METHOD FOR COMPENSATE CAVITY EFFECT IN AIRCRAFT EMBEDDED ANTENNA IMPEDANCE AND EMBEDDED ANTENNA ARRAY FOR AIRCRAFT

Abstract

Method for compensate cavity effect in aircraft embedded antenna impedance and Embedded antenna array for aircraft The present invention relates to a method for compensate cavity effect in aircraft embedded antenna impedance by using radiofrequency (RF) absorber materials applied to entirely embedded antennas (non-protruding installation) particularly used in aircraft. The invention also refers to embedded antenna arrays for aircraft using radiofrequency (RF) absorber materials to enhance and/or optimize its impedance matching.

Claims

1. Method for compensate cavity effect in aircraft embedded antenna impedance, comprising the steps of: (i) provide an embedment cavity; (ii) placing radiofrequency absorber material inside the embedment cavity enhancing the embedded antenna input impedance matching.

2. Method, according to claim 1, wherein the fact that the radiofrequency absorber material is placing in the embedment cavity lateral walls or bottom.

3. Method, according to claim 1, wherein the fact that it is applied for any frequency range including VLF, LF, VHF, UHF and SHF.

4. Embedded antenna array for aircraft, comprising an embedment cavity receiving ate least one radiofrequency absorber material placed inside the embedment cavity to enhance the embedded antenna input impedance matching.

5. Embedded antenna, according to claim 4, wherein the fact that the embedment cavity can have a plurality of shapes.

6. Embedded antenna, according to claim 5, wherein the fact that the radiofrequency absorber material can have a plurality of geometries and sizes.

7. Embedded antenna, according to claim 4, wherein the fact that the embedment cavity receives more than one radiofrequency absorber material placed inside the embedment cavity to enhance the embedded antenna input impedance matching.

Description

DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1illustrates the aircraft fuselage comprising a protruding antenna externally installed as known in the prior art and the embedded antenna of the present invention positioned at the similar region of aircraft fuselage;

[0017] FIG. 2 and Detail Aillustrate the embedded antenna of the present invention positioned inside the aircraft fuselage;

[0018] FIG. 3is a perspective view of a plurality of embedment cavities for the embedded antenna of the present invention;

[0019] FIG. 4is a perspective view of absorbers possible locations with different geometries;

[0020] FIG. 5is a perspective view of an embedment cavity for embedded antenna with more than one absorber material;

[0021] FIG. 6is an upper view of an embedment cavity for embedded antenna with more than one absorber material illustrated in FIG. 5;

[0022] FIG. 7is a perspective and front view of partially embedded antennas;

[0023] FIG. 8is a perspective and front view of fully embedded antennas; and

[0024] FIG. 9is a graphic demonstrating the efficiency of the proposed invention, by means of full-wave numerical simulations of the input impedance matching enhancement, as a function of VSWR (Voltage Standing Wave Ratio).

DETAILED DESCRIPTION OF THE INVENTION

[0025] Antennas (A) commercially available for aircraft installation necessarily need to have an external protruding part in the aircraft fuselage, as can be seen in FIG. 1. Usually, an aircraft has several antennas A all over the fuselage skin, each one for a specific purpose, meaning that several protruding parts are spreaded across the aircraft fuselage. As a result, these antennas A are responsible for producing drag and they compromises the aesthetics of the aircraft.

[0026] It is an object of the present invention, an embedded antenna 30 for aircraft, developed to extinguish the external protruding part of the antenna, since the entire antenna 30 is positioned inside the aircraft fuselage in an embedment cavity 31, as shown in FIGS. 1, 2 and detail A.

[0027] In this sense, the embedment cavity 31 of the embedded antenna 30 can have a plurality of shapes, as illustrated in FIG. 3. Each shape must have cavity lateral walls 33 and bottom 32, wherein the antenna components are positioned, including all elements that compose the active radiating part of the antenna and its interface connection and cables.

[0028] Besides the antenna components, the embedment cavity 31 also receives at least one radiofrequency absorber material 40, 41 (FIG. 4) placed inside the embedment cavity 31 to enhance the embedded antenna input impedance matching by absorbing electromagnetic wave as a load and eliminating multiple reflections of the waves that mismatch the antenna syntonization at the intended operating frequency band.

[0029] The radiofrequency absorber material 40, 41 can have a plurality of geometries and sizes to fit with the embedment cavity 31 several shapes. Further, the embedment cavity 31 can receive more than one radiofrequency absorber material 40, 41, as can be seen in FIGS. 5 and 6, placed inside the embedment cavity 31 to enhance the embedded antenna 30 input impedance matching. Thus, the present invention can use any kind of RF absorber and it is also possible to use absorbers with different electromagnetic characteristics or a combination of different types of absorbers, where the geometry and the amount of the absorbers are adjusted in function of their electromagnetic characteristics.

[0030] Another object of this invention is a method for compensate cavity effect in aircraft embedded antenna 30 impedance. This method comprises the steps of: [0031] (i) provide an embedment cavity 31; [0032] (ii) placing radiofrequency absorber material 40, 41 inside the embedment cavity 31 enhancing the embedded antenna 30 input impedance matching.

[0033] The radiofrequency absorber material 40, 41 is used to compensate the cavity effect in the antenna impedance due to its embedment and, consequently, significantly enhancing its input impedance matching.

[0034] The proposed method is independent of cavity 31 format and/or antenna topology. The radiofrequency absorber material 40, 41 is installed in the embedment cavity 31 and its geometry, quantity and position will depend on the absorber electromagnetic characteristics and the antenna required parameters.

[0035] The radiofrequency absorber material 40, 41 is placed in the cavity lateral walls 33 or bottom 32, according to a trade-off between the cavity embedment effect reduction and absorber quantity (volume).

[0036] It is important to note that this method is applied for any frequency range including VLF, LF, VHF, UHF and SHF.

[0037] Moreover, the method and the embedded antenna 30, objects of the present invention improve the input impedance matching for the antenna and/or antenna array and, consequently, enhance its radiation efficiency and gain; mechanical robustness; simplicity and functional frequency band, regardless the antenna topology.

[0038] FIG. 9 shows how the addition of absorbers decreases the level of VSWR in the frequency range target for the antenna operation. The lower value as possible for VSWR, the better is the antenna impedance matching. In this sense, the graphic of FIG. 9 demonstrates the efficiency of the proposed invention, by means of full-wave numerical simulations of the input impedance matching enhancement, as a function of VSWR. Therefore, the innovative use of the absorbers enables the construction of antennas with appropriate characteristics for installation without protuberances and complying with the aircraft requirements.

[0039] Furthermore, particularly for transport applications, including aerospace vehicles, the invention provides a fully or partially antenna and/or antenna array embedment (non-protruding installations), drag reduction, fuel-savings, maintenance cost reduction, aesthetic and safety improvements, as illustrated in FIGS. 7 and 8.

[0040] So, having described an example of a preferred embodiment, it should be understood that the scope of this invention covers other possible variations, being limited only by the content of the attached claims, including the possible equivalents.