Dual-polarized four-ridge horn antenna

Abstract

A dual-polarized four-ridge horn antenna disclosed by the present invention comprises a horn section and a waveguide section, the horn section comprises a horn shell and four ridges which are located in the horn shell and have the same structure, the four ridges form a cross-shaped structure, two ridges located on the same straight line are a pair, two feeder lines are configured in the waveguide section, and the waveguide section is provided with two feed lines. The two feeder lines respectively excite the pair of ridges at the same time, so that dual polarization is realized. The two pairs of ridges are excited at the same time to realize two polarization directions at the same time, and low-frequency cut-off wavelength is effectively reduced and high-frequency cut-off wavelength is improved by means of smooth transition of the ridge waveguides, so that the bandwidth of the horn antenna is widened.

Description

Technical Field

[0001] This invention belongs to the field of microwave communication technology, and more specifically, relates to a dual-polarized four-ridged horn antenna. Background Technology

[0002] The polarization state of electromagnetic waves is a crucial characteristic, characterized by the time-varying orientation of the electric field intensity vector at a given point in space. It is described by the trajectory of the endpoints of the electric field intensity vector over time, and includes three polarization types: linear, circular, and elliptical. In many cases, the polarization direction of electromagnetic waves plays a critical role in practical applications, being used in reflector antennas, imaging systems, sensors, and radomes. Traditional methods for controlling electromagnetic wave polarization include grating manipulation, dichroic crystal manipulation, and birefringence effect manipulation. Devices manufactured based on these principles are much larger than the wavelength of the electromagnetic waves operating in the specified frequency band, making their construction quite complex and costly. Metamaterials (artificial electromagnetic materials) are artificially constructed materials with special electromagnetic properties. These properties enable the control of electromagnetic wave transmission characteristics, including polarization.

[0003] Despite the numerous advantages of traditional horn antennas, they suffer from limitations in broadband operation. In recent years, to increase the frequency bandwidth of horn antennas, engineers have introduced corrugated wall and ridge transition techniques. Similar to ridge waveguides, the ridge segment in a horn antenna is used to lower the lower cutoff frequency of the dominant mode and broaden the single-mode bandwidth. Furthermore, this technique can be used in double-ridge or quad-ridge schemes to generate single-polarized and dual-polarized horn antennas. From microwave to optical frequencies, dual-polarized radiation modes are one of the most commonly used techniques to improve traffic processing capabilities. This technique is used for polarization diversity in radar and base station antennas, and many dual-polarized antennas such as patch antennas, horn antennas, and array antennas are now available. However, these devices operate at relatively low frequencies, have narrow bandwidths, and complex structures, which greatly limits their practical applications. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dual-polarized four-ridge horn antenna. By simultaneously exciting two pairs of ridges to achieve two polarization directions, and by utilizing the smooth transition of the ridge waveguide, the low-frequency cutoff wavelength is effectively reduced and the high-frequency cutoff wavelength is increased, thereby widening the bandwidth of the horn antenna.

[0005] To achieve the above-mentioned objective, the dual-polarized four-ridged horn antenna of the present invention includes a horn section and a waveguide section. The horn section includes a horn shell and four ridges with the same structure. The four ridges are located inside the horn shell and are placed opposite each other to form a cross structure. Two ridges located on the same straight line are a pair.

[0006] The waveguide section includes a ridge waveguide and two feed lines. The ridge waveguide connects four ridges, and the two feed lines simultaneously excite a pair of ridges to achieve dual polarization.

[0007] Furthermore, the ridge curve function is shown in the following equation:

[0008] ,

[0009] in, This represents the distance between the projection of a point on the ridge curve onto the bottom surface of the trumpet segment and the center of the cross structure. This indicates the height of a point on the ridge curve relative to the bottom surface of the trumpet segment. Represents the natural constant. This represents the rate of change of impedance of the ridge. , , For each preset constant, therein The value is the ridge spacing. Half of the ridge spacing The distance between the apex of the relative ridges. , Configure according to actual needs.

[0010] Furthermore, the impedance gradient rate of the ridge The range of values ​​is The minimum impedance gradient rate The calculation formula is:

[0011] ,

[0012] in, Indicates the length of the trumpet segment. This indicates the throat impedance of the horn section. This indicates the target aperture impedance of the horn section. The maximum permissible reflection coefficient;

[0013] Maximum impedance gradient rate The calculation formula is:

[0014] ,

[0015] in, This indicates the shortest wavelength in the operating frequency band.

[0016] Furthermore, the length of the trumpet segment The range of values ​​is ,in, This indicates the longest wavelength in the operating frequency band.

[0017] Furthermore, the maximum reflectance The calculation formula is:

[0018] ,

[0019] in, This indicates the maximum permissible voltage standing wave ratio (VSWR).

[0020] Furthermore, the intervertebral space of the ridges The range of values ​​is ,in Indicates the shortest wavelength in the operating frequency band. This indicates the length of the waveguide segment.

[0021] Furthermore, it also includes adding a reflective surface at the bottom of the waveguide section, which is connected to the upper surface of the ridge waveguide, thereby forming an inverted truncated cone-shaped reflective cavity inside the waveguide section.

[0022] The present invention relates to a dual-polarized four-ridged horn antenna, comprising a horn section and a waveguide section. The horn section includes a horn housing and four identical ridges located inside the horn housing. The four ridges form a cross structure, with two ridges on the same straight line forming a pair. Two feed lines are configured in the waveguide section, and the two feed lines simultaneously excite a pair of ridges, thereby achieving dual polarization.

[0023] The present invention has the following beneficial effects:

[0024] 1) This invention uses two feed lines to excite a pair of ridges respectively, so that the antenna has two polarization directions without changing its spatial position, and has a good voltage standing wave ratio;

[0025] 2) This invention utilizes the smooth transition of the ridge waveguide to effectively reduce the low-frequency cutoff wavelength and increase the high-frequency cutoff wavelength, thereby widening the bandwidth of the horn antenna;

[0026] 3) The present invention can further control the shape of the ridge curve, the size of the ridge spacing, and the length of the ridge waveguide to achieve the purpose of reducing high-order mode excitation and impedance matching.

[0027] 4) The present invention can further improve the electrical performance and bandwidth of the horn antenna by setting a reflecting surface at the bottom of the waveguide section.

[0028] 5) The basic structure of this invention is simple, and it can be made using 3D printing technology, making it easy to implement and process. Attached Figure Description

[0029] Figure 1 This is a structural diagram of a specific embodiment of the dual-polarized four-ridged horn antenna of the present invention;

[0030] Figure 2 This is a schematic diagram of the coordinate system for the ridge curve function in this embodiment;

[0031] Figure 3 This is the input matching curve diagram of the four-ridged horn antenna of the present invention in this embodiment;

[0032] Figure 4 This is the polarization pattern of the four-ridged horn antenna of the present invention at 160 GHz in this embodiment;

[0033] Figure 5 This is a voltage standing wave ratio (VSWR) curve of the four-ridged horn antenna of the present invention in this embodiment. Detailed Implementation

[0034] The specific embodiments of the present invention will now be described with reference to the accompanying drawings to enable those skilled in the art to better understand the invention. It should be particularly noted that in the following description, detailed descriptions of known functions and designs that might obscure the main content of the invention will be omitted here.

[0035] Example

[0036] Figure 1 This is a structural diagram illustrating a specific embodiment of the dual-polarized four-ridged horn antenna of the present invention. (See diagram below.) Figure 1 As shown, the dual-polarized quad-ridged horn antenna of the present invention includes a horn section 1 and a waveguide section 2. The components will be described in detail below.

[0037] The horn segment 1 includes a horn housing 11 and four identical ridges 12. The four ridges 12 are located inside the horn housing 11 and are placed opposite each other to form a cross structure. Two ridges 12 located on the same straight line are a pair.

[0038] The ridge curve needs to ensure that the characteristic impedance of the RF coaxial line smoothly transitions to free space along the ridge structure. To achieve this goal, a ridge curve function for each ridge 12 is designed in this embodiment. Figure 2 This is a schematic diagram of the coordinate system for the ridge curve function in this embodiment. For example... Figure 2 As shown, the expression for the ridge curve function in this embodiment is as follows:

[0039]

[0040] in, This represents the distance between the projection of a point on the ridge curve onto the bottom surface of trumpet segment 1 and the center of the cross structure. This indicates the height of a point on the ridge curve relative to the bottom surface of the trumpet segment. Represents the natural constant. This represents the impedance gradient rate of ridge 12. , , For each preset constant, therein The value is the ridge spacing. Half of the ridge spacing The distance between the apex of the relative ridges. , This embodiment is configured according to actual needs. =0.02, Can be determined , It was then obtained by solving the system of boundary condition equations.

[0041] Speaker segment 1 impedance from the throat A ridge structure is needed to transition to the target aperture impedance. Therefore, the impedance gradient rate can be determined based on the impedance transformation ratio and the target operating bandwidth of speaker segment 1 during design. The range of values The minimum impedance gradient rate can be obtained using Klofenstein's gradient theory (optimal exponential gradient). :

[0042] ,

[0043] in, This indicates the length of the speaker segment; the preferred value range in this embodiment is [value range missing]. , This indicates the longest wavelength in the operating frequency band. This indicates the throat impedance of the horn section. This indicates the target aperture impedance of the horn section. In this embodiment, the maximum allowable reflection coefficient is... The following formula is used to determine it:

[0044] ,

[0045] in, This indicates the maximum permissible voltage standing wave ratio (VSWR).

[0046] To avoid higher-order mode excitation and phase abrupt changes, the maximum impedance gradient rate is... The following formula is used for calculation:

[0047] ,

[0048] in, This indicates the shortest wavelength in the operating frequency band.

[0049] In practical applications, the impedance gradient rate can be... Perform a parameter scan within the range of values ​​and select an appropriate value.

[0050] In addition, in order to control the excitation mode of the horn antenna, a suitable ridge spacing needs to be set. This maximizes the transmission bandwidth of the horn antenna. The present invention has discovered through research that the ridge spacing... The wavelength can be determined based on the operating frequency of the horn antenna and the length of the waveguide section. Let the shortest wavelength of the operating frequency band be denoted as... ridge spacing Should meet Meanwhile, the length of the waveguide segment It also affects the intervertebral distance. Should meet Therefore, the ridge spacing The range of values ​​is Within this range, a ridge spacing is determined that ensures good impedance matching, suppresses higher-order mode excitation, and also considers the feasibility of fabrication. Excessively large ridge spacing will degrade the antenna's transmission mode and cause higher-order modes to appear prematurely. Within a certain range, a smaller ridge spacing is more beneficial to reducing the antenna's VSWR, but an excessively small ridge spacing will lead to mode deterioration, the appearance of higher-order modes, and other adverse effects, and will also have higher fabrication requirements and be more difficult to achieve.

[0051] Waveguide segment 2 includes a ridge waveguide 21 and two feed lines 22, wherein the ridge waveguide 21 connects four ridges 12, and the two feed lines 22 excite a pair of ridges 12 respectively to achieve dual polarization.

[0052] Compared to traditional rectangular waveguides, ridge waveguides lower the cutoff frequency, enabling lower-frequency impedance matching. The primary propagation mode, TE10, is cut off at a lower frequency, while higher-order modes such as TE20 and TE30 are suppressed, allowing the dominant mode to cut off at higher frequencies. Therefore, the operating bandwidth of a horn antenna with a ridge waveguide is significantly widened. Furthermore, the reduced equivalent impedance of the ridge waveguide makes impedance matching with commonly used 50Ω RF lines easier.

[0053] To achieve higher electrical performance and a wider operating bandwidth, this embodiment also improves waveguide segment 2 by abandoning the air cavity in the traditional waveguide structure. Instead, a reflecting surface 23 is added to the bottom of waveguide segment 2. The reflecting surface 23 is connected to the upper surface of the ridge waveguide 21, thereby forming an inverted frustum-shaped reflecting cavity inside waveguide segment 2. In this embodiment, the reflecting surface 23 is square. In practical applications, the side length of the reflecting surface 23 and its height from the bottom surface of waveguide segment 2 can be determined by parameter scanning.

[0054] To better illustrate the technical effects of this invention, a specific example is used to verify the invention through simulation. Table 1 is a list of parameters for the horn antenna used in this simulation verification.

[0055] parameter value impedance gradient rate 0.301 per mm intervertebral space d=0.11mm horn segment length 6.7mm Reflectance coefficient 0.231 Speaker height h=7.62mm Side length of the reflecting surface 0.25mm horn diameter 6.30mm Speaker wall thickness 0.2mm Ridge thickness 0.1mm The height of the power supply port 1 from the bottom surface 0.72mm The height of the power supply port 2 from the bottom surface 0.67mm inner conductor diameter of coaxial feeder 0.036mm outer conductor diameter of coaxial feeder 0.083mm Matching the upper section of the ladder 0.3mm Matching the lower step length 0.28mm Matching step height 0.5mm

[0056] Table 1

[0057] Figure 3 This is the input matching curve diagram of the four-ridged horn antenna of the present invention in this embodiment. Figure 3 As shown, in this embodiment, the input matching S11 curve of the four-ridged horn antenna of the present invention exhibits periodic fluctuations within the 140-220 GHz range, reflecting the broadband characteristics of the four-ridged horn antenna: Low frequency band (around 140-160 GHz): the curve drops from high to low values, indicating gradual optimization of the matching; Mid frequency band (around 160-180 GHz): a clear "valley" (optimal matching region) appears, indicating minimal reflection in this frequency band, with the lowest S11 value around -24 dB; High frequency band (around 180-220 GHz): the curve rises and then fluctuates. Within the broadband band, the values ​​are all below -10 dB.

[0058] Figure 4 This is the polarization pattern of the four-ridged horn antenna of the present invention at 160 GHz in this embodiment. Figure 4 As shown in the figure, the dual polarization of the four-ridged horn antenna in this embodiment is ±45° linear polarization. It can be seen from the figure that the -45° directivity is better and there is no obvious splitting phenomenon.

[0059] Figure 5 This is a voltage standing wave ratio (VSWR) curve of the four-ridged horn antenna of the present invention in this embodiment. Figure 5 As shown, in the 140GHz–220GHz range, the curves are smooth and almost all less than 1.6, which means that only 5.3% of the energy is reflected back. In the 155GHz–220GHz range, the VSWR is less than 1.5, which indicates that not only is each port well matched, but the isolation between the two ports is also very high. The energy of one port will not couple to the other port, ensuring the purity of the linear polarization.

[0060] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A dual-polarized four-ridged horn antenna, comprising a horn section and a waveguide section, characterized in that, The horn section includes a horn shell and four identical ridges. The four ridges are located inside the horn shell and are placed opposite each other to form a cross structure. Two ridges located on the same straight line are a pair. The waveguide section includes a ridge waveguide and two feed lines. The ridge waveguide connects four ridges, and the two feed lines simultaneously excite a pair of ridges to achieve dual polarization.

2. The dual-polarized four-ridged horn antenna according to claim 1, characterized in that, The ridge curve function is shown in the following equation: ， in, This represents the distance between the projection of a point on the ridge curve onto the bottom surface of the trumpet segment and the center of the cross structure. This indicates the height of a point on the ridge curve relative to the bottom surface of the trumpet segment. Represents the natural constant. This represents the rate of change of impedance of the ridge. , , For each preset constant, therein The value is the ridge spacing. Half of the ridge spacing The distance between the apex of the relative ridges. , Configure according to actual needs.

3. The dual-polarized four-ridged horn antenna according to claim 1, characterized in that, The impedance gradient rate of the ridge The range of values ​​is The minimum impedance gradient rate The calculation formula is: ， in, Indicates the length of the trumpet segment. This indicates the throat impedance of the horn section. This indicates the target aperture impedance of the horn section. The maximum permissible reflection coefficient; Maximum impedance gradient rate The calculation formula is: ， in, This indicates the shortest wavelength in the operating frequency band.

4. The dual-polarized four-ridged horn antenna according to claim 3, characterized in that, The length of the horn segment The range of values ​​is ,in, This indicates the longest wavelength in the operating frequency band.

5. The dual-polarized four-ridged horn antenna according to claim 3, characterized in that, The maximum reflectance The calculation formula is: ， in, This indicates the maximum permissible voltage standing wave ratio (VSWR).

6. The dual-polarized four-ridged horn antenna according to claim 1, characterized in that, The ridge spacing The range of values ​​is ,in Indicates the shortest wavelength in the operating frequency band. This indicates the length of the waveguide segment.

7. The dual-polarized four-ridged horn antenna according to claim 1, characterized in that, It also includes adding a reflecting surface at the bottom of the waveguide section, which is connected to the upper surface of the ridge waveguide, thereby forming an inverted truncated cone-shaped reflecting cavity inside the waveguide section.

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