JPH06500909A - linear array antenna - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] linear array antenna The present invention provides a linear array antenna with high efficiency. this kind of antenna is a synthetic aperture radar (Synthetic Aperture Radar) used especially in the field of space technology. This is particularly advantageous in the field of Aperture Radar (5AR).

The antennas used in such radars have the following characteristics: Has a high gain to suppress the output emitted from the radar to a small value, so that a constant scan of the ground is maintained within one altitude plane (the plane perpendicular to the orbit). In the azimuthal plane (the plane parallel to the orbit), it has a very sharp lobe with variable width. – Any point can be accessed very quickly (surveillance mission) and the same The same test point can be sequentially oriented at low and high incidence angles within 24 hours (vegetation observation). The scanning range in the altitude plane is extremely wide, as shown in the table below. The combined length of the antenna can be extended and a resolution of several meters parallel to the orbit can be obtained. , the scanning range in the azimuth plane to track the same area is smaller, In order to separate the backscatter of one ground and the backscatter of a vegetation zone, two straight lines are orthogonal to each other. having polarization (horizontal polarization H and vertical polarization V), ~The level of single interference wave is extremely low within the scanning range of the antenna. In order to be able to attach many radiating elements to one antenna, ・The radiating elements are as inexpensive as possible. It must have characteristics such as being compact and compact.

Large direct radiating antennas consisting of a very large number of planar radiating elements are identified above. cannot meet such requirements.

In fact, the array lobe theory states that the maximum value of the antenna deflection angle (θmax) is larger than the numerical value As soon as the value becomes large, the distance d between the phase control points of the antenna is determined by the formula: [In the formula, Bw is the main lobe of the array antenna directed perpendicular to the antenna. This indicates that the width of the bottom of the main lobe must be satisfied.

If this condition is not met, multiple array lobes will appear in the radiation pattern. Ru. The levels of these lobes are higher than the required level of the secondary lobes, so The tena gain is reduced and ambiguity occurs.

The above conditions are For one altitude scan, the pitch must be close to λ/2, For unidirectional scanning, the declination angle must be a small value compatible with a pitch close to λ. do not have, This includes the results.

However, when the antenna is very long, very sharp lobes and As a result of the above conditions, a huge number of sources are required to achieve this goal.

Three solutions are possible to reduce the number of control points and disrupt the periodicity of the irradiation law: This results in a widely spaced array that destroys the lobes of the array. In some cases, a very large gain reduction occurs.

By gradually increasing the spacing between the phase tube M sections as one moves away from the center of the antenna. The array has an irregular pitch. To prevent antenna gain reduction This solution requires a large number of different types of radiating elements, thus making the antenna completely It cannot be divided into congruent sub-panels, which increases costs.

The illumination in the azimuthal plane approximates as closely as possible the law of illumination for uniform apertures of the same length. An array formed from subarrays that has a law, in this case the position of the sight along an axis. The lobe of the subarray of the antenna when aligned is the radiation pattern of the subarray. removed by the first few zeros of the sequence.

This condition can no longer be met when there is a small azimuth scan, so the To keep the array lobe at a lower level than the sidelobes at large declinations Determine the maximum subarray length required.

Similarly, if the azimuth declination is not specified, a sub of length equal to the length of the antenna An array is appropriate. In fact, the length of the subarray is determined by the nose of the launch vehicle. The dimensions of the antenna panel (1 to 3 m) must be adjusted to fit the available space below the antenna. Therefore, it is limited.

In the end, the radiating element of synthetic aperture radar cannot meet all the above requirements. , that is, rProceedings of IGAR3S 1988J (289-29 Robert Peterson and Per Ingvarso published on page 4) n's paper, ``Planar array antenna for the European telemetry satellite ER3-1''. In particular, ER3-1 (1991), RADAR3AT (1995) and The slot guide used in SIR-C (X-5AR) has low loss. Nevertheless, bipolarization is easily achieved. The reason is that the altitude scanning range is wide, so H polarization and ■ polarization are Two different radiating guides must be combined and inserted into a small pitch array. This is because there is no such thing. Furthermore, if azimuth scanning is specified, the level of the array lobe It may be necessary to divide these guides into smaller sections to limit the This makes the production of the guide extremely complex or reduces its value. child technology has polarization in the C-band or higher frequencies without scanning in the azimuthal plane. Advantageous only in case of radar.

rProceedings of Workshopon printed a ntennas technique.

1ogy” (Las Cruces; 1979; 18-1 to 18-20) R. Murphy's paper, rSEASAT and Sr.R.A. 5EASAT (1978), s I R-A (1981), SIRB (1984> and J, ER3 (made in Japan, 19 The radiating elements printed on the L and S band honeycombs used in 92) are , lighter than the guide and capable of dual polarization. However, these elements are The loss per unit length is large, so the length of the subarray is equal to the wavelength (up to 10^ ) is limited to several times. With such losses, uniform illumination across the subarray cannot give you a shot.

The purpose of the linear array antenna of the present invention is to meet all of the above requirements.

The invention therefore provides a single column excited by at least one embedded feeder element. A linear array antenna consisting of a radiating element formed from an annular window, the antenna comprising: In order to completely prevent parasitic radiation originating from the feeder element, the feeder element must It is characterized by being included in the element and therefore not exposed to the radiation surface of the antenna. We propose a linear array antenna. Such an antenna simultaneously transmits two straight-line leakages. or with two circularly polarized waves (clockwise or counterclockwise). configured to emit (or receive) simultaneously.

In a preferred embodiment using only three stages of conductors, the antenna is an integral layer. - has a dome and a feeder stage. Preferably the antenna has a small thickness. Therefore, it is lightweight.

contains only substrates that are separated by conductive spacers with no mechanical continuity in the plane of the array. . Preferably the antenna completely prevents coupling between radiating elements and between feeders. In order to Contains cover.

According to a particular embodiment of the invention, the antenna is etched into the feeder stage and has an annular shape. It is a broadband antenna that uses a resonant disk that resonates at a frequency close to the window frequency. Ru.

According to another particular embodiment of the invention, the antenna is etched into the feeder stage. A two-band amplifier using a resonant disk that resonates at a frequency far from that of the annular window. It's Tena.

Such an antenna has many advantages. In particular, - less loss; The interference polarization level within one scanning range is low - since two single waves can be used, the present invention The array antenna can simultaneously transmit two linearly polarized waves or circular waves (clockwise and counterclockwise). capable of emitting (or receiving) - Wide altitude scanning range, one subarray can have a considerable length, the gain is large, and - similar polarization losses in the two polarizations, It has the following advantages.

The features and advantages of the invention will be apparent from the following non-limiting description based on an example of embodiment illustrated in the accompanying drawings. will be more fully understood.

FIG. 1 is an exploded view of a portion of a subarray of one embodiment of the antenna of the present invention.

2 and 3 show portions of subarrays of two variant embodiments of the antenna of the invention. This is an illustration.

4 and 5 show radiation patterns for horizontal and vertical polarization, respectively.

6 and 7 are two further modified embodiments of the invention.

The antenna of the present invention radiates so as to completely prevent parasitic radiation originating from the feeder. at least one implant included in the element and therefore not exposed to the radiation surface of the antenna; A near-array consisting of a row of annular slits excited by a feeder element. antenna.

This type of antenna radiates (or receives) two linearly polarized waves simultaneously or It is designed to emit two circularly polarized waves (right-handed or left-handed) simultaneously.

FIG. 1 shows a portion of a subarray of such an antenna.

The part is One radiating element cavity 11 and two polarization feeder channels 12 are provided. conductive material (e.g. aluminum, metallized carbon fiber or conductive material) a lower shell 10 made of plastic); It has the same expansion coefficient as the one-shell material, and has H-polarized and ■-polarized waves on its top surface. an extremely thin (for example, approximately 0.1 mm thick) first substrate 13 on which the reader 14 is etched; , - two polarized feeder channels 16 and an opening 17 above the cavity are formed; - a top surface 19 containing no copper plating and an etched ring; a second substrate 18 similar to the first substrate having the other surface 20 including a shaped window 21; The purpose of the substrate 18 is to center the annular window above the cavity and to align the radome mechanism. It is to fulfill one's ability.

As a floating strip line (triplaquesuspendu) For operation, the two shell halves 10.15 must be connected to the same potential . Such a connection is possible when the surfaces of the first substrate on opposite sides of the two shell halves are metalized. around the cavity so as to interconnect the two opposing surfaces. obtained by deploying a number of metal-coated openings.

10. Create and test 12 and 24 annular windows in subarrays of such antennas. did. The degree of specification that the subarray and its various components meet is shown below. According to a subarray like - Extremely thin substrate with low loss, silver-plated walls and low loss coefficient The feeder fabricated by floating strip line technology is completely lossless Realize the decline. The radiating element is also made using the same technique.

- low level of interfering polarization within the scanning range; Because it uses strip line technology Parasitic radiation of feeder lines and bends etched into the radiation plane can be prevented. fee Because the beam is symmetrical about the axis of the array, different radiation patterns are generated for the interfering polarization. It is formed. As a result, the already low level of interfering polarization of the annular window is within all scanning ranges. will be deleted.

- Can use dual polarization. Two outputs with a 90 degree phase difference in the center of the radiating subarray Since we insert a 3dB coupler with The annular window is excited by circularly polarized waves.

One altitude scan range is wide, feeder channel is used, so there is a risk of coupling between polarizations The subarray can be significantly miniaturized without the need for Therefore, the pitch in the altitude plane is considerably reduced. and a wide range of altitude declinations are allowed.

One subarray is quite long, and the feeder loss is small, so the irradiation of the subarray is almost uniform. have the same amplitude and phase. The length of the subarray is in the passband of the subarray. Limited only by changes in the laws of irradiation.

One gain is large, complete with the directivity of the radiating element and the directivity of the array network. Consistency is obtained. The reason is that concentric cavities with extremely precisely adjustable diameters This is because tees are used. The adjustment range is the circumference corresponding to the waveguide width λg at resonance. Almost part of the cavity with #(quasi-decouplee) window 6d Bi to 9 dBi of the window that resonates at 1.5λg. Therefore, this type of The range of 0.56-0.8λ rectangular networks required for rays is covered.

- The polarization loss of the two polarizations is comparable. The annular window overlapping the cavity is approximately It has a rotationally symmetrical radiation pattern. In the altitude plane, the radiation pattern accompanies one wave. does not change, so the same loss is guaranteed within the scanning range.

- Sub-arrays are reduced in cost and size.

A particularly advantageous embodiment of the antenna of the invention is shown in FIG. The substrate was formed from three substrates each having a thickness of about 0.1 mm. Each board is configured as follows. has been done.

The lower substrate 25 is RF feed connector 28. Locally copper plated around the two perimeters (area 27), and a lower surface 26 adhered to the structural panel; Completely copper plated (except for the RF feed opening) and used as a ground surface. Surface 30 and a metallized aperture 31 connecting the two surfaces; The intermediate substrate 32 is The surface 42 facing the partition formed by the conductive spacer 41 is copper plated. The lower surface 33 that has been The electrical connection between the copper-plated top surface 34 and the two ground planes in which the reader circuit 35 is located It has a metal-coated aperture 44 to ensure connection (the aperture 36 is for H polarization and V polarization). To solder the core of the connector 28, 29 that feeds the polarization feeder 35 ), the upper substrate 37 is Completely copper plated except for the area where the annular window 39 is present a lower surface 38 functioning as a ground surface; It has an upper surface 40 that does not contain any copper plating and functions as a radome.

These three substrates 25, 32 and 37 are electrically conductive substrates made of aluminum, for example. are separated by a spacer, which connects the annular window cavity and the feeder. channel.

After attaching the solder preform to the interface between the spacer and the copper-plated board, Assembly may be done in a single step by oven soldering, or The spacers may be tin plated; the materials and methods used in this type of embodiment are , guaranteeing excellent performance with respect to subarray cost and size.

Regarding temperature characteristics, as a small spacer with non-continuous dimensions in the plane of the array. A low expansion material that is compatible with e.g. carbon structural panels ensures a high degree of rigidity of the antenna. Tensile materials may be used.

If the azimuth declination is specified, the subarray can be considerably shortened, resulting in Therefore, a slight increase in antenna resistance loss is allowed.

A modification of the above antenna is shown in FIG. 3. The antenna of FIG. It is formed from a lower member 45 made of an electrically conductive material and an upper member 47 made of a dielectric material. It is.

In the lower member 45, the ground plane consists of a thin substrate 43, on which a spacer is placed. 46 is soldered.

The upper member 47 includes an annular window 49 on the upper surface 48 and a polarization feeder 51 on the lower surface 50. ．． 52 and a window exciter 53. Continuity of the annular window cavity in the substrate is ensured by a metallized aperture 54 connecting the spacer to the ground plane of the window. Ru. Two metal coated wires connect the dark ground between the probe and the stripline. The feeder is powered by a coaxial probe passing through the apertures 55,56.

In this variant of the invention, all the characteristics of the antenna of FIG. 1 are maintained. made In exchange for the advantage of simpler construction, the resistance loss was only slightly increased. short sub For arrays (〈10^) this loss is completely acceptable. The reason is, -The wires are supported by an extremely thin (approximately 0.1 mm) board, so the microphone ``Floating strip line'' where radio wave energy propagates essentially in a vacuum. Ida, and – “inverted miter” where most of the propagation takes place in a thicker (approximately 1 mm) dielectric substrate; This is because a "Crosstrip" feeder is used.

Accordingly, the present invention provides a sub-surface area of 0.66^1 m2 by any of these embodiments. A space radar with a synthetic aperture containing a 1,33^10m2 array of arrays. can form an antenna.

Avoid using additional feeder stages to feed small length radiating elements For this purpose, altitude scanning requires approximately 0.7λ pitch between subarrays at 5.3GHz. However, since the azimuth scanning is not specified at all, the dual polarization sub The present invention uses a subarray with 24 annular windows for which the array is most suitable. All of these requirements can be met.

The antenna therefore functions as both a feeder and a radiating element at a single level. . The lower and upper spacers are made of aluminum shell halves that are assembled by screws. Made from rest. Excitation of the two polarizations is carried out by a small coaxial prism placed near the center of the array. It is done by a robe.

The horizontally polarized and vertically polarized radiation patterns are shown in Figures 4 and 5. The polarization pattern 60.61 corresponds to the first few zeros of the aperture plane ±3.22 As shown by the "*J symbol" marked with °, the pattern of apertures with equal amplitude and equal phase is polarized. The closest on-axis interference polarization pattern 62.63 is 30 d in all passbands. It is less than B/max. To evaluate the quality of the antenna, two polarizations are used. The wave gain is expressed as the net of the array given by Equation 2, where S is the surface area of the antenna. should be compared with the theoretical orientation of the network.

Therefore, the loss for this value is 1.5d for both horizontal and vertical polarization. B and 2.5dB. These losses are 24-window excitation error for the equal amplitude, equal phase law - loss due to interfering polarization loss One resistance loss, Includes losses due to inconsistency in one person's efforts.

These results demonstrate the advantages of the present invention in manufacturing antenna linear subarrays. be understood.

According to the present invention, a double resonator antenna as shown in FIGS. 6 and 7 can be obtained. Operating the antenna to extend the overband or at two separated frequencies In order to disk 65 may be placed. The diameter of the disk 65 is determined by the resonance of the annular window located above. It can be freely adjusted so as to resonate at a frequency F2 different from the frequency F1.

- When F2 has a value close to Fl, the antenna can operate in wideband.

- When F2 is a value far from Fl, a two-band antenna is obtained. two fi Each of the controllers is adapted to a respective specific band and excites one of the two annular windows.

Such modifications can be applied to the two modifications of the invention described above. floating In stripline embodiments, an additional annular window is etched into the top or bottom surface of the top board. 1. FIGS. 6 and 7 respectively correspond to the variations of FIGS. 2 and 3. The upper base shown in FIG. The plate 37' is provided with a window 69 on its upper surface 67.

Metalized aperture to allow connection between window ground and stripline ground 66 are provided.

Although the present invention has been illustrated and described above based on preferred embodiments, the scope of the present invention It will, of course, be understood that the components described herein may be replaced by equivalent elements.

FIG. 6 Continuation of front page (72) Inventor Gomé-Henri, Michel France, 31240 Reunion , Ru deux Lantern Noir, 11

Claims (10)

[Claims] 1. a row of rings excited by at least one embedded feeder element (14); A linear array antenna consisting of a radiating element formed from a shaped window (21), In order to completely prevent parasitic radiation emanating from the feeder element, the feeder element A linear array that is included in the radiating element and therefore not exposed to the radiation surface of the antenna. antenna, which contains only substrates with a small thickness, and these substrates conductors with no mechanical continuity in the plane of the array to prevent differential expansion with the substrate. A linear array antenna characterized in that the antenna is separated by an electrically conductive spacer. 2. the antenna is configured to simultaneously radiate (or receive) two linearly polarized waves; The array antenna according to claim 1, characterized in that: 3. The antenna emits two circularly polarized waves (clockwise and counterclockwise) simultaneously (or 2. The array antenna according to claim 1, wherein the array antenna is configured to receive Tena. 4. Features include an integrated radome and a feeder that uses only three stages of conductors The array antenna according to claim 1. 5. Polarization of the subarrays to completely prevent coupling between radiating elements and between feeders. characterized by including shielding of radiating elements and feeders between waves and between adjacent subarrays; The array antenna according to any one of claims 1 to 4. 6. a radiating element cavity (11) and two polarization feeder channels (12); a lower shell half (10) made of a conductive material provided with; It has the same expansion rate as the material of the half-shell shell, and has horizontal and vertical feeders (1 4) is etched into an extremely thin first substrate (13); Two polarized feeder channels (16) and an opening (17) above the cavity are shaped. The upper shell half-break (15) made, The top surface (19) contains no copper plating and the other surface (19) contains an etched annular window (21). 20) and a second substrate (18) similar to the first substrate, The two halves (10 and 15) are connected to the same potential, and this connection have metal coatings on opposite surfaces and a cap to connect the two surfaces. by means of a first substrate having a number of metallized apertures arranged around the periphery of the holes; 2. The array antenna according to claim 1, wherein the array antenna is provided with: 7. including a lower substrate (25), an intermediate substrate (32), and an upper substrate (37), The lower substrate (25) is Localized copper plating (area 27) around the RF feed connectors (28, 29), and a lower surface (26) glued to the structural panel; Completely copper plated (except for the RF feed opening) and used as a ground surface. a surface (30) and a metallized aperture (44) connecting the two surfaces. the law of nature, The intermediate substrate (32) is The surface facing the partition formed by the conductive spacer (41) is copper plated. The lower surface (33) that has been cut and the surface (35) facing the partition and The wave feeder circuit has a copper plated top surface (34) and an electrical connection between the two ground planes. metal-coated apertures (44) to ensure connection; The upper substrate (37) is Completely copper plated except for where the annular window (39) is located for the strip line. a lower surface (38) functioning as a ground surface; It has an upper surface (40) that does not contain any copper plating and functions as a radome, These three substrates (25, 32 and 37) form the annular window cavity and feeder. The channel is separated by a conductive spacer (41) defining the channel. 2. The array antenna according to claim 1, wherein the array antenna has the following characteristics. 8. A lower member (45) made of a conductive material and an upper member (47) made of a dielectric material. ), including The ground surface of the lower member (45) has a small thickness to which the spacer (46) is soldered. The upper member (47) has an annular window (49) on the upper surface (48). and a polarization feeder (51, 52) and a window exciter (53) on the lower surface (59). The continuity of the annular window cavity in the board is such that there is a space on the ground plane of the window. The probe is secured by a metallized aperture (54) connecting the metal-coated apertures (55, 56) providing ground continuity between the ), the feeder is powered by a coaxial probe passing through the The array antenna according to claim 1. 9. a resonant feeder stage in which the antenna resonates at a frequency close to that of the annular window; Characterized by being a broadband antenna using an etched resonant disk (65) The array antenna according to any one of claims 1 to 8. 10. at a feeder stage where the antenna resonates at a frequency remote from the frequency of the annular window. A two-band antenna using an etched resonant disk (65), one band In one band, the feeder excites the resonant disk, and in the other band, the feeder excites the annular window. The array antenna according to any one of claims 1 to 5, characterized in that: