CA1081845A - Beam scanning - Google Patents
Beam scanningInfo
- Publication number
- CA1081845A CA1081845A CA250,493A CA250493A CA1081845A CA 1081845 A CA1081845 A CA 1081845A CA 250493 A CA250493 A CA 250493A CA 1081845 A CA1081845 A CA 1081845A
- Authority
- CA
- Canada
- Prior art keywords
- horn
- frequency
- dielectric material
- ghz
- antenna
- 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
Links
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
- H01Q3/22—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 orientation in accordance with variation of frequency of radiated wave
-
- 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
- H01Q19/06—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 refracting or diffracting devices, e.g. lens
- H01Q19/08—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 refracting or diffracting devices, e.g. lens for modifying the radiation pattern of a radiating horn in which it is located
Abstract
Abstract A method and apparatus for non-mechanical scanning of microwave antenna beams in which the reflecting or guiding surface of a directive antenna is provided with an asymmetrically shaped insert of a frequency sensitive dielectric material so as to cause a beam angle shift dependent upon the frequency of the microwave signal being transmitted from or received by the antenna.
Description
108~845 This inyention relates ta antenna beam scanning and more particularly to a nov~l method and apparatus os the non-mechanical scanning of a microwave antenna beam using a frequency sensitive di-electric loaded directive antenna system.
Scanning of antenna beams for many different purposes, is well known in the art and employs many conventional mechanical and electronic scanning techniques. Most mechanical techniques require relatively heavy equipment which can only be operated to ~can at relatively slow speeds and are therefore unsuitable for such purposes as continuous airborne radar scanning. The scanning speed is too low to develop the required raster and the inertial force~ developed in high speed aircraft manoeuvreg tendto jam or even destroy the relatively delicate mechanical scanner. Electronic techniques generally employ relatively expensive devices such as phase shifters to accomplish a beam angle shift at a single frequency or within a very narrow frequency band of the order of + 20 MHz. Many well known designs have been developed, particularly in the field of radar where 6ector scanning at a single frequency is desirable.
However, in the field of microwave radiometry it is highly desirable to trace the signature of the target, as a function of fre-quency, in order to uniquely classify the target. For example, if the rate of frequency sweep can be carefully chosen in relation to the time constant of the radiometer and modern frequency stabilizing loops, then the target may be spatially mapped by varying the look angle while being uniquely classified at each look angle from the multi-frequency tracking data. Such a system is particularly suitable for, for example, use in a microwave radiometer scanning device for aircraft which may be used, in an analogous manner to a ~canning radar beam, to locate and identify ground installations fr~m the air even in bad weather conditions such as fog or arctic white-out.
It has been found that a beam angle 6hift can be achieved by the use of wedge shaped ~requency-sensitive dielectric inserts or coat~
-- ~81845 ings on the reflecting or quiding surface of a directive antenna. It will be appreciated by those skilled in the art that substantially all dielectric materials are frequency sensitlve in a general and very gradual manner, but as used herein the term frequency sensitive dielectric materials is intended to mean dielectric materials of fixed physical dimensions and fixed relative dielectric constant ~r within the range of frequency sweep. Thus as the frequency is swept the electrical dimensions of the dielectric insert change accordingly as discussed in more detail hereinafter. Surprisingly it has been found that the effect of the dielectric material is to réduce the wave velocity thus increasing the wave number by the square root of the relative dielectric constant and hence increase the electrical size of the dielectric wedge region over the physical size. For a fixed frequency, this is equivalent to altering the angle of the reflecting surface by an amount which is almost equal to the square root of the relative dielectric constant. The resulting electrical dimensions, and hence the radiation pattern of the antenna are sensitive to the frequency of operation within the passband, regardless of the particular shape of the antenna selected. Thus the antenna may be any design which can be made to reflect asymmetrically by placing one or more dielectric wedges on the reflecting or guiding surface thereof. If, at the centre of the frequency band the design dimensions are such that the main lobe or beam is along the principal axis of the antenna, the position of this lobe or beam will deviate from the axis and swing from one side of the axis to the other as the frequency is swept from below the centre of the band to above. In effect, from a radiation pattern point of view, the antenna is only electrically symmetrical at the centre of the frequency band of operation and is progressively asymmetrical at all other frequencies.
It is, therefore, an ob~ect of the present invention to
Scanning of antenna beams for many different purposes, is well known in the art and employs many conventional mechanical and electronic scanning techniques. Most mechanical techniques require relatively heavy equipment which can only be operated to ~can at relatively slow speeds and are therefore unsuitable for such purposes as continuous airborne radar scanning. The scanning speed is too low to develop the required raster and the inertial force~ developed in high speed aircraft manoeuvreg tendto jam or even destroy the relatively delicate mechanical scanner. Electronic techniques generally employ relatively expensive devices such as phase shifters to accomplish a beam angle shift at a single frequency or within a very narrow frequency band of the order of + 20 MHz. Many well known designs have been developed, particularly in the field of radar where 6ector scanning at a single frequency is desirable.
However, in the field of microwave radiometry it is highly desirable to trace the signature of the target, as a function of fre-quency, in order to uniquely classify the target. For example, if the rate of frequency sweep can be carefully chosen in relation to the time constant of the radiometer and modern frequency stabilizing loops, then the target may be spatially mapped by varying the look angle while being uniquely classified at each look angle from the multi-frequency tracking data. Such a system is particularly suitable for, for example, use in a microwave radiometer scanning device for aircraft which may be used, in an analogous manner to a ~canning radar beam, to locate and identify ground installations fr~m the air even in bad weather conditions such as fog or arctic white-out.
It has been found that a beam angle 6hift can be achieved by the use of wedge shaped ~requency-sensitive dielectric inserts or coat~
-- ~81845 ings on the reflecting or quiding surface of a directive antenna. It will be appreciated by those skilled in the art that substantially all dielectric materials are frequency sensitlve in a general and very gradual manner, but as used herein the term frequency sensitive dielectric materials is intended to mean dielectric materials of fixed physical dimensions and fixed relative dielectric constant ~r within the range of frequency sweep. Thus as the frequency is swept the electrical dimensions of the dielectric insert change accordingly as discussed in more detail hereinafter. Surprisingly it has been found that the effect of the dielectric material is to réduce the wave velocity thus increasing the wave number by the square root of the relative dielectric constant and hence increase the electrical size of the dielectric wedge region over the physical size. For a fixed frequency, this is equivalent to altering the angle of the reflecting surface by an amount which is almost equal to the square root of the relative dielectric constant. The resulting electrical dimensions, and hence the radiation pattern of the antenna are sensitive to the frequency of operation within the passband, regardless of the particular shape of the antenna selected. Thus the antenna may be any design which can be made to reflect asymmetrically by placing one or more dielectric wedges on the reflecting or guiding surface thereof. If, at the centre of the frequency band the design dimensions are such that the main lobe or beam is along the principal axis of the antenna, the position of this lobe or beam will deviate from the axis and swing from one side of the axis to the other as the frequency is swept from below the centre of the band to above. In effect, from a radiation pattern point of view, the antenna is only electrically symmetrical at the centre of the frequency band of operation and is progressively asymmetrical at all other frequencies.
It is, therefore, an ob~ect of the present invention to
- 2 -: . . : ,: . ~, .: ,:, :.
.
~
provide a method for electronically scanning a microwave antenna beam in a simple and inexpensive manner.
It is another ob~ect of the present invention to provide apparatus for effecting a beam angle shift in a microwave antenna beam.
By one aspect of this invention there is provided a method for non-mechanical scanning of a microwave beam which comprises providing at least one reflecting surface of a directive antenna with at least one wedge shaped layer of a frequency sensitive dielectric material and directing a multi-frequency microwave beam thereagainst to thereby effect a beam angle shift.
By another aspect of this invention there is provided an apparatus for non-mechanical scanning of a microwave beam comprising:
directive antenna means having at least one guiding or reflecting surface; and at least one wedge shaped layer of a frequency~sensitive dielectric material in planar contact with at least part of said surface to thereby effect a beam angle shift of a multi-frequency microwave beam directed thereagainst.
The invention will be described in more detail hereinafter by reference to the accompanying drawings in which:
Figure 1 is a schematic view of a symmetrical 22 U-plane sector horn antenna of conventional design;
Figure 2 is a schematic view of a horn of Figure 1 modified to be asymmetrical about its axis and loaded with a dielectric wedge on the asymmetrical narrow dimension wall;
Figure 3 is a schematic view of a horn of Figure 1 with a dielectric wedge loading on both narrow dimension walls;
Figure 4 is a graph showing beam angle deflection for a horn of Figure 2 with a dielectric wedge angle of 7.5 at 9 GHz as a
.
~
provide a method for electronically scanning a microwave antenna beam in a simple and inexpensive manner.
It is another ob~ect of the present invention to provide apparatus for effecting a beam angle shift in a microwave antenna beam.
By one aspect of this invention there is provided a method for non-mechanical scanning of a microwave beam which comprises providing at least one reflecting surface of a directive antenna with at least one wedge shaped layer of a frequency sensitive dielectric material and directing a multi-frequency microwave beam thereagainst to thereby effect a beam angle shift.
By another aspect of this invention there is provided an apparatus for non-mechanical scanning of a microwave beam comprising:
directive antenna means having at least one guiding or reflecting surface; and at least one wedge shaped layer of a frequency~sensitive dielectric material in planar contact with at least part of said surface to thereby effect a beam angle shift of a multi-frequency microwave beam directed thereagainst.
The invention will be described in more detail hereinafter by reference to the accompanying drawings in which:
Figure 1 is a schematic view of a symmetrical 22 U-plane sector horn antenna of conventional design;
Figure 2 is a schematic view of a horn of Figure 1 modified to be asymmetrical about its axis and loaded with a dielectric wedge on the asymmetrical narrow dimension wall;
Figure 3 is a schematic view of a horn of Figure 1 with a dielectric wedge loading on both narrow dimension walls;
Figure 4 is a graph showing beam angle deflection for a horn of Figure 2 with a dielectric wedge angle of 7.5 at 9 GHz as a
- 3 -r ~
function of power (db);
Figure 5 is a graph showing beam angle deflection for a horn of Figure 2 with a dielectric wedge angle of 7.5 at 10 GHz as a function of power ~db); and Figure 6 is a graph showing beam angle deflection for a horn of Figure 2 with a dlelectric wedge angle of 7.5 at 10.88 GHz as a function of power (db).
Although the present invention is applicable to antennas of substantially any practical shape and dimension, the invention will be described hereinafter with particular reference to an H-plane sector horn structure desfgned to operate in the X-band (i.e. 8-12.4 GHz), as such a structure has particular suitability to a radiometer system.
A basic H-plane sectoral horn 1 is shown in Figure 1, with a flare angle ~ of 22, as measured between the flared walls 2 and 3 and symmetrical about the axis 4 of the horn. Horn 1 is also provided with a wavegulde structure 5 in known manner. A modified horn 1 is shown in Figure 2 in which the flare angle ~ is reduced by an amount ~ (approxi-mately 5~ on one side, along wall 3 as shown in Figure 2, and measured from corner A ad~acent the throat of the waveguide 5.
The asymmetrical horn is dielectrically loaded by inserting a wedge 6 of a frequency-sensitive dielectric material such as acrylic, ertalon (Trademark for a nylon type thermoplastic material sold by Miller Plastics Ltd., 19 Advance Road, Toronto, Canada~ or polyethylene along the wall 3 with the apex of the wedge adiacent the throat A of the waveguide. The angle (a) of the wedge 6 may be altered as required and as explained in more detail hereinafter.
In an alternative embodiment, as shown in Figure 3 a symmetri-cal horn as described with reference to Figure 1 is provided with two dielectric wedges 7 and 8 adjacent walls 2 and 3 respectively. Wedges .. . . . . . .
. ~ . . .
. ,: . . :- . .: . .
.
108~845 7 and 8 may be of the same dielectric materials in which case the wedge angles are different or alternatively the dielectric materials may be different and the wedge angles the same.
In operation a microwave beam of a selected frequency range within the general frequency range 1 GHz to 150 GHz and preferably of the order of 8 - 15 GHz i9 generated within the waveguide and transmitted from the horn antenna. Radiation pattern plots may be deve]oped as required to show the effect of the dielectric loading.
Example 1 ` A symmetrical horn as shown in Figure 1, an unloaded asymmetri-cal horn as described with reference to Figure 2 and an asymmetrical horn loaded with an acrylic wedge (dielectric constant ~= 2.59) on wall 3 were tested at frequencies of 8.0, 9.0, 10.0 and 10.88 GHz with 10 GHz as the mid frequency of the X-band. The wedge angle a of the dielectric s - 4a -~ - .
lOB1845 wedge wa~ vaxied between 1~5 and 7.5~ and xadi~ti~on pattern charts for the various frequencie~; and wedge angles were, plotted. Repre~entative charts are illustrated herein as Figures 4~6 respectively. The results are shown hereinbelow in Table 1.
Table 1 8.0 GHz 9.0 GHz 10 GHz 10.88 GHz O~ S!~ ~ llJ `p ~" G ¢~ ~" ¢ ~V . - . .
. .
1 1/2 lR 0 31/2R 31/2R1/2R 2R 1/2R 2R
2 1/4 1/2R 0 2R 4R 3L lR 2L 2R , 3 1/4 lL 3R 11/2R 4R 5L lR 71/2L lR
_ .
function of power (db);
Figure 5 is a graph showing beam angle deflection for a horn of Figure 2 with a dielectric wedge angle of 7.5 at 10 GHz as a function of power ~db); and Figure 6 is a graph showing beam angle deflection for a horn of Figure 2 with a dlelectric wedge angle of 7.5 at 10.88 GHz as a function of power (db).
Although the present invention is applicable to antennas of substantially any practical shape and dimension, the invention will be described hereinafter with particular reference to an H-plane sector horn structure desfgned to operate in the X-band (i.e. 8-12.4 GHz), as such a structure has particular suitability to a radiometer system.
A basic H-plane sectoral horn 1 is shown in Figure 1, with a flare angle ~ of 22, as measured between the flared walls 2 and 3 and symmetrical about the axis 4 of the horn. Horn 1 is also provided with a wavegulde structure 5 in known manner. A modified horn 1 is shown in Figure 2 in which the flare angle ~ is reduced by an amount ~ (approxi-mately 5~ on one side, along wall 3 as shown in Figure 2, and measured from corner A ad~acent the throat of the waveguide 5.
The asymmetrical horn is dielectrically loaded by inserting a wedge 6 of a frequency-sensitive dielectric material such as acrylic, ertalon (Trademark for a nylon type thermoplastic material sold by Miller Plastics Ltd., 19 Advance Road, Toronto, Canada~ or polyethylene along the wall 3 with the apex of the wedge adiacent the throat A of the waveguide. The angle (a) of the wedge 6 may be altered as required and as explained in more detail hereinafter.
In an alternative embodiment, as shown in Figure 3 a symmetri-cal horn as described with reference to Figure 1 is provided with two dielectric wedges 7 and 8 adjacent walls 2 and 3 respectively. Wedges .. . . . . . .
. ~ . . .
. ,: . . :- . .: . .
.
108~845 7 and 8 may be of the same dielectric materials in which case the wedge angles are different or alternatively the dielectric materials may be different and the wedge angles the same.
In operation a microwave beam of a selected frequency range within the general frequency range 1 GHz to 150 GHz and preferably of the order of 8 - 15 GHz i9 generated within the waveguide and transmitted from the horn antenna. Radiation pattern plots may be deve]oped as required to show the effect of the dielectric loading.
Example 1 ` A symmetrical horn as shown in Figure 1, an unloaded asymmetri-cal horn as described with reference to Figure 2 and an asymmetrical horn loaded with an acrylic wedge (dielectric constant ~= 2.59) on wall 3 were tested at frequencies of 8.0, 9.0, 10.0 and 10.88 GHz with 10 GHz as the mid frequency of the X-band. The wedge angle a of the dielectric s - 4a -~ - .
lOB1845 wedge wa~ vaxied between 1~5 and 7.5~ and xadi~ti~on pattern charts for the various frequencie~; and wedge angles were, plotted. Repre~entative charts are illustrated herein as Figures 4~6 respectively. The results are shown hereinbelow in Table 1.
Table 1 8.0 GHz 9.0 GHz 10 GHz 10.88 GHz O~ S!~ ~ llJ `p ~" G ¢~ ~" ¢ ~V . - . .
. .
1 1/2 lR 0 31/2R 31/2R1/2R 2R 1/2R 2R
2 1/4 1/2R 0 2R 4R 3L lR 2L 2R , 3 1/4 lL 3R 11/2R 4R 5L lR 71/2L lR
_ .
4 1/4 7L 0 51/2L 4R llL 11/2R SB 2R
5 1/4 5L 4R SB 4R 18R 2R 13R lR
6 1/2 SB 0 llR 4R 6~ 2R 2L 11/2R
7 1/2 191~4R 7R 4R 3R 711. llL lR
e,l ~ 2.59 (~ r of acrylic) o~-= Dielectric wedge angle (in tegrees~
t = Beam angle R- Right of standard horn beam angle at zero (in degrees) off axis L = Left of standard horn beam angle at zero (in degrees) off axis ~' ~ = Asymmetrical horn beam angle unloaded SB ~ Split beam.
With reference to Table 1, the beam angles are indicated right or left of the reference (symmetrical) horn zero or axis for each wedge angle. It will also be appreciated that the wedge angles 3.25 and 7.5 inticate a falrly uniform rate of disperslon from left to right. Figures 4, 5 and 6 also inticate that, at a given tielectric wedge angle, increasing frequency causes a significsnt beam angle shlft from right to left.
Example 2 A ~ymlDetrical horn as shown in Figure 1, having a flare angle --`` 1081845 22~ was modified hy placing dielect~ic wed~e infie~ts 7 and 8 on both of the narrow walls 2 and 3 as shown in Pigure 3. The inserts 7 and 8 were machinet from different dielectric materials, ertalon (dielectric constant ~= 4) and polyethylene (dielectric congtant ~ 2.28) respective-ly, and their respective wedge angles 2 and ô3 were different. Radia-tion pattern charts, similar to those illustrated in Figures 4 to 6, were prepared using a multi-frequency microwave beam in the X-band, as in ~xample 1. The resulting beam angle ~hift at different frequencies is summarized ln Table 2.
Table 2 ~2 ¦3 ¦ 8.0 GHZ 9.0 GHz 10 GHz10.9 GHz R - Right of standard horn beam angle at zero degrees off axis L ~ Left of standard horn beam angle at zero degrees off axis It will be seen from Table 2 that beam scannlng as a function of frequency is evident but that the rate of beam shift is asymmetrical within the frequency bant. Because the shift i~ ~ubstantially uniform ln the asymmetrical horn of Example 1, it i8 believed that an asymmetrical H-plane sectoral horn with dielectric loading on the one wall clo~est to the waveguide axis is to be preferred for beam scanning with frequency sweep. In special circumstances, however, and for specially shaped radiation patterns the use of a plurality of different wedges may be more effective.
Many modifications may be made to the apparatuR described herein without departing from the scope of the invention which may be practised in many ways not 6pecificall~ described herein. For example the shape and dimensions of the antenna are not critical to the invention but depends merely upon the use, function and frequency of the de~ired microwave beam scan. The dimensionsOf the antenna are primarily a function of the wavelength of the microwave beam and must be selected .. . .
' ` ~ '~' .' . ` :
:--` 1081845 :
depending upon the ulti~ate use cxitexia. Si~ilaxly the dielectric material to be employed for the wedges is merely a matter of design and suitability in a particular situation or environment. While the di-electric material has generally been described herein as a solid, generally thermoplastic material, it will be appreciated that it may be any frequency sensitive dielectric material which term will include liquids as well as solid materials. It will also be appreciated that a plurality of superimposed or partially supeTimposed wedgé 6haped layers of the same or different dlelectric materials may be employed.
, . ~ ~
:
e,l ~ 2.59 (~ r of acrylic) o~-= Dielectric wedge angle (in tegrees~
t = Beam angle R- Right of standard horn beam angle at zero (in degrees) off axis L = Left of standard horn beam angle at zero (in degrees) off axis ~' ~ = Asymmetrical horn beam angle unloaded SB ~ Split beam.
With reference to Table 1, the beam angles are indicated right or left of the reference (symmetrical) horn zero or axis for each wedge angle. It will also be appreciated that the wedge angles 3.25 and 7.5 inticate a falrly uniform rate of disperslon from left to right. Figures 4, 5 and 6 also inticate that, at a given tielectric wedge angle, increasing frequency causes a significsnt beam angle shlft from right to left.
Example 2 A ~ymlDetrical horn as shown in Figure 1, having a flare angle --`` 1081845 22~ was modified hy placing dielect~ic wed~e infie~ts 7 and 8 on both of the narrow walls 2 and 3 as shown in Pigure 3. The inserts 7 and 8 were machinet from different dielectric materials, ertalon (dielectric constant ~= 4) and polyethylene (dielectric congtant ~ 2.28) respective-ly, and their respective wedge angles 2 and ô3 were different. Radia-tion pattern charts, similar to those illustrated in Figures 4 to 6, were prepared using a multi-frequency microwave beam in the X-band, as in ~xample 1. The resulting beam angle ~hift at different frequencies is summarized ln Table 2.
Table 2 ~2 ¦3 ¦ 8.0 GHZ 9.0 GHz 10 GHz10.9 GHz R - Right of standard horn beam angle at zero degrees off axis L ~ Left of standard horn beam angle at zero degrees off axis It will be seen from Table 2 that beam scannlng as a function of frequency is evident but that the rate of beam shift is asymmetrical within the frequency bant. Because the shift i~ ~ubstantially uniform ln the asymmetrical horn of Example 1, it i8 believed that an asymmetrical H-plane sectoral horn with dielectric loading on the one wall clo~est to the waveguide axis is to be preferred for beam scanning with frequency sweep. In special circumstances, however, and for specially shaped radiation patterns the use of a plurality of different wedges may be more effective.
Many modifications may be made to the apparatuR described herein without departing from the scope of the invention which may be practised in many ways not 6pecificall~ described herein. For example the shape and dimensions of the antenna are not critical to the invention but depends merely upon the use, function and frequency of the de~ired microwave beam scan. The dimensionsOf the antenna are primarily a function of the wavelength of the microwave beam and must be selected .. . .
' ` ~ '~' .' . ` :
:--` 1081845 :
depending upon the ulti~ate use cxitexia. Si~ilaxly the dielectric material to be employed for the wedges is merely a matter of design and suitability in a particular situation or environment. While the di-electric material has generally been described herein as a solid, generally thermoplastic material, it will be appreciated that it may be any frequency sensitive dielectric material which term will include liquids as well as solid materials. It will also be appreciated that a plurality of superimposed or partially supeTimposed wedgé 6haped layers of the same or different dlelectric materials may be employed.
, . ~ ~
:
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for non-mechanical scanning of a microwave beam which comprises providing at least one reflecting surface of a directive antenna with at least one wedge shaped layer of a frequency sensitive dielectric material and directing a multi-frequency microwave beam, in a selected band within the frequency range 1 GHz - 150 GHz and which varies with time, to thereby effect a beam angle shift.
2. A method as claimed in claim 1 wherein said dielectric material is a thermoplastic material selected from the group comprising:
acrylic, polyethylene and ertalon?.
acrylic, polyethylene and ertalon?.
3. A method as claimed in claim 1 wherein said selected band is 8 - 12.4 GHz.
4. A method as claimed in claims 1, 2 or 3 wherein said dielectric material is coated onto one wall of an asymmetric H-plane sectoral horn antenna.
5. A method as claimed in claims 1, 2 or 3 wherein said dielectric material is coated onto opposed walls of a symmetrical H-plane sectoral horn antenna.
6. An apparatus for non-mechanical scanning of a microwave beam comprising:
directive antenna means having at least one guiding or reflecting surface; and at least one wedge shaped layer of a frequency sensitive dielectric material in planar contact with at least part of said surface to thereby effect a beam angle shift of a multi-frequency microwave beam, in a selected band within the frequency range 1 GHz-150 GHz and which varies with time, directed thereagainst.
directive antenna means having at least one guiding or reflecting surface; and at least one wedge shaped layer of a frequency sensitive dielectric material in planar contact with at least part of said surface to thereby effect a beam angle shift of a multi-frequency microwave beam, in a selected band within the frequency range 1 GHz-150 GHz and which varies with time, directed thereagainst.
7. An apparatus as claimed in claim 6 wherein said dielectric material is a thermoplastic material selected from the group comprising:
acrylic, polyethylene and ertalon?.
acrylic, polyethylene and ertalon?.
8. An apparatus as claimed in claim 6 wherein said antenna is an H-plane sectoral horn having said dielectric material coated onto at least one wall thereof.
9. An apparatus as claimed in claim 8 wherein said horn is a symmetrical horn having different said dielectric materials coated on opposed walls thereof.
10. An apparatus as claimed in claim 8 wherein said horn is an asymmetrical horn having said dielectric material coated on the wall thereof nearest the axis of said horn.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA250,493A CA1081845A (en) | 1976-04-20 | 1976-04-20 | Beam scanning |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA250,493A CA1081845A (en) | 1976-04-20 | 1976-04-20 | Beam scanning |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1081845A true CA1081845A (en) | 1980-07-15 |
Family
ID=4105734
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA250,493A Expired CA1081845A (en) | 1976-04-20 | 1976-04-20 | Beam scanning |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1081845A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0187671A2 (en) * | 1985-01-09 | 1986-07-16 | Kabushiki Kaisha Toshiba | Primary radiator for circularly polarized wave |
-
1976
- 1976-04-20 CA CA250,493A patent/CA1081845A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0187671A2 (en) * | 1985-01-09 | 1986-07-16 | Kabushiki Kaisha Toshiba | Primary radiator for circularly polarized wave |
| EP0187671A3 (en) * | 1985-01-09 | 1988-09-07 | Kabushiki Kaisha Toshiba | Primary radiator for circularly polarized wave |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |