EP0104173B1 - An electronically scanned antenna system having a linear array of yagi antennas - Google Patents
An electronically scanned antenna system having a linear array of yagi antennas Download PDFInfo
- Publication number
- EP0104173B1 EP0104173B1 EP82901744A EP82901744A EP0104173B1 EP 0104173 B1 EP0104173 B1 EP 0104173B1 EP 82901744 A EP82901744 A EP 82901744A EP 82901744 A EP82901744 A EP 82901744A EP 0104173 B1 EP0104173 B1 EP 0104173B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- aircraft
- yagi
- antenna system
- antenna
- antennas
- 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
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
- H01Q21/08—Arrays of individually energised antenna units similarly polarised and spaced apart the units being spaced along or adjacent to a rectilinear path
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/27—Adaptation for use in or on movable bodies
- H01Q1/28—Adaptation for use in or on aircraft, missiles, satellites, or balloons
- H01Q1/286—Adaptation for use in or on aircraft, missiles, satellites, or balloons substantially flush mounted with the skin of the craft
- H01Q1/287—Adaptation for use in or on aircraft, missiles, satellites, or balloons substantially flush mounted with the skin of the craft integrated in a wing or a stabiliser
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
- H01Q1/428—Collapsible radomes; rotatable, tiltable radomes
-
- 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
- H01Q19/28—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 a secondary device in the form of two or more substantially straight conductive elements
- H01Q19/30—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 a secondary device in the form of two or more substantially straight conductive elements the primary active element being centre-fed and substantially straight, e.g. Yagi antenna
-
- 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
- H01Q3/26—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 relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
Definitions
- the present invention relates to an antenna system for conformal mounting on an aircraft, comprising a linear array of Yagi antennas.
- Electronically scanned linear arrays of simple elements are well known. Such arrays are generally characterized by relatively low gain, and a broad elevation pattern. Arrays of Yagi antennas in which scanning is accomplished mechanically by rotating the entire array are also known. These arrays are unsatisfactory when conformal mounting in the plane of the array is required, e.g., on or within airfoil surfaces (wings and horizontal stabilizer) of an aircraft.
- United States Patent 2,236,393 discloses a broad bandwidth endfire antenna.
- United States Patent 3,182,330 (Blume) dislcoses an antenna array having non-uniform spacing of the individual elements.
- United States Patent 2,425,887 discloses an endfire antenna in which all the elements are energized with equal voltages in proper phase.
- United States Patent 3,258,774 discloses a series-fed phased antenna array. See also United States Patent 3,509,577 (Kinsey).
- United States Patent 2,419,562 discloses a binomial array for producing a clover leaf pattern having highly directive properties.
- a Yagi antenna is referenced in United States Patent 3,466,655 (Mayes et al).
- Endfire elements such as Yagi antennas are known to produce high density with narrow patterns in both planes (azimuth and elevation), and are therefore, according to conventional practice, considered unsuitable for wide angle electronic scanning when multiple elements are arrayed. (The scan angle limits being established by the width of the in-array element pattern).
- the present invention advantageously utilizes arrayed Yagi elements for wide angle scanning by employing mutual coupling between the elements to broaden the element pattern in the plane in which electronic scanning is desired.
- an antenna system for conformal mounting on an aircraft, comprising a linear array of Yagi antennas, each of the Yagi antennas including a driven element, a reflector member and a director member, each of which has a length less than the spacing between adjacent Yagi antennas, characterised in that the Yagi antennas each lie in the E-plane and are laterally spaced from one another a distance of between substantially 0.3 ⁇ and 0.9A centre to centre, and the antenna system further comprises means connected to the Yagi antennas for electronically scanning the antenna system main lobe in the E plane over an angle A substantially greater than the free space beam width of the individual Yagi antennas in the E plane, whereby said scan angle A can be greaterthan 90°.
- the invention also concerns an aircraft on which such an antenna system is conformally mounted, for example in a wing thereof.
- Electrode scanning as the term is used therein entails adjustments in the excitation coefficients (e.g., phase and amplitude) of the elements in the array in accordance with 'the direction in which the formation of a beam is desired.
- phase front is adjusted to steer the beam by individual control of the phase excitation of each radiating element.
- Phase shifters are electronically actuated to permit rapid scanning and are adjusted in phase to a value between 0 and 2n radians. While this method of electronic scanning is perhaps the most commonly used, other means may be employed to effect the same changes in the phase front of the array to produce steerage of the beam.
- Control of the excitation coefficients of the elements of the array is commonly known as "antenna feed", and includes all means for independently or dependently controlling the amplitude and phase of the signals to or from the individual elements of the antenna array, and dividing or combining means therefor.
- an antenna according to the present invention is generally illustrated at 10.
- the antenna 10 includes a linear array of Yagi elements 12 electronically coupled to an element driving network 14 which is conventionally known as an antenna feed.
- Each element 12 is laterally spaced a distance (D) between 0.3 ⁇ and 0.9 A apart, preferably about 0.55 ⁇ apart (center-to-center) to enhance the effects of mutual coupling between the elements 12, resulting in a broadened element pattern of the mainbeam in the plane of the array.
- the length (L) of each individual element 12 is approximately 1.25 ⁇ .
- a Yagi element 12A for use in the array of the present invention is shown.
- a Yagi array includes at least two parasitic elements in addition to the driven element.
- the Yagi element 12A includes six conductive elements 16,18, 20, 22, 24 and 26.
- Such a multiparasitic array is known as a 6-element beam.
- Each element has a diameter of approximately 0.01 ⁇ and a length of approximately 0.5 ⁇ .
- the six elements 16, 18, 20, 22, 24 and 26 are positioned in spaced parallel relationship along the same line of sight (transverse axis) with the spacing between adjacent elements being approximately .25 ⁇ .
- the six elements 16, 18, 20, 22, 24 and 26 are supported on a pair of nonconductive Plexiglass supports 28 and 30, e.g., by inserting the elements 16, 18, 20, 22, 24 and 26 into mating holes in the Plexiglass support.
- the supports 28 and 30 electrically insulate the elements 16, 18, 20, 22, 24 and 26 from one another, and advantageously are substantially invisible to the resulting electromagnetic waves.
- Element 16 is a reflector element, element 18 the driven element, and elements 20, 22, 24 and 26 the director elements.
- a coaxial cable 32 is electrically coupled to the driven element 18 for providing a signal thereto.
- the reflector 16 and directors 20-26 interact in a conventional manner to provide increased gain and unidirectiv- ity to the radiated signal pattern.
- the free-space half-power beam-widths of element 12A is 42° in the E plane and 48° in the H plane.
- ten Yagi elements 12A-J of the type shown in Fig. 2 are arranged in a linear array 10A.
- the elements 12A-J have a common reflector 16A and are closely spaced laterally a distance of between about 0.3 X and about 0.9 ⁇ apart, preferably about 0.55 ⁇ apart (center-to-center), to increase the effects of mutual coupling therebetween.
- the in-array pattern i.e., the angle over which the antenna mainlobe can be electronically scanned increases from 42° for the single endfire element 12A of Fig. 2 to greater than 90° in the array 10A.
- the narrow H plane pattern of 48° for the single element 12A is maintained in the array 10A.
- the effect of closely spacing the elements 12A in the linear array 10 is to broaden the element pattern in the plane of the array 10A (E plane) while preserving the narrow H plane pattern.
- the broadened E-plane pattern of the in-array element may be demonstrated as follows:
- the elements 12A-D and 12F-J have individual terminating impedances 34A-D and 34F-J coupled to ground 36 in the array 10A.
- the terminating impedances 34A-D and 34F-J are chosen to match the antenna driving point impedance to an antenna scan angle of 0° in the E-plane.
- the terminating impedances 34A-D and 34F-J are 50 ohms.
- Element 12E is monitored by meter 38 which measures the power received by element 12E when the array 10A is used as a receiving device to receive signals transmitted by a radiating device (not shown) positioned at sufficient distance from the array 10A so as to be in the far field of the array 10A.
- the power measured in meter 38 will vary in proportion to the in-array element pattern of element 12E. This method of pattern measurement is well known in the art.
- the in-array element pattern measured in this manner is approximately proportional to the gain of the array 10A as a function of angle when the outputs of all of the elements 12A-J are utilized to form a beam.
- the array 10A operates as follows: A feed means (not shown) applies transmission signals to a combining/dividing network 40 which splits the signals for transmission by the individual elements 42 of the array 44 (N elements are shown). N phase shifters 46 shift the phase of the signals in accordance with the direction in which a beam is desired. In applications where unequal amplitudes are desired for each antenna element to provide lower antenna sidelobes (commonly known as amplitude taper, the combining/dividing network 48 advantageously provides such a distribution.
- the antenna array 10A with its feed is linear, passive and bilateral and is subject to the law of reciprocity so that when it is used in the receiving mode its characteristics are unaltered.
- an aircraft 48 is illustrated with antenna arrays 10 B, C and D in accordance with the present invention positioned in the wing leading edges 50 and 52 and in the horizontal stabilizer 54.
- 360° azimuthal coverage is obtained by electronically scanning the arrays 10B-D and conventional side-looking antennas 56 and 58 mounted on opposite sides of the fuselage 60 in a back-to-back relationship.
- such an arrangement avoids the need for a large dome mounted on the fuselage 60 which must be mechanically rotated to provide the same 360° azimuthal coverage.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Astronomy & Astrophysics (AREA)
- Aviation & Aerospace Engineering (AREA)
- General Physics & Mathematics (AREA)
- Remote Sensing (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
- Aerials With Secondary Devices (AREA)
Abstract
Description
- The present invention relates to an antenna system for conformal mounting on an aircraft, comprising a linear array of Yagi antennas.
- Electronically scanned linear arrays of simple elements are well known. Such arrays are generally characterized by relatively low gain, and a broad elevation pattern. Arrays of Yagi antennas in which scanning is accomplished mechanically by rotating the entire array are also known. These arrays are unsatisfactory when conformal mounting in the plane of the array is required, e.g., on or within airfoil surfaces (wings and horizontal stabilizer) of an aircraft.
- Various antenna element configurations are known, United States Patent 2,236,393 (Beck et al.) discloses a broad bandwidth endfire antenna. United States Patent 3,182,330 (Blume) dislcoses an antenna array having non-uniform spacing of the individual elements. United States Patent 2,425,887 (Lindenblad) discloses an endfire antenna in which all the elements are energized with equal voltages in proper phase. United States Patent 3,258,774 (Kinsey) discloses a series-fed phased antenna array. See also United States Patent 3,509,577 (Kinsey). United States Patent 2,419,562 (Kandoian) discloses a binomial array for producing a clover leaf pattern having highly directive properties. A Yagi antenna is referenced in United States Patent 3,466,655 (Mayes et al).
- Moreover, generally in known antenna array construction mutual coupling is regarded as detrimental and means are taken to minimize its effect. In contrast the present invention utilizes mutual coupling to enhance antenna performance.
- Endfire elements such as Yagi antennas are known to produce high density with narrow patterns in both planes (azimuth and elevation), and are therefore, according to conventional practice, considered unsuitable for wide angle electronic scanning when multiple elements are arrayed. (The scan angle limits being established by the width of the in-array element pattern). In contrast with conventional practice, the present invention advantageously utilizes arrayed Yagi elements for wide angle scanning by employing mutual coupling between the elements to broaden the element pattern in the plane in which electronic scanning is desired.
- It is an object of the present invention to provide an antenna array having a high grain and narrow elevation beam, with a narrow azimuthal beam which can be electronically scanned throughout a wide azimuthal sector.
- It is a further object of the present invention to provide an antenna array of very small elevation so as to be suitable for installation on or within the airfoil surfaces of an aircraft, e.g., wing leading edges and the horizontal stabilizer trailing edge, usable with a suitable radome which is an integral part of the airfoil.
- It is a still further object of the present invention to provide an antenna array having a high gain and broadened in-array element pattern from increasing the angle over which the antenna mainlobe can be electronically scanned.
- It is a still further object of the present invention to broaden the narrow in-array element pattern of a Yagi antenna array.
- It is a still further object of the present invention to broaden the in-array pattern of a Yagi antenna array in one plane only.
- According to the invention there is provided an antenna system for conformal mounting on an aircraft, comprising a linear array of Yagi antennas, each of the Yagi antennas including a driven element, a reflector member and a director member, each of which has a length less than the spacing between adjacent Yagi antennas, characterised in that the Yagi antennas each lie in the E-plane and are laterally spaced from one another a distance of between substantially 0.3λ and 0.9A centre to centre, and the antenna system further comprises means connected to the Yagi antennas for electronically scanning the antenna system main lobe in the E plane over an angle A substantially greater than the free space beam width of the individual Yagi antennas in the E plane, whereby said scan angle A can be greaterthan 90°.
- The invention also concerns an aircraft on which such an antenna system is conformally mounted, for example in a wing thereof.
- "Electronic scanning" as the term is used therein entails adjustments in the excitation coefficients (e.g., phase and amplitude) of the elements in the array in accordance with 'the direction in which the formation of a beam is desired.
- It is well known to those skilled in the art that the beam of an antenna points in a direction that is normal to the phase front. In phased arrays the phase front is adjusted to steer the beam by individual control of the phase excitation of each radiating element. Phase shifters are electronically actuated to permit rapid scanning and are adjusted in phase to a value between 0 and 2n radians. While this method of electronic scanning is perhaps the most commonly used, other means may be employed to effect the same changes in the phase front of the array to produce steerage of the beam. Control of the excitation coefficients of the elements of the array is commonly known as "antenna feed", and includes all means for independently or dependently controlling the amplitude and phase of the signals to or from the individual elements of the antenna array, and dividing or combining means therefor.
- The present invention is illustrated in the accompanying drawings, in which:
- Figure 1 is a top plan view of a linear array of Yagi elements according to the present invention;
- Figure 2 is a perspective view of a Yagi element for the linear array of the present invention;
- Figure 3 is a top plan view of a linear array of Yagi elements of the type shown in Fig. 2 in which all the endfire elements have a common reflector;
- Figure 4 is a top plan view of a linear array of Yagi elements similar to Fig. 3 being scanned at an angle θo; and
- Figure 5 is a perspective view of an aircraft with parts broken away to indicate the mounting thereon of linear arrays of Yagi elements in accordance with the present invention.
- Referring to Fig. 1, an antenna according to the present invention is generally illustrated at 10. The
antenna 10 includes a linear array of Yagi elements 12 electronically coupled to anelement driving network 14 which is conventionally known as an antenna feed. - Each element 12 is laterally spaced a distance (D) between 0.3 λ and 0.9 A apart, preferably about 0.55 \ apart (center-to-center) to enhance the effects of mutual coupling between the elements 12, resulting in a broadened element pattern of the mainbeam in the plane of the array. The length (L) of each individual element 12 is approximately 1.25 λ.
- Referring to Fig. 2, a Yagi
element 12A for use in the array of the present invention is shown. As is well known, a Yagi array includes at least two parasitic elements in addition to the driven element. The Yagielement 12A includes sixconductive elements - The six
elements elements elements elements -
Element 16 is a reflector element, element 18 the driven element, andelements coaxial cable 32 is electrically coupled to the driven element 18 for providing a signal thereto. Thereflector 16 and directors 20-26 interact in a conventional manner to provide increased gain and unidirectiv- ity to the radiated signal pattern. The free-space half-power beam-widths ofelement 12A is 42° in the E plane and 48° in the H plane. - Referring to Fig. 3, ten Yagi
elements 12A-J of the type shown in Fig. 2 are arranged in alinear array 10A. Theelements 12A-J have acommon reflector 16A and are closely spaced laterally a distance of between about 0.3 X and about 0.9 λ apart, preferably about 0.55 λ apart (center-to-center), to increase the effects of mutual coupling therebetween. With such an arrangement, the in-array pattern, i.e., the angle over which the antenna mainlobe can be electronically scanned increases from 42° for thesingle endfire element 12A of Fig. 2 to greater than 90° in thearray 10A. The narrow H plane pattern of 48° for thesingle element 12A is maintained in thearray 10A. Thus the effect of closely spacing theelements 12A in thelinear array 10 is to broaden the element pattern in the plane of thearray 10A (E plane) while preserving the narrow H plane pattern. - The broadened E-plane pattern of the in-array element may be demonstrated as follows: The
elements 12A-D and 12F-J have individual terminatingimpedances 34A-D and 34F-J coupled toground 36 in thearray 10A. The terminatingimpedances 34A-D and 34F-J are chosen to match the antenna driving point impedance to an antenna scan angle of 0° in the E-plane. In the embodiment illustrated in Fig. 3, the terminatingimpedances 34A-D and 34F-J are 50 ohms. Element 12E is monitored by meter 38 which measures the power received by element 12E when thearray 10A is used as a receiving device to receive signals transmitted by a radiating device (not shown) positioned at sufficient distance from thearray 10A so as to be in the far field of thearray 10A. As thearray 10A is rotated in angle with respect to the radiating device, the power measured in meter 38 will vary in proportion to the in-array element pattern of element 12E. This method of pattern measurement is well known in the art. Moreover, it is also well known in the art that the in-array element pattern measured in this manner is approximately proportional to the gain of thearray 10A as a function of angle when the outputs of all of theelements 12A-J are utilized to form a beam. - With reference to Fig. 4, the
array 10A operates as follows: A feed means (not shown) applies transmission signals to a combining/dividing network 40 which splits the signals for transmission by the individual elements 42 of the array 44 (N elements are shown).N phase shifters 46 shift the phase of the signals in accordance with the direction in which a beam is desired. In applications where unequal amplitudes are desired for each antenna element to provide lower antenna sidelobes (commonly known as amplitude taper, the combining/dividing network 48 advantageously provides such a distribution. - The
antenna array 10A with its feed is linear, passive and bilateral and is subject to the law of reciprocity so that when it is used in the receiving mode its characteristics are unaltered. - Referring to Fig. 5, an
aircraft 48 is illustrated withantenna arrays 10 B, C and D in accordance with the present invention positioned in the wing leading edges 50 and 52 and in the horizontal stabilizer 54. With this arrangement 360° azimuthal coverage is obtained by electronically scanning thearrays 10B-D and conventional side-lookingantennas fuselage 60 in a back-to-back relationship. Advantageously, such an arrangement avoids the need for a large dome mounted on thefuselage 60 which must be mechanically rotated to provide the same 360° azimuthal coverage.
Claims (15)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US1982/000377 WO1983000952A1 (en) | 1982-03-26 | 1982-03-26 | An electronically scanned antenna system having a linear array of endfire elements |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0104173A1 EP0104173A1 (en) | 1984-04-04 |
EP0104173A4 EP0104173A4 (en) | 1984-09-28 |
EP0104173B1 true EP0104173B1 (en) | 1988-10-12 |
Family
ID=22167890
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP82901744A Expired EP0104173B1 (en) | 1982-03-26 | 1982-03-26 | An electronically scanned antenna system having a linear array of yagi antennas |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0104173B1 (en) |
JP (1) | JPS59500645A (en) |
BE (1) | BE892812A (en) |
DE (1) | DE3279118D1 (en) |
WO (1) | WO1983000952A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB9004024D0 (en) * | 1990-02-22 | 1997-03-12 | British Aerospace | Airborne radar |
FR2677813B1 (en) * | 1991-06-17 | 1994-01-07 | Tecnes Sa | LOW SIZE ACTIVE ANTENNA FOR METEOROLOGICAL SATELLITE. |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2407169A (en) * | 1941-05-26 | 1946-09-03 | Hazeltine Research Inc | System for locating radiated-signal reflectors |
US3373434A (en) * | 1964-12-01 | 1968-03-12 | Sperry Rand Corp | Lightweight antenna formed from net of dielectric cord, having metalized sectors thereon |
-
1982
- 1982-03-26 DE DE8282901744T patent/DE3279118D1/en not_active Expired
- 1982-03-26 WO PCT/US1982/000377 patent/WO1983000952A1/en active IP Right Grant
- 1982-03-26 JP JP57501770A patent/JPS59500645A/en active Granted
- 1982-03-26 EP EP82901744A patent/EP0104173B1/en not_active Expired
- 1982-04-08 BE BE0/207798A patent/BE892812A/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
EP0104173A4 (en) | 1984-09-28 |
JPS59500645A (en) | 1984-04-12 |
EP0104173A1 (en) | 1984-04-04 |
DE3279118D1 (en) | 1988-11-17 |
BE892812A (en) | 1982-08-02 |
WO1983000952A1 (en) | 1983-03-17 |
JPH0480561B2 (en) | 1992-12-18 |
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