US2884630A - Aerial assembly - Google Patents
Aerial assembly Download PDFInfo
- Publication number
- US2884630A US2884630A US647899A US64789957A US2884630A US 2884630 A US2884630 A US 2884630A US 647899 A US647899 A US 647899A US 64789957 A US64789957 A US 64789957A US 2884630 A US2884630 A US 2884630A
- Authority
- US
- United States
- Prior art keywords
- reflector
- aerial
- radiation
- main reflector
- plates
- 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.)
- Expired - Lifetime
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/12—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems
- H01Q3/14—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems for varying the relative position of primary active element and a refracting or diffracting device
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
- H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
- H01Q19/12—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
- H01Q25/002—Antennas or antenna systems providing at least two radiating patterns providing at least two patterns of different beamwidth; Variable beamwidth antennas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/01—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the shape of the antenna or antenna system
Definitions
- micro-wave aerial assemblies consist of a wave guide or co-axial feed which directs the microwave radiation at a reflector, and a dipole aerial may be used in conjunction with the wave guide or co-axial feed.
- the term aerial will be used hereafter as a general description of the source from which transmitted radiation is directed at a reflector in an aerial assembly.
- a particular application of the invention is to an aerial assembly for an airborne search radar system, where it is required to have a pattern of radiation in the form of a pencil beam for the location of airborne objects and an alternative pattern of radiation in the form of a beam obeying the cosecant-squared law for eflicient map reading of the ground below.
- a feature of my invention is a micro-wave aerial assembly for providing at least two alternative required patterns of radiation, comprising an aerial, a main reflector for determiningone of said required patterns of radiation, an auxiliary reflector, and means for effecting movement of the auxiliary reflector, through the main reflector, between two alternative positions, in a first of which the main reflector is located between the auxiliary reflector and the areial and in which the auxiliary reflector has negligible eflect on the required pattern of radiation determined by the main reflector and in the second of which positions the auxiliary reflector is located between the main reflector and the aerial and determines an alternative required pattern of radiation.
- Figure 1 is a diagrammatic front elevation of an aerial assembly constructed on known principles
- Figure 2 is a sectional side elevation of the reflector portions thereof.
- Figure 3 is a similar view to Figure 2, but showing one embodiment of my invention.
- Figures 4 and 5 show a sectional side elevation and a rear elevation respectively of another embodiment of my invention.
- an aerial A (not shown in detail), with the electric vector E orientated in the direction shown by the arrow, is mounted at or near the focal point of a main reflector B designed according to known principles to produce one required pattern of radiation.
- An auxiliary reflector C in the form of a series of thin parallel plates is mounted within the main reflector B. These plates are successively spaced apart by less than one-half wavelength and have leading edges which determine an alternative required pattern of radiation when the plates are positioned with respect to the feed from A so that the voltage vector of the incident radiation is parallel to them (as in Figure 1). Under these conditions, the plates behave as wave guides beyond cut-off and radiation is reflected from them in the vicinity of their leading edges.
- This change of relative position between the aerial A and the auxiliary reflector C can be effected by causing A or C to be rotatable.
- FIG. 3 One embodiment of the invention is shown in Figure 3.
- the main reflector B has vertical narrow slots through which may pass the plates of the auxiliary reflector C, the aerial (not shown) being mounted at or near the focal point of the main reflector B.
- a front elevation would be the same as Figure 1, the plates of reflector C protruding between the main reflector and the aerial, so that the auxiliary reflector determines the alternative required pattern of radiation, whereas by swinging the plates about a pivot D, the reflector C may be moved to a position to the rear of the main reflector, as in Figure 3, where C has negligible effect on the pattern of radiation determined by the main reflector B.
- the slots are very narrow compared with wavelength and are parallel to the voltage vector of the incident radiation. The slots thus have negligible effect on the pattern of radiation determined by the main reflector.
- the auxiliary reflector C may be in the form of a grating and its movement may be eflfected alternatively by sliding the plates through the slots in the main reflector instead of pivoting them as in the assembly of Figure 3. Such an arrangement is shown in Figures 4 and 5, in which the auxiliary reflector C slides on guides F through the main reflector B.
- the pattern of radiation from the aerial determined by the main reflector may be in the form of a pencil beam and the alternative pattern of radiation determined by the auxiliary reflector may be in the form of a beam obeying the so-called cosecant-squared law.
- This invention is also applicable to aerial assemblies in which the auxiliary reflector is so large that it is impracticable to rotate it according to known methods of beam switching, and where it is not permissible to rotate the feed because of unwanted effects from the resultant change of polarisation.
- a micro-wave aerial assembly for providing at least two alternative required patterns of radiation, comprising an aerial, a main reflector for determining one of said required patterns of radiation, an auxiliary reflector, and means for effecting movement of the auxiliary reflector, through the main reflector, between two alternative positions, in a first of which the main reflector is located between the auxiliary reflector and the aerial and in which the auxiliary reflector has negligible effect on the required pattern of radiation determined by the main reflector and in the second of which positions the auxiliary reflector is located between the main reflector and the aerial and determines an alternative required pattern of radiation.
- An aerial assembly according to claim 1, comprising pivoting means near an edge of the main reflector, the auxiliary reflector being pivotable about said pivoting means between said first and second positions.
- An aerial assembly according to claim 1, comprising means for slidably moving the auxiliary reflector through the main reflector between said first and second positions.
- auxiliary reflector comprises a plurality of thin plates having leading edges which determine the reflecting surface, said plates being substantially parallel and being successively spaced apart by a distance less than one-half wavelength, the main reflector having narrow slots through which the plates are movable, and in which radiation transmitted by the aerial has a voltage vector which is parallel with said plates.
- auxiliary reflector comprises a plurality of thin plates having leading edges which determine the reflecting surface, said plates being substantially parallel and being successively spaced apart by a distance less than onehalf wavelength, the main reflector having narrow slots through which the plates are movable, and in which radiation transmitted by the aerial has a voltage vector which is parallel with said plates.
Landscapes
- Aerials With Secondary Devices (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
Description
April 28, 1959 i A. G. G. H. ROBINSON 2,384,630
AERIAL ASSEMBLY Filed March 22, 1957 I 2 Sheets-Shet 1 Inventor April 2 8, 1959 A. G. G; H. ROBINSON 2,884,630
AERIAL ASSEMBLY Filed March 22, 1957 2 Sheets-Shet 2 Inventor Q tkM QoHnson A Item e y;
United States Patent AERIAL ASSEMBLY Arthur G. G. H. Robinson, Malmesbury, England, asflglllol to E. K. Cole Limited, Southend-on-Sea, Eng- Application March 22, 1957, Serial No. 647,899
Claims priority, application Great Britain March 27, 1956 9 Claims. (Cl. 343-756) Many micro-wave aerial assemblies consist of a wave guide or co-axial feed which directs the microwave radiation at a reflector, and a dipole aerial may be used in conjunction with the wave guide or co-axial feed. The term aerial will be used hereafter as a general description of the source from which transmitted radiation is directed at a reflector in an aerial assembly.
It is sometimes desired readily to change from one required pattern of radiation to another and an object of the present invention is to provide that facility.
A particular application of the invention is to an aerial assembly for an airborne search radar system, where it is required to have a pattern of radiation in the form of a pencil beam for the location of airborne objects and an alternative pattern of radiation in the form of a beam obeying the cosecant-squared law for eflicient map reading of the ground below.
A feature of my invention is a micro-wave aerial assembly for providing at least two alternative required patterns of radiation, comprising an aerial, a main reflector for determiningone of said required patterns of radiation, an auxiliary reflector, and means for effecting movement of the auxiliary reflector, through the main reflector, between two alternative positions, in a first of which the main reflector is located between the auxiliary reflector and the areial and in which the auxiliary reflector has negligible eflect on the required pattern of radiation determined by the main reflector and in the second of which positions the auxiliary reflector is located between the main reflector and the aerial and determines an alternative required pattern of radiation.
The above and other features of the invention will be more readily understood by a perusal of the following description having reference to the accompanying drawings in which Figure 1 is a diagrammatic front elevation of an aerial assembly constructed on known principles, and, Figure 2 is a sectional side elevation of the reflector portions thereof. Figure 3 is a similar view to Figure 2, but showing one embodiment of my invention. Figures 4 and 5 show a sectional side elevation and a rear elevation respectively of another embodiment of my invention.
In Figures 1 and 2 an aerial A (not shown in detail), with the electric vector E orientated in the direction shown by the arrow, is mounted at or near the focal point of a main reflector B designed according to known principles to produce one required pattern of radiation. An auxiliary reflector C in the form of a series of thin parallel plates is mounted within the main reflector B. These plates are successively spaced apart by less than one-half wavelength and have leading edges which determine an alternative required pattern of radiation when the plates are positioned with respect to the feed from A so that the voltage vector of the incident radiation is parallel to them (as in Figure 1). Under these conditions, the plates behave as wave guides beyond cut-off and radiation is reflected from them in the vicinity of their leading edges. When the plates of reflector C occupy a position at right angles to that which they occupy in Figure 1 (the aerial ice remaining in the same position), they have negligible etfect on the pattern of radiation determined by the main reflector, the radiation passing between them and being reflected by the main reflector B.
This change of relative position between the aerial A and the auxiliary reflector C and can be effected by causing A or C to be rotatable.
One embodiment of the invention is shown in Figure 3. In this case the main reflector B has vertical narrow slots through which may pass the plates of the auxiliary reflector C, the aerial (not shown) being mounted at or near the focal point of the main reflector B. When the auxiliary reflector C is in effective operation, a front elevation would be the same as Figure 1, the plates of reflector C protruding between the main reflector and the aerial, so that the auxiliary reflector determines the alternative required pattern of radiation, whereas by swinging the plates about a pivot D, the reflector C may be moved to a position to the rear of the main reflector, as in Figure 3, where C has negligible effect on the pattern of radiation determined by the main reflector B. The slots are very narrow compared with wavelength and are parallel to the voltage vector of the incident radiation. The slots thus have negligible effect on the pattern of radiation determined by the main reflector.
The auxiliary reflector C may be in the form of a grating and its movement may be eflfected alternatively by sliding the plates through the slots in the main reflector instead of pivoting them as in the assembly of Figure 3. Such an arrangement is shown in Figures 4 and 5, in which the auxiliary reflector C slides on guides F through the main reflector B.
The pattern of radiation from the aerial determined by the main reflector may be in the form of a pencil beam and the alternative pattern of radiation determined by the auxiliary reflector may be in the form of a beam obeying the so-called cosecant-squared law.
This invention is also applicable to aerial assemblies in which the auxiliary reflector is so large that it is impracticable to rotate it according to known methods of beam switching, and where it is not permissible to rotate the feed because of unwanted effects from the resultant change of polarisation.
I claim:
1. A micro-wave aerial assembly for providing at least two alternative required patterns of radiation, comprising an aerial, a main reflector for determining one of said required patterns of radiation, an auxiliary reflector, and means for effecting movement of the auxiliary reflector, through the main reflector, between two alternative positions, in a first of which the main reflector is located between the auxiliary reflector and the aerial and in which the auxiliary reflector has negligible effect on the required pattern of radiation determined by the main reflector and in the second of which positions the auxiliary reflector is located between the main reflector and the aerial and determines an alternative required pattern of radiation.
2. An aerial assembly according to claim 1, comprising pivoting means near an edge of the main reflector, the auxiliary reflector being pivotable about said pivoting means between said first and second positions.
3. An aerial assembly according to claim 1, comprising means for slidably moving the auxiliary reflector through the main reflector between said first and second positions.
4. An aerial assembly according to claim 2, in which the auxiliary reflector comprises a plurality of thin plates having leading edges which determine the reflecting surface, said plates being substantially parallel and being successively spaced apart by a distance less than one-half wavelength, the main reflector having narrow slots through which the plates are movable, and in which radiation transmitted by the aerial has a voltage vector which is parallel with said plates.
5. An aerial assembly according to claim 3, in which the auxiliary reflector comprises a plurality of thin plates having leading edges which determine the reflecting surface, said plates being substantially parallel and being successively spaced apart by a distance less than onehalf wavelength, the main reflector having narrow slots through which the plates are movable, and in which radiation transmitted by the aerial has a voltage vector which is parallel with said plates.
6. An aerial assembly according to claim 4, in which the main reflector is of the paraboloid type, the aerial being situated at least in the near vicinity of the focal point of the main reflector.
7. An aerial assembly according to claim 5, in which the main reflector is of the paraboloid type, the aerial be- 4 ing situated at least in the near vicinity of the focal point of the main reflector.
8. An aerial assembly according to claim 2, in which in said first position, the required pattern of radiation comprises a pencil beam and in which, in said second position, the alternative required pattern of radiation comprises a beam obeying the so-called cosecant-squared law.
9. An aerial assembly according to claim 3, in which in said first position, the required pattern of radiation comprises a pencil beam and in which, in said second position, the alternative required pattern of radiation comprises a beam obeying the so-called cosecant-squared law.
Bohnert et al. Oct. 9, 1951 Sichak Apr. 23, 195
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2884630X | 1956-03-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2884630A true US2884630A (en) | 1959-04-28 |
Family
ID=10917137
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US647899A Expired - Lifetime US2884630A (en) | 1956-03-27 | 1957-03-22 | Aerial assembly |
Country Status (3)
Country | Link |
---|---|
US (1) | US2884630A (en) |
DE (1) | DE1051918B (en) |
FR (1) | FR1173344A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4851858A (en) * | 1984-01-26 | 1989-07-25 | Messerschmitt-Boelkow-Blohm Gmbh | Reflector antenna for operation in more than one frequency band |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2570197A (en) * | 1949-06-16 | 1951-10-09 | John I Bohnert | Dual purpose antenna |
US2790169A (en) * | 1949-04-18 | 1957-04-23 | Itt | Antenna |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2680810A (en) * | 1952-02-12 | 1954-06-08 | Us Army | Microwave antenna system |
-
1957
- 1957-03-22 US US647899A patent/US2884630A/en not_active Expired - Lifetime
- 1957-03-25 DE DEC14572A patent/DE1051918B/en active Pending
- 1957-03-26 FR FR1173344D patent/FR1173344A/en not_active Expired
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2790169A (en) * | 1949-04-18 | 1957-04-23 | Itt | Antenna |
US2570197A (en) * | 1949-06-16 | 1951-10-09 | John I Bohnert | Dual purpose antenna |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4851858A (en) * | 1984-01-26 | 1989-07-25 | Messerschmitt-Boelkow-Blohm Gmbh | Reflector antenna for operation in more than one frequency band |
Also Published As
Publication number | Publication date |
---|---|
FR1173344A (en) | 1959-02-24 |
DE1051918B (en) | 1959-03-05 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3413637A (en) | Multifunction antenna having selective radiation patterns | |
Van Atta et al. | Contributions to the antenna field during World War II | |
US2736895A (en) | High frequency radio aerials | |
Duan et al. | Scattering from a circular disk: A comparative study of PTD and GTD techniques | |
US2884630A (en) | Aerial assembly | |
US2925595A (en) | Monopulse transmitting and receiving systems | |
US2597391A (en) | Antenna | |
Ohba | On the radiation pattern of a corner reflector finite in width | |
US3364490A (en) | Variable beamwidth antennas utilizing defocusing | |
US3242491A (en) | Inverted v-beam antenna system | |
US2187618A (en) | Radio beacon system | |
US2637847A (en) | Polarizing antenna for cylindrical waves | |
GB1416364A (en) | Generation of scanning radio beans | |
US2597339A (en) | Directional antenna | |
US2663016A (en) | Microwave antenna | |
US3044067A (en) | Aerial system having variable directional properties | |
US2028510A (en) | Transmitter for electromagnetic waves | |
GB817714A (en) | Aerial assembly | |
US3092834A (en) | Split parabolic radar antenna utilizing means to discriminate against crosspolarized energy | |
RU2662506C1 (en) | "antenna-fairing" system | |
Zavodny et al. | Primary surveillance radar of RSP-10M system | |
GB893008A (en) | Frequency sensitive rapid scanning antenna | |
Bach et al. | Comparison of three cross-polarisation prediction methods for reflector antennas | |
US2842766A (en) | Beam-shaping antenna systems | |
US2821707A (en) | Directional antenna |