A single-feed sinusoidal helical antenna based on cross-dipole structure

Abstract

The application discloses a single-feed sine spiral antenna based on a cross dipole structure and belongs to the technical field of wireless communication. The antenna comprises an upper layer radiation patch, a lower layer radiation patch, an upper layer medium, a lower layer medium, a ring-shaped parasitic metal patch and a coaxial connector; the upper layer radiation patch and the lower layer radiation patch each comprise two mutually orthogonal sine spiral structures, and the two sine spiral structures are connected through a phase shift loop; the upper layer radiation patch and the ring-shaped parasitic patch are respectively printed on the top and the bottom of the upper layer medium, and the lower layer radiation patch is printed on the bottom of the lower layer medium; the upper layer medium and the lower layer medium are concentrically attached together; the upper layer radiation patch and the lower layer radiation patch are respectively connected to the inner core and the outer shell of the coaxial connector to form a feed port; and the upper layer radiation patch and the lower layer radiation patch are centrally symmetrical with the medium circle center in a horizontal plane. The application has the broadband circular polarization characteristics of a traditional four-arm sine spiral antenna, is simple in structure and can meet the wireless communication requirements in different scenes.

Description

A single-fed sinusoidal spiral antenna based on a cross dipole structure Technical Field

[0001] This invention relates to the fields of wireless communication, satellite navigation and radar communication technology, and specifically to a single-fed sinusoidal spiral antenna structure design for use in wireless communication, satellite navigation and radar communication systems. Background Technology

[0002] Circularly polarized electromagnetic waves exhibit strong anti-interference characteristics and can be received by antennas of arbitrary linear polarization and the same circular polarization. Therefore, they are widely used in modern wireless communication, satellite navigation, and radar systems. With technological advancements, various forms of circularly polarized antennas have been researched and applied in different fields; however, designing a simple circularly polarized antenna with broadband characteristics remains a complex task. This is because designing a broadband circularly polarized antenna requires considering both broadband circular polarization characteristics and broadband impedance characteristics, making it difficult to balance both simultaneously. Among the many structural forms for realizing broadband circularly polarized antennas, non-frequency-varying antennas are relatively popular because, through proper design, they can radiate traveling wave electromagnetic waves, with the radiation impedance exhibiting periodic changes with frequency, making it relatively easy to obtain broadband characteristics. The four-arm sinusoidal spiral antenna is one such non-frequency-varying antenna. In traditional design methods, broadband circular polarization characteristics can be obtained by sequentially loading feeds of equal amplitude and phase differences of 0°, 90°, 180°, and 270° onto the four arms of a four-arm sinusoidal spiral antenna. Simultaneously, to obtain a more symmetrical radiation pattern, a balun feed structure for balanced-to-unbalanced conversion needs to be designed. This type of four-arm sinusoidal spiral antenna, due to the need for complex baluns and phase shifters, has a complex feeding structure that is difficult to design and manufacture.

[0003] In recent years, crossed dipole antennas have received widespread attention from scholars. The greatest advantage of this type of antenna lies in its simple feeding mechanism. Its basic element consists of two mutually orthogonal radiating patches connected by a phase-shift curve. The phase-shift curve provides a 90° phase shift, and the coaxial feed line itself provides a 180° phase shift. Therefore, the four radiating patches have phase differences of 0°, 90°, 180°, and 270°, enabling the radiation of circularly polarized waves. However, the operating bandwidth of these dipole antennas is limited by the selected basic element structure, typically resulting in a narrow bandwidth that is difficult to meet broadband operating requirements. Summary of the Invention

[0004] In view of this, this invention addresses the complex feeding and phase-shifting structures of traditional four-arm sinusoidal spiral antennas by proposing a cross-dipole structure four-arm sinusoidal spiral antenna that achieves broadband circular polarization without requiring a balun structure or additional phase shifters. Compared to traditional four-arm sinusoidal spiral antennas, the proposed four-arm sinusoidal spiral antenna retains the broadband circular polarization characteristics of traditional four-arm sinusoidal spiral antennas while possessing a simple structure, ease of fabrication, and better meeting the wireless communication needs of various scenarios.

[0005] A single-fed sinusoidal spiral antenna based on a cross dipole structure includes an upper radiating patch, a lower radiating patch, an upper dielectric, a lower dielectric, a ring-shaped parasitic metal patch, and a coaxial connector.

[0006] Both the upper and lower radiating patches include two mutually orthogonal sinusoidal spiral structures, which are connected by a phase-shifting loop.

[0007] The upper radiating patch and the annular parasitic patch are printed on the top and bottom of the upper dielectric, respectively, and the lower radiating patch is printed on the bottom of the lower dielectric. The upper and lower dielectrics are concentrically bonded together. The upper and lower radiating patches are connected to the inner core and outer shell of the coaxial connector to form a power supply port. The upper and lower radiating patches are centrally symmetrical about the center of the upper dielectric on the horizontal plane.

[0008] Furthermore, the sinusoidal spiral structure in the upper and lower radiating patches is composed of two sine curves C1 and C2, which are determined by the following equation in polar coordinates:

[0009]

[0010]

[0011] Where p is a positive integer, taking the values ​​1, 2, 3, ..., π is the mathematical constant pi, and R... p Let α be the radial distance between the starting point of the p-th curve segment and the origin. p And δ is a fixed angle, R p+1 and R p The relationship between them satisfies

[0012] R p+1 =τ p ·R p (3)

[0013] Where τ p It is a constant.

[0014] Furthermore, the minimum operating frequency of the single-fed sinusoidal spiral antenna can be determined by the following relationship:

[0015]

[0016] Where c is the speed of electromagnetic waves in a vacuum.

[0017] Furthermore, the phase-shifting ring consists of a gradually changing structure composed of an outer circular arc C3 and an inner Archimedean spiral C4. The radius of the outer circular arc C3 is Ra, and the polar coordinate equation of the inner Archimedean spiral C4 is as follows:

[0018] C4: ρ(θ)=Rb·(1+n·θ), θ0≤θ≤0° (5)

[0019] R b Let |θ0| be the initial radius of C4 (when θ = 0°), and |θ0| be the maximum angle of C4.

[0020] Furthermore, both the upper and lower dielectric layers are made of Rogers RO4003 dielectric with a dielectric constant of 3.55 and a cylindrical shape.

[0021] Furthermore, one end of the phase-shifting ring is connected to the radiating patch, and the other end is connected to the coaxial connector through a rectangular patch.

[0022] Beneficial effects:

[0023] 1. The four-arm sinusoidal spiral antenna with a cross-dipole structure proposed in this invention has two key advantages. First, the perimeter of the antenna phase-shifting loop is designed to be 1 / 4 of the wavelength corresponding to the selected center operating frequency, thus providing a 90° phase difference. Second, the upper and lower radiating patches are counter-fed through a coaxial feed port, providing equal amplitude, 180° feeds. Consequently, the phase differences of the four arms are 0°, 90°, 180°, and 270° respectively, allowing the antenna to generate circularly polarized waves without the need for an additional phase-shifting network at the feed port. The sinusoidal spiral structures in the radiating patches are located on the upper and lower surfaces of the upper and lower dielectric layers, forming a cross-dipole structure. Based on the characteristics of cross-dipole antennas, they can be directly fed through a coaxial feed. Traditional four-arm spiral antennas, with their four radiating arms on the same plane, require a balun structure to achieve a symmetric-to-asymmetric conversion to obtain a better radiation pattern. Therefore, the sinusoidal spiral antenna of this invention effectively overcomes the problems of complex feeding and phase-shifting network structures in traditional four-arm sinusoidal spiral antennas, which are difficult to design and manufacture.

[0024] 2. The phase-shifting ring of the present invention adopts a gradually changing structure composed of a circular arc and an Archimedean spiral, which can provide impedance matching characteristics within a wide bandwidth and greatly improve the matching performance between antenna radiation impedance and port impedance.

[0025] 3. This invention has strong applicability by changing the radius of the outer arc of the phase-shifting ring, the width of the rectangular patch, and the dimensions of the upper and lower dielectric diameters and heights, thus meeting the communication needs of different frequency bands. Attached Figure Description

[0026] Figure 1 is a structural diagram of the single-fed broadband circularly polarized sinusoidal spiral antenna with a cross dipole structure according to the present invention.

[0027] Figure 2 is a cross-sectional view of Figure 1;

[0028] Figure 3 is a structural diagram of the asymmetric radial patch of the present invention;

[0029] Figure 4 is a structural diagram of the phase-shifting ring and the rectangular patch of the present invention;

[0030] Figure 5 shows the antenna reflection coefficient S of the present invention. 11 Simulation curves of frequency variation;

[0031] Figure 6 shows the simulation curve of the antenna axial ratio AR of the present invention as a function of frequency.

[0032] Among them, 1-upper layer radiating patch, 1-1-first sine spiral structure, 1-2 second sine spiral structure, 1-3-phase shifting ring, 1-4-rectangular patch, 2-ring parasitic metal patch, 3-lower layer radiating patch, 4-upper layer dielectric, 5-lower layer dielectric, 6-coaxial connector. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] This invention provides a single-fed sinusoidal spiral antenna based on a cross-dipole structure, comprising an upper radiating patch 1, a lower radiating patch 3, an upper dielectric 4, a lower dielectric 5, a ring-shaped parasitic metal patch 2, and a coaxial connector 6, as shown in Figures 1 and 2. The upper radiating patch 1 is printed on the upper part of the upper dielectric 4, the ring-shaped parasitic metal patch 2 is printed on the bottom of the upper dielectric 4, and the lower radiating patch 3 is printed on the bottom of the lower dielectric 5. The coaxial connector 6 is located at the coaxial feed port. The ring-shaped parasitic metal patch 2 has a ring structure with inner and outer radii of D. n and D m .

[0035] Both the upper dielectric 4 and the lower dielectric 5 are made of Rogers RO4003 dielectric with a dielectric constant of 3.55. They are cylindrical in shape with a diameter of D. s The heights are h1 and h2 respectively; the upper medium 4 and the lower medium 5 are in close contact.

[0036] The upper radiating patch 1 and the lower radiating patch 3 are located at the top of the upper dielectric 4 and the bottom of the lower dielectric 5, respectively, and are centrally symmetrical about the center of the dielectric in the horizontal plane. Both the upper radiating patch 1 and the lower radiating patch 3 are connected by a phase-shifting ring 1-3 via mutually orthogonal first sinusoidal spiral structure 1-1 and second sinusoidal spiral structure 1-2, as shown in Figure 3. The upper radiating patch 1 and the lower radiating patch 3 are respectively connected to the inner core and outer shell of the coaxial connector 6.

[0037] The first sinusoidal spiral structure 1-1 and the second sinusoidal spiral structure 1-2 have the same structure, and are composed of two sinusoidal curves C1 and C2. C1 and C2 are determined by the following equation in polar coordinates:

[0038]

[0039]

[0040] Where p is a positive integer, taking the values ​​1, 2, 3, ..., π is the mathematical constant pi, and R... p Let α be the radial distance between the starting point of the p-th curve segment and the origin. p And δ is a fixed angle, R p+1 and R p The relationship between them satisfies

[0041] R p+1 =τ p ·R p (3)

[0042] Where τ p It is a constant. The minimum operating frequency of the antenna can be determined by the following relationship:

[0043]

[0044] The phase-shifting ring 1-3 has a gradually changing structure consisting of an outer circular arc C3 and an inner Archimedean spiral C4, as shown in Figure 4. The radius of C3 is Ra, and the polar coordinate equation of C4 is as follows:

[0045] C4: ρ(θ)=Rb·(1+n·θ), θ0≤θ≤0° (5)

[0046] R b Let |θ0| be the initial radius of C4 (when θ = 0°), and |θ0| be the maximum angle of C4.

[0047] Phase-shifting loops 1-3 employ a gradually changing structure composed of circular arcs and Archimedean spirals, which can provide impedance matching characteristics over a wide bandwidth and greatly improve the matching of antenna radiation impedance and port impedance.

[0048] One end of the phase-shifting ring 1-3 is connected to the radiating patch, and the other end is connected to the power supply port through a rectangular patch 1-4 with a width of Wf.

[0049] To verify the above design structure, the parameters were selected as shown in Table 1 below, and the antenna reflection coefficient S was obtained through simulation. 11 The simulation results, including the axial ratio (AR) of the circular polarization antenna as a function of frequency, are shown in Figures 5 and 6. The antenna's reflection coefficient is less than 10 dB within the 2.6-6.5 GHz range, exhibiting good impedance matching characteristics and an impedance bandwidth of 85.7%. The axial ratio of the circular polarization antenna is less than 3 dB within the 3.48-5.6 GHz range, demonstrating good circular polarization radiation characteristics, with a 3 dB circular polarization bandwidth of 46.7%. Simulation results indicate that the antenna designed in this invention possesses wide-bandwidth circular polarization characteristics. The selected parameters can be adjusted according to the antenna's operating frequency.

[0050] Table 1 Antenna Parameter Table

[0051]

[0052] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A single-fed sinusoidal spiral antenna based on a crossed dipole structure, characterized in that, The device includes an upper radiating patch, a lower radiating patch, an upper dielectric, a lower dielectric, an annular parasitic metal patch, and a coaxial connector. Both the upper and lower radiating patches comprise two mutually orthogonal sinusoidal spiral structures connected by a phase-shifting ring. The upper radiating patch and the annular parasitic patch are printed on the top and bottom of the upper dielectric, respectively, while the lower radiating patch is printed on the bottom of the lower dielectric. The upper and lower dielectrics are concentrically bonded together. The upper and lower radiating patches are connected to the inner core and outer shell of the coaxial connector, respectively, forming a power supply port. The upper and lower radiating patches are centrally symmetrical about the center of the upper dielectric on a horizontal plane.

2. The single-fed sinusoidal spiral antenna based on a cross-dipole structure as described in claim 1, characterized in that, The sinusoidal spiral structure in the upper and lower radiating patches is composed of two sinusoidal curves C1 and C2, which are determined by the following equation in polar coordinates: C1: , （1）C2： , (2) Where p is a positive integer, taking the values ​​1, 2, 3, ... Pi Let be the radial distance between the starting point of the p-th curve segment and the origin. and For a fixed angle, and The relationship between them satisfies (3) Among them It is a constant.

3. The single-fed sinusoidal spiral antenna based on a cross-dipole structure as described in claim 2, characterized in that, The minimum operating frequency of the single-fed sinusoidal spiral antenna can be determined by the following formula: (4) Where c is the speed of electromagnetic waves in a vacuum.

4. The single-fed sinusoidal spiral antenna based on a cross-dipole structure as described in claim 3, characterized in that, The phase-shifting loop consists of a gradually changing structure composed of an outer circular arc C3 and an inner Archimedean spiral C4. The radius of the outer circular arc C3 is Ra, and the polar coordinate equation of the inner Archimedean spiral C4 is as follows: C4: , (5) R b for The initial radius of C4, This is the maximum angle of C4.

5. The single-fed sinusoidal spiral antenna based on a cross-dipole structure as described in claim 3 or 4, characterized in that, One end of the phase-shifting ring is connected to the radiating patch, and the other end is connected to the coaxial connector through a rectangular patch.

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