Asymmetrically Constructed Radome

Abstract

An asymmetrically constructed radome for an aircraft and an aircraft having an antenna and a corresponding radome are described. The radome has a first layer with a first dielectric constant and a first layer thickness, and a second layer with a second dielectric constant and a second layer thickness. The first layer thickness and the second layer thickness are different from each other. The first layer includes a thermosetting material and the second layer includes a thermoplastic material. Such an asymmetrical radome structure improves the mechanical stability and electromagnetic transparency of the radome.

Claims

1. A radome for an aircraft, wherein the radome comprises: a first layer with a first dielectric constant; a second layer with a second dielectric constant; wherein the first layer and the second layer have different first and second layer thicknesses, respectively; wherein the first layer comprises a thermosetting material; and wherein the second layer comprises a thermoplastic material.

2. The radome as claimed in claim 1, wherein the first dielectric constant is different from the second dielectric constant.

3. The radome as claimed in claim 1, further comprising a third layer with a third dielectric constant; wherein the third layer is arranged between the first layer and the second layer.

4. The radome as claimed in claim 3, wherein the third dielectric constant is less than the first dielectric constant and/or less than or equal to the second dielectric constant.

5. The radome as claimed in claim 3, wherein the third layer has a third layer thickness, which is different from the first layer thickness and from the second layer thickness.

6. The radome as claimed in claim 3, wherein the third layer comprises a thermoplastic material.

7. The radome as claimed in claim 3, further comprising a fourth layer with a fourth dielectric constant and a fifth layer with a fifth dielectric constant; wherein the fifth layer is arranged between the second layer and the fourth layer; wherein the fifth dielectric constant is equal to the third dielectric constant; and wherein the fourth dielectric constant is equal to or less than the second dielectric constant.

8. The radome as claimed in claim 7, wherein the fifth layer comprises a thermoplastic material.

9. The radome as claimed in claim 7, wherein the fourth layer comprises a thermosetting material.

10. The radome as claimed in claim 7, wherein the fourth layer has a fourth layer thickness, which is different from the first layer thickness or from the second layer thickness.

11. The radome as claimed in claim 7, wherein the fifth layer has a fifth layer thickness, which is different from the third layer thickness.

12. The radome as claimed in claim 1, wherein the first layer comprises glass fibers.

13. An aircraft comprising: an antenna; and a radome as claimed in claim 1; wherein the radome is arranged over the antenna; wherein the first layer of the radome is arranged on a side of the aircraft facing away from the antenna; and wherein the radome covers the antenna and protects the antenna against external influences.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Exemplary embodiments are explained in greater detail below with reference to the attached drawings. The illustrations are schematic and not to scale. Identical reference signs refer to identical or similar elements. More specifically:

[0047] FIG. 1 shows a schematic sectional illustration of an asymmetrically constructed three-layer radome according to one exemplary embodiment.

[0048] FIG. 2 shows a schematic sectional illustration of an asymmetrically constructed five-layer radome according to one exemplary embodiment.

[0049] FIG. 3 shows a schematic illustration of an aircraft having an antenna and an asymmetrically constructed radome disclosed herein, according to one embodiment.

DETAILED DESCRIPTION

[0050] FIG. 1 shows a schematic sectional illustration of the layers of an asymmetrical radome 10 according to one exemplary embodiment. The radome 10 has a first layer 11 with a first dielectric constant ε.sub.1 and a first layer thickness d.sub.1, a second layer 12 with a second dielectric constant ε.sub.2 and a second layer thickness d.sub.2, and a third layer 13 with a third dielectric constant ε.sub.3 and a third layer thickness d.sub.3. The third layer 13 is arranged between the first layer 11 and the second layer 12 and connects them to one another.

[0051] The first layer 11 corresponds to the outside of the radome, i.e. in FIG. 3 the side facing away from the antenna 20 and the aircraft 100, and is formed from a thermosetting material, in particular from a cyanate ester resin or an epoxy resin reinforced with short or continuous quartz or glass fibers. As a result, the first layer 11 is mechanically very stable and withstands a bird strike or hail, for example, without being permanently deformed or broken. However, the first layer 11 does not absorb the impact energy, or does so only slightly, instead passing on the impact pressure and thus the impact energy via shock waves to the third layer 13 and the second layer 12. The first layer thickness d.sub.1 is determined by the mechanical requirements placed on the radome 10 and is designed in such a way that it withstands the aerodynamic loads and also any dynamic loads which may occur, such as those which result from bird strikes. In particular, the first layer thickness d.sub.1 is thus designed to withstand loads that are likely to occur, a certain safety margin being taken into consideration at the same time.

[0052] The second layer 12 is formed from a thermoplastic material, more specifically from a polyphenylene ether (PPE) reinforced with short or continuous quartz or glass fibers. This material is softer than the first layer 11 and can deform. As a result, the second layer 12 can absorb the impact energy which it receives from the first layer 11 (via the third layer 13).

[0053] The third layer 13 is likewise formed from a thermoplastic material but has a lower mechanical strength than the second layer 12 since, in contrast to the first layer 11 and the second layer 12, this second layer does not represent a surface of the radome 10 and therefore has to withstand mechanical loads to a lesser extent. The third layer 13 is enclosed by the first layer 11 and the second layer 12 and therefore has no direct contact with the outside. Since the third layer 13 is the softest layer of the radome 10, it absorbs a large part of the energy during impact events. The remaining energy is passed on to the second layer 12 and can be absorbed by the latter. The interface between the first layer 11 (thermosetting plastic) and the third layer 13 (thermoplastic) furthermore reduces the reflection of shock waves produced at the first layer 11 and thus reduces delamination damage.

[0054] Mechanically more stable materials generally have a higher dielectric constant. Since the first layer 11 and the second layer 12 correspond to (outer and inner) surfaces of the radome 10, they therefore have higher dielectric constants ε.sub.1, ε.sub.2 than the third layer 13. In particular, the first layer 11 has the highest dielectric constant ε.sub.1 since this must be mechanically the most stable as an outward-facing layer. The second dielectric constant ε.sub.2 is less than the first dielectric constant ε.sub.1 but greater than the third dielectric constant ε.sub.3.

[0055] The first layer thickness d.sub.1, the second layer thickness d.sub.2 and the third layer thickness d.sub.3 each differ from one another and are adapted in such a way as to achieve the necessary electromagnetic properties (transmission, reflection, phase fidelity, dielectric loss, distortion of the antenna pattern, etc.) of the radome 10 for the respective antenna application. The use of the thermoplastic layers 12, 13 having a low dielectric constant improves the electromagnetic performance of the radome 10 with respect to the entry phase delay and the antenna axial ratio and thus reduces directional errors and pattern distortions.

[0056] Although a radome 10 with three layers 11, 12, 13 is illustrated in FIG. 1, this embodiment is merely an example. The radome 10 can also have just two layers. In this case, the layer thickness of the (outer) first layer 11 is determined by the mechanical requirements, and the (inner) second layer 12 is adapted to meet the respective electromagnetic requirements.

[0057] FIG. 2 shows a radome 10 similar to that in FIG. 1. However, this radome 10 additionally has a fourth layer 14 with a fourth layer thickness d.sub.4 and a fourth dielectric constant ε.sub.4 as well as a fifth layer 15 with a fifth layer thickness d.sub.5 and a fifth dielectric constant ε.sub.5. The fourth layer 14 and the fifth layer 15 are each arranged inside the second layer 12 (in the direction of the antenna 20 in the installed state of the radome 10), wherein the fifth layer 15 lies between the second layer 12 and the fourth layer 14.

[0058] The fifth layer 15 can be formed from the same material as the third layer 13, i.e. ε.sub.5 is of the same size as ε.sub.3, and the fourth layer 14 can be formed from the same material as the second layer 12, i.e. ε.sub.4 is of the same size as ε.sub.2. However, in the radome 10 illustrated, the second layer 12 can also be formed from the same material as the first layer 11. In other words, the central layer (the second layer 12) is formed either from the same material as the outermost layer (first layer 11) or as the innermost layer (fourth layer 14). However, the layers 11, 12, 13, 14 and 15 have different layer thicknesses d.sub.1, d.sub.2, d.sub.3, d.sub.4 and d.sub.5. The thermoplastic intermediate layers, i.e. the third layer 13 and the fifth layer 15, each have lower dielectric constants ε.sub.3, ε.sub.5 than the remaining layers 11, 12, 14. However, other ratios of the dielectric constants to one another are also conceivable.

[0059] This structure permits a high mechanical stability (the thermoplastic intermediate layers serve as energy absorbers) with simultaneously advantageous electromagnetic properties of the radome 10 due to the low dielectric constants of the thermoplastic intermediate layers. By selecting suitable materials and layer thicknesses of such an asymmetrical radome, the electromagnetic properties can furthermore be adapted to the desired antenna application, in particular to the frequency ranges used and to different requirements in the transmission and reception modes.

[0060] It should be noted that, depending on the application and complexity of the application, there can also be more than three or five layers in the radome 10. In addition, it should be recognized that the layer structures in FIGS. 1 and 2 show only sections of a radome, and the radome is usually not designed to be flat but as a rule has a curved, for example parabolic, surface, allowing the radome 10 to be attached to the nose of an aircraft (such as the aircraft 100 from FIG. 3), for example. However, the radome 10 can also be designed to be flat, e.g. in order to cover an antenna arranged in a depression in the outer wall of an aircraft and to form a flush surface of the aircraft toward the outside.

[0061] FIG. 3 shows a schematic illustration of an aircraft 100 according to one exemplary embodiment. The aircraft 100 has an antenna 20 on the outside of the aircraft 100. A radome 10 covers the antenna 20.

[0062] The antenna 20 can be any conceivable transmitting and receiving device for electromagnetic signals, such as, for example, a communications antenna or a radar antenna.

[0063] The radome 10 covers the antenna 20 in such a way as to protect it from environmental influences such as, for example, aerodynamic loads, the effects of weather and bird strikes. The radome 10 can be constructed according to any of the embodiments disclosed herein.

[0064] Although FIG. 3 illustrates just one antenna 20 with one radome 10, the aircraft can also have more than one antenna 20 and more than one radome 10. In this case, the antennas 20 with the associated radomes 10 can be located at any conceivable and possible point on the aircraft 100. Moreover, it is also possible to cover more than one antenna 20 or antenna array with just one radome 10.

[0065] In addition, it should be noted that “comprising” or “having” does not exclude other elements or steps and “a” or “an” does not exclude a multiplicity. Furthermore, it should be noted that features or steps which have been described with reference to one of the above exemplary embodiments can also be used in combination with other features or steps of other exemplary embodiments described above. Reference signs in the claims are not to be regarded as a restriction.

[0066] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

LIST OF REFERENCE SIGNS

[0067] 10 antenna radome [0068] 11 first layer [0069] 12 second layer [0070] 13 third layer [0071] 14 fourth layer [0072] 15 fifth layer [0073] ε.sub.1 first dielectric constant [0074] ε.sub.2 second dielectric constant [0075] ε.sub.3 third dielectric constant [0076] ε.sub.4 fourth dielectric constant [0077] ε.sub.5 fifth dielectric constant [0078] d.sub.1 first layer thickness [0079] d.sub.2 second layer thickness [0080] d.sub.3 third layer thickness [0081] d.sub.4 fourth layer thickness [0082] d.sub.5 fifth layer thickness [0083] 20 antenna [0084] 100 aircraft