ANTENNA WITH MULTIPLE SINGLE RADIATORS

Abstract

antenna • with several individual radiators (1) forming an antenna field with one aperture in the x and y directions, • wherein the individual emitters (1) are each separated from each other by a partition (2, 21, 22), and • at least a part of the partitions (2, 21, 22) has a defect (3) protruding from the aperture, characterized in that the individual radiators (1) are open circular waveguides, the partitions (21) in the x-direction differ from the partitions (22) in the y-direction with respect to the wall thickness (d), and individual radiators (1) in the x-direction have a distance of less than λ and individual radiators (1) in the y-direction have a lamellar structure (4) in the partition (22).

Description

Technical area

[0001] The present invention relates to an antenna with multiple individual radiators. Such antennas are required, for example, for aeronautical satellite communications in the Ku and Ka bands. State of the art

[0002] The demand for wireless broadband channels for data transmission at very high data rates, particularly in the field of aeronautical (i.e., aircraft-based) satellite communications, is constantly increasing. Suitable antennas for this purpose must be compact and lightweight, while also meeting stringent requirements for transmission characteristics, as interference with neighboring satellites must be reliably excluded. Compact dimensions reduce the aircraft's payload and thus also operating costs. DE 10 2014 112 487 A1 shows an exemplary antenna as an array antenna with identical horn radiators, which requires minimal dimensions and radiates perpendicular to the antenna aperture.

[0003] A change in the radiation pattern occurs, for example, by rotating and pivoting the antenna, as described in DE 10 2015 101 721 A1. However, the movement of the antenna requires a certain amount of space beneath an aircraft-mounted radome, making aerodynamic losses unavoidable when mounted on an aircraft.

[0004] Horn antennas are suitable as individual antennas in fields and can also be designed for broadband applications. Horn antennas are excited by a small pin in the sense of electric field coupling and exhibit slight shifts in the radiation pattern from the center of the horn beam with respect to the radiating wavefront.

[0005] This results in positive interference between neighboring antenna horns, resulting in the radiation of electromagnetic power into undesired solid angle ranges. These couplings also generate resonances, which cause the following problems in the range of the respective resonant frequency: the input matching of the horns, the radiation pattern (directional pattern, lobe) of the horns, and the cross-polarization isolation of the horns are all impaired.

[0006] The antenna's performance is therefore significantly reduced in the range of the resonance frequencies of these interferences. Radiation characteristics, input matching, and resonance frequencies depend on the geometry of the horn and can only be adjusted independently of each other to a limited extent in the standard geometry.

[0007] Furthermore, it is known to electrically modify the antenna's radiation pattern by using phase control elements to adjust the phase difference between adjacent individual radiators of an antenna. An example of such a phase control element is known from DE 10 2016 112 583 A1.

[0008] WO 2014 / 005 699 A1 discloses an antenna system with at least two modules, each comprising at least two individual radiators, and microstrip line networks for feeding the individual radiators within a module, and waveguide networks for feeding the modules. While the use of microstrip lines generates significantly higher dissipative losses than waveguides, it reduces installation space. By combining only the necessary number of primary horn radiators in the modules, the dissipative losses can also be limited, and the inter-modular feed networks can then be designed as low-loss waveguides.

[0009] According to DE 10 2014 112 485 A1, an antenna with multiple horn antennas arranged in a plane is proposed, with adjacent horn antennas separated from each other by a horn edge. The horn edge protrudes at least partially from the plane of the horn antennas, thereby altering a current path between the coupling points of adjacent horn antennas. This allows a resonance occurring due to the coupling of the individual horn antennas to be shifted to frequencies outside the antenna's useful frequency band.

[0010] Furthermore, US 6 034 647 A discloses a boxhorn antenna array comprising a power splitter and a plurality of boxhorn sub-arrays having boxhorn radiators formed on a radiating surface of the array, the power splitter having a front side, a back side and a plurality of T-junctions coupling power to the plurality of boxhorn radiators.

[0011] US 2015 / 0048984 A1 describes a waveguide horn assembly. The assembly includes a rectangular metal plate machined to have a cross-section consisting of a plurality of rectangular holes arranged in the longitudinal direction of the rectangular metal plate, the lower part of each hole being formed as a rectangular waveguide and the upper part of each hole being formed as a horn; and a groove extending in the direction in which the plurality of holes are arranged and having a predetermined depth formed on two sides of the holes on the upper surface of the rectangular metal plate.

[0012] US 2016 / 0072190 A1 describes a radiating element comprising an antenna element, a radiating element edge, and a ridge. The antenna element may have an opening extending into the antenna element and an opening side defining an opening area of ​​the antenna element. The edge of the radiating element may surround the antenna element on the opening side. The ridge may be configured to separate the antenna element and the surrounding edge of the radiating element, at least on the opening side. The edge of the radiating element may be connected to the antenna element at a distance greater than zero from the opening side of the antenna element. Description of the invention

[0013] An object of the invention is therefore to provide an antenna using the simplest possible construction means, which has better aerodynamic properties.

[0014] The problem is solved by the subject matter of the independent claim. Advantageous developments of the invention are specified in the dependent claims, the description, and the accompanying figures.

[0015] An antenna according to the invention comprises several individual radiators that form an antenna field with an aperture in the x- and y-directions and emit electromagnetic radiation essentially in the z-direction. The individual radiators are each separated from one another by a partition. At least some of the partitions have an imperfection that interrupts the otherwise flat aperture in the z-direction. The imperfection can be in the form of a pin, a rectangular projection, or a rectangular depression.

[0016] However, the partition walls in the x-direction, which cross the x-direction (and thus separate adjacent individual radiators in the x-direction), differ from the partition walls in the y-direction in terms of wall thickness. Furthermore, the individual radiators in the x-direction are spaced apart by less than λ. The x-, y-, and z-directions are each aligned orthogonally to each other.

[0017] Due to the asymmetrical wall thickness, the individual radiators can be placed closer together in the x-direction than in the y-direction, so that when using phase-controlled individual radiators, the radiation pattern can be moved in this x-direction.

[0018] The maximum distance between two individual radiators should be max be: dmax=λ1+sin Θ0 λ: wavelength of the maximum operating frequency ΔΦ: Phase difference to the adjacent single radiator θ0 : Scan angle (deflection of the radiation lobe)

[0019] Advantageously, at least some of the individual radiators are non-square and aligned such that a larger number of individual radiators can be arranged in the x-direction than in the y-direction. This means that although the individual radiator is narrower in the x-direction than in the y-direction, a wider partition in the y-direction ensures that the impedance is similar in the x- and y-directions. As will be shown later, this becomes important when different polarizations are to be radiated via the antenna, for which the impedances, and thus the adaptation to free-space propagation, should not differ.

[0020] According to a further advantageous development of the antenna, the individual radiator has a lamellar structure in the partition wall crossing the y-direction. This allows the field, which would otherwise be attenuated by the wider partition wall and not distributed over the entire area, to be better distributed across the entire aperture and contributes to a high antenna gain. In other words, the lamellar structure contributes to an equal antenna gain in the x- and y-direction despite possibly a smaller number of individual radiators in the y-direction by providing a surface impedance, which allows the electromagnetic field to be guided along the surface and thus increases the radiating area.

[0021] Advantageously, the lamellar structure has one or more grooves with a depth of less than λ / 4 and greater than λ / 20, preferably less than λ / 8 and greater than λ / 12, particularly preferably approximately λ / 10, where λ is the wavelength of the electromagnetic radiation. For the antenna's dimensioning, λ is based on the center frequency of the frequency band used.

[0022] In order to adjust a capacity formed by the lamellar structure, a groove of the lamellar structure has a width of less than half and more than a quarter, preferably of about a third of the depth of the groove.

[0023] Advantageously, the defects protrude from the respective partition walls. The defects in the partition walls in the x-direction of adjacent individual radiators are wider than the defects in the partition walls in the y-direction of adjacent individual radiators. It has been shown that the defects are advantageously located centrally on the partition walls, symmetrically and periodically across the aperture. For example, almost all partition walls contain defects. With appropriately dimensioned width and height of the defects, resonances in the antenna's radiation pattern are shifted in such a way that the so-called "scan blindness" is avoided or greatly reduced when radiating at all relevant radiation angles around the z-direction.

[0024] The properties of the antenna according to the invention are particularly advantageous when at least some of the individual radiators of the antenna array are phase-controlled. Phase control is achieved, for example, by connecting the antenna to a transmitting / receiving device via a feed network, with phase control elements arranged in the feed network. Due to a compressed arrangement of the individual radiators in the x-direction, it is advantageous if a control device controls the phase control elements in such a way that a deflection of the antenna's radiation pattern from the z-direction occurs predominantly in the x-direction. The phase control element can be arranged in the feed network close to the individual radiator to enable a compact antenna design.

[0025] The antenna can be constructed particularly compactly if the individual radiators are designed as open waveguides. Unlike hollow radiators, the individual radiators are then not funnel-shaped, meaning the radiation aperture and waveguide cross-section are identical or very similar, resulting in a compressed and shorter individual radiator in the z-direction due to the elimination of the funnel.

[0026] The individual radiators are open circular waveguides. If open circular waveguides are used for the individual radiators, which can be connected to a feed network of circular waveguides, then rotationally symmetric (and thus rotatable) and low-loss phase control elements can be used, as described, for example, in DE 10 2016 112 583 A1.

[0027] A further advantageous compaction of the antenna is achieved if at least some of the individual radiators are filled with a dielectric. This dielectric advantageously has a rotationally symmetrical shape and is arranged along a radiation axis of the individual radiator. This allows the dielectric to be formed together, possibly in one piece, with a dielectric of the phase control element and to move within the individual radiator. The impedance matching of the individual radiator can be further improved if the dielectric has a projection toward the aperture. This step in the dielectric, whose diameter and height can be adjusted, improves the impedance matching.

[0028] If the antenna is designed with a turntable on which the antenna field is arranged flat, then by rotating the turntable and deflecting the antenna characteristic in only one direction (x-direction), any radiation lobes can be achieved without having to tilt the antenna. This significantly reduces the required radome. If the deflection of the antenna characteristic up to 90° from the z-direction is not possible, but is required, the missing angular range can be compensated by slightly tilting the antenna. Thus, a tilt of the antenna field of just 20° would be sufficient to illuminate the entire hemisphere with a radiation characteristic that can be deflected up to 70° using phase shifters.

[0029] The individual radiators of the antenna field of the antenna can advantageously be connected to a transmitting / receiving device via a feed network in such a way that the transmitting / receiving device feeds two signals of different polarization into the feed network, which can be transmitted or received in a well-adapted manner via the antenna. Short character description

[0030] An advantageous embodiment of the invention is explained below with reference to the accompanying figures. They show: Fig. 1 a section of an antenna with several individual radiators and a turntable for rotation, Fig. 2 a single radiator in plan view, Fig. 3 a single radiator in sectional view, and Fig. 4 a single radiator with a phase control element and feed network behind it.

[0031] The figures are merely schematic representations and serve only to illustrate the invention. Identical or equivalent elements are provided with the same reference numerals throughout.

[0032] A plurality of individual radiators 1, which are arranged adjacent to each other in the x- and y-direction in an antenna field, form Fig. 1, together with a turntable 13, which is shown only schematically, forms an antenna. The turntable 13 can rotate, thereby moving the antenna field to any desired angle. The individual radiators 1 are separated from each other in the x- and y-directions by partition walls 2. The shape and width of the partition walls 2 differ, as explained later, in the x- and y-directions.

[0033] The surface of the antenna, aligned in the z-direction, forms an aperture of the antenna, from which electromagnetic radiation is emitted in the radiation direction R, either in the z-direction or with a deflection of up to 70° from the z-direction. As explained later, a deflection of the radiation pattern, particularly of a main lobe, is planned, so that the radiation direction R can actually differ from the z-direction by a scan angle.

[0034] The antenna array is essentially square, with a larger number of individual radiators 1 arranged in the x-direction than in the y-direction. This is made possible by the fact that the individual radiators 1 themselves are not square, but are narrower in the x-direction than in the y-direction. Therefore, the distance between the individual radiators 1 is also smaller in the x-direction than in the y-direction. In the x-direction, the distance d should be as small as possible. max dmax=λ1+sinΘ0 must not be exceeded. If this value is exceeded, disturbing side lobes (grating lobes) will appear in the directional pattern. The larger the desired swivel range, the smaller the spacing must be. In the y-direction, the spacing of the individual antenna elements 1 is greater than in the x-direction, but still smaller than the wavelength λ of the maximum operating frequency to be served.

[0035] The individual radiators 1 to Fig. 2 are constructed identically, with the partition walls 21 in the x-direction being narrower than the partition walls 22 in the y-direction. As in Fig. 3, the wall thickness d of the partition 21 in the x-direction (the partition 21 crosses the x-direction and is perpendicular to it) is smaller than the wall thickness d of the partition 22 in the y-direction. The larger wall thickness d in the y-direction is used for a lamella structure 4 in the partition 22. The lamella structure 4 is formed by a groove 10, which projects into the partition 22 opposite to the z-direction. Fig. 1 - two individual radiators 1 are arranged in a row in the y-direction, then there are two grooves between the radiation openings (cavities) of the individual radiators 1, one for each individual radiator 1.

[0036] An impurity point 3 in the form of a pin is arranged on each of the four partition walls 21, 22. The pin protrudes from the partition walls 21, 22 in the z-direction and is located centrally in each case. This results in a periodic and symmetrical arrangement of the impurities 3 across the antenna field.

[0037] A cavity is formed between the partition walls 21, 22, which is at least partially filled by a dielectric 11, e.g., Teflon, with a dielectric constant ε > 1. This dielectric 11 is approximately flush with the aperture and advantageously fills the entire cavity, preventing dirt from accumulating during antenna operation. The partition walls 21, 22 and the remaining structure of the individual radiators 1 are made of metal or are metal-coated.

[0038] Accordingly Fig. 3, a height h of the defects 3 on the partition walls 21, 22 is similar, while the width bs of the defects 3 on the partition walls 21, 22 differs in the x- and y-directions. The height h is less than λ / 4 and at least λ / 10. On the partition wall 22 in the y-direction, the defects 3 are arranged on the outer lamella from the center point of the individual radiator. Thus, only one defect 3 is provided for each of the x- and y-directions between two adjacent individual radiators 1; each individual radiator 1 "shares" the defect 3 with the adjacent individual radiators 1. Impurities 3 on the partition wall 22 in the y-direction can be omitted if necessary.

[0039] A width br of the groove 10 is approximately λ / 10, a depth t of the groove 10 is approximately one-third of the width br of the groove, i.e. λ / 30. The individual radiator 1 is not designed as a horn radiator with a funnel, but as an open waveguide section, so that the waveguide does not expand and has a similar cross-section over the length of the individual radiator 1. In the z-direction, a projection 12 is formed on the dielectric 11. This projection has a specific height and a specific diameter, which results in a desired optimal adaptation of the antenna impedance to the free-space radiation.

[0040] Fig. 4 shows the single radiator 1 from Fig. 2 and Fig. 3 in a sectional view, in which the open waveguide section continues seamlessly into a feed network 5, which in turn comprises a waveguide. Both aligned waveguides are circular waveguides, so that an additional possibility arises for a phase control element 7 to be rotatably mounted in the circular waveguide. The phase control element 7 is arranged near the individual radiator 1 and constructed according to the specifications of DE 10 2016 112 583 A1. The phase control element 7 is arranged to be rotatable about a rotation axis D, thus also being rotationally symmetrical.

[0041] Within the feed network 5, two couplings 9 are connected to the phase control element 7. These couplings serve to feed separate signals into the waveguide for two separate, mutually orthogonal polarizations, for example, a horizontal polarization H and a vertical polarization V. The couplings 9 are preferably rotated by 90° relative to one another, i.e., arranged perpendicular to one another in the waveguide. From the couplings 9, the signals of both polarizations V, H are forwarded via microstrip lines and waveguides to a transmitting / receiving device 6 in the receiving case, or in the transmitting case, the signals of both polarizations V, H are emitted by the transmitting / receiving device 6 via the couplings 9 into the waveguide and the individual radiator 1.

[0042] Since the single radiator 1 after Fig. 4 as one of many elements of the antenna field - see Fig.1 - the feed network 5 also has the function of summing up the signals from the plurality of individual radiators and passing them on in summed form to the transmitting / receiving device 6.

[0043] The antenna further comprises a control device 8, which is connected to both the phase control element 7 and the transmitting / receiving device 6. This enables the control device 8 to deflect the radiation pattern in the x-direction by setting different phase positions of the signals on the adjacent individual radiators 1, here the individual radiators 1 adjacent in the x-direction.

[0044] For this purpose, the phase difference of adjacent individual radiators Δϕ=2πλd sin θ0.

[0045] Deflection in the y-direction is not provided. In conjunction with a rotation of the antenna aperture on the turntable 13 (and, if necessary, a slight tilt of the antenna aperture), the radiation pattern can be aligned to any angle. For an aircraft-mounted antenna, this enables an extremely compact design that is flat due to the absence of large-volume tilting elements and eliminates the need for a bulky radome. At the same time, the design of the defects and the lamella structure 4 prevents disruptive resonances in the aperture surface, resulting in high efficiency and thus maximum antenna gain even over large tilting ranges of the radiation pattern.

[0046] Due to the short distance between the individual radiators 1, it is difficult to integrate a feed network 5. Due to the larger distances between the individual radiators 1 in the y-direction and the large-area radiation provided by the lamellar structure 4 and short open waveguide sections instead of horn antennas, it was possible to integrate the feed network 5 in a small installation space while still maintaining a high antenna gain. LIST OF REFERENCE SYMBOLS 1 single radiator 2 partition wall 3 Fault point 4 Lamellar structure 5 Food network 6 Transmitting / receiving device 7 Phase actuator 8 Control device 9 Coupling 10 grooves 11 Dielectric 12 Lead in the dielectric 13 turntables 21, 22 partition walls R Radiation direction D axis of rotation H, V polarization directions λ wavelength bs Width of the fault h Height of the fault t Depth of the groove br Width of the groove d wall thickness of the partition wall

Claims

[1] Antenna • with several individual radiators (1) which form an antenna field with an aperture in the x and y directions, • wherein the individual radiators (1) are each separated from one another by a partition wall (2, 21, 22), and • at least some of the partition walls (2, 21, 22) have a defect (3) protruding from the aperture, characterized by that the individual radiators (1) are open circular waveguides, the partition walls (21) in the x-direction differ from the partition walls (22) in the y-direction with regard to the wall thickness (d), and individual radiators (1) in the x-direction have a distance of less than λ and individual radiators (1) in the y-direction have a lamellar structure (4) in the partition wall (22). [2] Antenna according to claim 1, wherein a larger number of individual radiators (1) are arranged in the x-direction than in the y-direction. [3] Antenna according to claim 1, wherein the lamellar structure (4) has a groove (10) with a depth (t) of less than λ / 4 and greater than λ / 20, preferably less than λ / 8 and greater than λ / 12, particularly preferably of approximately λ / 10. [4] Antenna according to one of claims 1 or 3, wherein the lamellar structure (4) has a groove (10) with a width (br) of less than λ / 10 and greater than λ / 50, preferably less than λ / 20 and greater than λ / 40, particularly preferably of approximately λ / 30. [5] Antenna according to one of the preceding claims, in which the imperfections (3) protrude from the respective partition wall (2, 21, 22) and imperfections (3) of the partition walls (21) in the x-direction of adjacent individual radiators (1) are wider than imperfections (3) of the partition walls (22) in the y-direction of adjacent individual radiators (1). [6] Antenna according to one of the preceding claims, in which at least some of the individual radiators (1) of the antenna field are phase-controlled and the antenna is connected to a transmitting / receiving device (6) by a feed network (5), phase actuators (7) being arranged in the feed network (5). [7] Antenna according to claim 6, wherein a control device (8) controls the phase actuators (7) in such a way that a deflection of a radiation characteristic occurs predominantly in the x-direction. [8] Antenna according to one of claims 6 or 7, wherein the phase control elements (7) in the feed network (5) are arranged close to the individual radiators (1). [9] Antenna according to claim 1, wherein the open circular waveguides are connected to a feed network (5) of circular waveguides. [10] Antenna according to one of the preceding claims, in which at least a part of the individual radiators (1) is filled with a dielectric (11). [11] Antenna according to claim 10, wherein the dielectric (11) has a rotationally symmetrical shape and is arranged along a radiation axis (R) of the individual radiators (1). [12] Antenna according to claim 11, wherein the dielectric (11) has a projection (12) in the direction of the aperture. [13] Antenna according to one of the preceding claims, with a turntable (13) on which the antenna field is arranged flat. [14] Antenna according to one of the preceding claims, in which at least the individual radiators (1) of the antenna field are connected to a transmitting / receiving device (6) by a feed network (5), the transmitting / receiving device (6) feeding two signals of different polarization (V, H) into the feed network (5).

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