Dual-band end-on-fire antenna based on discone structure

Abstract

The invention discloses a dual-band end-on-fire antenna based on a discone structure. The dual-band end-on-fire antenna mainly solves the problems that an airborne platform antenna is large in aperture number, large in end-on-fire direction and low in angular domain gain. The antenna comprises a radome (1), an antenna body (2) and a duplexer (3), and the radome (1) is located on the uppermost layer, has a broadband wave-transparent characteristic and is used for protecting a radiation structure in the antenna body; the antenna body (2) is located in the middle layer, comprises a discone, a radiation oscillator, an insulator and a matching body, and is used for transmitting and receiving electromagnetic waves; the disc cone comprises a cone body with an adjustable angular domain range, a mounting flange used for being connected with an antenna housing and an adjusting cavity capable of transmitting dual-band signals, the duplexer (3) is located on the lowest layer and used for transmitting two signals with different frequencies at the same time and isolating the two signals, and it is guaranteed that the antenna can normally work at the same time in the two frequency bands. The antenna aperture number can be reduced, the large angular domain gain of the antenna in the end-fire direction can be improved, and the antenna is simple in structure, convenient to process and capable of being used on an airborne platform.

Description

Technical Field

[0001] The invention belongs to the field of radar equipment antennas, and in particular relates to a dual-band end-fire antenna which can be used on an airborne platform. Background Art

[0002] With the development of wireless communication technology and the expansion of aircraft functional requirements, more and more radar equipment is installed on aircraft, making the density of airborne radar equipment higher and higher. Antennas are installed on the surface of the aircraft as the front end of radar equipment sensors. In order to meet the needs of installing more radar equipment in a limited installation environment, it is necessary to design antennas in a miniaturized and integrated manner.

[0003] The patent document with application number 202010747676.2 discloses a microstrip array disc-cone composite conformal antenna, which is formed by a metal cone and a metal disc embedded and fixed on the bottom of the reflective cavity. A 2×2 rectangular radiating patch unit is provided on the dielectric substrate fixed on the metal disc. The rectangular radiating patch unit is fed in parallel through a one-to-four microstrip power divider. The disc-cone antenna and the microstrip array antenna form a composite antenna that can radiate horizontal omnidirectional vertical polarization signals and horizontal polarization signals directional to the zenith. Although the antenna can be dual-band composite, the maximum gain of the microstrip array antenna points to the normal direction, and the gain is low in a large angular range in the end-fire direction. Therefore, a spatial blind spot will be generated when it is used, which cannot meet the communication requirements in the end-fire direction; in addition, since the antenna is composed of a microstrip array radiating patch, a dielectric substrate, a metal disc, a metal column, a metal cone, a patch probe, a frustum probe and a reflective cavity, the number of structures is large, so the processing technology is relatively complex. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and to propose a dual-band end-fire antenna based on a disk-cone structure to simplify the antenna structure and use one antenna to meet the communication requirements of a large angular range in the end-fire direction in two working frequency bands at the same time.

[0005] The technical solution for realizing the purpose of the present invention is as follows:

[0006] A dual-band end-fire antenna based on a disc-cone structure comprises a radome 1, an antenna body 2, and a duplexer 3, and is characterized in that:

[0007] The antenna body 2 includes a disc cone 21, a radiation oscillator 22, an insulator 23 and a matching body 24;

[0008] The disk cone 21 includes a cone body 211, a mounting flange 212 and an adjustment cavity 213, wherein the cone body 211 is located at the uppermost layer, the mounting flange 212 is located at the middle layer, and the adjustment cavity 213 is located at the lowermost layer;

[0009] The radiation vibrator 22 is located inside the insulator 23, and the two are coaxial;

[0010] The insulator 23 is located directly above the matching body 24 , and the two are tightly fitted and both are located inside the disc cone 21 .

[0011] Furthermore, the top diameter of the cone 211 is φ1, the bottom diameter is φ2, the height is h1, and the distance between the top of the cone and the top of the insulator 23 is h3. By adjusting these parameters, the radiation direction of the antenna can be adjusted so that the angular range of the end-fire direction of the antenna meets the design requirements.

[0012] Furthermore, the radiation vibrator 22 has a diameter of φ5 and a height of h4; the insulator 23 has a diameter of φ4 and a height of h5, and h5 is not less than the distance h3 between the top of the cone 211 and the top of the insulator 23, and is not greater than the height h4 of the radiation vibrator 22; the parameters of the radiation vibrator 22 and the insulator 23 are adjusted simultaneously so that the antenna can operate simultaneously in two frequency bands.

[0013] Furthermore, the matching body 24 is made of metal and has any one of a stepped, arc-shaped gradient, and conical structure, and is used to adjust the impedance matching between the disc cone 21, the radiation oscillator 22, and the insulator 23 so that the standing wave coefficient of the antenna meets the design requirements.

[0014] The adjusting cavity 213 has an inner cavity length L1, a width W1, a height h2, and a chamfer radius R1. The height h2 is not less than the height of the matching body 24. The inner cavity length L1 and the width W1 are determined by the transmission characteristics of the rectangular waveguide so that the adjusting cavity 213 can transmit electromagnetic waves in the two working frequency bands of the antenna.

[0015] Furthermore, the antenna cover 1 adopts a wide-band multi-layer structure and is tightly fixed on the upper surface of the mounting flange 212, so that the upper surface of the mounting flange is tightly fitted with the lower surface of the antenna cover. The material used is a wave-transmitting material to ensure good wave transmission performance within the two working frequency bands of the antenna, thereby reducing the energy loss of the antenna radiating outward.

[0016] Furthermore, the duplexer 3 includes three ports 31, 32, and 33. The first port 31 is consistent with the inner size of the adjustment cavity 213 and is tightly connected so that the upper surface of the duplexer 3 is tightly fitted with the lower surface of the antenna body 2; the second port 32 and the third port 33 both adopt a rectangular structure, and their sizes are determined according to the transmission characteristics of the rectangular waveguide so that their transmission frequency meets the dual-band working requirements of the antenna.

[0017] The present invention has the following advantages:

[0018] 1. The antenna body of the present invention adopts a disk-cone structure with wide-band characteristics. Through the combination of the cone, the insulator and the radiating oscillator, it can not only adjust the antenna angular range, but also enable the antenna to work in two frequency bands at the same time, thereby fully improving the aperture utilization of the airborne platform and reducing the number of antenna apertures.

[0019] 2. The present invention introduces a matching body to achieve good impedance matching of the antenna, so both end-fire directions of the two working frequency bands have higher gains, meeting the end-fire communication requirements of the radar equipment.

[0020] 3. The present invention has a simple structure, is easy to model and process, and has great practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 is a schematic diagram of the antenna body in the present invention;

[0023] Figure 3 It is a schematic diagram of the structure of the duplexer in the present invention;

[0024] Figure 4 This is a simulation result diagram of the K-band standing wave coefficient of an embodiment of the present invention;

[0025] Figure 5 This is a simulation result diagram of the K-band directional pattern of an embodiment of the present invention;

[0026] Figure 6 This is a simulation result diagram of the Ka-band standing wave coefficient of an embodiment of the present invention;

[0027] Figure 7 This is a diagram of the simulation results of the Ka-band directional pattern of an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The embodiments and effects of the present invention are described in detail below with reference to the accompanying drawings.

[0029] Reference Figure 1 The antenna of this embodiment includes a radome 1, an antenna body 2, and a duplexer 3. The radome 1 is located at the top layer, and has a broadband wave-transmitting property, and is used to protect the radiation structure inside the antenna and radiate energy outward; the antenna body 2 is located in the middle layer, and is used to transmit and receive electromagnetic waves; the duplexer 3 is located in the bottom layer, and is used to simultaneously transmit signals of two different frequency bands, and isolate the two signals from each other, so as to ensure that the antenna can simultaneously transmit or receive signals of two frequency bands.

[0030] In this embodiment, the first working frequency band is set to but not limited to 24.5 GHz to 24.9 GHz; the second working frequency band is set to but not limited to 32.4 GHz to 32.8 GHz, and the end-fire angle ranges of the first frequency band and the second frequency band are set to but not limited to -90° to -37° and 37° to 90°.

[0031] The installation environment of this embodiment is the surface of an airborne platform. The radome 1 is located at the uppermost layer of the antenna and is exposed to the outside of the platform. It needs to meet complex environmental requirements, such as salt spray, mold, sand and dust, etc. The material of the radome is a wave-transmitting material that meets the environmental requirements. The radome is preferably a broadband multi-layer structure, and the wave transmittance T is calculated as follows:

[0032]

[0033] in, A i =D i =cosh(jγ i d i ), B i =Z 0i sinh(jγ i d i ), C i = sinh(jγ i d i ) / Z 0i ; λ represents the operating frequency, di represents the thickness of the i-th layer, represents the complex relative permittivity of the i-th layer, θ i represents the incident angle, n represents the number of material layers, and T represents the transmission coefficient.

[0034] The radome adopts a three-layer hemispherical curved surface structure, and the material arrangement from outside to inside is as follows:

[0035] The first layer material is selected from but not limited to cyanate quartz fiber cloth with a dielectric constant of 3.1, a loss tangent of 0.008, and a thickness of 0.3 mm;

[0036] The second layer material is selected from but not limited to paper honeycomb with a dielectric constant of 1.06, a loss tangent of 0.0035, and a thickness of 2.0 mm;

[0037] The third layer material is selected from but not limited to cyanate quartz fiber cloth with a dielectric constant of 3.1, a loss tangent of 0.008, and a thickness of 0.3 mm.

[0038] By substituting the performance parameters of the three materials into the above-mentioned calculation formula for wave transmittance, it can be obtained that the wave transmittance of the antenna cover is greater than 95% in the two working frequency bands, that is, the wave transmission performance is good, the loss of the antenna's outward radiation energy is small, and the design requirements are met.

[0039] refer to Figure 2 The antenna body 2 includes a disk cone 21, a radiation oscillator 22, an insulator 23 and a matching body 24, wherein the disk cone 21 is located at the outermost layer, the radiation oscillator 22 is located inside the insulator 23 and the two are coaxial, and the insulator 23 is located directly above the matching body 24, and the two are closely attached and are both located inside the disk cone 21, such as Figure 2 (a) shown.

[0040] The disk cone 21 is made of metal, and includes a cone 211, a mounting flange 212 and an adjustment cavity 213. The cone 211 is narrow at the top and wide at the bottom, and is located at the top layer; the mounting flange 212 is located at the middle layer, and its upper surface is tightly fitted and fixed to the lower surface of the antenna cover 1; the adjustment cavity 213 is located at the bottom layer, and adopts an air cavity structure, with an inner cavity length of L1, a width of W1, a chamfer radius of R1, a height of h2 and not less than the height of the matching body 24, as shown in FIG. Figure 2 (b) as shown.

[0041] The radiation vibrator 22 is a metal column structure, and is used to radiate electromagnetic waves outward.

[0042] The insulator 23 adopts a columnar structure and is used to isolate the disc cone 21 and the radiation vibrator 22 so as to electrically isolate the two and avoid current interference between the two, thereby ensuring the stability of the radiation signal.

[0043] The matching body 24 is made of metal and may adopt a stepped structure, an arc-shaped gradient structure, a conical structure, etc. It is used to achieve impedance matching between the disc cone 21, the radiation oscillator 22, and the insulator 23 so that the standing wave coefficient of the antenna meets the design requirements.

[0044] The top diameter of the cone 211 is φ1, the bottom diameter is φ2, the cone height is h1, and the distance between the top of the cone and the top of the insulator 23 is h3. The diameter of the radiation vibrator 22 is φ5, the height is h4, and the diameter of the insulator 23 is φ4 and the height is h5. The height h5 is not less than the distance h3 between the top of the cone and the top of the insulator 23, and is not greater than the height h4 of the radiation vibrator. By adjusting the above parameters through simulation, the dual-band working requirements and angular range requirements of the antenna can be met, and the radiation characteristics of the antenna can be optimized.

[0045] refer to Figure 3 The duplexer 3 is a three-port waveguide device, and its three ports are a first port 31, a second port 32, and a third port 33.

[0046] The cavity size of the first port 31 is consistent with the inner cavity size of the adjustment cavity 213, and the two are tightly connected, so that the upper surface of the duplexer 3 and the lower surface of the antenna body 2 are closely fitted;

[0047] The second port 32 and the third port 33 both adopt a rectangular structure, and the inner cavity size is determined according to the transmission characteristic formula of the rectangular waveguide, and the operating frequencies thereof meet the first and second frequency band requirements of the antenna respectively.

[0048] When the antenna of the present invention is working, two frequency bands can be transmitted and received at the same time, or one frequency band can be transmitted and the other frequency band can be received. When the antenna is in the transmitting state, the signal transmitted by the rear-end radar device selects a suitable port from the second port 32 and the third port 33 according to its working frequency band to enter the duplexer, and then enters the adjustment cavity 213 of the antenna body through the first port 31 of the duplexer 3, and reaches the radiation vibrator 22 through the matching body 24 to be converted into electromagnetic waves, and finally radiates outward through the antenna cover 1. When the antenna is in the receiving state, the external electromagnetic wave is received by the radiation vibrator 22 of the antenna body 2 through the antenna cover 1, and then enters the adjustment cavity 213, reaches the first port 31 of the duplexer 3 through the matching body 24, and finally reaches the rear-end radar device through the second port 32 or the third port 33 of the duplexer 3.

[0049] As an example, the parameters of the components of the antenna of the present invention are set as follows:

[0050] The cone 211 has a top diameter φ1 of 22 mm, a bottom diameter φ2 of 38.8 mm, a cone height h1 of 11 mm, and a distance h3 between the cone top and the insulator 23 of 8.15 mm;

[0051] The mounting flange 212 has a diameter φ3 of 59 mm;

[0052] The adjusting cavity 213 has an inner cavity length L1 of 8.636 mm, a width W1 of 4.318 mm, a chamfer radius R1 of 1 mm, and a height h2 of 11 mm;

[0053] The radiation vibrator 22 has a diameter φ5 of 1 mm and a height h4 of 10.95 mm;

[0054] The insulator 23 is made of, but not limited to, polytetrafluoroethylene with a dielectric constant of 2.08 and a loss tangent of 0.021, a diameter φ4 of 3 mm, and a height h5 of 9.95 mm.

[0055] The matching body 24 adopts a three-step structure, the first step has a size of 3.2 mm×3 mm, the second step has a size of 2.4 mm×3 mm, and the third step has a size of 1.3 mm×3 mm;

[0056] The inner cavity size of the first port 31 of the duplexer 3 is consistent with the inner cavity size of the adjustment cavity 213, that is, the length is 8.636mm, the width is 4.318mm, and the chamfer radius is 1mm; the operating frequency of the second port 32 is 24.5GHz~24.9GHz, and the inner cavity length is calculated to be but not limited to 8.636mm and the width is but not limited to 4.318mm according to the transmission characteristics of the rectangular waveguide;

[0057] The operating frequency of the third port 33 is 32.4 GHz to 32.8 GHz, and the inner cavity length thereof is but not limited to 7.112 mm, and the width thereof is but not limited to 3.556 mm.

[0058] The inner cavity length L1 and width W1 of the adjustment cavity 213 are calculated according to the following transmission characteristic formula of the rectangular waveguide:

[0059]

[0060] In the formula is the cutoff wavelength of the transverse electric wave with guided mode index m and n, It is the cut-off wavelength of the transverse magnetic wave with guided mode wave index m and n, where m and n are two arbitrary positive integers representing the guided mode wave index.

[0061] Since the condition for the guided mode to be transmitted in the waveguide is that the cut-off wavelength is greater than the working wavelength, and the present invention includes two working frequency bands, the above-mentioned cut-off wavelength should be greater than both working wavelengths at the same time.

[0062] In this example, the main mode of rectangular waveguide transmission is selected as TE 10 , that is, m = 1, n = 0. According to the working wavelength of the given working frequency band, the minimum cut-off wavelength is 12.25 mm. Substituting it into the above formula, we can get the inequality: L1>6.125 mm;

[0063] According to other structural dimensions of this example, a suitable value is selected as the initial value of L1, and the width W1 is set to half of the length L1, that is, in this example, L1 is 8.636 mm and the width W1 is 4.318 mm.

[0064] The parameters of the radiating element 22 and the insulator 23 are determined through simulation optimization. First, an antenna model is established in the simulation software, and then the parameters of the radiating element 22 and the insulator 23 are set as variables. By changing these variables, the simulation results of the directional patterns of the two frequency bands of the antenna are compared, and finally a set of parameters that meet the simulation results of the design requirements are selected.

[0065] The parameters of the matching body 24 are determined by simulation optimization. First, an antenna model is established in the simulation software. Secondly, the dimensions of the three steps of the matching body 24 are set as variables. By changing these variables, the simulation result change image of the standing wave coefficient of the antenna is compared, and one variable that meets the design requirements is taken as the final value of the parameter.

[0066] The effect of the present invention can be further illustrated by the following simulation results.

[0067] 1. Simulation conditions

[0068] The HFSS electromagnetic simulation software is used to establish the electromagnetic simulation model of the embodiment of the present invention using the above example parameters, and the operating frequency bands are the K band and the Ka band.

[0069] 2. Simulation content

[0070] Simulation 1: The K-band standing wave coefficient of the electromagnetic simulation model of the embodiment of the present invention is simulated, and the result is as follows: Figure 4 .

[0071] from Figure 4 It can be seen that the corresponding standing wave coefficient of the antenna is 1.2127 when the center frequency is 24.7 GHz, and the maximum standing wave coefficient in the frequency band of 24.5 GHz to 24.9 GHz is 1.2283, corresponding to the frequency of 24.9 GHz, indicating that the K-band standing wave coefficient of the antenna of the present invention is less than 1.23 in the range of 24.5 GHz to 24.9 GHz.

[0072] Simulation 2: The K-band radiation pattern of the electromagnetic simulation model of the antenna of the embodiment of the present invention is simulated, and the result is as follows: Figure 5 .

[0073] from Figure 5 It can be seen that the minimum gain of the antenna in the angular range of -90° to -37° is 1.4247dB, corresponding to an angle of -90°; the minimum gain of the antenna in the angular range of 37° to 90° is 1.6040dB, corresponding to an angle of 90°. This indicates that the gain of the antenna of the present invention in the K-band end-fire direction in the angular range of -90° to -37° and the angular range of 37° to 90° is greater than 1.4dB.

[0074] Simulation 3: The Ka-band standing wave coefficient of the electromagnetic simulation model of the antenna of the embodiment of the present invention is simulated, and the result is as follows: Figure 6 .

[0075] from Figure 6It can be seen that the corresponding standing wave coefficient of the antenna is 1.1539 when the center frequency is 32.6 GHz, and the maximum standing wave coefficient in the frequency band of 32.4 GHz to 32.8 GHz is 1.1969, corresponding to the frequency of 32.4 GHz. This shows that the Ka-band standing wave coefficient of the antenna of the present invention is less than 1.20 in the range of 32.4 GHz to 32.8 GHz.

[0076] Simulation 4: The Ka-band radiation pattern of the electromagnetic simulation model of the antenna of the embodiment of the present invention is simulated, and the result is as follows: Figure 7 .

[0077] from Figure 7 It can be seen that the minimum gain of the antenna in the angular range of -90° to -37° is 1.3732dB, and the corresponding angle is -90°; the minimum gain of the antenna in the angular range of 37° to 90° is 1.2431dB, and the corresponding angle is 90°, indicating that the gain of the antenna of the present invention in the end-fire direction of the Ka band in the angular range of -90° to -37° and the angular range of 37° to 90° is greater than 1.2dB.

[0078] The above simulation results verify that the dual-band end-fire antenna based on the disk-cone structure of the present invention has the advantages of a small standing wave coefficient, the ability to work simultaneously in two frequency bands, and high gain in a large angular range in the end-fire direction within the two frequency bands in which it operates, and has broad application prospects on airborne equipment platforms.

[0079] The above description is only a specific example of the present invention and does not constitute any limitation to the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, it is possible to make various modifications and changes in form and details without departing from the principles and structures of the present invention. For example, in addition to the stepped structure adopted in this embodiment, the structure of the matching body can also adopt an arc-shaped gradient structure and a conical structure. The multi-layer structure adopted by the antenna cover is not limited to three layers and the structural shape is not limited to a hemispherical surface. These modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A dual-band end-fire antenna based on a disc-cone structure, comprising a radome (1), an antenna body (2), and a duplexer (3), characterized in that: The antenna body (2) comprises a disc cone (21), a radiation oscillator (22), an insulator (23) and a matching body (24); The disk cone (21) comprises a cone body (211), a mounting flange (212) and an adjustment cavity (213), wherein the cone body (211) is located at the uppermost layer, the mounting flange (212) is located at the middle layer, and the adjustment cavity (213) is located at the lowermost layer; The radiation oscillator (22) is located inside the insulator (23), and the two are coaxial; The insulator (23) is located directly above the matching body (24), and the two are tightly fitted and both are located inside the disc cone (21).

2. The antenna according to claim 1, characterized in that The top diameter of the cone (211) is φ1, the bottom diameter is φ2, the height is h1, and the distance between the top of the cone and the top of the insulator (23) is h3. By adjusting these parameters, the antenna radiation direction is adjusted so that the angular domain range of the antenna end-fire direction meets the design requirements.

3. The antenna according to claim 1, characterized in that: The radiation vibrator (22) has a diameter of φ5 and a height of h4; The insulator (23) has a diameter of φ4 and a height of h5, and h5 is not less than the distance h3 between the top of the cone (211) and the top of the insulator (23), and is not greater than the height h4 of the radiation oscillator (22); By adjusting the parameters of the radiation oscillator (22) and the insulator (23) at the same time, the antenna can work in two frequency bands at the same time.

4. The antenna according to claim 1, characterized in that: The matching body (24) is made of metal and has any one of a stepped, arc-shaped, or conical structure, and is used to adjust the impedance matching between the disc cone (21), the radiation oscillator (22), and the insulator (23) so that the standing wave coefficient of the antenna meets the design requirements.

5. The antenna according to claim 1, characterized in that The adjustment cavity (213) has an inner cavity length L1, a width W1, a height h2, and a chamfer radius R1, wherein the height h2 is not less than the height of the matching body (24), and the inner cavity length L1 and the width W1 are determined by the transmission characteristics of the rectangular waveguide so that the adjustment cavity (213) can transmit electromagnetic waves in two working frequency bands of the antenna.

6. The antenna according to claim 1, characterized in that The antenna cover (1) adopts a broadband multi-layer structure and is tightly fixed to the upper surface of the mounting flange (212), so that the upper surface of the mounting flange and the lower surface of the antenna cover are closely fitted. The material used is a wave-transmitting material to ensure good wave transmission performance in the two working frequency bands of the antenna, thereby reducing the energy loss of the antenna radiating outwards.

7. The antenna according to claim 1, characterized in that: The duplexer (3) comprises three ports (31, 32, 33); the first port (31) is consistent in size with the inner cavity of the adjustment cavity (213) and is tightly connected so that the upper surface of the duplexer (3) is tightly fitted with the lower surface of the antenna body (2); the second port (32) and the third port (33) both adopt a rectangular structure, and their sizes are determined according to the transmission characteristics of the rectangular waveguide so that their transmission frequency meets the dual-band working requirements of the antenna.

8. The antenna according to claim 3, characterized in that: The radiating oscillator (22) and the insulator (23) are adjusted by establishing an antenna model in simulation software, setting the parameters of the radiating oscillator (22) and the insulator (23) as variables, and comparing the simulation results of the directional patterns of the two frequency bands of the antenna by changing these variables. When the simulation results of one set of parameters meet the design requirements, the parameter adjustment is completed.

9. The antenna according to claim 4, characterized in that: The matching body (24) realizes impedance matching between the adjusting disk cone (21), the radiating vibrator (22), and the insulator (23). An antenna model is established in simulation software, and the shape and specific size of the matching body (24) are set as variables. By changing these variables, the simulation result change image of the standing wave coefficient of the antenna is compared. When the simulation result of one set of variables meets the design requirements, the impedance matching is completed.

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