EP0709914B1 - RF seeker head antenna system for missiles - Google Patents

Description

The invention relates to a housed in a missile Antenna system according to the preamble of the claim 1 and claim 2.

A long-range missile for locating radar systems or the like requires an HF antenna system to find the target, that in a very wide frequency range a monopulse bearing in azimuth or elevation direction. Because in one Missile next to the HF radar seeker head depending on the task also other sensors, e.g. optronic or millimeter wave sensors, for target location and target tracking, the HF antenna system must be used with this System regarding space requirements and undisturbed mode of operation be tolerable. This means that there is no blanking or shading by a closed surface or components the antenna may arise.

Missiles with multi-sensors, i.e. with HF antennas and optronic Sensors are known for the detection of radar systems. A four-armed planar spiral antenna is used as the HF antenna used with the help of a complex passive Feed network made up of hybrid couplers in sum mode and in differential mode operate over a very wide range can.

The spiral antenna is a broadband antenna shape, but in terms of polarization it works in a very limited way Wise. By their structure and how they work is namely the direction of rotation of the immanent circular polarization fixed. It can be either right or left circular Polarization and the respective polarization components to process. Determining the lowest operating frequency is the aperture diameter of the spiral antenna. The difference mode M2 requires a circumference of the radiating active area of at least two wavelengths.

An alternative, also planar antenna form, the so-called Sinus antenna, which is known from EP 0 198 578 B1 and electrically viewed with the logarithmic-periodic dipole antenna is related, can detect all polarizations. However, similar to a monopulse bearing with a differential mode to be able to perform as with the spiral antenna they have at least eight arms. There would also be one more complex dining network than necessary with the spiral antenna. Sinus antennas with more than four arms that have an aperture diameter of, for example, half a wavelength have the lowest operating frequency, but are currently not available.

The object of the invention is a very broadband over several Octave effective RF seeker antenna system suitable for monopulse direction finding for a missile to create that with additional sensors regarding space requirements and undisturbed Mode of action is compatible and any polarization allows.

This task is carried out in a generic antenna system by the in the characterizing part of claim 1 or that specified in the characterizing part of claim 2 Features resolved.

The logarithmic periodic dipole antenna is for example from the essay by D.E. Isbell: "Log Periodic Dipole Arrays" in "IRE Transactions on Antennas and Propagation", May 1960, S. 260 to 267 known. It is one of the almost frequency-independent and thus very broadband antenna shapes. In the Cross dipole design are both orthogonal linear polarizations to disposal. All other polarizations can be on one of the two outputs with a maximum loss of 3 dB become. Loss of polarization can be achieved with the help of a 90 ° / 3dB hybrids a left or right circular polarization be formed. Over a very wide frequency band of several Octaves can therefore process any polarization without exception become. Similar to the planar sine antenna there is also an "active" depending on the frequency Area "for the radiation behavior Operating frequency always excited several half-wave dipoles.

According to the invention, the longitudinal axes of the four or three logarithmic-periodic cross dipole antennas at an angle to each other inclined that in the entire operating frequency range Phase centers of the respective active cross dipoles approximately maximum 0.7 · λ are apart. This will affect the Radiation behavior of unfavorable interferometer properties avoided, as in an axially parallel arrangement with increasing frequency and thus increasing electrical antenna distances would occur.

By capacitive loads applied in an advantageous manner at the ends of the half-wave dipoles can be in the lower frequency range the mechanical dimensions are considerably reduced so that a greatly reduced base diameter, which then allows the attachment of further sensors, can be achieved. Two unabridged half-wave dipoles side by side would otherwise have a dimension for the lower frequency may require trouble-free accommodation no more sensors.

The empty space in the missile cross section offers thus an inexpensive integration option for additional sensors as required for a millimeter wave antenna system with monopulse direction finder or other sensors.

Compared to a group of four system according to claim 1 needs a triple system according to claim 2 at about logarithmic-periodic cross dipole antennas that remain the same size less installation volume. This stands for other sensors, e.g. optronic sensors, a larger cross-sectional area available in the missile.

The triple antenna system can be designed that the three log-periodic cross dipole antennas so are arranged to each other that their phase centers are the corner points form an isosceles triangle, the base of which runs horizontally. The base can be either below or be on top so that a top of the triangle is exactly on top or below. In this case there is azimuth symmetry completely undisturbed. Depending on your needs, a triangular arrangement be cheaper with the tip up or down.

The triple antenna system can also be designed that the three log-periodic cross dipole antennas are arranged to each other so that their phase centers form the corner points of an isosceles triangle whose Base runs vertically. The base can either be based on the left or the right side, so that there is a The tip of the triangle is on the far right or left outside. In this case, the symmetry of the elevation is completely undisturbed.

With a group of four antenna systems, the signals of the respective individual lobes of the four log-periodic Cross dipole antennas in a conventionally designed monopulse comparator network be interconnected so that there is an amplitude and phase comparison of sum and difference diagrams can be carried out in elevation and azimuth.

Because of the azimuth and elevation difference necessary for monopulse for tracking in both planes must be in the horizontal and vertical distances of the individual log-periodic Cross dipole antennas next to the open space for others Sensors also take into account the broadband monopulse quality become.

With a triple antenna system, the disturbed symmetry in the elevation diagram or in the azimuth diagram by the in claim 7 advantageous combination specified in Monopulse feed network corrected.

Dual polarized log-periodic dipole antennas are for their usability in facilities in the field of electronic support measures ESM (= Electronic Support Measures) from the essay by G. S. Hardie, H.B. Sefton Jr .: "Fixed Beam and Mechanically Steerable Antennas" in the journal "Microwave Journal", Sept. 1984, pages 143 to 156, in particular pages 149 and 150 are known. A The embodiment described there has a cross section Cross shape and is made up of two orthogonally polarized log-periodic Dipole arrangements composed. she covers a frequency range of several octaves, for example from, different polarizations due to Selection of one of the two dipole radiator series (i.e. vertical or horizontal linear polarization) or by combination of the two output signals in a broadband 90 ° hybrid (i.e. left circular polarization or right circular polarization) can be adjusted, and is in a foamed Radome included.

The invention is explained below with reference to five figures.

Fig. 1

die prinzipielle Anordnung eines mit vier logarithmisch-periodischen Kreuzdipolantennen versehenen Antennensystems nach der Erfindung in einer Ansicht von vorne,

Fig. 2

eine Schnittansicht II-II des Antennensystems nach Fig. 1,

Fig. 3

die schematische Querschnittsansicht einer vorteilhaften Integrationsmöglichkeit eines "multi mode"-Suchkopfs, der ein Antennensystem nach der Erfindung mit vier logarithmisch-periodischen Kreuzdipolantennen enthält,

Fig. 4

in einer schematischen Seitenansicht des Vorderteiles eines Flugkörpers eine vorteilhafte Einbaumöglichkeit eines Antennensystems nach der Erfindung,

Fig. 5

die schematische Ansicht der Schaltung eines Monopuls-Speisenetzwerks für ein Antennensystem nach der Erfindung mit vier logarithmisch-periodischen Kreuzdipolantennen,

Fig. 6

in einer Ansicht von vorne eine Anordnung eines mit drei logarithmisch-periodischen Kreuzdipolantennen versehenen Antennensystems nach der Erfindung mit zusätzlichem Sensor,

Fig. 7

ebenfalls in einer Ansicht von vorne eine andere Anordnung eines mit drei logarithmisch-periodischen Kreuzdipolantennen versehenen Antennensystems nach der Erfindung mit zusätzlichem Sensor, und

Fig. 8

die schematische Ansicht der Schaltung eines Monopuls-Speisenetzwerks für ein Antennensystem nach der Erfindung mit drei logarithmisch-periodischen Kreuzdipolantennen.

Show it:

Fig. 1

the basic arrangement of an antenna system provided with four log-periodic cross dipole antennas according to the invention in a view from the front,

Fig. 2

2 shows a sectional view II-II of the antenna system according to FIG. 1,

Fig. 3

FIG. 2 shows a schematic cross-sectional view of an advantageous possibility of integrating a "multi-mode" seeker head which contains an antenna system according to the invention with four log-periodic cross-dipole antennas,

Fig. 4

a schematic side view of the front part of a missile an advantageous installation option of an antenna system according to the invention,

Fig. 5

2 shows the schematic view of the circuit of a monopulse feed network for an antenna system according to the invention with four log-periodic cross-dipole antennas,

Fig. 6

in a view from the front an arrangement of an antenna system according to the invention provided with three log-periodic cross dipole antennas with an additional sensor,

Fig. 7

also in a view from the front another arrangement of an antenna system provided with three log-periodic cross-dipole antennas according to the invention with an additional sensor, and

Fig. 8

the schematic view of the circuit of a monopulse feed network for an antenna system according to the invention with three log-periodic cross-dipole antennas.

Fig. 1 shows a view from the front and Fig. 2 in one Sectional view II-II of Fig. 1 one of four closely adjacent arranged, logarithmic-periodic cross dipole antennas 1, 2, 3 and 4 existing antenna group, which acts as an RF seeker antenna system forward in a long-range missile for locating radar systems or the like shall be. The four log periodic Cross dipole antennas 1, 2, 3 and 4 are on a circular, for example, dielectric carrier plate 5 attached in such a way that the cross dipole antennas 1 and 2 and below the cross dipole antennas 3 and 4 horizontally next to each other and the Cross dipole antennas 1 and 3 and next to it the cross dipole antennas 2 and 4 are vertically one below the other. The four log periodic Cross dipole antennas 1, 2, 3 and 4 protrude with their longitudinal axes 6, 7, 8 and 9 to the front, whereby in with respect to a central one, perpendicular to the carrier plate 5 standing axis 10 there is symmetry. The two crossed Dipole radiator rows of each cross dipole antenna 1, 2, 3 and 4 ensure that the two orthogonal linear polarizations separately and at the same time for the recycling of related Signals are available. The longitudinal axes 6, 7, 8 and 9 are inclined to each other so that in the whole Operating frequency range the phase centers of the currently active Cross dipole antennas 1, 2, 3 and 4 about a maximum of 0.7 · λ apart lie.

Fig. 3 shows a schematic cross-sectional view advantageous integration option of a so-called "multi mode "seeker head, which includes an RF antenna system contains according to the invention. That on a circular, e.g. dielectric carrier plate 11 eccentrically attached RF antenna system consists of four closely spaced log-periodic cross dipole antennas 12, 13, 14 and 15. Apart from the eccentric position on the carrier plate 11 is correct from the four cross dipole antennas 12, 13, 14 and 15 composed group of four with that according to the figures 1 and 2 agree in principle. By the eccentric However, offset of the group of four upwards creates a free space 16, in which a further sensor can be arranged can. This free space 16 results just like the free spaces 17, 18 and 19 e.g. for an additional millimeter wave antenna system 17, a laser rangefinder 18 and another sensor 19 by a special measure to the log-periodic cross dipole antennas 12, 13, 14 and 15. Through capacitive loads at the ends of the half-wave dipoles of the four log-periodic cross dipole antennas 12, 13, 14 and 15 can namely in the lower frequency range the mechanical dimensions are considerably reduced, so that there is a significantly smaller base diameter for the group of four reach as the diameter of the support plate 11 leaves. Two unabridged half-wave dipoles side by side otherwise, i.e. without the capacitive loads, for the lower frequency require a dimension that is quite a bit is larger than the diameter of the carrier plate 11. The not filled space in the cross section of a missile within a Radoms 20 thus offers an inexpensive integration option for the millimeter wave antenna system at the location of the Free space 17 and for additional sensors at the locations of the Free spaces 16, 18 and 19.

4 is a schematic side view of the front part of a missile, in which under a Radom 20 is a very broadband HF search body antenna system is housed according to the invention. This antenna system consists of a group 21 of four spatially narrow adjacent single antennas, which are logarithmic-periodic Cross dipole antennas are formed. The Longitudinal axes 22, 23, 24 and 25 (in Fig. 4 are only those Axes 23 and 25 of the two front cross dipole antennas visible) of these log-periodic cross dipole antennas run inclined to each other so that in the whole Operating frequency range the phase centers of the currently active Cross dipoles are approximately a maximum of 0.7 · λ apart. The signals of the individual log-periodic cross dipole antennas the group of four 21 are via polarization switches 26, 27, 28 and 29 interconnected in a monopulse feed network 30 in such a way that an amplitude and phase comparison of Sum and difference diagrams in elevation and azimuth can be carried out. Also in this embodiment are the dipoles of the four log-periodic cross dipole antennas Half-wave dipoles, the ends of which are capacitively loaded are, so that a significantly smaller base diameter Group of four 21 is reached. The empty space in the Missile cross section thus offers a very advantageous integration option for further sensors.

FIG. 5 shows in a block diagram a monopulse comparator network, as is provided for example in the arrangement according to FIG. 4 as a monopulse feed network 30. The signals coming from the four log-periodic cross dipole antennas are labeled A, B, C and D. They are first fed to two hybrid circuits 31 and 32, the output signals of which then act on two further hybrid circuits 33 and 34. At the outputs of the two hybrid circuits 33 and 34, a total humming signal Σ and a total difference signal Δ _AZ for the azimuth and a total difference signal Δ _EL for the elevation are then output for any polarization set. This conventionally constructed monopulse comparator network according to FIG. 5 is interconnected such that an amplitude and phase comparison of sum and difference diagrams in elevation and azimuth can be carried out. It is pointed out once again that the logarithmic-periodic cross-dipole antenna is able to provide both linear polarizations. All other polarizations can be received at one of the two outputs with a maximum loss of 3 dB. With the help of a 90 ° / 3 dB hybrid, polarization loss-free left and right circular polarization can be formed.

Fig. 6 shows a front view of one of three closely adjacent arranged, logarithmic-periodic cross dipole antennas 35, 36 and 37 existing antenna group, the RF seeker antenna system forward in a missile with a long Range for locating radar systems or similar housed shall be. The three log periodic Cross dipole antennas 35, 36 and 37 are on a circular, for example dielectric carrier plate 38 is attached in such a way that the two cross dipole antennas 35 and 36 are each horizontal lie next to each other and the cross dipole antenna 37 centrally is arranged above. The three log periodic Cross dipole antennas 35, 36 and 37 are arranged relative to one another that their phase centers 39, 40 and 41 are the cornerstones of a form isosceles triangle, the base of which is horizontal runs. The base of this triangle is shown in FIG. 6 Embodiment below, so that a tip of the triangle is right at the top. In this case there is azimuth symmetry completely undisturbed. The elevation symmetry is on the other hand disturbed because in the upper half of the antenna system only one log-periodic Cross dipole antenna exists, namely antenna 37, and in the lower half two log-periodic cross dipole antennas, namely antennas 35 and 36 are present. The three log-periodic cross dipole antennas 35, 36 and 37 protrude forward with their longitudinal axes 42, 43 and 44. The two crossed dipole radiator rows of each cross dipole antenna 35, 36 and 37 ensure that the two orthogonal linear polarizations separately and at the same time for recycling of related signals are available. The Longitudinal axes 42, 43 and 44 are inclined at an angle to one another, that the phase centers 39, 40 and 41 of the active cross dipole antennas 35, 36 and 37 about a maximum of 0.7 · λ apart. The unfilled one 45th place in the cross section of the missile below the three log-periodic cross dipole antennas 35, 36 and 37 existing antenna systems offers an additional Sensor, e.g. an optronic sensor, an inexpensive integration option.

Fig. 7 also shows a front view of one of three logarithmic-periodic Cross dipole antennas 46, 47 and 48 existing antenna group, the RF seeker antenna system in the front of a missile with a long range for locating radar systems or similar should be accommodated. The three log periodic Cross dipole antennas 46, 47 and 48 are on one circular, for example dielectric carrier plate 49 so attached that the two cross dipole antennas 46 and 47 each lie horizontally next to each other and the cross dipole antenna 48 is arranged centrally below. The three log periodic Cross dipole antennas 46, 47 and 48 are like this arranged to each other that their phase centers 50, 51 and 52nd form the corner points of an isosceles triangle whose Base runs horizontally. The base of this triangle is in in Fig. 7 embodiment shown above, so that a tip of the triangle is located just below. Also in this Case, the azimuth symmetry is completely undisturbed, whereas the Elevation symmetry is disturbed because in the upper one Half of the antenna system two antennas are provided and there is only one antenna in the lower half. The three log-periodic cross dipole antennas 46, 47 and 48 protrude forward with their longitudinal axes 53, 54 and 55. The two crossed dipole radiator rows of each cross dipole antenna 46, 47 and 48 ensure that the two orthogonal linear polarizations separately and at the same time for recycling of related signals are available. The Longitudinal axes 53, 54 and 55 are inclined at an angle to one another, that the phase centers 50 in the entire operating frequency range, 51 and 52 of the active cross dipole antennas 46, 47 and 48 are approximately a maximum of 0.7 · λ apart. The unfilled one Place 56 in the cross section of the missile below the the three log-periodic cross dipole antennas 46, 47 and 48 existing antenna systems offers an additional Sensor, e.g. an optronic sensor, an inexpensive integration option.

FIG. 8 shows in a block diagram a monopulse feed network as can be provided, for example, in an advantageous manner for the antenna system in the arrangement according to FIG. 7. The signals coming from the three log-periodic cross dipole antennas are labeled A, B and C. In the monopulse feed network shown, three 3dB dividers 57, 58 and 59 are provided, the inputs of which are each connected to one of the three log-periodic cross-dipole antennas. Signal A thus arrives at the input of the 3dB divider 57, signal B at the input of the 3dB divider 58 and signal C at the input of the 3dB divider 59. In each case an output of the two 3dB dividers 57 and 58, that is to say on the input side are connected to the logarithmic-periodic cross-dipole antennas with their phase centers in the two base corner points of the isosceles triangle, are connected to a terminating resistor 60 or 61. The other output of the two 3dB dividers 57 and 58 is connected to an input of one of two 3dB / 180 ° hybrid circuits 62 and 63, the second input of which is connected to an output of the third 3dB distributor 59, that is to say its input is connected to the logarithmic-periodic cross-dipole antenna which is not in a base vertex of the isosceles triangle. In each case the difference output of the two 3dB / 180 ° hybrid circuits 62 and 63 is with an input of a first further 3dB / 180 ° hybrid circuit 64 and the sum output of the two 3dB / 180 ° hybrid circuits 62 and 63 with one input a second further 3dB / 180 ° hybrid circuit 65 connected. The total difference signal Δ _El are at the two outputs of the first further 3dB / 180 ° hybrid circuit 64 in the elevation and the total differential signal Δ _Az in azimuth and the sum output of the second further 3dB / 180 ° hybrid circuit 65, to whose differential Output a terminating resistor 66 is present, the total signal ∑.

The disturbed elevation symmetry is corrected by the combination in the monopulse feed network shown in FIG. 8. This disturbance arises because there are two log-periodic cross-dipole antennas in the upper half of the antenna system and only one such cross-dipole antenna in the lower half. With the help of the monopulse feed network shown in FIG. 8, the total difference signal Δ _Az in azimuth is formed from the signals A and B originating from the two adjacent antennas, in the form of Δ Az = A / 2 - B / 2 and the total difference signal Δ _El in the elevation from the signals A, B and C originating from all three antennas according to the equation Δ El = A / 2 + B / 2 - C.

The total signal Σ is composed of the three signals A, B and C as follows: Σ = A / 2 + B / 2 + C.

Claims (7)

1. A very broad band RF seeker head antenna system, which is effective over a plurality of octaves, and which is accommodated under a radome at the front of a missile which is suitable for the detection of radar devices or the like, consisting of a group of individual antennas which are mounted in close spatial proximity to each other on a backplate, e.g. a dielectric backplate, and which are interconnected via a monopulse supply network so that an amplitude and phase comparison can be made of elevation and azimuth sum and difference diagrams,
   characterised in that
   four logarithmic-periodic crossed dipole antennas (1, 2, 3, 4) are provided as the individual antennas of the group, the longitudinal axes (6, 7, 8, 9) of which are inclined in relation to each other so that over the entire operating frequency range the phase centres of the crossed dipoles which are active each time are situated at a maximum of about 0.7 . λ apart.
2. A very broad band RF seeker head antenna system, which is effective over a plurality of octaves, and which is accommodated under a radome at the front of a missile which is suitable for the detection of radar devices or the like, consisting of a group of individual antennas which are mounted in close spatial proximity to each other on a backplate, e.g. a dielectric backplate, and which are interconnected via a monopulse supply network so that an amplitude and phase comparison can be made of elevation and azimuth sum and difference diagrams,
   characterised in that
   three logarithmic-periodic crossed dipole antennas (35, 36, 37) are provided as the individual antennas of the group, the longitudinal axes (42, 43, 44) of which are inclined in relation to each other so that over the entire operating frequency range the phase centres (39, 40, 41) of the crossed dipoles which are active each time are situated at a maximum of about 0.7 . λ apart.
3. An antenna system according to claims 1 or 2,
   characterised in that
   the dipoles of the logarithmic-periodic crossed dipole antennas (1, 2, 3, 4) are halfwave dipoles, the ends of which are subjected to capacitive loading.
4. An antenna system according to any one of claims 1 to 3,
   characterised in that
   the group consisting of the logarithmic-periodic crossed dipole antennas (12, 13, 14, 15) is accommodated in the front of the missile so that free spaces (16 to 19) are formed in the missile cross-section in which further sensors, e.g. optronic or millimetre wave sensors, can be disposed.
5. An antenna system according to claim 2,
   characterised in that
   the three logarithmic-periodic crossed dipole antennas (35, 36, 37) are disposed in relation to each other so that their phase centres (39, 40, 41) form the apices of an isosceles triangle, the base of which is horizontal.
6. An antenna system according to claim 2,
   characterised in that
   the three logarithmic-periodic crossed dipole antennas are disposed in relation to each other so that their phase centres form the apices of an isosceles triangle, the base of which is vertical.
7. An antenna system according to claims 5 or 6,
   characterised in that
   three 3dB separators (57, 58, 59) are provided in the monopulse supply network, the input of each of which is connected to one of the three logarithmic-periodic crossed dipole antennas (46, 47, 48; signals A, B and C), that one output of each of the two 3dB separators (57, 56), the inputs of which are connected to the logarithmic-periodic crossed dipole antennas(46, 47; signals A, and B) with their phase centres situated at the two base apices of the isosceles triangle, are connected to a terminating resistor (60, 61), and the other output of each is fed to the input of one of two 3dB/180° hybrid circuits (62, 63), the second input of each of which is connected to an output of the third 3dB separator (59), the input of which is connected to the logarithmic-periodic crossed dipole antenna (48; signal C) which is not situated on a base apex of the isosceles triangle, that the differential output of each of the two 3dB/180° hybrid circuits (62, 63) is connected to an input of a first, further 3dB/180° hybrid circuit (64), and the summing output of the two 3dB/180° hybrid circuits (62, 63) is connected to an input of a second, further 3dB/180° hybrid circuit (65), and that the total differential signal (Δ_El) for the elevation and the total differential signal (A_Az) for the azimuth are output at the two respective outputs of the first, further 3dB/180° hybrid circuit (64), and the total summing signal (Σ) is output at the summing output of the second further 3dB/180° hybrid circuit (65), at the differential output of which a terminating resistor (66) is situated.

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