GB2192310A - Tunable RF cavity device - Google Patents
Tunable RF cavity device Download PDFInfo
- Publication number
- GB2192310A GB2192310A GB08415215A GB8415215A GB2192310A GB 2192310 A GB2192310 A GB 2192310A GB 08415215 A GB08415215 A GB 08415215A GB 8415215 A GB8415215 A GB 8415215A GB 2192310 A GB2192310 A GB 2192310A
- Authority
- GB
- United Kingdom
- Prior art keywords
- capacitor element
- cavity
- movable
- coil
- control device
- 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
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/7136—Arrangements for generation of hop frequencies, e.g. using a bank of frequency sources, using continuous tuning or using a transform
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P7/00—Resonators of the waveguide type
- H01P7/06—Cavity resonators
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J1/00—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general
- H03J1/0008—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/7136—Arrangements for generation of hop frequencies, e.g. using a bank of frequency sources, using continuous tuning or using a transform
- H04B2001/71365—Arrangements for generation of hop frequencies, e.g. using a bank of frequency sources, using continuous tuning or using a transform using continuous tuning of a single frequency source
Landscapes
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
A tunable RF cavity device, more especially for use in a frequency hopping RF transmitting and receiving system, comprises a RF cavity (10) mounted to a buttress support (12) for an activator assembly (14), said assembly comprising a dynamic capacitor having a cylindrical movable capacitor element (16) in overlapping relationship to a cylindrical fixed capacitor element (18) constituting the central conductor of the RF cavity, the movable capacitor element (16) carrying a voice coil (24) supplied with position signals via a servo-feedback loop by a position sensor having a core (30) and stator (32) carried by the movable and fixed capacitor elements. <IMAGE>
Description
SPECIFICATION EFeakydeviceforRFtransmissfon alid reception Fieldofthe teventiorl! Thisinvention relatesto a RF cavity device and more especiallytoza RF cavity device which is tunable to differing wavelengths, more especially in order to enablefrequency hopping in a communications channel.
Background to the Invention
In radio communications systems, especially in the militaryfield, frequency hopping is a technique
resorted to in orderto obviatejamming, or less importantly, eavesdropping. Normally, two stations, forexamplean aircraft and a ground control station, are ableto communicate by use oftransmitter/ receivers (transceivers) operational on a communications channel of selected carrier frequency. Each transceiver connects with an RFcavity matched through a T-couplerto the aerial.
With frequency hopping,the carrier frequency is changed,typicallyten two fifteen times a second for slow hopping, in accordance with a pre-arranged frequency plan synchronously followed at the two communicating stations.
However, when frequency hopping is employed, constant re-matching ofthe RF cavity, T-coupler and aerial is necessary.
PriorArt
U.S. Patent No. 4173032 discloses a binary capacitor. A battery of such binary capacitors can provide a large plurality of stable states which enablefrequency hopping in a communications system. Howeversuch a system is relatively complex and expensive.
The Invention
In accordance with the invention,there is provided an RF cavity device tunable by a dynamic capacitor which has a fixed capacitor element in variable overlapping relationship within the cavity to a movable capacitor element, said movable capacitor element being driven by an electrical coil movable in a magnetic field responsively to the supply of position signals representative of the frequency to which the cavity is to be tuned.
Preferably, the movable capacitor element, which carries the electrical coil, is supported on an air bearing, thereby to ensurefastand accurate response totheapplied position signals.
In a preferred arrangment,the movable capacitor element is a thin walled cylinder, supported on the inside of an annular plenum chamber having orifices in its innerwall through which airjets pass to form a thin annular air layer constituting the air bearing. One end ofthethin walled cylinder projects axiallyfrom within the plenum chamber into an adjacent RF cavity, whereat it overlaps a thin walled cylindrical fixed capacitor element.A cylindrical voice coil is mounted to the other end ofthe movable capacitor element and isthereby, CocatediGe roone pateregffli:onetarnagEzetie circuit having soft pole pieces,
According to another aspect ofthe invention, there is provided a frequency hopping PRFcavitytransmit- ting and receivinXgjsystem comprising an RF cavity tunable buy a dynamic capacitor having and electrical driving coil, a tranceivercoupled tothe RF cavity and generating a required carrier frequency signal, and a processor for generating a required position signal corresponding to the required frequency signal and forsupplytothedrivingcoil.
Preferably the required position signal is fed through a servo loop control device, and the dynamic capacitor carries a position sensorfor supplying a position feedback signal to the control device, whereby the coil is driven by a position difference signal.
A modified T-coupler, which is preferably also adjusted to ensure absolute matching to the RF cavity frequency, may likewise be coupled to the servo loop control device, which acts to supply a drive current to said T-coupler.
Thetunable RF cavity employed in the frequency hopping system may conveniently be constituted by the preferred cavity arrangement heretofore de scribed, the position sensortaking the form of a sensor core carried at the one end ofthethin walled movable capacitor element and sensorstator carried by the thin walled fixed capacitor element.
Description of drawings
In the accompanying drawings:
Figure 1 is an axial cross-section through atunable RF cavity device; and
Figure 2 is a diagrammatic illustration of a frequency hopping RFtransmitting and receiving systems.
Description ofembodiment In Figure 1,the reference 10 denotes and RF cavity.
This is attached to a-buttress support 12 for an activator assembly, generally referenced 14, which is employed to tune the cavity to a selected RF carrier frequency.
The activator assembly comprises a thin walled cylindrical movable dynamic capacitor element 16, in overlapping relation to a thin walled fixed capacitor element 1 8which constitutes the central conductor of the Rf cavity.
Within the buttress support 12, the dynamic-capaci torelement 16 is supported on an air bearing 17 formed byan annular plenum chamber20 having an apertured interior wall 22 through which airjets sustain an air layer supporting said dynamic capacitor element 1 6for substantially frictionless axial movement.
At the end remote from the Rf cavity 10, the dynamic capacitor 16 carries an electrical coil, which may conveniently be referred to as a voice coil 24. This extendsthrough an annular gap at one poleofa magnetic circuit formed by an annular permanent magnet 26 with mildsteel pole pieces 28.
Atthe other end, the dynamic capacitor element 16 conveniently carries a position sensor core 30 which cooperates with sensor stator32 carried bathe The drawing(s) originally filed was {were) informal and the print here reproduced is taken
from a later filed formal copy.
The claims were filed later than the filing date within the period prescribed by Rule 25(1)
of the Patents Rules 1982.
central conductor 18.
In use, the voice coil 24 is supplied with position signals representing the required RFcarrierfrequency to which the cavity 10 isto be matched. The position sensor 30,32, when provided, is able to supply a position feedback signal which, via a servo loop, enables the position signals to be related two position difference signals representing at any instantthe difference between the required position ofthe dynamic capacitor element and its actual position.
Figure 2 shows a frequency hopping RFtransmitting and receiving system utillising the tunable Rf cavity device of Figure 1. This device is indicated by the reference 40 in Figure 2.
A transmitting/receiving set (transceiver) 42 feeds or receives an RF signal (typically having a frequency hopped carrier signal in the range 225 to 400 MHz) to orfrom the cavity device 40 and also, in accordance with a pre-arranged frequency plan, supplies a required frequency signal to a microprocessor44. The
RFcavity is conveniently coupled to an adjustable T-coupler 46 which connects with an aerial 48. The invention aims to effect continual re-matching ofthe system, including the fixed aerial 48, to the frequency hopped carriersignal.
Forth is purpose, the microprocessor 44 produces a required position signal which is fed to a servo loop control device 50, the latter providing the drive current to the voice coil ofthetunable RF cavity device 40.A corresponding drive currents supplied to the adjustable T-coupler46. The tunable RF cavity device 40 returns a position feedback signal to the control device 50, thereby completing a servo loop wherein the drive current is related to the instantaneous difference between the actual position ofthe dynamic capacitor and its required positionfora given RF carrier frequency. When correspondence is achieved a "seek complex" signal is fed bckto the processorfrom the servo control device. The system is capable of carrying outfrequency hopping at a slow rate, typically ofthe order of 10 to 15 hops per second.
In practice,the system takes the form of a frequency hopping unit 52 which is interposed between the transceiver an the aerial.
Various modifications ofthe frequency hopping system, including the tunable RF cavity device in- corporated therein, are possible within the scope of the invention hereinbefore defined.
Claims (11)
1. An RF cavity device tunable by a dynamic capacitor which has a fixed capacitor element in variable overlapping relationship within the cavity to a movable capacitor element, said movable capacitor element being driven by an electrical coil movable in a magnetic field responsively to the supply of position signals representative ofthe frequency to which the cavity is to be tuned.
2. A device according to claim 1, wherein the
movable capacitor element carries the electrical coil.
3. A device according to claim 1 or2,whereinthe movable capacitor element is supported on a air
bearing.
4. A device according to claim 3, wherein the
movable capacitor element is a thin-walled cylinder
supported on the inside of an annular plenum chamber having orifices in its innerwall through which airjets pass to form athin annularairlayer constituting the air bearing.
5. A device according to claim 4, wherein one end ofthe movable cylindrical capacitor element projects axially from within the plenum chamber into an adjacent RF cavity, whereat it overlaps a thin-walled, cylindrical, fixed capacitor element.
6. A device according to claim 5, wherein the electrical coil is a cylindrical voice coil mounted tothe other wend ofthe movable capacitor element.
7. A device according to claim 6,wherein the voice coil is movable in the magnetic field at one pole region of a magnetic circuit having soft pole pieces.
8. Afrequency hopping RF cavity transmitting and receiving system comprising an RFcavitytunabie by a dynamic capacitor having an electrical driving coil, a transceiver coupled to the RF cavity and generating a required carrier frequency signal, and a processor for generating a required position signal corresponding -to the required frequency signal and forsupplyto the driving coil.
9. A system according to claim 8,wherein the required position signal is fed through a servo-loop
control device, and the dynamic capacitor carries a position sensorfor supplying a position feedback signal to the control device, whereby the coil is driven buy a position difference signal.
10. A system according to claim 9, wherein a modified T-coupler, adjusted to match the RF cavity frequency, is coupied to the servo-loop control device to enable said control device to supply a drive current to said coupler.
11. Afrequencyhopping RFcavitytransmitting and receiving system substantially as herein before described with reference to the accompanying drawings.
11. Asystem according to claim 9 orclaim 10, whereinthetunable RF cavity is a device according to any of claims 1 to 7, the position sensortaking the form of a sensor core carried by the movable capacitor elementandasensorstatorcarried by the fixed capacitor element.
12. Atunable RF cavity device substantially as hereinbefore described with reference to the accompanying drawings.
13. Afrequency hopping RFcavitytransmitting and receiving system substantially as hereinbefore described with reference to the accompanying drawings.
Amendments to the claims have been filed, and havethefollowing effect: Claims 1-13above have been deleted ortextually
amended.
Newortextuallyamended claims have been filed as follows:
CLAIMS
1. Afrequency hopping transmitting and receiving system comprising an RF cavitytunable by a dynamic capacitor having an electrical driving coil, a transceiv
er coupled to the RF cavity and generating a required
frequency signal, and a processor for generating a
position signal corresponding to the required fre
quencysignal andforsupplytothe driving coil,
whereby the cavity is tuned to act as a filter passing a
carrierfrequencyselected by the position signal.
2. A system according to claim 1, wherein the position signal is fed through a servo-loop control device, and the dynamic capacitor carries a position sensorfor supplying a position feedback signal to the control device,wherebythe coil is driven by a position difference signal.
3. A system according to claim 2, wherein a modified T-coupler, adjusted to match the RF cavity frequency, is coupled to the servo-loop control device to enable said control device to supply a drive current to said coupler.
4. A system according to any one of claims 1 to 3, wherein the RF cavity is tunable by a dynamic capacitor which has a fixed capacitor element in variable overlapping relationship within the cavity to a movable capacitor element, said movable capacitor element being driven by an electrical coil movable in a magneticfield responsively to supply ofthe position signals.
5. A system according to claim 4, wherein the movable capacitor element carries the electrical coil.
6. A system according to claim 4 or claim 5, wherein the movable capacitor element is supported on an air bearing.
7. A system according to claim 6, wherein the movable capacitor element is athin-walled cylinder supported on theinside of an annular plenum chamber having orifices in its inner wall through which airjets pass to form a thin annular air layer constituting the air bearing,
8. A system according to claim 7, wherein one end ofthe movable cylindrical capacitorelement projects axiallyfromwithinthe plenum chamber into an adjacent RFcavity,whereat it overlaps a thin-walled, cylindrical, fixed capacitor element.
9. A system according to claim 8, wherein the electrical coil is a cylindrical voice coil mounted to the other end ofthe movable capacitor element
10. Asystem according to claim 9, wherein the voice coil is movable in the magneticfield at one pole region ofa magnetic circuit having soft pole pieces.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08415215A GB2192310B (en) | 1984-06-14 | 1984-06-14 | Tunable rf cavity device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08415215A GB2192310B (en) | 1984-06-14 | 1984-06-14 | Tunable rf cavity device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2192310A true GB2192310A (en) | 1988-01-06 |
| GB2192310B GB2192310B (en) | 1988-05-25 |
Family
ID=10562443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08415215A Expired GB2192310B (en) | 1984-06-14 | 1984-06-14 | Tunable rf cavity device |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2192310B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2697948A1 (en) * | 1992-11-10 | 1994-05-13 | Commissariat Energie Atomique | Device forming an artificial capacitive surface admittance, application to the realization of two-dimensional cavities, resonators and antennas. |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB592929A (en) * | 1942-05-01 | 1947-10-03 | Western Electric Co | Improvements in or relating to magnetron apparatus for producing high frequency electrical oscillations |
| GB622057A (en) * | 1944-05-24 | 1949-04-26 | Philips Nv | Improvements in resonant circuits for use with ultra-short waves |
| GB627340A (en) * | 1944-06-02 | 1949-08-08 | Philips Nv | Improvements in or relating to tunable electric resonators |
| GB635574A (en) * | 1946-05-08 | 1950-04-12 | Standard Telephones Cables Ltd | Electron discharge devices of the magnetron type |
| GB708833A (en) * | 1951-07-30 | 1954-05-12 | Gen Electric Co Ltd | Improvements in or relating to high frequency electrical oscillators |
| GB769959A (en) * | 1954-05-31 | 1957-03-13 | Csf | Improvements in or relating to ultra high frequency oscillators |
| GB1078508A (en) * | 1965-08-09 | 1967-08-09 | English Electric Valve Co Ltd | Improvements in or relating to magnetrons |
| GB1095717A (en) * | 1964-09-29 | 1967-12-20 | Litton Industries Inc | Tunable microwave electron discharge devices |
| GB1149008A (en) * | 1966-08-10 | 1969-04-16 | Westinghouse Electric Corp | Coaxial magnetron |
| GB1296958A (en) * | 1970-06-15 | 1972-11-22 | ||
| US4234855A (en) * | 1978-02-02 | 1980-11-18 | Societa Italiana Telecomunicazioni Siemens S.P.A. | System for linearly tuning a microwave oscillator |
-
1984
- 1984-06-14 GB GB08415215A patent/GB2192310B/en not_active Expired
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB592929A (en) * | 1942-05-01 | 1947-10-03 | Western Electric Co | Improvements in or relating to magnetron apparatus for producing high frequency electrical oscillations |
| GB622057A (en) * | 1944-05-24 | 1949-04-26 | Philips Nv | Improvements in resonant circuits for use with ultra-short waves |
| GB627340A (en) * | 1944-06-02 | 1949-08-08 | Philips Nv | Improvements in or relating to tunable electric resonators |
| GB635574A (en) * | 1946-05-08 | 1950-04-12 | Standard Telephones Cables Ltd | Electron discharge devices of the magnetron type |
| GB708833A (en) * | 1951-07-30 | 1954-05-12 | Gen Electric Co Ltd | Improvements in or relating to high frequency electrical oscillators |
| GB769959A (en) * | 1954-05-31 | 1957-03-13 | Csf | Improvements in or relating to ultra high frequency oscillators |
| GB1095717A (en) * | 1964-09-29 | 1967-12-20 | Litton Industries Inc | Tunable microwave electron discharge devices |
| GB1078508A (en) * | 1965-08-09 | 1967-08-09 | English Electric Valve Co Ltd | Improvements in or relating to magnetrons |
| GB1149008A (en) * | 1966-08-10 | 1969-04-16 | Westinghouse Electric Corp | Coaxial magnetron |
| GB1296958A (en) * | 1970-06-15 | 1972-11-22 | ||
| US4234855A (en) * | 1978-02-02 | 1980-11-18 | Societa Italiana Telecomunicazioni Siemens S.P.A. | System for linearly tuning a microwave oscillator |
Non-Patent Citations (1)
| Title |
|---|
| INTRODUCTION TO RADAR SYSTEMS M.I. SKOLNIK, MCGRAW-HILL 1962 PP. 208-9 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2697948A1 (en) * | 1992-11-10 | 1994-05-13 | Commissariat Energie Atomique | Device forming an artificial capacitive surface admittance, application to the realization of two-dimensional cavities, resonators and antennas. |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2192310B (en) | 1988-05-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| NO20005772D0 (en) | The mobile communication apparatus | |
| CA2144291A1 (en) | Control Target Surveillance System | |
| AU3013489A (en) | Radio frequency transceiver apparatus | |
| IE900871L (en) | Frequency control apparatus for a digital radio receiver | |
| EP0302455A3 (en) | Booster | |
| CA2072792A1 (en) | Radio transceiver and related method of frequency control | |
| GB1567065A (en) | Antenna system with automatic depolarzation correction | |
| AU553652B2 (en) | Frequency-hopping radio communications | |
| GB2192310A (en) | Tunable RF cavity device | |
| GB673050A (en) | Improvements in or relating to radio range-indicating systems | |
| JPH07202601A (en) | Radio transceiver | |
| JPH0457123B2 (en) | ||
| DE3373247D1 (en) | Tuner for a communication apparatus | |
| AU7445591A (en) | Method and apparatus for tuning and matching an nmr coil | |
| AU8489391A (en) | Radio communication apparatus capable of producing an announce with a reduced error | |
| ES454917A1 (en) | Process for preparing oxazolo{8 3,2-a{9 pyrrolo{8 2,1-c{9 pyrazine derivatives | |
| GB2248950A (en) | A voltage step up regulator | |
| ATA502680A (en) | Phase compensated controlled oscillator for e.g. colour TV - has filter network arranged in feedback loop of amplifier for eliminating phase shift caused by parasitic capacitance | |
| FR2453552A1 (en) | Mobile radio broadcast relay - uses radio sound to frequency modulate selected oscillator generated VHF carrier | |
| JPS5348609A (en) | Afc unit | |
| GB2167258A (en) | Optical communications system | |
| JPS5597749A (en) | Information signal transmitter | |
| GB2258961A (en) | Frequency control system | |
| JPH03133201A (en) | Dielectric resonator controlled oscillator | |
| JPS6484927A (en) | Burst synchronizing system for time division multiple access satellite communication system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930614 |