GB2163909A - Beacon tracking system - Google Patents
Beacon tracking system Download PDFInfo
- Publication number
- GB2163909A GB2163909A GB08521498A GB8521498A GB2163909A GB 2163909 A GB2163909 A GB 2163909A GB 08521498 A GB08521498 A GB 08521498A GB 8521498 A GB8521498 A GB 8521498A GB 2163909 A GB2163909 A GB 2163909A
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- GB
- United Kingdom
- Prior art keywords
- mode
- waveguide
- auxiliary
- antenna
- pair
- 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.)
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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
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/213—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies
- H01P1/2131—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies with combining or separating polarisations
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
- G01S3/28—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics
- G01S3/32—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics derived from different combinations of signals from separate antennas, e.g. comparing sum with difference
- G01S3/325—Automatic tracking systems
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/16—Auxiliary devices for mode selection, e.g. mode suppression or mode promotion; for mode conversion
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
Abstract
A beacon tracking system for an antenna 1 comprises a mode coupler 2 having a central waveguide 3 located in the antenna feed chain, and at least two pairs of diametrically opposite rectangular auxiliary waveguides 7, 8 coupled to the central waveguide 3. Each of the auxiliary waveguides 7, 8 is designed to extract, at the beacon frequency, a fundamental mode and a higher order mode resulting from off-axis signals, which combine to produce a resultant radiation pattern lobe representative of antenna boresight deviation, in the azimuth and elevation planes, in respective pairs. An electronic switching device 12 operates to connect the outputs from the auxiliary waveguides 7, 8 in a predetermined repetitive sequence to a tracking receiver 13 which analyses the outputs in turn to provide antenna pointing error correction signals DELTA x and DELTA y by effectively comparing the amplitude of the radiation pattern lobe in each auxiliary waveguide 7, 8 with the boresight amplitude. <IMAGE>
Description
SPECIFICATION
Beacon tracking system
In communications systems, particularly satellite communications systems, in which microwave RF signals are received or relayed by an antenna, it is essential for efficient operation of the system that the axis of the antenna is maintained pointing in a predetermined direction. When the antenna is pointing correctly it is said to be on boresight and even small deviations of the antenna off boresight lead to a marked decrease in signal strength and purity.
Consequently, such antennas are provided with an automatic tracking system designed to detect any pointing error and to correct the direction of the antenna accordingly.
Tracking systems are well known in which a discreet beacon signal is used and the pointing error is detected from one or more higher order modes propagated in addition to the fundamental mode from the beacon signal in the antenna feed chain when the antenna is off boresight. The modes required to derive the tracking information are extracted from the antenna feed chain using a suitable mode coupler, and are processed by a tracking receiver to derive error signals which represent the magnitude and direction of the pointing error and which are used to correct the antenna direction.In most of these systems the higher order modes required for tracking are isolated from each other and from the beacon fundamental mode before deriving the pointing error signals, and while the systems are generally very sensitive, they tend to be rather bulky and also require complex tracking receivers which render the systems extremely expensive. An example of such a tracking system is described in European patent specification number 0,014,692.
The aim of the present invention is to provide a beacon tracking system which, although perhaps not quite as sensitive as the above monopulse tracking systems (i.e. operating with a deep null on boresight), can be realised relatively inexpensively.
To this end, according to the invention, a beacon tracking system for a microwave communications antenna comprises a mode coupler having a central waveguide which forms part of the antenna feed chain and receives the fundamental and higher order modes generated by the horn in response to off axis signals received by the horn, and at least two pairs of diametrically opposite rectangular auxiliary waveguides coupled to the periphery of the central waveguide and containing filter means for rejecting the communication band frequencies but not the beacon frequency, the auxiliary waveguides being positioned and arranged so that, for off axis signals of a given polarisation, each auxiliary waveguide of one pair extracts at the beacon frequency a fundamental mode and a higher order mode which combine in the auxiliary waveguide to produce a resultant radiation pattern lobe representative of the antenna boresight deviation in the azimuth plane, and each auxiliary waveguide of another pair extracts at the beacon frequency a fundamental mode and a higher order mode which combine in the auxiliary waveguide to produce a resultant radiation pattern lobe representative of the antenna boresight deviation in the elevation plane, and a tracking receiver which is arranged to be connected to the outputs of the auxiliary waveguides in a repetitive predetermined sequence by switching means and which determines the pointing error and appropriate correction signals from the amplitudes of the radiation pattern lobes in the auxiliary wave guides relative to the boresight amplitude. As will be appreciated, the auxiliary waveguides of each diametrically opposite pair extract the same fundamental and higher order modes as each other, but with one or other in opposite phase, and enable the direction of the boresight deviation in the azimuth or elevation plane to be determined.
With a tracking system in accordance with the invention, although the higher order modes used for tracking are extracted separately from each other, they are each extracted with a fundamental mode and are not separated therefrom for processing by the receiver. The tracking receiver does not therefore operate by reference to a deep null on boresight, but instead carries out a sequence of radiation pattern amplitude comparisons and slope evaluations relative to the boresight condition directly from the auxiliary waveguide outputs. A tracking receiver capable of doing this is relatively simple and inexpensive to provide, and is well within the capabilities of an ordinary skilled person in that field.
The number and positions of the auxiliary waveguide pairs required will depend on the signal polarisation with which the antenna is to be used, which may be single linear (vertical or horizontal), dual linear, or circular; the higher order modes which are to be extracted in addition to the fundamental modes and which will usually be selected from those which cut off relatively close to the fundamental mode and which will propagate as the fundamental TE1o rectangular mode in the auxiliary waveguide; and the phase relationships required between the higher order tracking modes and the fundamental modes at the beacon frequency in the coupling planes, which is either in phase or antiphase and is determined by the distances of the coupling planes from the aperture of the horn.
For a circular waveguide system and a linearly polarised beacon signal the required tracking information can be obtained using the orthogonal TE21(H) and TE21(V) higher order modes, and for this purpose the mode coupler may have a first pair of the auxiliary waveguides extending at right angles to the direction of polarisation and coupled longitudinally to the central waveguide for extracting the TE21(H) mode with the fundamental TE mode corresponding to the direction of polarisation, and a second pair of the auxiliary waveguides extending at 45 degrees with respect to the first pair and coupled longitudinally to the central waveguide in the same transverse coupling plane as the first pair of auxiliary wave guides for extracti ng th e TE2,(V) mode with the same fundamental TE11 mode as the first pair.
Alternatively, the tracking information may be obtained using the TE21(H) and TM01 higher order modes, and in this case the mode coupler may have a first pair of the auxiliary waveguides extending at right angles to the direction of polarisation and coupled longitudinally to the central waveguide for extracting the TE2, (H) mode with the fundamental TE71 mode corresponding to the direction of polar isation, and a second pair of the auxiliary waveguides extending in the direction of polarisation and coupled transversely to the central waveguide in a coupling plane which is spaced axially from that of the first pair of auxiliary waveguides for extracting the TMo1 mode and the same fundamental TEI1 mode as the first pair.
In each of the above cases, by providing the mode coupler with the auxiliary waveguide pairs required for tracking both vertical and horizontal linearly polarised signals, the tracking system will be capable of tracking dual linearly polarised and circularly polarised signals.
Preferably the mode coupler is designed so that the fundamental mode and the higher order mode coupled at each auxiliary waveguide are coupled at substantially equal amplitudes. In other words, the higher order mode coupling level shouid be designed to be as high as possible and thefundamen- tal mode coupling level should be suitably reduced since the strength of the fundamental mode in the central waveguide is inherently greater than that of the higher order modes and this would otherwise be reflected in the corresponding coupled modes in the auxiliary waveguide.By reducing the coupling level of the fundamental mode in this way the amplitude difference between the combined radiation pattern peak and the boresight peak is greater than it would otherwise have been, thus increasing the strength of the pointing error signal which is processed by the receiver.
In connection with this, the central waveguide of the mode coupler preferably includes mode reflecting filter means which provides a short circuit reflecting plane for the higher order mode which is to be extracted by each diametrically opposite pair of auxiliary waveguides, the plane being spaced downstream (i.e. in the receive direction of the antenna) from the coupling plane defined by the relevant auxiliary waveguide pair by a distance such as to produce constructive interference in the coupling plane between the incident and reflected higher order mode at the beacon frequency, thus maximising the coupling efficiency of the higher order mode.
Similarly, the mode reflecting filter means may provide a short circuit reflecting plane for the fundamental mode at the beacon frequency (but not of course atthe communication channel frequencies), and the coupling level of the fundamental mode to the auxiliary waveguides can be controlled by the positioning of this reflecting plane.
As will be appreciated, the efficient operation of the tracking system in accordance with the invention, at least with linearly polarised signals, is dependent upon the correct orientation of the mode coupler with respect to the polarisation direction of the signals received by the antenna. Preferably therefore the tracking system is provided with a polarisation sensor which is designed to detect any angular displacement of the antenna feed chain (and hence the mode coupler) relative to the beacon signal polarisation, and means responsive to the polarisation sensor for providing appropriate signals for correcting the orientation of the antenna.The polarisation sensor may take the form of a rectangular waveguide which, in use, is coupled longitudinalliy to the central waveguide of the antenna feed chain in an angular position relative to the auxiliary waveguides of the mode coupler such that it will sense unwanted polarisation components which will occur if the antenna rotates from the correct orientation, and the output from the polarisation sensor may be connected to the correction signal supply means via the switching means. Conveniently, the polarisation sensor may be coupled to the mode reflecting filter section of the mode coupler.
Some examples of the tracking system in accordance with the invention will now be described briefly with reference to the accompanying diagrammatic drawings, in which:
Figure lisa perspective view of the RF feed chain of a reflector antenna fitted with an example of a tracking system in accordance with the invention designed for operation with a vertical linearly polarised beacon signal;
Figure 2 is a transverse section through the mode coupler of Figure 1 indicating the modes which are coupled from the central circular waveguide to the rectangular auxiliary waveguides;
Figures 3a to 3d are diagrams illustrating how the radiation patterns of the modes coupled to the auxiliary waveguides of Figures 1 and 2 combine to produce resultant pattern lobes in the auxiliary waveguides from which the tracking information can be derived;;
Figure 4 is a view similar to that of Figure 2, but showing the arrangement of the auxiliary waveguides and the modes coupled thereto in the mode coupler of a similar tracking system for operation with a horizontal linearly polarised beacon signal;
Figure 5is a perspective view of the mode coupler of a further example of the tracking system for tracking with a vertical linearly polarised beacon;
Figure 6 is a view similar to that of Figure 5 but showing the mode coupler of the corresponding system for tracking with a horizontal linearly polarised beacon; and
Figure 7 is a view similar to those of Figures 5 and 6 but showing the mode coupler of the corresponding system for tracking with dual linearly polarised or circularly polarised beacon signals.
The antenna feed chain shown in Figure lisa circular waveguide system and is designed to cater for both the down link and up link frequency bands of a satellite communications system, and a beacon frequency which is below the lower frequency down link band. For example, the down link band may be from 12.5 to 12.75 GHz, the up link band from 14.25 to 14.5 GHz, and the beacon frequency may be 11.45
GHz.
As shown, the feed chain comprises a corrugated conical horn 1 which generates the fundamental HE11 mode when the antenna is on boresight, and generates this fundamental mode and the higher order HE21 and E02 modes when the antenna is off boresight. The throat of the horn 1 is connected by a suitable matching section to the central smoothwalled circular waveguide 3 of a tracking mode coupler 2 which includes a tapering mode reflecting filter section 4, and this filter section 4 is connected to a polariser 5 which, in turn, is connected to a conventional orthogonal mode transducer 6 for inserting and extracting the transmitted and received signals Tx and Rx respectively in the communication frequency bands.
The HE, HE21, and E02 modes in the horn 1 become the TE11, TE21, and TM01 modes in the smooth walled circular waveguide 3 of the mode coupler 2, and in this example the mode coupler 2 has two pairs 7 and 8 of diammetrically opposite matching rectangular auxiliary waveguides coupled to the central waveguide 3 for extracting the TE11 and TE21 modes at the beacon frequency for tracking purposes. Each auxiliary waveguide 7, 8 includes filter means (represented by the dots 9) for rejecting signals at frequencies in the communication bands, and is coupled longitudinally to the central circular waveguide 3, i.e. via a coupling aperture or port P which extends parallel to the axis of the central waveguide 3.The coupling apertures of the diammetrically opposite pair of auxiliary waveguides 7 (ports P1 and P2) are positioned to extract the TE11(V) fundamental mode and opposite phases of the higher orderTE21(H) mode as indicated in Figure 2, and the coupling apertures (ports P3 and P4) of the diammetrically opposite pair of auxiliary waveguides 8, which extend from the central waveguide 3 at an angle of 45 degrees with respect to the waveguides 7, are positioned to extract the TE11(V) fundamental mode and opposite phases of the higher order TE21(V) mode.The plane of the coupling apertures or ports P1 - P4 is positioned at an axial distance from the aperture 10 of the horn 1 such that there will be a quadrature phase difference between the TE11 and TE21 modes over this distance at the beacon frequency.
The outputs from the auxiliary waveguides 7 and 8 are conducted via co-axial cables 11 as indicated to an electronic switching unit 12 which operates to connect the outputs in sequence to a tracking receiver 13 at a predetermined sampling rate, which may be up to twenty thousand times per second. The tracking receiver 13 is synchronised with the switching unit 12 and analyses the output as described earlier to determine the mangitude and direction of any pointing error and to provide azimuth and elevation correction signals Ax and Ay for driving the antenna steering system. Further details of the switching unit and the tracking receiver are not described since it is considered that devices suitable for carrying out the described functions can easily be constructed by competent electronics and tracking receiver engineers using known techniques.
As indicated in Figures 3a to 3d, the output from each auxiliary waveguide has a radiation pattern which is the resultant of combining the radiation patterns of the fundamental and higher order modes extracted by the auxiliary waveguide, and has characteristics (i.e. amplitude and slope) determined by the direction and magnitude of the antenna deviation from boresight. For example, Figure 3a shows a resultant radiation pattern lobe of the output from the auxiliary waveguide 7 into which the
TE11(V) and TE21(H) modes are coupled in phase by port P1, and provides vertical polarisation azimuth plane tracking information for pointing error to the left.Figure 3b shows a resultant radiation pattern lobe of the output from the auxiliary waveguide 7 into which the TE11(V) and TE21(H) modes are coupled in antiphase by port P2, and provides vertical polarisation azimuth plane tracking information for pointing error to the right. Figure 3c shows a resultant radiation pattern lobe of the output from the auxiliary waveguide 8 into which the TE11(V) and
TE21(V) modes are coupled in phase by port P3, and provides vertical polarisation elevation plane tracking information for pointing error upwards.Figure 3d shows a resultant radiation pattern lobe of the output from the auxiliary waveguide 8 into which the
TE11(V) and TE2,(V) modes are coupled in antiphase by port P4, and provides vertical polarisation elevation plane tracking information for pointing error downwards.
The tapering mode reflecting filter section 4 of the mode coupler 2 is designed to reflect all modes except the fundamental TE11 modes at the communication channel frequencies, providing a reflection plane for the TE21 modes at the beacon frequency in a position to maximise the coupling efficiency of the
TE21 modes to the auxiliary waveguides 7 and 8. The filter section 4 also provides a reflecting plane for the
TE11 mode at the beacon frequency, but in a position such that, in conjunction with the ports P1 - P4, the coupling efficiency of the TE11(V) mode at the beacon frequency is relatively moderate so that the amplitudes of the coupled TE11 and TE21 modes in the auxiliary waveguides are substantially the same.
As shown in Figure 1, mounted on the mode reflecting filter section 4 is a further rectangular auxiliary waveguide 14 which is arranged to act as a polarisation sensor. This further rectangular waveguide 14 also has filter means for rejecting all frequencies other than the beacon frequency, and is coupled longitudinally to the filter section 4 by a port P5 in a plane perpendicular to that containing the pair of auxiliary waveguides 7.The polarisation sensorwaveguide 14 will detect the presence of the unwanted TE11(H) mode which will occur if the antenna rotates from the correct alignment with respect to the polarisation (linear vertical) of the beacon signal, and the output from the waveguide 14 is conducted by a further co-axial cable 11 to a fifth input of the switching unit 12 so that it is regularly sampled by the tracking receiver 13 and used thereby to provide an antenna orientation correction signal A if necessary.
For tracking with a linear horizontally polarised beacon signal, the tracking system may be identical to that shown in Figure 1, except that the mode coupler 2 would be rotated through 90 degrees to move the auxiliary waveguides 7 and 8 to the positions shown in Figure 4. In this case, the auxiliary waveguides 7 (ports 1 and 2) extract the TE11(H) fundamental mode and opposite phases of the TE21(H) higher order mode, whilethe auxiliary waveguides 8 (ports 3 and 4) extract the TE11(H) fundamental mode and opposite phases of the TE21 (V) modes.
Instead of using the TE21 (V) and TE21 (H) modes for tracking, a tracking system in accordance with the invention may usetheTE21(H) mode and the TMo1 mode, and examples of mode coup!ers suitable for this purpose for linear vertically and horizontally polarised beacon signals are shown in Figures 5 and 6 respectively.In each case, the central circular waveguide 15 has a pair of diammetrically opposite matching rectangular auxiliary waveguides 16 coupled longitudinally to the central waveguide and extending in directions perpendicular to the direction of beacon signal polarisation, and afurther pair of diammetrically opposite matching rectangular auxiliary waveguides 17 coupled transversely to the central waveguide 15 and extending in directions parallel to the direction of poiarisation. As in the previous examples each of the auxiliary waveguides 16, 17 includes filter means (not shown) for rejecting frequencies in the communication bands.The two pairs of auxiliary waveguides 16 and 17 are separated axially by a tapering section 18 of the central waveguide providing a reflecting plane for the TE2, (H) mode in a position which maximises the coupling of the mode to the auxiliary waveguides 16 atthe beacon frequency.Similarly, a further tapering section 19 of the central waveguide beyond the auxiliarywaveguides 17 provides a reflecting plane for the TM01 mode such that coupling of the TMo1 mode to the auxiliary waveguides 17 at the beacon frequency is maximised, and also a reflecting plane for the TE11 mode at the beacon frequency positioned to provide substantiallyequal amplitude coupling of the TE and TE27 modes to the auxiliary waveguides 16 and substantially equal amplitude coupling of the TE11 and TMo1 modes to the auxiliary waveguides 17. The mode couplers will also be provided with a polarisation sensor (not shown) as in the previous examples. The actual modes which are coupled to the auxiliary waveguides 16 and 17 in each case, and their relative phases, are indicated in
Figures Sand 6 adjacent the relevant waveguides.
The mode coupler shown in Figure 7 is effectively a combination of the two couplers shown in Figures 5 and 6 and is for a tracking system capable of tracking with dual linear or circularly polarised beacon signals.
Claims (13)
1. A beacon tracking system for a microwave communications antenna, comprising a mode coupler having a central waveguide which forms part of the antenna feed chain and receives the fundamental and higher order modes generated by the horn in response to off axis signals received by the horn, and atleasttwo pairs of diametrically opposite rectangular auxiliary waveguides coupled to the periphery of the central waveguide and containing filter means for rejecting the communication band frequencies but notthe beacon frequency, the auxiliary waveguides being positioned and arranged so that, for off axis signals of a given polarisation, each auxiliarywaveguide of one pair extracts at the beacon frequency a fundamental mode and a higher order mode which combine in the auxiliary waveguide to produce a resultant radiation pattern lobe representative of the antenna boresight deviation in the azimuth plane, and each auxiliary waveguide of another pair extracts at the beacon frequency a fundamental mode and a higher order mode which combine in the auxiliary waveguide to produce a resultant radiation pattern lobe representative of the antenna boresight deviation in the elevation plane, and a tracking receiver which is arranged to be connected to the outputs of the auxiliary waveguides in a repetitive predetermined sequence by switching means and which determines the pointing error and appropriate correction signals from the amplitudes of the radiation pattern lobes in the auxiliary waveguides relative to the boresight amplitude.
2. Atracking system according to claim 1,in which the central waveguide is a circular waveguide and, for tracking a linearly polarised beacon signal, the mode coupler has a first pair of the auxiliary waveguides extending at right angles to the direction of polarisation and coupled longitudinally to the central waveguide for extracting the TE21(H) mode with the fundamental TE11 mode corresponding to the direction of polarisation, and a second pair of the auxiliary waveguides extending at45 degrees with respect to the first pair and coupled longitudinally to the central waveguide in the same transverse coupling plane as the first pair of auxiliary waveguides for extracting the TE2, (V) mode with the same fundamental TE11 mode as the first pair.
3. Atracking system according to Claim 1, in which the central waveguide is a circular waveguide and,fortracking a linearly polarised beacon signal, the mode coupler has a first pair of the auxiliary waveguides extending at right angles to the direction ofpolarisation and coupled longitudinally to the central waveguide for extracting the TE21 (H) mode with the fundamental TE11 mode corresponding to the direction of polarisation, and a second pair of the auxiliary waveguides extending in the direction of polarisation and coupled transversely to the central waveguide in a coupling plane which is spaced axially from that of the first pair of auxiliary waveguides for extracting the TM01 mode and the same fundamental TE mode as the first pair.
4. Atracking system according to Claim 2 or
Claim 3, in which the mode coupler has third and fourth pairs of auxiliary waveguides which are arranged similarly to the first and second pairs respectively but are displaced 90" relative thereto aboutthe central waveguide axis, whereby the tracking system is capable of tracking dual linearly polarised and circularly polarised beacon signals.
5. Atracking system according to any one of the preceding Claims, in which the mode coupler is arranged so that the fundamental mode and the higher order mode coupled at each auxiliary waveguide are coupled at substantially equal amplitudes.
6. Atracking system according to any one of the preceding Claims, in which the central waveguide of the mode coupler includes mode reflecting filter means which provides a short circuit reflecting plane for the higher order mode which is to be extracted by each diametrically opposite pair of auxiliary waveguides, the plane being spaced downstream (i.e. in the receive direction of the antenna) from the coupling plane defined by the relevant auxiliary waveguide pair by a distance such as to produce constructive interference in the coupling plane between the incident and reflected higher order mode at the beacon frequency, thus maximising the coupling efficiency of the higher order mode.
7. Atracking system according to Claim 6, in which the mode reflecting filter means also provides a short circuit reflecting plane for the fundamental mode at the beacon frequency, the position of this reflecting plane determining the coupling level of the fundamental mode to the auxiliary waveguides.
8. Atracking system according to any one of the preceding Claims, comprising a polarisation sensor which is desigried to detect any angular displacement of the antenna feed chain (and hence the mode coupler) relative to the beacon signal polarisation, and means responsive to the polarisation sensor for providing appropriate signals for correcting the orientation of the antenna.
9. Atracking system according to Claim 8, in which the polarisation sensor comprises a rectangular waveguide which, in use, is coupled longitudinally to the central waveguide of the antenna feed chain in an angular position relative to the auxiliary waveguides of the mode coupler such that it will sense unwanted polarisation components which will occur if the antenna rotates from the correct orientation.
10. Atracking system according to Claim 9, in which the output from the polarisation sensor is connected to the correction signal supply means via the switching means.
11. A tracking system according to any one of
Claims 8 to 10 when dependent on Claim 6 or Claim 7, in which the polarisation sensor is coupled to the mode reflecting filter section of the mode coupler.
12. Atracking system according to Claim 1, substantially as described with reference to Figures 1 to 3 or any one of Figures 4 to 7 of the accompanying drawings.
13. An antenna including a beacon tracking system according to any one of the preceding Claims.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8421837 | 1984-08-29 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8521498D0 GB8521498D0 (en) | 1985-10-23 |
| GB2163909A true GB2163909A (en) | 1986-03-05 |
| GB2163909B GB2163909B (en) | 1987-11-04 |
Family
ID=10565990
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08521498A Expired GB2163909B (en) | 1984-08-29 | 1985-08-29 | Beacon tracking system |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2163909B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2625843A1 (en) * | 1988-01-13 | 1989-07-13 | Thomson Csf | MODE TRANSFORMER FOR HYPERFREQUENCY ENERGY TRANSMISSION CIRCUIT |
| GB2300274A (en) * | 1995-04-04 | 1996-10-30 | Univ Manchester | Waveguide arrangement for electromagnetic analysis of materials |
| EP1261066A2 (en) * | 2001-05-23 | 2002-11-27 | Marconi Mobile SpA | Improvements in or relating to diplexer apparatus |
| WO2012172565A1 (en) * | 2011-06-14 | 2012-12-20 | Indian Space Research Organisation | Wideband waveguide turnstile junction based microwave coupler and monopulse tracking feed system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1115660A (en) * | 1964-11-20 | 1968-05-29 | Comp Generale Electricite | Improvements in automatic tracking systems for high frequency aerials |
| EP0014692A2 (en) * | 1979-02-07 | 1980-08-20 | Telefonaktiebolaget L M Ericsson | Mode coupler in an automatic angle tracking system |
-
1985
- 1985-08-29 GB GB08521498A patent/GB2163909B/en not_active Expired
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1115660A (en) * | 1964-11-20 | 1968-05-29 | Comp Generale Electricite | Improvements in automatic tracking systems for high frequency aerials |
| EP0014692A2 (en) * | 1979-02-07 | 1980-08-20 | Telefonaktiebolaget L M Ericsson | Mode coupler in an automatic angle tracking system |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2625843A1 (en) * | 1988-01-13 | 1989-07-13 | Thomson Csf | MODE TRANSFORMER FOR HYPERFREQUENCY ENERGY TRANSMISSION CIRCUIT |
| WO1989006869A1 (en) * | 1988-01-13 | 1989-07-27 | Thomson-Csf | Mode transformer for hyper-frequency power transmission circuit |
| US5059928A (en) * | 1988-01-13 | 1991-10-22 | Thomson Csf | Mode transformer for microwave energy transmission circuit |
| GB2300274A (en) * | 1995-04-04 | 1996-10-30 | Univ Manchester | Waveguide arrangement for electromagnetic analysis of materials |
| EP1261066A2 (en) * | 2001-05-23 | 2002-11-27 | Marconi Mobile SpA | Improvements in or relating to diplexer apparatus |
| EP1261066A3 (en) * | 2001-05-23 | 2003-08-13 | Marconi Mobile SpA | Improvements in or relating to diplexer apparatus |
| WO2012172565A1 (en) * | 2011-06-14 | 2012-12-20 | Indian Space Research Organisation | Wideband waveguide turnstile junction based microwave coupler and monopulse tracking feed system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8521498D0 (en) | 1985-10-23 |
| GB2163909B (en) | 1987-11-04 |
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