Conformal looped metal cavity omni-directional antenna based on aperture radiation

Abstract

The application discloses a conformal annular metal cavity omnidirectional antenna based on slot radiation and belongs to the technical field of antennas, which comprises an annular metal cavity for containing a columnar carrier; two rectangular slots are symmetrically formed on the side wall of the annular metal cavity; two coaxial feeding structures; and a conical metal cavity is coaxially arranged on the periphery of the annular metal cavity and used for balancing the electric field phases of the two rectangular slots. After the two rectangular slots are excited, the directly radiated electric field in the horizontal plane has the problem of uneven electric field distribution, which causes the radiation recess to exist unevenly in the horizontal plane pattern. By loading the conical metal cavity around the annular metal cavity, the introduction of the conical metal cavity metal balances the rectangular slot and the radiated horizontal plane electric field, improves the electric field distribution, and improves the omnidirectional characteristics and horizontal plane gain of the antenna.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a conformal annular metal cavity omnidirectional antenna based on slot radiation. Background Technology

[0002] With the development of wireless communication technology, the functions of high-speed flight vehicle systems are becoming increasingly complex, and the requirements for them are also becoming more stringent. Antennas are a crucial component of flight vehicle systems, and their structure is closely related to the performance of the flight vehicle. Currently, various antennas are installed in flight vehicles, such as navigation, communication, radar, and altimeter antennas. For the communication system of a flight vehicle, to prevent the receiving antenna from being affected by the flight vehicle's motion attitude and thus avoiding signal loss, the designed antenna must meet omnidirectional characteristics. For some cylindrical flight vehicles, it is difficult to achieve omnidirectional radiation characteristics by mounting a single antenna on the side of the vehicle. The current mainstream method is to use conformal array antennas loaded on the side of the vehicle or to install an omnidirectional antenna on the head of the vehicle. Side-loaded conformal array antennas often involve a large number of elements and complex feeding networks. This often leads to design difficulties and increased manufacturing costs. For top-mounted omnidirectional antennas, their radiation pattern is often affected by the metal structure of the vehicle itself, which greatly limits the antenna installation due to the shape of the vehicle's head. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of the prior art and provide a conformal annular metal cavity omnidirectional antenna based on slot radiation.

[0004] The objective of this invention is achieved through the following technical solution: a conformal annular metallic cavity omnidirectional antenna based on slot radiation, the antenna comprising:

[0005] An annular metal cavity with a cylindrical cavity at its center for accommodating a cylindrical carrier; a first rectangular slit and a second rectangular slit are symmetrically formed on the sidewalls of the annular metal cavity;

[0006] The first coaxial feed structure and the second coaxial feed structure are located inside the annular metal cavity and are used to excite the two rectangular gaps to generate radiation.

[0007] A conical metal cavity is coaxially fitted around the annular metal cavity. The conical metal cavity is used to balance the phase of the electric field radiated from the two rectangular slits.

[0008] In one example, an annular gap is formed between the conical metal cavity and the annular metal cavity.

[0009] In one example, the annular gap exists between the upper portion of the conical metal cavity and the annular metal cavity.

[0010] In one example, the annular metal cavity is further provided with a plurality of metal short-circuit posts, which penetrate the upper and lower surfaces of the annular metal cavity.

[0011] In one example, the metal short-circuit posts are circumferentially and uniformly distributed on the annular metal cavity.

[0012] In one example, the first and second coaxial feed structures employ a stepped feed structure.

[0013] It should be further noted that the technical features corresponding to the above antenna examples can be combined or replaced to form new technical solutions.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1. Radiation is achieved by directly exciting the rectangular slots on both sides of the annular metal cavity using two coaxial feed structures. The center of the annular metal cavity is hollowed out to reserve a cylindrical space, providing installation space for the cylindrical carrier and enabling conformal installation with the side of the cylindrical carrier. This design makes the carrier's metal structure a component of the antenna system rather than an interference source, thus fundamentally avoiding the adverse effects of the carrier on the radiation pattern.

[0016] Furthermore, the electric field directly radiated by the two rectangular slots after excitation will have an uneven electric field distribution on the horizontal plane, resulting in an uneven radiation pattern and radiation dips on the horizontal plane, which affects the omnidirectional radiation characteristics of the horizontal plane. This application loads a conical metal cavity around the annular metal cavity. The introduction of the metal in the conical metal cavity balances the electric field of the rectangular slots and the radiated horizontal plane, improves the electric field distribution, and enhances the omnidirectional characteristics and horizontal plane gain of the antenna.

[0017] 2. By forming a circular slot between the conical metal cavity and the annular metal cavity, the electric field of the conical metal cavity can be balanced and optimized, and radiated uniformly into the horizontal plane in a phase-independent mode. This directly and significantly improves the horizontal non-circularity of the antenna, transforming its radiation pattern from a concave shape to an ideal "O" shape. Furthermore, placing the circular slot between the upper part of the conical metal cavity and the annular metal cavity allows for the formation of a low-profile, top-radiating integrated cavity module.

[0018] 3. By loading a metal short-circuit post, an inductive load is introduced. The resonant frequency of the antenna can be adjusted by changing the radius of the metal short-circuit post, thus achieving flexible design of the operating frequency.

[0019] 4. Impedance matching can be achieved through a stepped feeding structure, thereby expanding the antenna bandwidth. Attached Figure Description

[0020] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The accompanying drawings are provided to provide a further understanding of the present application and constitute a part of the present application. The same reference numerals are used in these drawings to denote the same or similar parts. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application.

[0021] Figure 1 This is a top view of an antenna provided as an example of the present invention;

[0022] Figure 2 This is a schematic diagram of an antenna structure provided as an example of the present invention;

[0023] Figure 3 A comparison diagram of one-dimensional horizontal plane gain curves with and without the antenna loaded with a conical metal cavity, provided as an example of the present invention;

[0024] Figure 4 A comparison diagram of two-dimensional horizontal plane gain curves with and without the antenna loaded and conical metal cavity provided as an example of the present invention;

[0025] Figure 5 This is a diagram showing the radiated electric field distribution of an unloaded conical metal cavity, as provided in an example of the present invention.

[0026] Figure 6 This is a diagram showing the radiated electric field distribution of a loaded conical metal cavity, as provided in an example of the present invention.

[0027] Figure 7 Antenna |S provided as an example of the present invention 11 |Graph;

[0028] Figure 8 This is an example of the antenna's one-dimensional horizontal plane gain curve provided by the present invention;

[0029] Figure 9 This is a two-dimensional horizontal plane gain curve of an antenna provided as an example of the present invention;

[0030] Figure 10 This is a two-dimensional vertical plane gain curve of an antenna provided as an example of the present invention.

[0031] In the figure: 1-First coaxial power supply structure; 2-Second coaxial power supply structure; 3-Metal short-circuit post; 4-Annular metal cavity; 5-Conical metal cavity; 6-Annular gap; 7-First rectangular gap; 8-Second rectangular gap. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] In one example, a conformal annular metallic cavity omnidirectional antenna based on slot radiation is described, which includes an annular metallic cavity, two coaxial feed structures, and a conical metallic cavity.

[0035] Among them, such as Figures 1-2 As shown, the annular metal cavity 4 is the core radiating structure of the entire antenna. The annular metal cavity is ring-shaped with a central cylindrical cavity to accommodate a cylindrical carrier, allowing for conformal mounting with the side of the cylindrical carrier. Optionally, the inner radius of the annular metal cavity is designed to be 70mm to directly accommodate a cylindrical carrier with a diameter of 140mm; the outer radius of the annular metal cavity is 85mm, and the height is 15mm, forming a low-profile annular resonant cavity.

[0036] Furthermore, such as Figures 1-2 As shown, two rectangular slots 7 and 8 of the same length are symmetrically opened on both sides of the annular metal cavity. The radiation from the first and second rectangular slots can be equivalent to an electric dipole, which can initially realize the omnidirectional radiation characteristics of the antenna. Preferably, two rectangular slots with a length of 260 mm and a width of 3 mm are loaded on both sides of the annular metal cavity.

[0037] Furthermore, such as Figures 1-2 As shown, a first coaxial feed structure 1 and a second coaxial feed structure 2 are provided on both sides of the annular metal cavity near the center point of the rectangular slots. The coaxial feed structures excite the two rectangular slots for radiation. Preferably, the coaxial feed structures adopt a stepped feed structure, with the lower half of the conductor having a radius of 0.5 mm and a height of 13 mm; the upper half has a radius increased to 1.5 mm and a height of 2 mm. This dual-feed direct excitation method avoids a complex feed network and simplifies the design.

[0038] Furthermore, such as Figures 1-2 As shown, a conical metal cavity 5 is loaded around the annular metal cavity 4. The introduction of the conical metal cavity 5 can balance the electric field radiated by the rectangular slot antenna, improve the phase of the horizontal electric field radiated by the two rectangular slots, and reduce the cancellation of the electric field between the horizontal planes.

[0039] The antenna in this example has a hollowed-out ring-shaped metal antenna at its center, with an overall lateral dimension of 178mm and a height of 15mm. The antenna is made entirely of metal, is hollow inside, has a simple structure, is lightweight, and can be nested into the side of the cylindrical flight vehicle without affecting its structural strength or aerodynamic characteristics.

[0040] In one example, such as Figures 1-2 As shown, an annular gap 6 is formed between the conical metal cavity 5 and the annular metal cavity 4. Preferably, the annular gap 6 exists between the upper part of the conical metal cavity 5 and the annular metal cavity 4. Specifically, the radius of the upper part of the conical metal cavity is smaller than the radius of the lower part of the conical metal cavity, and the inner radius of the upper part of the conical metal cavity is larger than the outer radius of the annular metal cavity, so that an annular gap is formed between the upper part of the conical metal cavity and the annular metal cavity. At this time, a cavity is formed between the lower part of the conical metal cavity and the annular metal cavity. Preferably, the upper surface radius of the conical metal cavity is 86 mm, the lower surface radius is 89 mm, and the height is 15 mm. The upper surface of the conical metal cavity forms an annular gap with a width of 1 mm with the upper side of the annular metal cavity. It should be noted that in order to achieve conformal installation of the antenna and the carrier, the conical metal cavity and the carrier are connected by a fixing structure (such as a flange).

[0041] This example demonstrates how forming a circular gap between a conical metal cavity and an annular metal cavity can balance and optimize the electric field of the conical metal cavity, allowing it to radiate uniformly onto the horizontal plane in a phase-in-phase mode. This directly and significantly improves the horizontal non-circularity of the antenna, transforming its radiation pattern from a concave shape to an ideal "O" shape.

[0042] In one example, such as Figures 1-2 As shown, the annular metal cavity is further provided with multiple metal short-circuit posts 3. In this example, 12 metal short-circuit posts 3 are preferably provided, and the metal short-circuit posts 3 penetrate the upper and lower surfaces of the annular metal cavity. Optionally, the radius of the metal short-circuit posts is 1.1 mm and the height is 15 mm. Preferably, the metal short-circuit posts are evenly distributed circumferentially on the annular metal cavity, and the resonant frequency of the antenna can be adjusted by adjusting the radius of the metal short-circuit posts.

[0043] Combining the above examples, a preferred embodiment of the present invention is obtained, in which the omnidirectional antenna includes a ring-shaped metal cavity, a coaxial feed structure, and a conical metal cavity. Specifically, two first rectangular slots and a second rectangular slot of equal length are loaded on both sides of the ring-shaped metal cavity. The two slots are excited by coaxial feed near the center point of the rectangular slots on both sides of the ring-shaped metal cavity for radiation. The coaxial excitation posts use a stepped feed to achieve impedance matching and further extend the antenna bandwidth. Twelve metal short-circuit posts are loaded inside the ring-shaped metal cavity to adjust the resonant frequency of the antenna. A conical metal cavity is loaded around the ring-shaped metal cavity, and the upper part of the conical metal cavity forms a circular annular slot with the ring-shaped metal cavity. The introduction of the metal cavity can balance the electric field radiated by the rectangular slot antenna, improve the phase of the horizontal electric field radiated by the two rectangular slots, reduce the electric field cancellation between the horizontal planes, and improve the electric field distribution. The conical metal cavity and the ring-shaped metal cavity form a new circular annular slot, which directly participates in the antenna radiation, that is, uniform radiation is achieved through the circular annular slot, further improving the omnidirectional non-circularity characteristics of the antenna.

[0044] To illustrate the improved electric field distribution effect of the conical metal cavity in this application, simulation results of the horizontal plane gain curves of the conical metal cavity with and without loading on the outer side are presented when the antenna operates at 1.43 GHz. Figures 3-4 As shown. The effect of the conical metal cavity on the overall electric field distribution of the antenna is as follows. Figures 5-6 As shown, the electric field is significantly improved and the electric field distribution is more uniform after the introduction of the conical metal cavity.

[0045] Simulations were performed on a preferred example antenna of the present invention. A metal cylindrical carrier with a radius of 70 mm and a height of 90 mm was embedded in the center of the antenna for joint simulation. Antenna |S 11 Simulation results are as follows Figure 7 As shown, |S 11 The frequency band below -10dB is 1.41GHz-1.46GHz, and the one-dimensional graph of the horizontal plane gain is shown below. Figure 8 As shown, its horizontal gain is greater than -3.75 dB across the entire frequency band. The two-dimensional plots of the antenna's horizontal and vertical gain are shown below. Figure 9 and Figure 10 As shown in the figure, the antenna of the present invention presents an "O" shape on the horizontal plane and an inverted "8" shape on the vertical plane throughout the entire frequency band. Therefore, the antenna of the present invention has good omnidirectional radiation characteristics throughout the entire frequency band and is suitable for cylindrical flight carrier systems.

[0046] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A conformal annular metallic cavity omnidirectional antenna based on slot radiation, characterized in that, include: An annular metal cavity with a cylindrical cavity at its center for accommodating a cylindrical carrier; The annular metal cavity has a first rectangular slit and a second rectangular slit symmetrically opened on its sidewall; The first coaxial feed structure and the second coaxial feed structure are located inside the annular metal cavity and are used to excite the two rectangular gaps to generate radiation. A conical metal cavity is coaxially fitted around the annular metal cavity. The conical metal cavity is used to balance the phase of the electric field radiated by the two rectangular slits. A circular gap is formed between the conical metal cavity and the annular metal cavity.

2. The conformal annular metallic cavity omnidirectional antenna based on slot radiation according to claim 1, characterized in that, The annular gap exists between the upper part of the conical metal cavity and the annular metal cavity.

3. The conformal annular metallic cavity omnidirectional antenna based on slot radiation according to claim 1, characterized in that, The annular metal cavity is also provided with a plurality of metal short-circuit posts, which penetrate the upper and lower surfaces of the annular metal cavity.

4. The conformal annular metallic cavity omnidirectional antenna based on slot radiation according to claim 3, characterized in that, The metal short-circuit posts are evenly distributed circumferentially on the annular metal cavity.

5. The conformal annular metallic cavity omnidirectional antenna based on slot radiation according to claim 1, characterized in that, The first and second coaxial power supply structures adopt a stepped power supply structure.

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