EP0233282A1 - Antenne orientable en fonction du faisceau - Google Patents

Antenne orientable en fonction du faisceau

Info

Publication number
EP0233282A1
EP0233282A1 EP19860906041 EP86906041A EP0233282A1 EP 0233282 A1 EP0233282 A1 EP 0233282A1 EP 19860906041 EP19860906041 EP 19860906041 EP 86906041 A EP86906041 A EP 86906041A EP 0233282 A1 EP0233282 A1 EP 0233282A1
Authority
EP
European Patent Office
Prior art keywords
antenna system
conductive
waveguide
adjustable
spacing
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.)
Withdrawn
Application number
EP19860906041
Other languages
German (de)
English (en)
Inventor
Milton R. Seiler
Harry V. Winsor
John E. Clifford
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Battelle Memorial Institute Inc
Original Assignee
Battelle Memorial Institute Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Battelle Memorial Institute Inc filed Critical Battelle Memorial Institute Inc
Publication of EP0233282A1 publication Critical patent/EP0233282A1/fr
Withdrawn legal-status Critical Current

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
    • H01Q3/44—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 electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
    • H01Q3/443—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 electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element varying the phase velocity along a leaky transmission line

Definitions

  • This invention relates to directional antenna systems involving the interaction of dielectric waveguides and nearby periodic structures. It is especially useful for changing the angle of maximum radiation or reception of an antenna by changing over a continuous range the period of the nearby periodic conductive structure.
  • a beam-steerable antenna has applications such as in radar and seeker systems, communications systems, and satellite television reception. There is a need for,a simple, low-cost method of constructing beam- steerable antennas or phased arrays.
  • microwave phased arrays achieve beam steering by high-speed phase shifters that comprise discrete PIN (positive intrinsic negative) diodes or ferrite devices. These phase shifters set the electrical phase on elements of the array. It is difficult and expensive to build discrete phase-shift devices for extremely high operating frequencies (e.g. in the millimeter-wave region of the spectrum) .
  • 30adjusted periodic structure can radiate about 90 percent of the total input power to the dielectric waveguide.
  • the relationship between the fixed period I of the periodic structure in meters and the directi ⁇ n of maximum wave propagation measured as the angle ⁇ in radians relative to the load end of the waveguide can be derived from theoretical considerations.
  • the propagation constant on the fixed periodic structure is given by Floquet's Theorem [J.C. Slater, Microwave Electronics, D. Van Nostrand Co., p 170 (1950).]:
  • B 0 propagation constant of dominant waveguide mode
  • ⁇ - l period of periodic structure
  • the normal radiation mode of interest is associated with -t -1. There is one dominant radiation lobe for the condition
  • a combined waveguide and periodic structure with a desired fixed pointing angle ⁇ can be constructed by use of a periodic structure with a fixed period I.
  • Andrenko et al (1978) refer to a fixed periodic structure made of a grooved metallic block, such as illustrated in Figure 2, as a "diffraction - grating" with period I . They mention a possibility of stepwise adjustment of directivity in their mm band antenna array by mounting diffraction gratings of different periods on a cylindrical barrel which rotates around its axis. However, they suggest only discrete variation and do not mention any way of varying directionality over a continuous range.
  • This invention relates to a directional antenna system in which the beam can be steered over a wide angle relative to the axis of the antenna.
  • the beam-steerab antenna for transmitting and/or receiving electromagnetic energy of a frequency at which the waveguide propagates is based on the principles of "diffraction electronics".
  • a typical beam-steerable antenna comprises a dielectric waveguide and an adjustable periodic structure in a lengthwise region adjacent and substantially parallel to the waveguide.
  • a typical adjustable periodic structure can comprise a coiled helical spring in which the plurality of conductiv portions of the wire are equally spaced apart and means are provided to expand or compress the spring to vary the spacing between the coils of the spring.
  • the spring typically contains a metallic core to guide the helical coils. The distance between the periodic structure and the dielectric waveguide and any small tilt of the axis relative to the dielectric waveguide are adjusted. for maximum power.
  • Alternative adjustable periodic structures for use -in this invention are bellows-like flexible members, kinematic chains, and threaded polyhedrons.
  • the means to adjust the spacing are chosen as appropriate for the type of periodic structure such as linear actuators, motors, solenoids, which would be obvious to those skilled in the art.
  • a periodic structure in the form of a hollow bellows could have the spacing adjusted by increasing or decreasing air pressure.
  • the adjustable periodic structure is on a thin metallic - or metal-coated tape that is moved between a storage reel and a takeup reel to a tape position containing the desired spacing of conductive lines formed between intervening slots in the tape.
  • conductive elements with the desired spacing could be printed on a non-conductive tape by computer-controlled, conductive ink-jet printer on demand or for preformed tapes.
  • the adjustabl periodic structure comprises a photoconductive surface with periodic conductive bands produced by light diffracted by overlapping transparent ruled gratings forming moire fringes of frequency proportional to the adjustable angle between lines on the two gratings.
  • the adjustable periodic structure comprises a photoconductive surface with periodic conductive bands produced by light diffracted by an acousto-optical device or optically focused light produced by computer controlled selective activation of an array of diode lasers.
  • the adjustabl periodic structure comprises periodic conductive bands in an adjacent semiconductor surface adjustable by control of the electron beam in a cathode ray tube.
  • Figure 1 is a schematic front view of a test setup used for measuring the beam pointing angle resulting from the interaction of a dielectric waveguide with an adjacent periodic structure according to this invention.
  • Figure 2 is an enlarged schematic front sectional view of a waveguide and periodic structure as in Figure 1, showing the important dimensions.
  • Figure 3 is an enlarged schematic front view of a waveguide as in Figure 1 with an adjustable periodic structure comprising portions of a spring.
  • Figure 4 is a graph of data showing the change in relative beam power and beam angle at several frequencie for a fixed period.
  • Figure 5 is a graph of relative beam power versus beam angle for the waveguide and periodic structure of Figure 3 at one spacing of the coils of the spring.
  • Figure 6 is a graph of data for the waveguide and periodic structure of Figure 3 showing the beam pointing angle as a function of period resulting from adjustment of the spacing of coils of the spring periodic structure in accordance with this invention.
  • Figure 7 is a graph of data showing the linear correlation of half-power beamwidth as a function of wavelength, period, and beam angle.
  • Figure 8 is a partial sectional axial view of a waveguide-spring adjustable periodic structure showing a modified spring coil.
  • Figure 9 is a partial sectional axial view of one coil of a modified helical spring.
  • Figure 10 is a partial sectional axial view of one coil of a rectangular spring.
  • Figure 11 is a schematic perspective view of a bellows-like adjustable periodic structure.
  • Figure 12 ' is a schematic view of an adjustable bellows periodic structure and waveguide.
  • Figure 13 is a schematic view of a kinematic chain adjustable periodic structure and waveguide.
  • Figure 14 is a schematic perspective view of a variable-pitch threaded polyhedron adjustable periodic structure.
  • Figure 15 is a schematic view of a movable tape adjustable periodic structure and waveguide.
  • Figure 16 is a schematic perspective view of a waveguide and the conductive ink lines on the tape of the adjustable periodic structure of Figure 15.
  • Figure 17 is a schematic view of a preformed perforate tape type adjustable periodic structure.
  • Figure 18 is a schematic sectional view of a waveguide and periodic structure comprising periodic conductive bands in an adjacent photoconductive surface adjustable by optical gratings.
  • Figure 19 is a partial sectional view as indicated at 19-19 in Figure 18.
  • Figure 20 is a schematic view of the moire fringe pattern indicated at 20-20 in Figure 18.
  • Figure 21 is a schematic view of a waveguide and a periodic structure comprising periodic conductive bands in an adjacent photoconductive surface adjustable by an acousto-optical device producing a plurality of light beams.
  • Figure 22 is a schematic view of a waveguide and a periodic structure comprising periodic conductive bands in an adjacent photoconductive surface adjustable by an acousto-optical light scanning device.
  • Figure 23 is a schematic view of a waveguide , and a periodic structure comprising periodic conductive bands in an adjacent photoconductive surface adjustable by computer control of activation of an array of diode lasers and optically focused light.
  • Figure 24 is a schematic view of a dielectric antenna showing the directions of radiation for surfaces of the periodic structure below the antenna.
  • Figure 25 is a schematic view of a dielectric antenna showing the directions of radiation for surfaces of the periodic structure above the antenna.
  • Figure 26 is a schematic view of a waveguide and a periodic structure comprising periodic conductive bands in an adjacent semiconductor surface adjustable by control of the electron beam in a cathode ray tube.
  • Figure 27 is a sectional view as indicated at 27-27 in Figure 26. CARRYING OUT THE INVENTION
  • test setup shown in Figure 1
  • the test setup was used to measure the beam pointing angle ⁇ as a function of the period I for adjustable periodic structures according to this invention after first validating the test setup with a periodic structure of fixed period.
  • a standard horn antenna 20 was used to measure the radiation pattern and a calibrated thermistor 21 and power meter 22 served as the detector.
  • the arc radius of 0.6 ensured that the horn was in the far field of the radiation pattern.
  • the test setup was designed for an operating frequenc of 94 GHz.
  • a cw klystron 23 was used as the source of electromagnetic energy with a circulator (isolator) 24 and frequency meter 25.
  • a standard W-band waveguide termination 26 was used at the load end with another thermistor 21 and power meter 22 connected by a 20 ' dB coupler 27.
  • the dielectric waveguide antenna 28 was connected in the test setup through lengths of WR-10 waveguide
  • Polystyrene ( ⁇ r 2.56) was used for the dielectric and was cut to have the same nominal cross-section as the slot in the metal waveguides (i.e. 0.127 x 0.254 cm) .
  • the dielectric strip was about 10 cm long and, for a few millimeters back from either end, the top and bottom surfaces were tapered into a wedge shape.
  • An electric field probe (not shown) was fabricated and was used with a crystal detector to probe the fields along the dielectric 28 in the absence of a periodic structure. The wavelength ( ⁇ g) the dielectric strip 28 was found to be 2.6 mm at 94 H z .
  • the periodic structure 30 was placed on a tilt ' platform 31 to provide a small tilt angle (approximately 10-20 milliradians) , as shown in Figure 2, with a nominal distance ⁇ of
  • a spring 32 as shown in Figure 3, was used in place of the fixed periodic structure 30 shown in Figure 2.
  • the spring 32 was selected which could be stretched and compressed to vary the period I over the range indicated in equation (5).
  • Such a readily available spring had a diameter of 5.5 mm, and consisted of 32 spiral coils with a wire diameter of 0.5 mm.
  • a brass rod of 5 mm diameter was used as the core 33.
  • the resultant radiation pattern is shown in Figure 5, normalized to the gain at beam maximum (the "gain” of the spring 32 was about 5 dB below that of the brass structure 30). No tilt was applied to the spring 32.
  • the length, L, of the spring 32 was varied from " a minimum of 45.3 mm to a maximum of 99 mm, in steps of about 2.5 mm, to steer the beam from an angle ⁇ » 166° to ⁇ » 80°.
  • the variation of pointing angle ⁇ with spring coil spacing or period I is shown in Figure 6.
  • the "diffraction electronics" antenna is a self-excited array where each element of the periodic structure is driven in series. It would be expected that the total length of the array, L, as shown in Figure 3, would dictate the half-power beamwidth of the radiated pattern.
  • the half-power beamwidth, ⁇ in radians, should be approximately
  • the adjustable periodic structure can be a conventional helical spring 32 as shown in Figure 3.
  • the term "spring” is used in the broadest sense that will accomplish the function intended and might have a slightly different configuration than a conventional spring in some applications.
  • Figure 8 shows an enlarged partial axial view of a spring 32* on a core 33 that has been flattened slightly on the surface 36 adjacent the waveguide 28 so that the distance ⁇ is more uniform under the width of the waveguide compared to the variable distance of a conventional spring shown as a dashed line 38 in Figure 8.
  • Figure 9 shows an alternative modification of a spring 32" in which a portion of the helical coil has an upraised flat surface 36' parallel to the waveguide which is advantageous if the spring diameter is small relative to the width of the waveguide.
  • Figure 10 shows an alternative modification in which the coils of the spring 39 are rectangular in shape rather than circular and the wire cross section can be rectangular rather than circular and the cross section of the core 33' can be rectangular rather than circular which has the advantage of maintaining the flat surface 36" parallel to the waveguide 28 as the individual coils of the spring 39 slide along the core 33' during adjustment of the coil spacing.
  • the controlling means comprises means for varying the length of the spring and thus the spacing between corresponding points on successive turns and thus the period I .
  • the controlling means is typically an actuator 34 as indicated in Figure
  • linear actuators can be used such as pneumatic actuators, hydraulic actuators, motorized screw actuators, solenoid actuators, or other means known to those skilled in the art.
  • Figure 11 shows an alternative embodiment of this invention wherein the adjustable periodic structure 40 is a bellows-like flexible member of which the outer edges 41 form the spaced-apart positions.
  • Figure 12 shows an alternative embodiment in which the adjustable periodic structure is a bellows 42 and ' the controlling means can be an air supply 43 to affect by variation in air pressure the length of the bellows 42 and the spacing of the outer edges 44 of the bellows.
  • FIG. 13 shows an alternative embodiment of this invention in which the adjustable periodic structure is a kinematic chain 45 comprising a plurality of isosceles drag links 46 (lazy tongs) with the conductive portions
  • FIG 14 shows an alternative embodiment of the invention in which the adjustable periodic structure comprises approximately equally spaced identical polyhedron
  • the first polyhedron 48 which are internal threaded to fit on the external threads of a cylindrical member 49 having a plurality of portions threaded with threads of variable pitch.
  • the first polyhedron 48 which need not move along the cylindrical member 49 can be on an unthreaded portion of the cylinder 49'.
  • the second polyhedron 48' is mounted on an adjacent threaded portion 50 of the cylinder having x threads per unit length; the second polyhedron 48" is mounted on the next adjacent portion of the cylinder 50' having 2x threads per unit length and so on to a last polyhedron 48 n mounted on a last [(n-l)th] threaded portion 50 11 "" 1 of the cylinder having (n-l)x threads per unit length.
  • the polyhedrons 48,48' ,48", 48 n are constrained by guiding means 51 for prevention of rotation of the polyhedrons while allowing axial movement of the polyhedrons along the cylindrical member 49.
  • Controlling means 34 are provided for rotating the cylinder 49 and effecting a variation of spacing of the polyhedrons and the conductive surfaces 47' adjacent a dielectric waveguide not shown in Figure 14.
  • Figures 15 and 16 show an alternative embodiment of the present invention wherein the adjustable periodic structure comprises spaced lines 52 of conductive ink on a non-conductive paper tape 53 as shown in Figure 16 that is moved at high speed between a supply spool 54 and a take-up spool 55 as shown in Figure 15.
  • the lines of conductive ink can be formed practically instan ⁇ taneously on the tape by a high-speed jet printer 56 before the tape moves approximately parallel to the axis of the adjacent waveguide 28.
  • the spacing of the lines 52 of conductive ink is controlled by controlling the speed of the tape 53.
  • the embodiment of the invention shown in Figures 15 and 16 allows rapid changes of beam angle ⁇ .
  • An alternative modification of the aforementioned embodiment would use a preformed tape containing conductive spaced parallel lines on a non-conductive tape as might be produced by a conductive-ink jet printer or other means. Portions of the tape (e.g.
  • approximately the length of the waveguide would contain equal spaced lines of period £ and an adjacent portion of the tape would contain equal spaced lines of slightly different period, £ + ⁇ £, and so on such that the total tape contained a plurality of portions with conductive lines of slightly different periods.
  • Means for movement of the tape between the two spools to a position such that the portion of the tape with lines of the desired period, £, was adjacent the waveguide would control the structure period and beam-pointing angle ⁇ .
  • FIG. 17 An alternative modification of the aforementioned preformed tape is shown in Figure 17 where the adjustable periodic structure consists of portions of tape 57 comprising parallel perforations 58 separating parallel conductive lines 59 which could be preformed on suitable tape (e.g. thin metal tape, metal-coated tape, or conducti coating on tape) by mechanical slotting, electroforming, or other means known to those skilled in the art.
  • suitable tape e.g. thin metal tape, metal-coated tape, or conducti coating on tape
  • Figures 18,19, and 20 show an alternative embodiment of the invention wherein the adjustable periodic structure comprises a photoconductive surface 60 with periodic conductive bands produced by light from a source 61 through moire fringe bands 62 resulting from overlapping transparent ruled gratings 63,64.
  • the gratings 63,64 are adjacent and parallel to the dielectric waveguide 28 over its length and fixed at one end by a bond for flexible gratings or by a pivot for rigid gratings and movable at the other end relative to each other in a plane parallel to the grating surfaces.
  • the alternating light bands 62' and dark bands 62 with a period £ as shown in Figure 20 result from relative movement of the gratings through a distance x per unit length of grating L'.
  • the relative movement x/L', of the gratings required is small and can be accomplished by several' means such as the simple lever device 65 shown in Figure 19 connected to a suitable actuator to twist lever 65 at pivot 66.
  • FIGs 21,22, and 23 show alternative embodiments of the invention wherein the beam steering of the antenna is accomplished by non-mechanical means.
  • the adjustable periodic structure comprises a thin photoconductive surface 60 on a transparent substrate 70 with periodic conductive bands 62' produced in the photoconductive material by light rays 71,71',80 that are uniformly spaced an adjustable distance £ where they strike the surface of the photoconductor 60.
  • a laser 90 or other light source is diffracted into a plurality of separate light beams 71 by an acousto-optical device 73. The latter device
  • the Bragg cell 73 is sometimes referred to as a Bragg cell and has been used for spectrum analysis.
  • the Bragg cell is usually a block of glass or ⁇ yrstalline material such as lithium niobate approximately 1 cm x 1 cm in cross section and up to 10-20 centimeters long.
  • a piezoelectric transducer 74 is bonded to the end. When the transducer
  • a traveling acoustic wave 76 is set up in the material.
  • the acoustic - energy causes slight changes in the refractive index between the peaks 76 and valleys of the acoustic pressure.
  • ⁇ the reflections from the index change, add in phase, and Bragg diffraction takes place.
  • a portion of the input light beam 72 is deflected and can be imaged on the photoconductive surface 60.
  • the angle of deflection is proportional to the sound frequency generated by the acoustic transducer 74 in response to the drive signal 75. If there are multiple signals at different frequencies in the drive signal 75, there will be multiple defracted light beams 71.
  • the multiple signals in the drive signal 75 are a uniform series of frequencies f, f + ⁇ , f + 2 ⁇ , f + 3 ⁇ ... f + n ⁇ , a plurality of diffracted light beams 71 of angles , a + ⁇ x, ⁇
  • the value of £ can be adjusted by adjusting the incremental frequency ⁇ to accomplish beam steering by change in angle ⁇ of the beam relative to the axis of the dielectric waveguide.
  • An alternative modification using a similar acousto- optic device 73 as in Figure 21, operates as a scanning device as shown in Figure 22.
  • the laser beam 72 is rapidly diffracted through successive angles ⁇ , ⁇ + ⁇ x, ⁇ + 2 ⁇ x, ⁇ + 3 ⁇ x, ⁇ + n ⁇ x by successive changes in frequency f, f + ⁇ ' , f + 2 ⁇ , f + 3 ⁇ , f + n ⁇ of the drive signal 75' to the piezoelectric transducer 74.
  • the sweep rate (complete cycle of discrete frequencies) of the diffracted beam 71* is made fast relative to the inherent decay rate of conductivity in the illuminated; photoconductive material.
  • Figure 23 shows an embodiment in which the light source is a laser diode array 77 comprising a plurality of individual laser diodes 78 which are selectively activated by a computer 79 to produce individual light rays 80.
  • a convex lens 81 is used to focus the light rays 80 on the photoconductive surface 60.
  • a sufficient number of laser diodes 78 are used in the array 77 such that by computer-controlled electrical activation of selected laser diodes, periodic conductive bands
  • the beam 82 is shown schematically as emanating from the dielectric waveguide 28 in a direction 82 opposite from the periodic conductive structure 60.
  • the periodic conductive surface 83 is depicted as a segmented line in close proximity to the dielectric waveguide 28. Evanescent mode coupling causes a surface excitation on the periodic structure 83.
  • the adjustable periodic structure 83 is positioned on the opposite side of the dielectric waveguide 28 from the desired beam propagation direction 82 to avoid interference with the beam as shown in Figure 24.
  • the photoconductive surface 60 can be located on top of the dielectric waveguide 28 and, by the use of mirrors or other means to direct the light rays to the photoconductive surface 60, minimize interference with the beam 82 propagated in the direction of the adjustable periodic structure 83 as shown in Figure 25.
  • a photoconductive surface 60 was positioned on top of the dielectric waveguide 28 and in close proximity ( ⁇ a 1 to 5 mm).
  • the photo ⁇ conductive surface 60 comprised n-type amorphous silicon (dark resistivity of approximately 2000-3400 ohm-cm) in a film 1 micrometer thick on transparent substrate 70 of glass (microscope slide).
  • the opposite surface of the substrate 70 contained a mask of opaque grating lines alternating with transparent lines to provide a period £ ⁇ 2.1 mm.
  • the photoconductive surface was illuminated by a remote laser (Nd:YAG, 1.06 micrometer, 16 millijoules per pulse, 10 pulses per second, 3 nanoseconds per pulse).
  • the laser beam was expanded so as to fill a reflecting mirror 6.3 cm in diameter.
  • the reflected beam passed through a cylindrical lens (400 mm focal length) so that a rectangular area of 6 mm by 63 mm was illuminated near the polystyrene waveguide 28.
  • the measured beam angle ⁇ would have been 104 degrees which corresponds to data in Figure " 6 for similar conditions of the klystron source 23 operating at a frequency of 94 Ghz.
  • the experiment demonstrated that a periodic structure comprising light induced conductive bands in a photoconductor surface 60 can be used for beam steering with results similar to those achieved with a periodic brass structure 30 as in Figure 2.
  • the use of a photoconductive surface with equally spaced conductive bands adjustable by computer control of the light source, as in Figure 23, is advantageous for a beam steerable antenna with rapid adjustment of beam angle by non-mechanical means.
  • FIGs 26 and 27 show an alternative embodiment of the invention wherein beam steering of the antenna is accomplished by non-mechanical means using cathode- ray-tube (CRT) technology.
  • the adjustable periodic structure comprises a thin semiconductor film 92 with periodic conductive bands 94 produced therein by an electron beam 90 where it strikes the surface of the semiconductor film 92.
  • This embodiment of the invention uses an electron beam 90, rather than light rays 71,71' ,80, as in Figures 21,22, and 23, and thus the adjustable periodic structure 92 must be enclosed in a vacuum tube 86.
  • CRT technoloy is used to control the location of the conductive bands 94 that are uniformly spaced an adjustable distance £.
  • the cathode ray tube 85 comprises a vacuum tube 86 typically constructed of glass, an electron gun 88 typical of those used in laboratory oscilloscopes, and means 87,87' for deflecting the electron beam 90.
  • Beam control means 87' is used to write a conductive band 94 in the semiconductor film 92 as shown in Figure 27.
  • Beam control means 87 as shown in Figure 26 is used to write a plurality of spaced conductive bands 94 in the semiconductor film 92 during a single scan of the electron beam 90.
  • the number of conducting bands 94 written across the semiconductor film 92 and hence their period £ determines the beam steering angle ⁇ of the radiated beam 82.
  • Methods of providing appropriate electrical signals to the beam control means 87,87' to obtain the desired written electron beam pattern of conductive bands 94 on the semiconductor film 92 are well known in CRT technology.
  • the width and spacing of the conductive bands 94 can be controlled electronically.
  • the conductive bands 94 can be any width by writing a plurality of closely spaced conductive lines with the electron beam 90.
  • the width of the conductiv bands 94 is approximately one-half of the period £.
  • the persistence of the conductive bands 94 of the electron beam pattern written on the semiconductor 92 would be one lifetime of the semiconductor excess carriers for a single scan of the beam 90, or indefinitely long for multiple writing of the same pattern.
  • the persistence of the conductive bands should be comparable to the scan time so that the period £ can be changed quickly when desired (e.g. microseconds).
  • the use of cathode-ray-- tube technology provides a method of achieving high beam steering rates with rapid adjustment of the period £ of the periodic structure by non-mechanical means.
  • the dielectric waveguide 28' is an integral part of the cathode ray tube 85 forming the faceplate of the vacuum tube 86 with vacuum-tight seals 91.
  • the material of the dielectric waveguide 26' should be compatible with the remainder of the vacuum tube 86 to produce vacuum-tight seals 91.
  • Preferred materials for the waveguide 28' are glass, quartz, a ceramic such as aluminum oxide or any other low-loss dielectric including polyethylene.
  • the dielectric waveguide 28' is the faceplate of the vacuum tube 86.
  • the vacuum tube 86 could completely surround the waveguide 28*.
  • a typical faceplate (not shown in Figures 26 and 27) for a CRT such as glass could be positioned on the opposite side of the waveguide from 5 the adjustable periodic structure 92, spaced from, and essentially parallel to, the waveguide 28'.
  • the radiated beam 82 would propagate through said faceplate.
  • the semiconductor 92 is typically a thin film on the order of 1 micron thickness of a material such 0 as silicon or gallium arsenide and must be supported in some manner that positions it the optimum distance from the dielectric waveguide 28'.
  • the support 93 can be a thin layer of glass on which the
  • the support 93 is shown attached to the walls of the vacuum tube 86. Alternatively, the support 93 could be attached to the waveguide 28'.
  • the support 93 can be designed
  • the support 93 should be thin so that the conductive:.bands
  • the support 93 should be on the order of 1 mm in thickness or less. This precludes use of the glass faceplate of the typical vacuum tube 86 as the support 93 for the semiconductor 92.
  • the dielectric waveguide 28' which serves as the faceplate of the vacuum tube 86 can be made of glass or other materials. An important design consideration is that the material of the support 93 in the area of the semiconductor 92 have a lower dielectric constant than the waveguide 28' for best performance.
  • the material of the support 93 over the area of the semiconductor 92 can be made of porous glass or air-foamed glass that has a low dielectric constant relative to solid glass.
  • the material of the support 93 over the area of the semiconductor 92 can be made of porous glass or air-foamed glass that has a low dielectric constant relative to solid glass.
  • the outside walls of the vacuum tube 86 can be coated with microwave beam adsorber material or reflector material so as to maximize the power in the beam 82 at angle ⁇ .
  • An advantage of the embodiment of the invention based on CRT technology as shown in Figures 26 and 27 is that the amount of power in the beam 82 radiated by the waveguide 28' (or received) can be controlled by the amount of conductivity in the bands 94 in the semiconductor 92.
  • the conductivity of the bands 94 can be varied, although the relationship between power and conductivity may not be linear.
  • the conductivity of the bands 94 can be controlled by the number of closely spaced lines written by the electron beam 90 for a single conductive band 94.
  • bands in the center of the periodic pattern could be written more strongly than the bands at the edge of the pattern so as to affect excitation amplitude taper and side-lobe control of the radiated pattern.
  • the above concept of controlling beam power (radiating • or receiving) can also be applied to other embodiments of this invention which utilize photoconductors and light to form conductive bands in the adjustable periodic structure by control of the intensity of the light source (e.g. light source 61 in Figures 18 and 19; laser light source 90 in Figures 21 and 22; laser light diodes 78 in Figure 23) .

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Abstract

Un système d'antenne directionnel comprend un guide d'ondes (28) diélectrique allongé permettant de transmettre et/ou recevoir de l'énergie électromagnétique à une fréquence à laquelle le guide d'ondes la propage, un organe réglable (32) possédant une pluralité de parties conductrices écartées le long d'une région allongée adjacente et sensiblement parallèle au guide d'ondes, et un organe de commande (34) faisant varier dans une plage continue l'écartement entre les parties conductrices, de manière à commander l'angle de rayonnement maximum.
EP19860906041 1985-08-22 1986-08-12 Antenne orientable en fonction du faisceau Withdrawn EP0233282A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US76852485A 1985-08-22 1985-08-22
US768524 1985-08-22

Publications (1)

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EP0233282A1 true EP0233282A1 (fr) 1987-08-26

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Application Number Title Priority Date Filing Date
EP19860906041 Withdrawn EP0233282A1 (fr) 1985-08-22 1986-08-12 Antenne orientable en fonction du faisceau

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EP (1) EP0233282A1 (fr)
JP (1) JPS63500698A (fr)
WO (1) WO1987001243A1 (fr)

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CN107275788B (zh) * 2017-07-03 2020-01-10 电子科技大学 一种基于金属微扰结构的毫米波扇形波束柱面龙伯透镜天线
WO2019157567A1 (fr) * 2018-02-16 2019-08-22 The University Of Queensland Antenne directive à panneau plat
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