An airborne shortwave folded dipole antenna

Abstract

The application discloses an airborne short-wave folded dipole antenna, comprising two parallel folded dipoles which are connected with feeding signals with a phase difference of 180 degrees respectively, wherein the folded dipole comprises a bending structure, a straight metal structure, two L-shaped branch loading structures and a metal transition structure; the bending structure is composed of a plurality of metal branches which are connected in sequence, and is used for prolonging a current path; one end of the straight metal structure is a feeding point, and the other end is connected with the metal transition structure; the two L-shaped branch loading structures are located on the two sides of the straight metal structure respectively, the short edges of the two L-shaped branch loading structures are connected with a point of the straight metal structure, and the long edges of the two L-shaped branch loading structures are parallel to the straight metal structure and extend to a feeding direction on the straight metal structure; the other end of the metal transition structure is connected with the bending structure, so as to form a metal loop with the bending structure and the straight metal structure. The application can realize miniaturization of the airborne short-wave antenna, and ensure that the antenna has high gain.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to an airborne shortwave folded dipole antenna. Background Technology

[0002] Shortwave communication refers to radio communication using electromagnetic waves with a frequency range of 3MHz to 30MHz. Shortwave communication is characterized by its simple equipment, ease of maintenance, and long transmission distance, and is widely used in airborne and shipborne communication. Airborne shortwave communication systems, with shortwave antennas at their core, play a crucial role in enabling long-distance communication for aircraft. With the rapid development of wireless communication technology and the aerospace industry, airborne equipment is becoming more diverse and integrated. Smaller, wider-bandwidth antennas are better able to cope with complex electromagnetic environments and are of great significance in modern electronic warfare and stealth anti-sabotage. To ensure good communication performance, airborne antennas should have an omnidirectional horizontal radiation pattern.

[0003] In existing technologies, airborne shortwave antennas are mostly mast antennas mounted on aircraft platforms. These antennas are large and exposed outside the tail section. Although mast antennas can produce omnidirectional radiation patterns, their exposure on the aircraft platform can easily affect the aircraft's aerodynamic performance and provides poor concealment. Furthermore, long-distance communication requires antennas with high gain, which necessitates even larger mast antennas. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides an airborne shortwave folded dipole antenna.

[0005] The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] An airborne shortwave folded dipole antenna, concealed within the aircraft fuselage, comprises two parallel folded dipoles. Each of the two folded dipoles is connected to a feed signal with a 180° phase difference. Each folded dipole includes a bent structure, a straight metal structure, two L-shaped stub loading structures, and a metal transition structure.

[0007] The bending structure is composed of multiple metal branches connected end to end in sequence, which is used to extend the current path in the folded oscillator.

[0008] The straight metal structure has one end serving as the feed point for the airborne shortwave folded dipole antenna and the other end connected to the metal transition structure.

[0009] The two L-shaped stub loading structures are located on both sides of the straight metal structure, respectively; the short sides of the two L-shaped stub loading structures are connected to a point on the straight metal structure, and the long sides are parallel to the straight metal structure and extend in the power feeding direction on the straight metal structure.

[0010] The metal transition structure is connected at one end to the straight metal structure and at the other end to the bent structure, so as to form an open metal loop together with the bent structure and the straight metal structure.

[0011] Optionally, the airborne shortwave folded dipole antenna further includes a balun for balancing the current amplitude of the feed signals entering the two folded dipoles.

[0012] Optionally, the airborne shortwave folded dipole antenna further includes an antenna tuner for matching the input impedance and external impedance of the airborne shortwave folded dipole antenna.

[0013] Optionally, the antenna tuner is connected to an external transmitter via an RF coaxial cable or an RF coaxial connector.

[0014] Optionally, in the bending structure, the metal branches that connect end to end are perpendicular to each other.

[0015] Optionally, the length of the folded dipole is 0.28λ to 0.4λ, the width is 0.001λ to 0.003λ, and the spacing between two folded dipoles is 0.13m to 0.18m, where λ is the antenna operating wavelength.

[0016] Optionally, the plurality of metal branches, the straight metal structure, the L-shaped branch loading structure, and the metal transition structure are all composed of or formed of metal strips, and the metal strips that are connected in the structure are welded together.

[0017] Optionally, the width of the metal strips constituting or forming the plurality of metal branches, the straight metal structure, and the metal transition structure is 10mm to 26mm, and the thickness is 0.8mm to 1.2mm; the width of the metal strips constituting the L-shaped branch loading structure is narrower than the width of the metal strips forming the straight metal structure.

[0018] Optionally, the other end of the bent structure is not connected to the metal transition structure and is connected to the aircraft structure.

[0019] The airborne shortwave folded dipole antenna provided by this invention features two folded dipoles arranged in parallel, meaning they can be horizontally aligned. This significantly reduces the antenna's longitudinal height, making it suitable for concealed installation within the aircraft fuselage without affecting the aircraft's aerodynamic performance. Furthermore, the two folded dipoles are each connected to a feed signal with a 180° phase difference. When the feed signal input to the antenna excites equal-amplitude, opposite-current pairs on the surfaces of the two folded dipoles, it generates a dipole-like radiation pattern. Each folded dipole includes a bending structure to extend the current path within the antenna, thereby increasing the antenna's electrical length within a smaller space and improving its gain. Additionally, each folded dipole has an L-shaped stub loading structure to improve the antenna's impedance characteristics, further ensuring high gain. Therefore, the airborne shortwave folded dipole antenna provided by this invention possesses both high-gain radiation performance and a miniaturized structure, making it suitable for long-distance communication under concealed airborne installation conditions.

[0020] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an airborne shortwave folded dipole antenna provided in an embodiment of the present invention;

[0022] Figure 2 yes Figure 1 A schematic diagram of the folded dipole element in the antenna shown;

[0023] Figure 3 An exemplary schematic diagram of the installation of an airborne shortwave folded dipole antenna provided in an embodiment of the present invention is shown;

[0024] Figure 4 The length and width dimensions of the airborne shortwave folded dipole antenna provided in an embodiment of the present invention are illustrated by way of example.

[0025] Figure 5 This is a schematic diagram of another airborne shortwave folded dipole antenna provided in an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of another airborne shortwave folded dipole antenna provided in an embodiment of the present invention;

[0027] Figure 7 This is a diagram showing the internal structural dimensions of an airborne shortwave folded dipole antenna provided in an embodiment of the present invention.

[0028] Figures 8(a), 8(b), and 8(c) show the horizontal radiation pattern comparison curves of the antenna provided by the embodiment of the present invention at 8MHz, 15MHz, and 24MHz in simulations before and after loading the aircraft, respectively.

[0029] Figure 9 The simulation results of the peak gain of the airborne shortwave folded dipole antenna provided in the embodiment of the present invention as a function of frequency are shown. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0031] To achieve miniaturization of airborne shortwave antennas while maintaining high gain, this invention provides an airborne shortwave folded dipole antenna that can be concealed within the aircraft fuselage. (See also...) Figure 1 As shown, the antenna includes two parallel folded elements 1; these two folded elements 1 are respectively connected to feed signals with a phase difference of 180°. Thus, when the feed signals input into the antenna excite equal-amplitude and opposite-current signals on the surfaces of the two folded elements 1, a dipole-like radiation mode can be generated, thereby improving the antenna's radiation pattern non-circularity. It is understandable that the parallel arrangement of the two folded elements 1 allows for lateral arrangement relative to the aircraft fuselage, significantly reducing the antenna's longitudinal height, making it more suitable for concealed installation on the aircraft fuselage without affecting the aircraft's aerodynamic performance.

[0032] See Figure 2 As shown, each folded oscillator 1 includes: a bent structure 11, a straight metal structure 14, two L-shaped branch loading structures 12, and a metal transition structure 13.

[0033] The bent structure 11 is composed of multiple metal branches connected end-to-end in sequence, used to extend the current path in the folded oscillator 1. These metal branches can all be of equal length, or they can be arranged in various ways... Figure 2 Not all of the above are equal. Preferably, the metal branches connected end to end are perpendicular to each other, which can achieve better matching performance. Of course, the metal branches connected end to end are not perpendicular to each other, which can also achieve the effect of extending the current path.

[0034] One end of the straight metal structure 14 is the feed point 15 for the shortwave folded dipole antenna, and the other end is connected to the metal transition structure 13.

[0035] Two L-shaped stub loading structures 12 are located on both sides of the straight metal structure 14. The short sides of these two L-shaped stub loading structures 12 are connected to a point on the straight metal structure 14, and the long sides are parallel to the straight metal structure 14 and extend in the power feeding direction on the straight metal structure 14.

[0036] The metal transition structure 13 connects to a straight metal structure 14 at one end and a bent structure 11 at the other end, forming an open metal loop together with the bent structure 11 and the straight metal structure 14. It is understood that the end of the bent structure 11 connected to the metal transition structure 13 is its own power input, while the other end can be connected to the structural ground of the aircraft in a practical installation scenario, such as the metal structure connecting to the aircraft fuselage or the leading edge spars of the tail fin (e.g.,...). Figure 3 This reduces the likelihood of antenna performance degradation or functional loss due to lightning strikes.

[0037] In practice, the multiple metal branches, straight metal structure 14, L-shaped branch loading structure 12, and metal transition structure 13 in the bent structure 11 are all formed or composed of metal strips. Preferably, the width of the metal strips constituting or forming the bent structure 11, the straight metal structure 14, and the metal transition structure 13 can be 10mm to 26mm, and the thickness can be 0.8mm to 1.2mm. The width of the metal strip constituting the L-shaped branch loading structure 12 is narrower than the width of the metal strip constituting the straight metal structure 14. These metal strips are preferably made of copper or gold. This ensures that the folded element 1 can withstand high transmission power without causing the antenna to be too heavy. As can be seen, the airborne shortwave folded element 1 antenna provided in this embodiment of the invention has a simple structure, is easy to process, and the metal strips can be printed on the aircraft skin, making it very suitable for conformal antenna installation, thus meeting the installation requirements of the antenna within the limited size of the airborne platform. In addition, to ensure the structural stability of the antenna, insulating materials can be further used in this embodiment of the invention to fix the position of the folded element 1.

[0038] In this embodiment of the invention, each folded dipole 1 includes a bending structure 11, which extends the current path in the antenna, thereby increasing the electrical length of the antenna within a smaller physical size, effectively reducing the antenna size and improving the antenna gain. Furthermore, each folded dipole 1 also has an L-shaped stub loading structure 12, which improves the antenna's impedance characteristics, further ensuring the antenna's high gain characteristics. Therefore, the airborne shortwave folded dipole antenna 1 provided by this embodiment of the invention possesses both high-gain radiation performance and a miniaturized structure, making it suitable for long-distance communication under airborne concealed installation conditions.

[0039] Preferably, see Figure 4As shown, in this embodiment of the invention, the length of the folded vibrator 1 is 0.28λ to 0.4λ, and the width is 0.001λ to 0.003λ, where λ is the antenna operating wavelength. The spacing between the two folded vibrators 1 is preferably 0.13m to 0.18m. It can be understood that the length direction of the folded vibrator 1 is parallel to the direction of the straight metal structure 14, and correspondingly, the width direction of the folded vibrator 1 is the direction in which the metal transition structure 13 extends towards its two ends.

[0040] In an optional embodiment, the airborne shortwave folded dipole antenna 1 provided in this embodiment of the invention may further include: a balun 2, used to balance the current amplitude of the feed signals entering the two folded dipoles 1.

[0041] See Figure 5 As shown, in this embodiment, the balun 2 receives a single-ended RF signal as input and outputs two differential signals, which are then fed into two folded oscillators 1. In practice, the balun 2 can also be called a balun-to-unbalance converter, mainly used to make the phase difference between the two feed signals closer to the ideal 180°.

[0042] based on Figure 5 In one optional implementation of the embodiment shown, the airborne shortwave folded dipole antenna 1 provided in this embodiment of the invention may further include: an antenna tuner 3, used to match the input impedance and external impedance of the airborne shortwave folded dipole antenna 1.

[0043] See Figure 6 As shown, the input terminal of the antenna tuner 3 is connected to an external impedance, and the output terminal is connected to the input terminal of the balun 2. The external impedance can be the output impedance of an external transmitter or the output impedance of an external RF circuit, etc. The antenna tuner 3 can be connected to an external transmitter via an RF coaxial cable 4 or an RF coaxial connector; however, the method of connecting the antenna tuner 3 to the external transmitter is not necessarily limited to this.

[0044] Figure 6 The specific working process of the airborne shortwave folded dipole antenna 1 is as follows: the radio frequency signal enters the antenna tuner 3 through the radio frequency coaxial line 4, and the radio frequency signal with the maximum radiated energy is obtained through impedance matching. The matched radio frequency signal then enters the balun 2, and is then sent to the upper and lower folded dipoles 1 through the feed lines to radiate to the external space.

[0045] With the addition of antenna tuner 3, the airborne shortwave folded dipole antenna 1 provided in this embodiment of the invention can achieve impedance matching in a wide bandwidth, thereby achieving high transmission efficiency under wide bandwidth operating conditions and making it suitable for application in frequency hopping spread spectrum communication.

[0046] In a preferred embodiment, see Figure 7As shown, the width W1 of the folded oscillator 1 is 0.018m, the thickness is 1mm, and the spacing between two folded oscillators 1 is 0.15m. The bent structure 11 includes 6 first metal branches, 3 second metal branches, and 8 third metal branches; wherein, the length L1 of the first metal branch is 0.16m, the length L2 of the second metal branch is 0.7m, and the length L3 of the third metal branch is 0.15m. The length L4 of the metal transition structure 13 is 0.29m. The length L5 of the straight metal structure 14 is 2.87m. The distance from the connection point between the short side of the L-shaped branch loading structure 12 and the straight metal structure 14 to the feed point is L6 = 0.5m, the length L7 of the long side of the L-shaped branch loading structure 12 is 2.22m, the length L8 of the short side is 0.04m, and the width W2 of both the long and short sides is 0.006m.

[0047] Based on this embodiment, the antenna was simulated to evaluate the performance of the airborne shortwave folded dipole antenna provided in this embodiment under airborne conditions. In the simulation, the aircraft platform dimensions were set as follows: length 40m, wingspan 58m, height 4.5m, and the antenna was mounted on the leading edge of the aircraft tail. The airborne shortwave folded dipole antenna in conjunction with the aircraft was simulated using the full-wave electromagnetic field simulation software ANSYS HFSS 19.0. The simulation results are as follows:

[0048] Figures 8(a), 8(b), and 8(c) show the horizontal radiation patterns of the antenna provided in this embodiment of the invention at 8MHz, 15MHz, and 24MHz before and after loading the aircraft, respectively. The longitude coordinates of the polar coordinate curves represent angles ranging from 0° to 360°, and the latitude coordinates represent antenna gain ranging from -20dBi to 5dBi.

[0049] As can be seen from the comparison, without the aircraft, the airborne shortwave folded dipole antenna provided in this embodiment of the invention exhibits good horizontal omnidirectional radiation characteristics at different frequency points within the frequency band, with a pattern non-circularity of less than 1 dBi. After the aircraft is loaded, due to the influence of the aircraft, the horizontal pattern circularity of the antenna changes slightly, but it still maintains good horizontal omnidirectional radiation characteristics, with a horizontal gain greater than -5 dBi. This indicates that the antenna provided in this embodiment of the invention is less affected by the fuselage and still has high gain and omnidirectional radiation characteristics after the aircraft is loaded.

[0050] Figure 9 The simulation results of the peak gain of the airborne shortwave folded dipole antenna provided in the embodiment of the present invention as a function of frequency are shown. The horizontal axis represents the frequency in MHz, ranging from 5 to 25 MHz, and the vertical axis represents the maximum gain amplitude in decibels, in dBi, ranging from -4 dBi to 8 dBi.

[0051] Depend on Figure 9As can be seen, the airborne shortwave folded dipole antenna provided in this embodiment of the invention, after being loaded onto an aircraft, exhibits continuously increasing gain in the 5MHz-25MHz frequency band as the frequency increases. The peak gain across the entire frequency band is higher than -5dBi, the average gain is approximately 1.5dBi, and the maximum gain reaches 4.4dBi. The peak gain is greater than 0dBi at frequencies above 10MHz. Compared to traditional telescopic airborne shortwave antennas, the airborne shortwave folded dipole antenna provided in this embodiment of the invention, based on a simple structure, possesses excellent gain characteristics, with a peak gain greater than -5dBi across the entire frequency band and good horizontal radiation pattern non-circularity. This achieves high gain and omnidirectional radiation for airborne shortwave antennas, thereby improving the communication distance of airborne shortwave systems.

[0052] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0054] Although this application has been described herein in conjunction with various embodiments, other variations of the disclosed embodiments can be understood and implemented by those skilled in the art in carrying out the claimed application by reviewing the accompanying drawings, the disclosure, and the appended claims.

[0055] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. An airborne shortwave folded dipole antenna, characterized in that, Hidden within the aircraft fuselage, the airborne shortwave folded dipole antenna comprises: two parallel folded dipoles (1); each of the two folded dipoles (1) is connected to a feed signal with a phase difference of 180°, and each folded dipole (1) comprises: a bent structure (11), a straight metal structure (14), two L-shaped stub loading structures (12), and a metal transition structure (13); wherein, The bent structure (11) is composed of multiple metal branches connected end to end in sequence, and is used to extend the current path in the folded oscillator; The straight metal structure (14) has one end as the feed point of the airborne shortwave folded dipole antenna and the other end connected to the metal transition structure (13). The two L-shaped stub loading structures (12) are located on both sides of the straight metal structure (14); the short sides of the two L-shaped stub loading structures (12) are connected to a point on the straight metal structure (14), and the long sides are parallel to the straight metal structure (14) and extend in the power feeding direction on the straight metal structure (14); The metal transition structure (13) is connected at one end to the straight metal structure (14) and at the other end to the bent structure (11), so as to form an open metal loop together with the bent structure (11) and the straight metal structure (14).

2. The airborne shortwave folded dipole antenna according to claim 1, characterized in that, Also includes: A balun (2) is used to balance the current amplitude of the feed signal entering the two folded oscillators (1).

3. The airborne shortwave folded dipole antenna according to claim 2, characterized in that, Also includes: Antenna tuner (3) is used to match the input impedance and external impedance of the airborne shortwave folded dipole antenna.

4. The airborne shortwave folded dipole antenna according to claim 3, characterized in that, The antenna tuner is connected to an external transmitter via an RF coaxial cable or an RF coaxial connector.

5. The airborne shortwave folded dipole antenna according to claim 1, characterized in that, In the bent structure (11), the metal branches that are connected end to end are perpendicular to each other.

6. The airborne shortwave folded dipole antenna according to claim 1, characterized in that, The length of the folded dipole (1) is 0.28λ to 0.4λ, the width is 0.001λ to 0.003λ, the spacing between the two folded dipoles (1) is 0.13m to 0.18m, and λ is the antenna operating wavelength.

7. The airborne shortwave folded dipole antenna according to claim 1, characterized in that, The plurality of metal branches, the straight metal structure (14), the L-shaped branch loading structure (12), and the metal transition structure (13) are all composed of or formed of metal strips.

8. The airborne shortwave folded dipole antenna according to claim 7, characterized in that, The width of the metal strips that make up or form the plurality of metal branches, the straight metal structure (14), and the metal transition structure (13) is 10 mm to 26 mm and the thickness is 0.8 mm to 1.2 mm. The width of the metal strip that makes up the L-shaped branch loading structure (12) is narrower than the width of the metal strip that makes up the straight metal structure (14).

9. The airborne shortwave folded dipole antenna according to claim 1, characterized in that, The other end of the bent structure (11) that is not connected to the metal transition structure (13) is connected to the aircraft structure.

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