Unidirectional broadband spiral slot antenna based on rectangular coaxial waveguide and manufacturing method

Abstract

The invention discloses a rectangular coaxial waveguide-based unidirectional broadband spiral slot antenna and a manufacturing method thereof, and relates to the technical field of broadband unidirectional circularly polarized antenna design. The antenna structure is based on a rectangular coaxial waveguide, the broadband performance of the antenna is realized by using the broadband-pass characteristic of the rectangular coaxial waveguide, and meanwhile, the sizes of inner and outer conductors of the coaxial waveguide are reasonably adjusted, so that the characteristic impedance of the waveguide approaches 50 omega. According to the invention, the use of a balun and a matching network is effectively avoided, and the antenna structure is greatly simplified.

Description

Technical Field

[0001] This invention relates to the field of broadband unidirectional circularly polarized antenna design technology, specifically to a unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide and its manufacturing method. This invention achieves unidirectional broadband circularly polarized radiation performance by etching spiral slots into a rectangular coaxial waveguide. Furthermore, since the antenna input impedance can be optimized through the inner and outer conductor dimensions of the rectangular coaxial waveguide, no additional balun or feed network is required, resulting in a simple and reliable structure. Background Technology

[0002] The statements in this section are provided only as background information in connection with this disclosure and may not constitute prior art.

[0003] Circularly polarized antennas are widely used in satellite communications, military, and commercial fields due to their advantages such as reduced polarization mismatch and suppression of multipath crosstalk. Furthermore, broadband characteristics are essential for achieving high system versatility and low cost. Therefore, various types of broadband circularly polarized antennas have been proposed, such as helical antennas, irregularly shaped slot antennas, eccentrically fed dipoles, artificial magnetic conductors (AMCs), and improved cross dipoles.

[0004] Furthermore, for satellite communication systems and some applications requiring high security, in addition to broadband antenna characteristics, unidirectional radiation performance is also required. A common method to achieve unidirectional radiation is to add a reflector at a distance of one-quarter of the wavelength below the radiator; however, achieving unidirectional radiation using a traditional reflector results in a high profile. Therefore, subsequent researchers used a circular, high-impedance surface to replace the traditional reflector ground plane, effectively reducing the antenna's profile height; however, this also correspondingly increased the overall complexity of the antenna.

[0005] For highly integrated communication systems, a simple feeding structure is another factor worth considering. Circularly polarized antennas are generally divided into single-fed and dual-fed feeding structures. While single-fed circularly polarized antennas have a simple feeding structure, their bandwidth is usually relatively narrow. Dual-fed circularly polarized antennas, although offering extended bandwidth, increase cost and size due to the use of power dividers or couplers, thus increasing antenna complexity and hindering its application. Therefore, designing a simple unidirectional broadband circularly polarized antenna is a problem that antenna researchers urgently need to solve. Some researchers have used coplanar waveguides to feed Archimedean spiral antennas, avoiding the use of additional baluns and matching networks, while still achieving bidirectional radiation performance.

[0006] Therefore, this invention proposes a novel broadband unidirectional circularly polarized antenna structure. This structure is based on a rectangular coaxial waveguide, utilizing the broadband pass-through characteristics of the rectangular coaxial waveguide to achieve the antenna's broadband performance. Simultaneously, the dimensions of the inner and outer conductors of the coaxial waveguide are rationally adjusted to make the waveguide's characteristic impedance approach 50 Ω. This effectively avoids the use of baluns and matching networks, greatly simplifying the antenna structure. Summary of the Invention

[0007] The purpose of this invention is to achieve unidirectional broadband circularly polarized radiation performance based on a rectangular coaxial waveguide. Addressing the difficulty in reconciling unidirectional and broadband radiation, this invention proposes a unidirectional broadband helical slot antenna based on a rectangular coaxial waveguide and its manufacturing method. It abandons the traditional ground-floor introduction method, using a rectangular coaxial waveguide as a substrate and etching helical slots on its narrow sides to radiate electromagnetic waves. This method optimizes the antenna input impedance by adjusting the dimensions of the inner and outer conductors, avoiding the introduction of additional baluns and feed networks, ultimately achieving broadband unidirectional circularly polarized radiation performance with a simple structure.

[0008] The technical solution of the present invention is as follows: A unidirectional broadband helical slot antenna based on a rectangular coaxial waveguide includes: a rectangular coaxial waveguide, a helical slot, and an absorption resistor; The rectangular coaxial waveguide includes an inner conductor and an outer conductor, and the rectangular coaxial waveguide is configured as a traveling wave structure. The helical slot is etched on the upper surface of the outer conductor of the rectangular coaxial waveguide for radiating electromagnetic waves; The absorption resistor is connected to the end of the rectangular coaxial waveguide and is used to absorb the reflected current at the end. The inner port of the rectangular coaxial waveguide is directly fed through a coaxial interface.

[0009] Furthermore, the spiral gap is an Archimedean spiral gap, and its trajectory satisfies Archimedean equation:

[0010] in: The distance from the center trajectory of the gap to the origin of the coordinate system; This is the minimum inner diameter of the spiral; The spiral growth rate; The spiral angle.

[0011] Furthermore, the rectangular coaxial waveguides are arranged according to the Archimedes spiral equation; the outer conductor includes a metal conductor plane added to the upper surface of the rectangular coaxial waveguides, and the spiral slot is etched on the upper surface of the metal conductor.

[0012] Furthermore, the resistance of the absorption resistor is 100Ω, and the absorption resistor is welded to the outer port of the rectangular coaxial waveguide.

[0013] Furthermore, the outer conductor width of the rectangular coaxial waveguide With the width of the inner conductor The ratio of the outer conductor thickness to the outer conductor thickness. With inner conductor thickness The ratios are all ; By adjusting the ratio and the width of the inner conductor This makes the input impedance of the rectangular coaxial waveguide approach 50Ω.

[0014] Furthermore, the spiral growth rate .

[0015] This invention also proposes a method for manufacturing a unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide, comprising the following steps: Step S1: Based on the higher-order mode TE of the coaxial waveguide m1 Theoretical formulas are used to calculate the initial dimensions of the inner and outer conductors of the rectangular coaxial waveguide corresponding to the target frequency; Step S2: Calculate the minimum inner diameter of the spiral slot based on the target frequency bandwidth. and helix outer diameter ; Step S3: Based on the highest frequency wavelength of the operating bandwidth and the lowest frequency wavelength Determine the initial number of turns of the spiral slot. ; Step S4: Set the inner and outer conductor dimensions, inner and outer diameter dimensions, and number of turns of the spiral for the rectangular coaxial waveguide according to the previously calculated theoretical values, and then wrap it with an Archimedean spiral to realize the overall structural base of the antenna; Step S5: On the outer conductor surface of the rectangular coaxial waveguide, the spiral slot is etched along a trajectory that satisfies the Archimedes spiral equation; the spiral slot cuts the current on the inner wall of the waveguide and forms an excitation electric field on both sides of the slot to achieve electromagnetic radiation performance; Step S6: The inner port of the rectangular coaxial waveguide is directly fed through a coaxial interface, without the need for additional baluns and matching networks, so as to achieve coaxial excitation with a simple structure. Step S7: Connect the absorption resistor to the end of the rectangular coaxial waveguide to absorb the reflected current at the end of the waveguide, so as to ensure the traveling wave characteristics of the electromagnetic field in the rectangular coaxial waveguide. Step S8: Adjust the inner and outer conductor dimensions of the rectangular coaxial waveguide to optimize the lowest and highest radiation frequencies of the antenna so that it covers the target operating bandwidth; and combine the reflection coefficient performance to comprehensively determine the final inner and outer conductor dimensions, absorption resistance value, and number of turns of the helical slot.

[0016] Furthermore, the higher-order mode TE in step S1 m1 The theoretical formula is as follows:

[0017] in, The operating cutoff wavelength, Where is the radius of the inner conductor. Let be the radius of the outer conductor.

[0018] Further, step S2 includes: , .

[0019] Further, step S3 includes: .

[0020] Compared with existing technologies, the advantages of this invention are: To address the inherent contradiction between unidirectional and broadband radiation performance, existing technologies often involve adding reflective backplates and artificial metamaterial structures, which almost exclusively solve the problem in the vertical dimension. This inevitably leads to drawbacks such as higher cross-sectional dimensions and increased antenna complexity. This invention transforms the unidirectional performance into a lateral solution by using a helical waveguide, avoiding the introduction of vertical structures and effectively mitigating the resonant characteristics of the reflector, thus laying the foundation for broadening the bandwidth of the unidirectional radiation antenna.

[0021] Specifically, an Archimedean spiral slot antenna based on an ideal coaxial waveguide is proposed. This antenna achieves radiation by creating an Archimedean spiral slot along the narrow side of the ideal coaxial waveguide. Because of the direct use of the ideal coaxial waveguide, this structure can directly achieve directional radiation, avoiding the need for a reflector floor and thus solving the drawbacks of narrow bandwidth and high profile associated with floor reflectors. Simultaneously, the inherent wideband passivity of the ideal coaxial waveguide creates conditions for broadband radiation. Furthermore, since the impedance of the ideal coaxial waveguide can be controlled by adjusting the dimensions of the inner and outer conductors, in practical design, the input impedance of the waveguide can be optimized through appropriate inner and outer conductor dimensions. This allows the antenna to be directly fed through a coaxial interface at the inner port of the waveguide without the need for additional baluns and matching networks, significantly reducing the antenna's structural size and complexity.

[0022] In summary, the helical slot antenna proposed in this invention avoids the use of reflectors by employing a coaxial waveguide, thus broadening the bandwidth and simplifying the antenna structure. The use of an absorption resistor absorbs reflected current at the port end, further optimizing the antenna's impedance performance. By adjusting the impedance of the inner and outer conductors, a direct coaxial interface feeding method is achieved, avoiding the need for additional baluns and feeding networks, simplifying the antenna's feeding structure, and ultimately realizing the design goal of a unidirectional broadband circularly polarized antenna with a simple structure. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0024] Figure 1 This is a top view of the antenna structure; Figure 2 This is a side view of the antenna structure. Figure 3 This is a schematic diagram of the antenna's internal port interface; Figure 4 Gain and axial ratio performance as a function of parameter w s A diagram illustrating the changes; Figure 5 This is a schematic diagram showing how the gain and axial ratio performance vary with parameters w2 and k; Figure 6 This is a schematic diagram showing how the gain and axial ratio performance vary with parameter l2. Figure 7 This is a simulation diagram of the final antenna reflection coefficient and axial ratio performance; Figure 8 This is a simulation diagram of the final antenna line-of-sight gain performance; Figure 9 The final antenna yoz plane normalized radiation pattern at 2.5 GHz; Figure 10 The final antenna yoz plane normalized radiation pattern at 4GHz; Figure 11 The final antenna xoz plane normalized radiation pattern at 2.5 GHz; Figure 12 The final normalized radiation pattern of the antenna xoz plane at 4GHz. Detailed Implementation

[0025] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0026] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0027] Example 1 This embodiment achieves unidirectional broadband circularly polarized radiation performance based on a rectangular coaxial waveguide. Addressing the incompatibility between unidirectional and broadband radiation, it abandons the traditional floor-mounted approach and uses a rectangular coaxial waveguide as a substrate, etching spiral slots on its narrow side (i.e., the upper surface of the outer conductor) to radiate electromagnetic waves. A traveling-wave structure is employed, utilizing the broadband pass-through characteristics of the coaxial waveguide to lay the foundation for broadband radiation performance. Simultaneously, a 100 Ω absorption resistor is added at the waveguide end to absorb reflected current, further widening the bandwidth. To achieve circularly polarized radiation characteristics, the rectangular coaxial waveguide and waveguide slots satisfy Archimedes' equations to form a non-frequency-variable circularly polarized radiation structure. By adjusting the dimensions of the inner and outer conductors of the coaxial waveguide, the input impedance of the waveguide is brought close to 50 Ω, allowing the antenna to be directly fed through the coaxial interface, thus achieving broadband unidirectional circularly polarized radiation performance with a simple structure.

[0028] Please see Figure 1 and Figure 2 In this embodiment, specifically, a unidirectional broadband helical slot antenna based on a rectangular coaxial waveguide includes: a rectangular coaxial waveguide, a helical slot, and an absorption resistor; The rectangular coaxial waveguide includes an inner conductor and an outer conductor, and the rectangular coaxial waveguide is configured as a traveling wave structure. The helical slot is etched on the upper surface of the outer conductor of the rectangular coaxial waveguide for radiating electromagnetic waves; The absorption resistor is connected to the end of the rectangular coaxial waveguide and is used to absorb the reflected current at the end. The inner port of the rectangular coaxial waveguide is directly fed through a coaxial interface.

[0029] In this embodiment, specifically, the spiral gap is an Archimedes spiral gap, and its trajectory satisfies Archimedes' equation:

[0030] in: The distance from the center trajectory of the gap to the origin of the coordinate system; This is the minimum inner diameter of the spiral; The spiral growth rate; The spiral angle.

[0031] In this embodiment, specifically, the rectangular coaxial waveguides are arranged according to the Archimedes spiral equation; the outer conductor includes a metal conductor plane added to the upper surface of the rectangular coaxial waveguide, and the spiral slot is etched on the upper surface of the metal conductor.

[0032] In this embodiment, specifically, the resistance of the absorption resistor is 100Ω, and the absorption resistor is welded to the outer port of the rectangular coaxial waveguide.

[0033] In this embodiment, specifically, the outer conductor width of the rectangular coaxial waveguide With the width of the inner conductor The ratio of the outer conductor thickness to the outer conductor thickness. With inner conductor thickness The ratios are all ; By adjusting the ratio and the width of the inner conductor This makes the input impedance of the rectangular coaxial waveguide approach 50Ω.

[0034] In this embodiment, specifically, the spiral growth rate .

[0035] This embodiment also proposes a method for manufacturing a unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide, including the following steps: Step S1: Based on the higher-order mode TE of the coaxial waveguide m1 Theoretical formula:

[0036] Calculate the initial dimensions of the inner and outer conductors of the rectangular coaxial waveguide corresponding to the target frequency. The operating cutoff wavelength, Where is the radius of the inner conductor. Let be the radius of the outer conductor.

[0037] Step S2: Calculate the minimum inner diameter of the spiral slot based on the target frequency bandwidth. and helix outer diameter :

[0038]

[0039] in, The minimum inner diameter of the spiral. The outer diameter of the helix. The wavelength at the highest frequency point within the operating bandwidth. It is the wavelength at the lowest frequency point within the operating bandwidth.

[0040] Step S3: Based on the highest frequency wavelength of the operating bandwidth and the lowest frequency wavelength Determine the initial number of turns of the spiral slot. :

[0041] Step S4: Set the inner and outer conductor dimensions, inner and outer diameter dimensions, and number of turns of the spiral for the rectangular coaxial waveguide according to the previously calculated theoretical values, and then wrap it with an Archimedean spiral to realize the overall structural base of the antenna; Step S5: On the upper surface of the outer conductor of the rectangular coaxial waveguide (i.e., the narrow side of the rectangular coaxial waveguide), the spiral slot is etched according to a trajectory that satisfies the Archimedes spiral equation; the spiral slot cuts the current on the inner wall of the waveguide and forms an excitation electric field on both sides of the slot to achieve electromagnetic radiation performance; Step S6: The inner port of the rectangular coaxial waveguide is directly fed through a coaxial interface, without the need for additional baluns and matching networks, so as to achieve coaxial excitation with a simple structure. Step S7: Connect the absorption resistor to the end of the rectangular coaxial waveguide to absorb the reflected current at the end of the waveguide, so as to ensure the traveling wave characteristics of the electromagnetic field in the rectangular coaxial waveguide. Step S8: Adjust the inner and outer conductor dimensions of the rectangular coaxial waveguide to optimize the lowest and highest radiation frequencies of the antenna so that it covers the target operating bandwidth; and combine the reflection coefficient performance to comprehensively determine the final inner and outer conductor dimensions, absorption resistance value, and number of turns of the helical slot.

[0042] Example 2 Example 2 is a specific application of a unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide and its manufacturing method proposed in Example 1.

[0043] See Figure 1An Archimedean spiral slit is etched on the narrow side of a rectangular coaxial waveguide, with a slit width w. s =3mm, satisfying Archimedes' equation r = r0 + aφ, where r is the distance from the center trajectory of the slit to the origin, a = 11 / 2π is the spiral growth rate, and φ is the spiral encirclement angle. st to φ end The total number of spiral slots in the antenna is 8.

[0044] See Figure 2 The rectangular coaxial waveguide is also arranged in a similar manner to the Archimedean spiral equation. The inner conductor width is w2 = 4 mm, the inner conductor thickness is l2 = 12.5 mm, the outer conductor width is w3 = w2 * k, the outer conductor thickness is l3 = l2 * k, where k = 2.6, and the waveguide has 8.25 spiral loops. To improve unidirectional radiation performance, a metal conductor plane with etched spiral slots is added to the upper surface of the waveguide. This conductor has a width w1 = 243 mm and a length l1 = 243 mm.

[0045] See Figure 3 The waveguide port interface has a rectangular distribution of inner and outer conductors. The inner port of the waveguide is directly fed, and the outer port of the waveguide is welded with a 100Ω absorption resistor to absorb the reflected current at the end of the waveguide.

[0046] See Figure 4 The antenna slot width was simulated and optimized, as the width of the helical slot has a certain impact on the antenna's radiation intensity. Increasing the slot width effectively promotes the coupling of more energy through the helical slot, thus increasing the antenna's line-of-sight gain. However, the lowest radiation frequency shifts accordingly towards higher frequencies. Considering both axial ratio performance and the lowest radiation frequency, w s = 3 mm is a better choice.

[0047] See Figure 5 The antenna's inner-outer conductor size ratio k and inner conductor width w2 were jointly simulated and optimized, as the widths of the inner and outer conductors affect the current distribution within the waveguide, thus influencing the antenna's radiation performance. The results in the figure show that the antenna's lowest radiation frequency decreases as k and w2 increase, while the line-of-sight gain increases accordingly. This is because, with a suitable k value, as w2 increases, the overall cavity size increases, shifting the lowest radiation frequency to lower frequencies.

[0048] See Figure 6Parametric simulations were performed to optimize the waveguide inner conductor thickness l2. Similar to the effect of w2 on the lowest radiation frequency of the antenna, the waveguide inner conductor thickness l2 may be more sensitive to the antenna's axial ratio performance. The figure shows that as l2 increases, the antenna's line-of-sight gain continuously increases, the axial ratio performance improves, and the overall frequency band shifts towards lower frequencies, but deteriorates at higher frequencies. Considering both the antenna profile and radiation performance, an inner conductor thickness of l2 = 12.5 mm is a potential choice.

[0049] Based on the above analysis, the general design principles for the proposed antenna can be derived as follows: First, select an appropriate overall cavity size according to the application frequency band; then, optimize the in-band radiation characteristics by adjusting the ratio of the inner and outer conductor dimensions to obtain good gain-to-axis ratio performance. A slot width w s A rectangular coaxial single-helix slot antenna with an inner conductor width of 3 mm, an inner conductor size ratio of k=2.6, an inner conductor width of w2=4 mm, and an inner conductor thickness of l2=12.5 mm was simulated and analyzed using three-dimensional electromagnetic simulation software.

[0050] See Figure 7 The figure shows the simulated axial ratio and reflection coefficient performance of the antenna at this size as a function of frequency. As shown in the figure, the 3 dB axial ratio bandwidth and the impedance bandwidth of less than -15 dB are both 85.7% (2~5 GHz). Ultra-wideband circularly polarized radiation performance is achieved.

[0051] See Figure 8 The gain of the antenna along its line of sight varies with frequency; the gain is approximately 2 dB within the 2.15–4.4 GHz band. The antenna has an effective line-of-sight gain bandwidth of 68.7% (2.15–4.4 GHz). Simulations were performed on the normalized radiation patterns of the YOZ and XOZ planes at 2.5 GHz and 4 GHz frequencies for the antenna. (See [link / reference]). Figure 9 , Figure 10 , Figure 11 , Figure 12 The antenna's cross-polarization level increases with frequency, reaching approximately -15 dB at 4 GHz. It's worth noting that the antenna's radiation direction slightly deviates from the line-of-sight direction with increasing frequency. This is because at high frequencies, the effective radiation area of ​​the antenna is more complex, exhibiting a certain degree of asymmetry about the line-of-sight. Furthermore, the antenna's front-to-back ratio exceeds 20 dB, achieving good unidirectional right-hand circular polarization radiation performance along the line of sight.

[0052] In summary, the unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide proposed in this invention has a broadband radiation bandwidth of 68.7% (2.15~4.4 GHz), a front-to-back ratio of 20 dB, and a simple feeding structure. This demonstrates that the design goals of a unidirectional broadband circularly polarized antenna have been achieved with a simple structure.

[0053] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0054] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A unidirectional broadband helical slot antenna based on a rectangular coaxial waveguide, characterized in that, include: Rectangular coaxial waveguide, helical slot, and absorption resistor; The rectangular coaxial waveguide includes an inner conductor and an outer conductor, and the rectangular coaxial waveguide is configured as a traveling wave structure. The helical slot is etched on the upper surface of the outer conductor of the rectangular coaxial waveguide for radiating electromagnetic waves; The absorption resistor is connected to the end of the rectangular coaxial waveguide and is used to absorb the reflected current at the end. The inner port of the rectangular coaxial waveguide is directly fed through a coaxial interface.

2. The unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide according to claim 1, characterized in that, The spiral gap is an Archimedean spiral gap, and its trajectory satisfies Archimedean equation: in: The distance from the center trajectory of the gap to the origin of the coordinate system; This is the minimum inner diameter of the spiral; The spiral growth rate; The spiral angle.

3. A unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide according to claim 2, characterized in that, The rectangular coaxial waveguides are arranged according to the Archimedes spiral equation; the outer conductor includes a metal conductor plane added to the upper surface of the rectangular coaxial waveguides, and the spiral slot is etched on the upper surface of the metal conductor.

4. A unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide according to claim 1, characterized in that, The absorption resistor has a resistance of 100Ω and is welded to the outer port of the rectangular coaxial waveguide.

5. A unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide according to claim 1, characterized in that, The outer conductor width of the rectangular coaxial waveguide With the width of the inner conductor The ratio of the outer conductor thickness to the outer conductor thickness. With inner conductor thickness The ratios are all ; By adjusting the ratio and the width of the inner conductor This makes the input impedance of the rectangular coaxial waveguide approach 50Ω.

6. A unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide according to claim 2, characterized in that, The spiral growth rate .

7. A method for manufacturing a unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide, characterized in that, Includes the following steps: Step S1: Based on the higher-order mode TE of the coaxial waveguide m1 Theoretical formulas are used to calculate the initial dimensions of the inner and outer conductors of the rectangular coaxial waveguide corresponding to the target frequency; Step S2: Calculate the minimum inner diameter of the spiral slot based on the target frequency bandwidth. and helix outer diameter ; Step S3: Based on the highest frequency wavelength of the operating bandwidth and the lowest frequency wavelength Determine the initial number of turns of the spiral slot. ; Step S4: Set the inner and outer conductor dimensions, inner and outer diameter dimensions, and number of turns of the spiral for the rectangular coaxial waveguide according to the previously calculated theoretical values, and then wrap it with an Archimedean spiral to realize the overall structural base of the antenna; Step S5: On the outer conductor surface of the rectangular coaxial waveguide, the spiral slot is etched along a trajectory that satisfies the Archimedes spiral equation; the spiral slot cuts the current on the inner wall of the waveguide and forms an excitation electric field on both sides of the slot to achieve electromagnetic radiation performance; Step S6: The inner port of the rectangular coaxial waveguide is directly fed through a coaxial interface, without the need for additional baluns and matching networks, so as to achieve coaxial excitation with a simple structure. Step S7: Connect the absorption resistor to the end of the rectangular coaxial waveguide to absorb the reflected current at the end of the waveguide, so as to ensure the traveling wave characteristics of the electromagnetic field in the rectangular coaxial waveguide. Step S8: Adjust the inner and outer conductor dimensions of the rectangular coaxial waveguide to optimize the lowest and highest radiation frequencies of the antenna so that it covers the target operating bandwidth; By combining the reflection coefficient performance, the final dimensions of the inner and outer conductors, the absorption resistance value, and the number of turns of the spiral slit are determined.

8. A method for manufacturing a unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide according to claim 7, characterized in that, The higher-order mode TE in step S1 m1 The theoretical formula is as follows: in, The operating cutoff wavelength, Where is the radius of the inner conductor. Let be the radius of the outer conductor.

9. A method for manufacturing a unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide according to claim 7, characterized in that, Step S2 includes: , .

10. A method for manufacturing a unidirectional broadband spiral slot antenna based on a rectangular coaxial waveguide according to claim 7, characterized in that, Step S3 includes: .

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