A miniaturized S-band omnidirectional conformal antenna

Abstract

The present invention proposes a miniaturized S-band omnidirectional conformal antenna, comprising an antenna cover, a metal back cavity with an opening at the upper end, and a radiator arranged in the metal back cavity; the antenna cover is installed at the opening position of the metal back cavity; the radiator adopts a disk-cone antenna structure, and four parasitic director arrays are evenly distributed on the periphery of the radiator, and the parasitic director array includes a short-circuit column with a guide metal sheet fixed at the upper end, and the lower end of the short-circuit column is fixed at the bottom of the metal back cavity. The four parasitic director arrays distributed on the periphery of the radiator of the present invention can, on the one hand, guide the upward directional pattern caused by the embedded metal cavity back to the azimuth plane, effectively improving the gain of the antenna under the premise of achieving broadband characteristics, and on the other hand, can add a resonance point at a low-frequency position, thereby compensating for the influence of the rapid narrowing of the impedance bandwidth of the disk-cone antenna caused by the reduction in the size of the metal back cavity on the broadband characteristics of the antenna, and effectively realizing miniaturization.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology and relates to a miniaturized S-band omnidirectional conformal antenna which can be applied to embedded installation of fast mobile equipment such as aircraft, vehicles or ships. Background Art

[0002] Antennas are the eyes and ears of wireless communication, and their performance directly determines the quality of wireless communication systems. Antennas on aircraft, vehicles, or ships that need to move quickly are often required to be embedded and have low profile characteristics. At the same time, the antennas are also required to have a compact space and miniaturization characteristics.

[0003] The frequency band of 2GHz-4GHz is defined as the S band, which is generally used in satellite and airborne radar communications. Omnidirectional antennas have received widespread attention due to their omnidirectional and uniform radiation in the azimuth plane, and their non-circularity in the azimuth plane is usually required to be less than 3dB. Commonly used S-band omnidirectional antennas are dipoles and monopoles, but the antenna profiles of these two forms are relatively high, generally 0.25λ. max For example, the commonly used airborne knife-shaped antenna has a relatively high profile height and protrudes from the surface of the aircraft, and is not applicable in some scenes with a lower profile.

[0004] The disc-cone antenna is widely used in low-profile omnidirectional conformal antennas because of its broadband characteristics, easy processing and low cost. The disc-cone antenna evolved from the biconical antenna. One of the cones of the biconical antenna is replaced by a metal disk to become a biconical antenna. When the disc-cone antenna is used to conform to the device, it is required to be embedded in a metal back cavity. This disc-cone antenna with a metal back cavity can easily meet the broadband characteristics without limiting the size. However, as the size of the back cavity gradually decreases, the bandwidth will decrease rapidly, and it will not be able to meet the broadband characteristics. It may even cause the radiation pattern to be distorted and lose the omnidirectional characteristics.

[0005] The disc-cone antenna with a back cavity will cause the antenna pattern to warp upward due to the presence of the back cavity, which will lead to a decrease in the gain in the azimuth plane. For example, the patent application with application publication number CN117691366A and titled "A high-gain airborne platform omnidirectional conformal antenna based on metamaterials" discloses an omnidirectional conformal antenna that uses metamaterials to achieve high gain. The invention has a low-profile antenna unit in the middle of a polygonal metal cavity, and artificial surface plasmons of metamaterials are radially arranged in the bottom surface of the polygonal metal cavity and around the periphery of the low-profile antenna unit. The polygonal antenna cover covers the polygonal metal cavity and is conformal to the metal bottom plate. This invention improves the azimuth plane gain of the omnidirectional antenna by confining electromagnetic waves to the propagation direction through the distribution of artificial surface plasmons. However, the introduction of radially distributed metamaterial metal columns results in a larger radial surface size. In addition, the omnidirectional conformal antenna has the defect of still low azimuth plane gain due to the upward warping of the radiation pattern caused by the embedded metal cavity during use. The low-frequency gain of this invention is only increased to -2.08dBi. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and propose a miniaturized S-band omnidirectional conformal antenna, aiming to improve the gain of the antenna and achieve miniaturization while achieving broadband characteristics.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present invention includes an antenna cover 1, a metal back cavity 2 with an opening at the upper end, and a radiator 3 arranged in the metal back cavity; the antenna cover 1 is installed at the opening position of the metal back cavity 2; the radiator 3 adopts a disk-cone antenna structure, and four parasitic guide arrays 5 are evenly distributed on the periphery of the radiator 3, and the parasitic guide array 5 includes a short-circuit column 52 with a guide metal sheet 51 fixed at the upper end, and the lower end of the short-circuit column 52 is fixed to the bottom of the metal back cavity 2.

[0008] As an optimization, the antenna cover 1 is made of a dielectric plate.

[0009] As an optimization, the metal back cavity 2 is provided with a flange at its opening to be connected to the conformal carrier.

[0010] As an optimization, the radiator 3 includes a metal disk 31 and a metal cone 32 which are arranged up and down and do not contact each other, and four short-circuit probes 33 fixed on the lower surface of the metal disk 31; the metal cone 32 is fixed on the bottom of the metal back cavity 2.

[0011] As an optimization, the central axis of the metal cone 32 coincides with the central axis of the metal disk 31 ; the four short-circuit probes 33 are distributed on a virtual circle with the central axis of the metal disk 31 as the center.

[0012] As an optimization, the antenna further includes a feeding probe 4 , which passes through the bottom of the metal back cavity 2 and the through hole set on the metal cone 32 , and its central conductor is connected to the metal disk 31 , and its outer conductor is connected to the metal back cavity 2 .

[0013] As an optimization, the guide metal sheet 51 is in a butterfly-shaped structure.

[0014] As an optimization, the guide metal sheet 51 adopts a butterfly structure with a rectangular shape and a V-shaped groove on one side facing the radiator 3 .

[0015] As an optimization, the guide metal sheet 51 adopts a butterfly structure with a rectangular shape and an arc-shaped groove on one side facing the radiator 3 .

[0016] As an optimization, the height of the radiator 3 is greater than the height of the parasitic director array 5 .

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The four parasitic director arrays distributed on the periphery of the radiator of the present invention can guide the upward radiation pattern caused by the embedded metal cavity back to the azimuth plane, effectively improving the gain of the antenna while achieving broadband characteristics. The simulation results show that the present invention can achieve a minimum gain of -1.78dBi in the azimuth plane radiation pattern within the range of 2.025GHz-2.475GHz.

[0019] 2. The four parasitic director arrays evenly distributed on the periphery of the radiator of the present invention can add a resonance point at a low-frequency position, thereby compensating for the influence of the rapid narrowing of the impedance bandwidth of the disc-cone antenna caused by the reduction in the size of the metal back cavity on the broadband characteristics of the antenna. The simulation results show that, under the premise of achieving broadband characteristics, the size of the metal back cavity can be reduced to 0.44 times the maximum wavelength λmax of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 for Figure 1 A partial top view of

[0022] Figure 3 The voltage standing wave ratio curve diagram of the present invention and the basic discone antenna without a parasitic director array;

[0023] Figure 4 The radiation pattern of the basic discone antenna of the present invention and the basic discone antenna without parasitic director at 2.025 GHz.

[0024] Figure 5The radiation pattern of the basic discone antenna of the present invention and the basic discone antenna without parasitic director at 2.125 GHz.

[0025] Figure 6 The radiation pattern of the basic discone antenna of the present invention and the basic discone antenna without parasitic director at 2.225 GHz.

[0026] Figure 7 The radiation pattern of the basic discone antenna of the present invention and the basic discone antenna without parasitic director at 2.325 GHz.

[0027] Figure 8 The radiation pattern of the basic discone antenna of the present invention and the basic discone antenna without parasitic director at 2.475 GHz. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] Embodiment 1: The guide metal sheet 51 of this embodiment adopts a butterfly structure with a V-shaped groove.

[0030] Reference Figure 1 and Figure 2 The present invention comprises an antenna cover 1, a metal back cavity 2 with an upper opening, a radiator 3 arranged in the metal back cavity, a feeding probe 4 and four parasitic guide arrays 5.

[0031] The antenna cover 1 is made of a dielectric sheet. Its thickness and dielectric constant can be selected according to the requirements. This embodiment uses a plate made of PEEK material with glass fiber, and its shape is an octagon. The antenna cover covers the upper part of the metal back cavity 2, can be completely embedded in the metal back cavity 2, and is flush with the upper surface of the metal back cavity 2, which can protect the antenna inside the cavity.

[0032] Metal back cavity 2, with an octagonal cavity inside, the minimum size of the octagonal cavity is only 0.44λ max , the depth is only 0.08λ max The opening position is provided with a flange connected to the carrier to be conformed, and its shape is determined by the device to be conformed. It can be arrow-shaped, regular hexagonal, circular or square.

[0033] The radiator 3 has a structure as follows Figure 2 The figure shows the basic structure of the disc-cone antenna, which is evolved from the biconical antenna. The cone of the biconical antenna is replaced by a metal disc, which can reduce the cross-sectional height of the antenna by half. The radiator 3 includes a metal disc 31 and a metal cone 32 arranged up and down and not touching each other with a spacing of 1mm, and four short-circuit probes 33 fixed on the lower surface of the metal disc 31; the metal cone 32 is fixed on the bottom of the metal back cavity 2. The diameter of the metal disc 31 is 0.27λmax The upper diameter of the metal cone 32 is 22 mm, and the lower diameter is 23 mm. Four short-circuit probes 33 are evenly distributed on a virtual circle with a radius of 16.5 mm and a perpendicular midline of the metal disk 31 as the center, and one end is connected to the bottom surface of the metal disk 31, and the other end is connected to the bottom plate of the metal back cavity 2. The shape is a cross. The introduction of the short-circuit probe can broaden the impedance bandwidth of the antenna, and the cross structure can increase the current path on the short-circuit probe and improve the impedance matching characteristics of the antenna.

[0034] The feeding probe 4 is an SMN connector for feeding high-frequency current into the antenna. Its inner conductor passes through the metal back cavity 2 and the metal cone 32 and is connected to the metal disk 31. The middle dielectric layer passes through the metal back cavity 2 and the metal cone 32 and is flush with the upper surface of the metal cone 32.

[0035] Parasite leads to array 5, such as Figure 2 , evenly distributed on a virtual circle with a radius of 25.8 mm and a perpendicular midline of the metal disk 31 as the center. It is composed of a butterfly-shaped guiding metal sheet 51 and a short-circuit post 52. The parasitic guiding array can introduce a new resonance point within the required frequency band, broaden the impedance bandwidth of the antenna, and achieve miniaturization of the antenna under broadband conditions. At the same time, it plays a certain guiding role on the antenna radiation pattern, significantly improving the gain of the low-frequency azimuth plane.

[0036] The working principle of the present invention is that a high-frequency current is fed in from a coaxial line feed 4 to excite the metal cone 32 and the metal disk 31, thereby exciting a high-frequency current on the metal cone 32 and the metal disk 31, and at the same time coupling a high-frequency current on the metal sheet 5, thereby introducing a new resonance point and broadening the impedance bandwidth of the antenna.

[0037] This embodiment constructs a small-size, low-profile broadband omnidirectional antenna unit, which can achieve miniaturization under the premise of broadband. By loading a parasitic guide metal sheet 5 around the disc cone antenna, a new resonance point is introduced inside the required frequency band, thereby widening the impedance bandwidth of the antenna. At the same time, the guide metal sheet 5 can play a guiding role at low frequencies, thereby improving the gain of the antenna at low frequencies.

[0038] Embodiment 2: The other structures of this embodiment are the same as those of Embodiment 1, and only the structure leading to the metal sheet 51 is adjusted. This embodiment adopts a butterfly structure with an arc-shaped groove.

[0039] The following is a further description of the technical effects of the present invention in conjunction with the simulation results:

[0040] 1. Experimental content:

[0041] Simulation 1, the voltage standing wave ratio of Example 1 and the basic discone antenna without parasitic director array are compared and simulated, and the results are as follows: Figure 4 shown.

[0042] Simulation 2, the radiation patterns of Example 1 and the basic discone antenna without parasitic director array at different frequencies are compared and simulated, and the results are as follows: Figure 5-8 shown.

[0043] 2. Experimental results analysis:

[0044] Reference Figure 3 It can be seen that the simple disc-cone antenna can only achieve a standing wave less than 2 in the range of 2.29-2.58 GHz, but after adding the parasitic director array, it can achieve a standing wave less than 2 in the range of 1.99-2.53 GHz. The addition of the parasitic director array introduces a new resonance point at low frequency, which improves the impedance bandwidth of the antenna.

[0045] Reference Figure 4 It can be seen that at 2.025GHz, the gain is significantly increased after adding the parasitic director array. After adding the director structure, the minimum gain of the antenna azimuth plane changes from -2.83dBi without the director structure to -1.63dBi, and the minimum gain increases by 1.2dBi.

[0046] Reference Figure 5 It can be seen that at 2.125GHz, the minimum gain of the antenna azimuth plane changes from -2.43dBi without the guide structure to -1.48dBi after adding the parasitic guide structure, and the minimum gain increases by 0.95dBi.

[0047] Reference Figure 6 It can be seen that at 2.225GHz, the minimum gain of the antenna azimuth plane changes from -2.03dBi without the guide structure to -1.45dBi after adding the parasitic guide structure, and the minimum gain increases by 0.58dBi.

[0048] Reference Figure 7 It can be seen that at 2325GHz, the minimum gain of the antenna azimuth plane changes from -1.68dBi without the guide structure to -1.41dBi after adding the parasitic guide structure, and the minimum gain increases by 0.27dBi.

[0049] Reference Figure 8 It can be seen that at 2475GHz, the minimum gain of the antenna azimuth plane changes from -1.86dBi without the guide structure to -1.78dBi after adding the parasitic guide structure, and the minimum gain increases by 0.08dBi.

[0050] from Figure 3-Figure 8 It can be seen that the present invention can be used in a minimum size of 0.44λ max , with a depth of 0.08λ maxInside the metal back cavity, the standing wave ratio is less than 2 within the 22% relative impedance bandwidth, and the omnidirectional radiation with a minimum azimuth gain greater than -1.78dBi in the frequency band of 2.025GHz-2.475GHz is achieved, and the out-of-roundness is less than 1dB.

Claims

1. A miniaturized S-band omnidirectional conformal antenna, comprising a radome (1), a metal back cavity (2) with an upper opening, and a radiator (3) arranged in the metal back cavity; the radome (1) is installed at the opening of the metal back cavity (2); the radiator (3) adopts a disc-cone antenna structure, characterized in that: The radiator (3) comprises a metal disk (31) and a metal cone (32) which are arranged up and down and do not contact each other, and four short-circuit probes (33) fixed on the lower surface of the metal disk (31); four parasitic guide arrays (5) are evenly distributed on the periphery thereof, and the parasitic guide array (5) comprises a short-circuit column (52) with a guide metal sheet (51) fixed at the upper end, and the lower end of the short-circuit column (52) is fixed to the bottom of the metal back cavity (2); the antenna also comprises a feeding probe (4), the feeding probe (4) passes through the bottom of the metal back cavity (2) and the through hole provided on the metal cone (32), the central conductor of the feeding probe (4) is connected to the metal disk (31), and the outer conductor is connected to the metal back cavity (2).

2. The antenna according to claim 1, characterized in that The antenna cover (1) is made of a dielectric plate.

3. The antenna according to claim 1, characterized in that The metal back cavity (2) is provided with a flange at its opening for connection with the carrier to be conformed.

4. The antenna according to claim 1, characterized in that: The metal cone (32) is fixed at the bottom of the metal back cavity (2).

5. The antenna according to claim 4, characterized in that: The central axis of the metal cone (32) coincides with the central axis of the metal disk (31); the four short-circuit probes (33) are distributed on a virtual circle with the central axis of the metal disk (31) as the center.

6. The antenna according to claim 1, characterized in that The guide metal sheet (51) is in the shape of a butterfly structure.

7. The antenna according to claim 6, characterized in that The guide metal sheet (51) has a butterfly structure with a rectangular shape and a V-shaped groove on one side facing the radiator (3).

8. The antenna according to claim 6, characterized in that The guide metal sheet (51) has a butterfly structure with a rectangular shape and a circular arc groove on one side facing the radiator (3).

9. The antenna according to claim 1, characterized in that: The radiator (3) has a height greater than the height of the parasitic director array (5).

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