Landscapes
- Waveguide Switches, Polarizers, And Phase Shifters (AREA)
- Particle Accelerators (AREA)
Abstract
A Faraday rotator type reciprocal phase shifter in which, a yoke (13) disposed on the side surface of a ferri- magnetic material (1) for constituting a magnetic circuit has one or more apertures (16) therethrough. Thereby the magnetic circuit is divided into inner and outer circumferential portions (14, 15). A detector winding (7) passes through the apertures and detects flux in the outer portion (15), so that flux only near the center of the ferrimagnetic material (1) is detected by the winding. By means of a comparator circuit (Figure 2), the detector winding is adapted to control a drive winding (6). It is stated that this arrangement reduces temperature dependence of the phase shifter. <IMAGE>
Description
SPECIFICATION
Faraday rotator type reciprocal phase shifter
Background of the invention
Field of the invention
The present invention relates to Faraday rotator type reciprocal phase shifters and more particularly to a reciprocal phase shifter improved in characteristics of the phase shift amount with temperature.
Description of the prior art
Faraday rotator type reciprocal phase shifter as shown in Fig. 1 has been used in prior art. In the figure, reference numeral 1 designates a ferrimagnetic material of square cross-section with side surface coated by metal. Permanent magnets 2 each having four side surfaces are arranged around the ferrimagnetic material 1 so as to form N-pole and S-pole opposed in a prescribed direction thereby first and second circularly polarized wave generators 3, 4 are constituted. A yoke 5 to form a magnetic circuit is disposed on side surface of the ferrimagnetic material 1. A magnetizing lead wire 6 is wound on the ferrimagnetic material 1 and a lead wire 7 for detecting the total magnetic flux is wound on the yoke 5, thus a Faraday rotator 8 is constituted.
Operation of the Faraday rotator type reciprocal phase shifter 1 shown in Fig. 1 will now be described.
In Fig. 1 , the first and second circularly polarized wave generators 3, 4 have function to convert linearly polarized wave (TEto mode wave) entered in the phase shifter into circularly polarized wave and to convert the circularly polarized wave passed through the Faraday rotator 8 into the linearly polarized wave again.
The Faraday rotator 8 varies the intensity of magnetization within the ferrimagnetic material 1 in the axial direction, thereby it varies the permeability with respect to circularly polarized wave and hence the phase of circularly polarized wave.
Accordingly, in the phase shifter of Fig. 1, linearly polarized wave entered from one end is converted into circularly polarized wave and this is converted again into the linearly polarized wave by the phase variation in response to the intensity of magnetism within the Faraday rotator 8.
Thereby function as a phase shifter is effected.
Since the phase variation, i.e. phase shift amount in the Faraday rotator type phase shifter is proportional to flux variation within the ferrimagnetic material 1, the phase shift amount can be controlled by controlling the flux variation.
In order to control the phase shift amount in the Faraday rotator type reciprocal phase shifter of Fig. 1, a system of detecting the total flux variation within the ferrimagnetic material 1 by means of the lead wire 7 wound on the yoke 5 and controlling the total flux variation has been used in the prior art.
Fig. 2 is a block diagram of a driving circuit used to control the phase shift amount of the
Faraday rotator type reciprocal phase shifter in the prior art. In the figure, the driving circuit is composed of an exciter 9, an integrator 10 and a comparator 11. Operation of the driving circuit will now be described.
Current is flowed through the magnetizing lead wire 6 by the exciter 9 thereby the magnetic circuit comprising the ferrimagnetic material 1 and the yoke 5 of the conventional Faraday rotator type reciprocal phase shifter is magnetized in the saturated state. Current in this case is referred to as a reset current.
Then the reset current is interrupted and the magnetic circuit remains in the saturated magnetizing state.
Assuming that current is flowed through the magnetizing lead wire 6 in the reverse direction with respect to the reset current, the current in this case is referred to as a set current.
The lead wire 7 for detecting the total flux is wound on the yoke 5 which constitutes the magnetic circuit in co-operation with the ferrimagnetic material 1, and induced voltage V corresponding to time variation of the total flux is detected by the lead wire 7. The induced voltage
V is integrated with time by the integrator 10 into following equation (1) and converted into voltage v being proportional to the total flux variation sS.
v(cc)=-JVdt (1)
The converted voltage v is compared with reference voltage 1 2 (set corresponding to a phase shift of required amount) in the comparator 11.
As soon as the voltage v coincides with the reference voltage 12, the exciter 9 interrupts the set current and the magnetization is varied from that in saturation remaining state by a prescribed amount and then remains again.
Circularly polarized wave passed through the ferrimagnetic material 1 in the residual magnetization state is subjected to phase variation being approximately proportional to the total flux varaition 4.
As above described, the conventional Faraday rotator type reciprocal phase shifter detects the total flux variation within the ferrimagnetic material 1 using the lead wire 7 wound on the yoke 5 for detecting the total flux and controls the variation using the driving circuit so as to control the phase shift. However, the phase shifter driven in such manner has disadvantages in that the phase shift of required amount cannot be obtained when the temperature varies.
In other words, there is shown in Fig. 3 the relation of the total flux variation amount and the phase shift amount at temperatures Tr, T2 in the conventional Faraday Rotator type reciprocal phase shifter. In Fig. 3, there is shown in a tendency for reduced phase shift at the lower temperature in spite of constant amount of the total flux variation which is kept constant.
Summary of the invention
An object of this invention is to provide a
Faraday rotator type reciprocal phase shifter which is little influenced by variations in temperature and can obtain the required phase shift amount.
An another object of this invention is to provide a Faraday rotator type reversible phase shifter which is simple in construction.
The objects can be obtained by such structure that the conventional Faraday rotator type reversible phase shifter is improved so as to detect fluxes adjacent the center of ferrimagnetic body which mainly contribute to variations in phase.
In greater detail, a separated portion is arranged on the yoke contributing the magnetic circuit, whereby the flux adjacent the center of the ferrimagnetic body is detected through the separated portion. On the basis of the detected results, the phase shift is controlled and thereby the above-mentioned objects can be attained.
Brief description of the drawings
Fig. 1 is a perspective view of a Faraday rotator type reciprocal phase shifter of the prior art,
Fig. 2 is a block diagram of a driving circuit used to control the phase shift amount in the phase shifter of Fig. 1;
Fig. 3 is a graph illustrating example of relation between the total flux variation and the phase shift in the phase shifter of Fig. 1;
Fig. 4 is a graph illustrating distribution of the transmission power density of circularly polarized wave within transverse cross-section of a ferrimagnetic material;
Fig. 5 is a graph illustrating distribution of the transmission power density of circularly polarized wave within the transverse cross-section of ferrimagnetic material;;
Fig. 6 is a graph illustrating variation amount of the residual flux density within the transverse cross section of ferrimagnetic material at the temperatureT1, T2 CC; Fig. 7A and Fig. 7B are graphs illustrating B--H curve of the magnetic circuit;
Fig. 8 is a perspective view of a Faraday rotator type reciprocal phase shifter as an embodiment of the invention;
Fig. 9 is a longitudinal sectional view of the phase shifter in Fig. 8; and
Fig. 10 is a perspective view of a phase shifter as another embodiment of the invention.
Description of the preferred embodiment
Prior to explanations on the embodiments of this invention, there will be described the principle of this invention on the basis of analyzed results by the inventors concerning the relation of the influence of temperature variations per the phase shift amount.
In the conventional phase shifter as shown in
Fig. 3, the phase shift amount is reduced when the temperature lowers even if the total flux variation amount is kept constant. This tendency is caused by two phenomena, i.e. that transmission power density of circularly polarized
wave within the ferrimagnetic material 1 is
distributed unequally in the transverse cross
section of the ferrimagnetic material 1 and that
distribution of the residual flux density in the
transverse cross-section of the ferrimagnetic
material 1 varies with temperature.
Cause of these two phenomena will now be
described in detail. It is also described that control
of the total flux variation depends on variation of
the phase shift with temperature.
Referring to Fig. 4 the transmission power
density distribution of circularly polarized wave
will be described. The figure shows the
transmission power density of circularly polarized
wave in the transverse cross-section of the
ferrimagnetic material 1 having square crosssection. Since circularly polarized wave is
composite wave of TE10 mode wave and TEo1 mode wave, distribution of the transmission power
is concentrated near the center of the ferrimagnetic material 1. This makes clear that the flux variation near the center of the
ferrimagnetic material 1 mainly contributes to the
phase variation of circularly polarized wave.
Reason why the residual flux density is distributed unequally in the transverse crosssection of the ferrimagnetic material 1 and why the distribution varies with temperature will now be described.
In Fig. 5, solid line (a) shows distribution of the saturated residual flux density in the transverse cross-section of the ferrimagnetic material 1 after the reset current flows. As clearly seen from the figure, distribution of the residual flux density is uniform in this state.
Then the set current is flowed in the reverse direction to there set current by means of the driving circuit until the total flux variation attains a prescribed value thereby the magnetic circuit is magnetized. In the magnetic circuit composed of the ferrimagnetic material 1 and the yoke 5, DC magnetic field applied to the outer circumferential side shall be represented by Hout and that applied to the inner circumferential side be H,,. Since the magnetic path length is longer in the outer circumferential side than in the inner circumferential side, H is less than Hjn As above described, at the portion near the periphery of the ferrimagnetic material 1 constituting the magnetic circuit on the outer circumferential side, the intensity of magnetization caused by the set current is weak in comparison to that at portion near the center of the ferrimagnetic material 1 constituting the magnetic circuit on the inner circumferential side.
Thus, near the centre, the difference of the residual flux density after interrupting the reset current and after interrupting the set current, i.e.
the residual flux density variation becomes small.
As a result, the residual flux density is distributed unequally. Example of distribution of the residual flux density in the transverse cross-section of the ferrimagnetic material 1 in this condition is shown in broken line (b) in Fig. 5.
Fig. 6 shows the residual flux density variation in the transverse cross-section of the ferrimagnetic material 1 after the set current flows so that the total flux variation of equal amount is given at the temperature T1, T2 (Tt < T2).
As clearly seen from the figure, distribution of the residual flux density variation in the transverse cross-section of the ferrimagnetic material 1, with equal variation of total flux, varies with temperature.
The reason why the unequal distribution of variation of the residual flux density varies with temperature will be described referring to Fig. 7.
Fig. 7A and Fig. 7B are graphs illustrating examples of B-H curve of the ferrimagnetic material used in the magnetic circuit at the temperature T1, T2. As clearly seen from the figures, the magnetic circuit cannot easily magnetize at lower temperature thereby the coercive force Hc becomes large. In order to vary the total magnetic flux by a prescribed amount, the set current hence the DC magnetic field in the ferrimagnetic material 1 must be increased at low temperature state in comparison to high temperature state. Since ratio of Hout to Hin determined by ratio of the magnetic path length is constant, difference between Hout and Hin becomes large at lower temperature when the DC magnetic field is increased.Accordingly, as shown in Fig. 7A and Fig. 7B, difference of the residual flux density variation Bout, Bjn becomes large at low temperature state T1 in comparison to high temperature state T2.
Thus distribution of the residual flux density variation in the transverse cross-section of the ferrimagnetic material 1 varies with temperature as shown in Fig. 6.
Accordingly, conventional Faraday rotator type reciprocal phase shifter has disadvantages in that the residual flux density variation near the center of the ferrimagnetic material 1 mainly contributing to the phase variation becomes smaller than that in peripheral portion at low temperature state in comparison to high temperature state, and the phase shifter is driven using a control system dependent on the total flux variation, thereby the phase shift amount becomes smaller than a prescribed value.
Fig. 8 is a perspective view of a Faraday rotator type reciprocal phase shifter as an embodiment of this invention, and Fig. 9 is a longitudinal sectional view of the phase shifter. In the figures, each reference numeral identical to that of Fig. 1, designates the same or similar part.
In the Faraday rotator type reciprocal phase shifter according to this invention, each yoke 1 3 is provided with aperture means in the form of a slot 1 6 so that a first magnetic circuit 14 corresponding to the inner circumferential side of the total magnetic circuit and a second magnetic circuit 1 5 corresponding to the outer circumferential side are divided in a prescribed cross-section area ratio. The lead wire 7 is wound through the slot 1 6 and surrounds the second magnetic circuit 1 5 so as to detect the flux near the center of the ferrimagnetic material 1.If the set current flows in the magnetizing lead wire 6 and the magnetic circuit is magnetized in such structure, the flux near the center of the ferrimagnetic material 1 passes through the second magnetic circuit 1 5. Thus the lead wire 7 wound to surround the second magnetic circuit 1 5 of the yoke 1 3 can detect the voltage proportional to the flux variation only near the center of the ferrimagnetic material 1. Since the flux variation near the center of the ferrimagnetic material 1 mainly contributes to the phase variation as above described, if the driving circuit performs the phase control using the voltage proportional to the flux variation the phase shift of required amount can be obtained in spite of the temperature variation.
Above mentioned embodiment has four yokes 13, and the lead wire 7 for detecting the flux near the center of the ferrimagnetic material 1 is wound on each yoke 13. However, this invention is not limited to such constitution but any phase shifter has similar effect if it has one or more yokes 1 3 and the lead wire 7 for detecting the flux near the center of the ferrimagnetic material 1 is wound on each yoke 13.
Furthermore, although the above mentioned embodiment is described using the ferrimagnetic material 1 of square cross-section, any phase shifter of this invention has similar effect if the metal-coated ferrimagnetic material has a crosssection to allow the circularly polarized wave to pass through.
Furthermore, although the above mentioned embodiment is described using aperture 1 6 of substantially rectangular slot form, this invention is not limited to such constitution but other embodiments such as that shown Fig. 10 may be used. In Figure 10 one or more aligned small circular section holes 17 are provided.
As above described, in the Faraday rotator type reciprocal phase shifter according to the present invention, a yoke has at least one hole and a lead wire for detecting flux near the center of a ferrimagnetic material is wound through the hole or holes, thereby only the flux variation corresponding to the phase shift can be detected.
Accordingly, the present invention has effect that a phase shift of required amount can be obtained with reduced temperature variation dependence.
Claims (4)
1. Faraday rotator type reciprocal phase shifter comprising two circularly polarized wave generators each having four permanent magnets arranged around a ferrimagnetic material with a side surface coated by metal so that N-pole and
S-pole are opposed in prescribed direction; a yoke arranged on the side surface of the ferrimagnetic material so as to form a magnetic lead wire wound on the ferrimagnetic material; and a magnetizing lead wire would on the ferrimagnetic material; wherein a separating means for dividing the magnetic circuit into an inner portion and an outer circumferential portion is formed on part of the yoke, detector means are provided for detecting the magnetic flux only near the center of the ferrimagnetic material and drive means arranged to act in response to the flux detected by the detector means.
2. A reciprocal phase shifter as set forth in
Claim 1, in which the separating means is formed by an aperture or apertures provided on part of the yoke so that the magnetic circuit is divided into inner and outer circumferential portions.
3. A reciprocal phase shifter as set forth in
Claim 2, in which the aperture provided on part of the yoke is a substantially rectangular slot extending along the longitudinal direction of the yoke.
4. A reciprocal phase shifter substantially as described with reference to or as illustrated in
Figures 8 to 10 of the accompanying drawings.
4. A reciprocal phase shifter as set forth in
Claim 2, in which the apertures provided on part of the yoke is composed of a plurality of small holes which are aligned along the longitudinal direction of the yoke.
5. A reciprocal phase shifter as set forth in any of claims 2 to 4 in which the detector means comprises a lead wire which passes through the aperture or apertures on part of the yoke and surrounds flux in the magnetic circuit at the outer circumferential portion.
6. A reciprocal phase shifter substantially as described herein with reference to or as illustrated in Figures 8 to 10 of the accompanying drawings.
New claims filed on 3 January 1984.
Superseded claims-all claims.
New claims:
1. Faraday rotator type reciprocal phase shifter comprising two circularly polarized wave generators each having four permanent magnets arranged around a ferrimagnetic material with a side surface coated by metal so that N-pole and
S-pole are opposed in prescribed direction; a yoke arranged on the side surface of the ferrimagnetic material so as to form a closed magnetic circuit; a magnetizing lead wire wound on the ferrimagnetic material; wherein a separating means for dividing the magnetic circuit into an inner portion and an outer circumferential portion is formed on part of the yoke, detector means are provided for detecting the magnetic flux only near the center of the ferrimagnetic material and drive means arranged to act in response to the flux detected by the detector means;
said separating means is formed by an aperture
or apertures provided on part of the yoke so
that the magnetic circuit is divided into inner
and outer circumferential portions;
said detector means comprises a lead wire
which passes through the aperture or
apertures on part of the yoke and surrounds
flux in the magnetic circuit at the outer
circumferential portion.
2. A reciprocal phase shifter as set forth in
Claim 1 in which the aperture provided on part of the yoke is a substantially rectangular slot extending along the longitudinal direction of the yoke.
3. A reciprocal phase shifter as set forth in
Claim 1 in which the apertures provided on part of the yoke are composed of a plurality of small holes which are aligned along the longitudinal direction of the yoke.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14725582A JPS5937702A (en) | 1982-08-25 | 1982-08-25 | Faraday rotary polarizer type reversible phase shifter |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8322534D0 GB8322534D0 (en) | 1983-09-21 |
| GB2129227A true GB2129227A (en) | 1984-05-10 |
| GB2129227B GB2129227B (en) | 1986-01-02 |
Family
ID=15426091
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08322534A Expired GB2129227B (en) | 1982-08-25 | 1983-08-22 | Faraday rotator type reciprocal phase shifter |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5937702A (en) |
| GB (1) | GB2129227B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2580429A1 (en) * | 1985-04-15 | 1986-10-17 | Dassault Electronique | Microwave phase shifting device with shared magnetic circuit. |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0824995B2 (en) * | 1987-11-13 | 1996-03-13 | トヨタ自動車株式会社 | Disappearance model assembly method for casting |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB880721A (en) * | 1959-11-02 | 1961-10-25 | Hughes Aircraft Co | Microwave phase shifter |
-
1982
- 1982-08-25 JP JP14725582A patent/JPS5937702A/en active Granted
-
1983
- 1983-08-22 GB GB08322534A patent/GB2129227B/en not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB880721A (en) * | 1959-11-02 | 1961-10-25 | Hughes Aircraft Co | Microwave phase shifter |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2580429A1 (en) * | 1985-04-15 | 1986-10-17 | Dassault Electronique | Microwave phase shifting device with shared magnetic circuit. |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2129227B (en) | 1986-01-02 |
| JPS5937702A (en) | 1984-03-01 |
| GB8322534D0 (en) | 1983-09-21 |
| JPS6341243B2 (en) | 1988-08-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19960822 |