A planar end-fire dual-band circularly polarized antenna

Abstract

The present application relates to the technical field of antenna, in particular to a kind of flat end-fire dual-frequency circularly polarized antenna, including flat microstrip magnetic dipole, delay line, electric dipole with reverse elongated branch and feed coaxial conductor.Flat microstrip magnetic dipole forms closed current path by three short-circuit edges, and open-circuit edge is connected to the delay line arranged along the first direction.Electric dipole with reverse elongated branch includes the first part of electric dipole reversely arranged along the second direction, the second part of electric dipole forwardly arranged along the second direction, the first part of narrow-width reverse elongated branch forwardly arranged along the second direction and the second part of narrow-width reverse elongated branch reversely arranged along the second direction, wherein electric dipole with reverse elongated branch forms symmetrical structure by mirror image layout.Feed coaxial conductor is connected to flat microstrip magnetic dipole, and excites electric dipole to generate phase difference.The present application realizes receiving 2.46GHz and 5.58GHz signals simultaneously.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, in particular to a planar end-fire dual-band circularly polarized antenna. BACKGROUND

[0002] In recent years, due to the characteristics of low profile and main radiation beam parallel to the antenna plane, planar end-fire circularly polarized antennas have attracted extensive attention. Using a pair of parallel complementary dipole structures is the main method to realize planar end-fire circularly polarized antennas. The existing related antenna technical solutions are as follows:

[0003] I. M. Ye et al. proposed a method based on a pair of printed electric dipoles [IEEE Antennas Wireless Propag. Lett, vol. 16, pp. 20-23, 2017], which uses printed electric dipoles to provide horizontal polarization components, but it can only work in a single frequency band;

[0004] II. Zhang Haipeng et al. proposed a method based on the combination of electric dipoles and loop antennas [Proceedings of the 2023 National Antenna Conference of the China Electronics Society (Part 1), 2023.094490], which can cover 2.4 GHz and 5.0 GHz. However, this antenna needs to introduce two horizontal polarization components, i.e. electric dipoles and loop elements, to realize the dual-band circular polarization characteristics. In addition, due to the inherent omnidirectional radiation of the loop antenna, the gain of the low frequency in the end-fire direction is low. At the same time, this antenna needs to introduce an additional metal shorting post to connect the two arms of the loop element, thereby increasing the complexity and cost of processing and manufacturing;

[0005] III. L. Wang et al. proposed a dual-band end-fire circularly polarized antenna based on two pairs of printed electric dipole antennas [IEEE Transactions on Antennas and Propagation, vol. 70, no. 2, pp. 969-976, Feb. 2022, doi: 10.1109 / TAP.2021.3111160], which introduces printed electric dipoles working at 2.4 GHz and 5.0 GHz to provide the horizontal components required for circular polarization. However, this scheme has obvious shortcomings. On the one hand, to meet the 90° phase difference, the bent delay line structure greatly increases the design complexity and manufacturing cost. On the other hand, additional narrow slot structures need to be introduced to adjust the high-frequency vertical polarization mode, thereby increasing the design complexity.

[0006] From the above, most of the existing technical solutions can only work in a single frequency band, and it is an urgent technical problem to be solved to research a planar end-fire circularly polarized antenna with dual-frequency characteristics. On the other hand, the current scheme for realizing dual-frequency end-fire circular polarization usually adopts a combined type structure, including a combination of a ring and an electric dipole and a double electric dipole, thereby increasing the complexity and cost of the antenna structure.

[0007] Therefore, it is of great significance to research and manufacture a planar end-fire circularly polarized antenna with simple structure and WLAN dual-band communication. SUMMARY

[0008] In view of the deficiencies of the prior art, the present application discloses a planar end-fire dual-frequency circularly polarized antenna.

[0009] The technical scheme adopted by the present application is as follows:

[0010] A planar end-fire dual-frequency circularly polarized antenna comprises:

[0011] A planar microstrip magnetic dipole has three short-circuit edges and one open-circuit edge, wherein the open-circuit edge is used for radiating energy;

[0012] A delay line is arranged along a first direction and connected with the open-circuit edge; the delay line unit comprises a first part of the delay line and a second part of the delay line;

[0013] An electric dipole with a reverse elongated branch comprises a first part of the electric dipole arranged in a reverse direction along a second direction, a second part of the electric dipole arranged in a forward direction along the second direction, a first part of the reverse elongated branch arranged in a forward direction along the second direction, and a second part of the reverse elongated branch arranged in a reverse direction along the second direction; wherein the first part of the electric dipole and the second part of the electric dipole and the first part of the reverse elongated branch and the second part of the reverse elongated branch are mirror-imaged about the central axis of the planar microstrip magnetic dipole;

[0014] The width of the first part of the reverse elongated branch along the first direction is smaller than the width of the first part of the electric dipole along the first direction;

[0015] The width of the second part of the reverse elongated branch along the first direction is smaller than the width of the second part of the electric dipole along the first direction;

[0016] A feed coaxial conductor is arranged in the planar microstrip magnetic dipole for generating an excitation signal to excite the electric dipole with the reverse elongated branch to generate a phase difference.

[0017] In one embodiment of the present application, the planar microstrip magnetic dipole includes a first substrate, a second substrate, a first short-circuit element, a second short-circuit element and a third short-circuit element; the first substrate and the second substrate are arranged in parallel; the first short-circuit element and the third short-circuit element are respectively arranged on the short sides of the first substrate, and the second short-circuit element is arranged on the long side of the first substrate; the first short-circuit element, the second short-circuit element and the third short-circuit element are arranged as three short-circuit edges for connecting the first substrate and the second substrate.

[0018] In one embodiment of the present application, the first part of the delay line is connected to the open-circuit edge of the first substrate, and the second part of the delay line is connected to the open-circuit edge of the second substrate.

[0019] In one embodiment of the present application, the sum of the length of the delay line along the first direction and the width of the electric dipole with the reverse elongated stub along the first direction ranges from 26 mm to 29 mm.

[0020] In one embodiment of the present application, the width of the first part of the delay line along the second direction and the width of the second part of the delay line along the second direction both range from 0.6 mm to 4.1 mm.

[0021] In one embodiment of the present application, the length of the first part of the electric dipole along the second direction and the length of the second part of the electric dipole along the second direction both range from 29 mm to 34 mm; and the width of the first part of the electric dipole along the first direction and the width of the second part of the electric dipole along the first direction both range from 3 mm to 8 mm.

[0022] In one embodiment of the present application, the length of the first part of the reverse elongated stub along the second direction and the length of the second part of the reverse elongated stub along the second direction both range from 13 mm to 15 mm; and the width of the first part of the reverse elongated stub along the first direction and the width of the second part of the reverse elongated stub along the first direction both range from 0.1 mm to 2 mm.

[0023] In one embodiment of the present application, the length of the planar microstrip magnetic dipole along the second direction ranges from 95 mm to 115 mm, the width along the first direction ranges from 38 mm to 40 mm, and the height ranges from 2.5 mm to 5 mm.

[0024] In one embodiment of the present application, one end of the feeding coaxial conductor is connected to the first substrate, and the other end is connected to the second substrate.

[0025] In one embodiment of the present application, the distance between the center of the feeding coaxial conductor and the second shorting element is in the range of 10mm-17.5mm.

[0026] The above technical solution of the present application has the following advantages compared with the prior art:

[0027] The planar end-fire dual-band circularly polarized antenna provided by the present application only uses a pair of printed electric dipoles and a reverse elongated branch structure to provide the low-frequency and high-frequency horizontal polarization components required by dual-band circular polarization, so that the antenna realizes circularly polarized radiation in two frequency ranges and has the advantage of simple structure.

[0028] The planar end-fire dual-band circularly polarized antenna provided by the present application is beneficial to reducing back radiation and improving gain in the end-fire direction.

[0029] The planar end-fire dual-band circularly polarized antenna provided by the present application reduces the design complexity and manufacturing cost of such antennas, and does not need to use two independent horizontal polarization unit structures as in the prior art; at the same time, it also does not need to use a bent delay line to meet the phase requirement of the dual-band, and has the beneficial effects of simple structure and low complexity. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to make the content of the present application easier to be clearly understood, the present application will be further described in detail below according to specific embodiments of the present application and in conjunction with the accompanying drawings.

[0031] Figure 1 is a structural schematic diagram of the planar end-fire dual-band circularly polarized antenna in the present application.

[0032] Figure 2 is a top view of the planar end-fire dual-band circularly polarized antenna in the present application.

[0033] Figure 3 is a side view of the planar end-fire dual-band circularly polarized antenna in the present application.

[0034] Figure 4 is a parameter schematic diagram of the planar end-fire dual-band circularly polarized antenna in the present application.

[0035] Figure 5 is a reflection coefficient performance diagram of the planar end-fire dual-band circularly polarized antenna in the present application.

[0036] Figure 6 is an antenna axial ratio performance diagram of the planar end-fire dual-band circularly polarized antenna in the present application.

[0037] Figure 7 is an antenna gain performance diagram of the planar end-fire dual-band circularly polarized antenna in the present application.

[0038] Figure 8is the YOZ plane pattern of the planar end-fire dual-frequency circularly polarized antenna at the frequency of 2.46 GHz in the application.

[0039] Figure 9 is the YOZ plane pattern of the planar end-fire dual-frequency circularly polarized antenna at the frequency of 5.58 GHz in the application.

[0040] Figure 10 is the XOY plane pattern of the planar end-fire dual-frequency circularly polarized antenna at the frequency of 2.46 GHz in the application.

[0041] Figure 11 is the XOY plane pattern of the planar end-fire dual-frequency circularly polarized antenna at the frequency of 5.58 GHz in the application.

[0042] Figure 12 is the antenna reflection coefficient performance diagram of the planar end-fire dual-frequency circularly polarized antenna under different W1 in the application.

[0043] Figure 13 is the antenna axial ratio performance diagram of the planar end-fire dual-frequency circularly polarized antenna under different W1 in the application.

[0044] Figure 14 is the antenna reflection coefficient performance diagram of the planar end-fire dual-frequency circularly polarized antenna under different W2 in the application.

[0045] Figure 15 is the antenna axial ratio performance diagram of the planar end-fire dual-frequency circularly polarized antenna under different W2 in the application.

[0046] Figure 16 is the antenna reflection coefficient performance comparison diagram of the planar end-fire dual-frequency circularly polarized antenna under the condition of having or not having a reverse extension stub in the application.

[0047] Figure 17 is the antenna axial ratio performance comparison diagram of the planar end-fire dual-frequency circularly polarized antenna under the condition of having or not having a reverse extension stub in the application.

[0048] Figure 18 is the antenna gain performance comparison diagram of the planar end-fire dual-frequency circularly polarized antenna under the condition of having or not having a reverse extension stub in the application.

[0049] Explanation of the drawing marks in the specification:

[0050] 10, planar microstrip magnetic dipole; 11, first substrate; 12, second substrate; 13, first short circuit element; 14, second short circuit element; 15, third short circuit element;

[0051] 21, first part of the delay line; 22, first part of the electric dipole; 23, first part of the reverse extension stub;

[0052] 31 second portion of the delay line; 32 second portion of the electric dipole; 33 second portion of the reverse elongated stub;

[0053] 40 feed coaxial conductor. DETAILED DESCRIPTION

[0054] The application will be further described below in conjunction with the drawings and specific embodiments so that those skilled in the art can better understand and implement the application, but the embodiments are not intended to limit the application.

[0055] The foregoing and other technical contents, features and effects of the present application will be clearly presented in the following detailed description of embodiments in conjunction with the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, are only reference to the direction of the drawings. Therefore, the directional terms are used to illustrate and not to limit the application, and in all embodiments, the same reference numerals represent the same elements.

[0056] In the prior art, planar end-fire circularly polarized antennas are concerned due to their low profile and the characteristic that the main beam is parallel to the plane of the antenna. Existing solutions mostly use complementary dipole structures to achieve end-fire circular polarization, but there are generally problems of single-frequency operation or complex structure. For example, a solution using a combination of printed electric dipoles and loop antennas needs to introduce a metal short-circuit column, increasing the processing complexity; a double electric dipole solution relies on a bent delay line structure, making it difficult to adjust the high-frequency mode. In the WLAN dual-band communication scenario, existing antennas are difficult to simultaneously achieve circular polarization characteristics for 2.4 GHz and 5.0 GHz frequency bands while maintaining structural simplicity and radiation efficiency.

[0057] To solve the above problems, an antenna without complex combination structure needs to be designed. Through analysis, it is found that a planar microstrip magnetic dipole has three short-circuit edges and one open-circuit edge, which can form a magnetic dipole radiation mode. If an electric dipole with a reverse elongated stub with phase difference adjustment function is set on the open-circuit edge, a horizontal polarization component can be excited simultaneously. Further considering the mirror-symmetrical layout, the electric dipole with a reverse elongated stub can produce a horizontal current distribution at dual frequency bands, thereby avoiding the introduction of additional structures to achieve dual-frequency circular polarization.

[0058] Embodiment One

[0059] In combination Figures 1 to 3The embodiment provides a planar end-fire dual-frequency circularly polarized antenna, which comprises a planar microstrip magnetic dipole 10, a delay line, an electric dipole with a reverse elongated branch and a feeding coaxial conductor 40. The planar microstrip magnetic dipole 10 forms a closed current path through three short-circuit edges, and an open-circuit edge is connected to the delay line arranged in a first direction. The delay line comprises a first part 21 of the delay line and a second part 31 of the delay line. The electric dipole with the reverse elongated branch comprises a first part 22 of the electric dipole arranged reversely in a second direction, a second part 32 of the electric dipole arranged forwardly in the second direction, a first part 23 of the reverse elongated branch arranged forwardly in the second direction and a second part 33 of the reverse elongated branch arranged reversely in the second direction. The first part 22 of the electric dipole and the second part 32 of the electric dipole and the first part 23 of the reverse elongated branch and the second part 33 of the reverse elongated branch are arranged in mirror image about a central axis of the planar microstrip magnetic dipole 10. The first part 23 of the reverse elongated branch has a width in the first direction smaller than that of the first part 22 of the electric dipole in the first direction. The second part 33 of the reverse elongated branch has a width in the first direction smaller than that of the second part 32 of the electric dipole in the first direction. The feeding coaxial conductor 40 is arranged on the planar microstrip magnetic dipole 10 and used for generating an excitation signal to excite the electric dipole with the reverse elongated branch to generate a phase difference.

[0060] The planar microstrip magnetic dipole 10 refers to a closed loop structure formed by a metal plane and a short-circuit element, and can be specifically implemented by connecting upper and lower parallel metal layers through a short-circuit column, and the open-circuit edge thereof serves as an energy radiation port. The inner conductor and the outer conductor of the feeding coaxial conductor 40 are connected to the upper and lower metal planes, for example, a coaxial line vertically penetrating a dielectric substrate is used to excite a vertical electric field through asymmetric feeding.

[0061] In the embodiment, a local coordinate system is established with a center point of the planar microstrip magnetic dipole 10 as a coordinate origin, a direction of a long side of the planar microstrip magnetic dipole 10 as an X-axis direction, a direction of a wide side of the planar microstrip magnetic dipole 10 as a Y-axis direction and a height direction of the planar microstrip magnetic dipole 10 as a Z-axis direction, as shown in FIGS. 1 and 2. Figure 1 Figure 2

[0062] ​​Specifically, the planar microstrip magnetic dipole 10 forms a magnetic dipole operating mode through three short-circuit sides, while the delay line connected by the open side and the electric dipole with reverse extension stubs generate horizontal polarization components. The planar microstrip magnetic dipole 10 provides the vertical polarization components required for circular polarization in both low-frequency and high-frequency bands; the first portion 21 and the second portion 31 of the delay line are arranged along a first direction, firstly ensuring that the low-frequency band meets the required 90° phase difference, thereby achieving circular polarization radiation; the first portion 22 and the second portion 32 of the electric dipole provide the low-frequency horizontal polarization components; the first portion 23 and the second portion 33 of the reverse extension stubs provide the high-frequency horizontal polarization components and simultaneously ensure that the high-frequency band meets the 90° phase difference. This structure achieves dual-frequency circular polarization radiation through a planar layout without the need for additional short-circuit posts or bent delay lines.

[0063] It is understood that in this embodiment, the first direction refers to the Y-axis direction, and the positive direction of the first direction refers to the positive Y-axis direction, and the negative direction of the first direction refers to the negative Y-axis direction; the second direction refers to the X-axis direction, and the positive direction of the second direction refers to the positive X-axis direction, and the negative direction of the second direction refers to the negative X-axis direction.

[0064] It should be noted that the structure provided in this embodiment can generate left-handed circular polarization characteristics in both frequency bands. If the positions of the first part 22 and the second part 32 of the electric dipole, as well as the first part 23 and the second part 33 of the reverse extension stub are interchanged, right-handed circular polarization characteristics in both frequencies will be achieved.

[0065] This embodiment further proposes a planar microstrip magnetic dipole 10 comprising a first substrate 11, a second substrate 12, a first short-circuit element 13, a second short-circuit element 14, and a third short-circuit element 15. The first substrate 11 and the second substrate 12 are arranged in parallel. The first short-circuit element 13 and the third short-circuit element 15 are respectively disposed on the short side of the first substrate 11, and the second short-circuit element 14 is disposed on the long side of the first substrate 11. The first short-circuit element 13, the second short-circuit element 14, and the third short-circuit element 15 are configured as three short-circuit sides for connecting the first substrate 11 and the second substrate 12.

[0066] The first substrate 11 and the second substrate 12 refer to the metal layer structure that constitutes the planar microstrip magnetic dipole 10. Specifically, they can be made of copper or copper-clad layers on a printed circuit board, and are arranged in parallel to form the radiation cavity required for electromagnetic field distribution.

[0067] The first short-circuit element 13, the second short-circuit element 14, and the third short-circuit element 15 refer to conductive structures that connect the upper and lower metal layers. Specifically, they can be made of copper or vertically welded metal pillars, forming a current loop through physical connection and controlling the electromagnetic field boundary conditions.

[0068] The shorted side refers to a zero potential region of an electromagnetic field formed by a shorted element, and is used to define the energy radiation direction and optimize the impedance matching characteristics.

[0069] Specifically, the first substrate 11 and the second substrate 12 form a closed current path through three shorted elements, wherein the first shorted element 13 and the third shorted element 15 are distributed on both sides of the short side, and the second shorted element 14 is located in the middle of the long side. This layout makes the planar microstrip magnetic dipole 10 form an asymmetric field distribution on the open side, and cooperates with the delay line structure of the electric dipole unit to realize dual-frequency circularly polarized radiation. When the feeding coaxial conductor 40 passes through the first substrate 11 and the second substrate 12, a vertical electric field component is generated under the boundary condition formed by the shorted elements, thereby exciting a dual-frequency circularly polarized beam in the end-fire direction.

[0070] The embodiment further proposes a planar end-fire dual-frequency circularly polarized antenna, wherein the first part 21 of the delay line is connected to the open side of the first substrate 11, and the second part 31 of the delay line is connected to the open side of the second substrate 12.

[0071] The first part 21 of the delay line and the second part 31 of the delay line refer to microstrip transmission paths arranged along the first direction for adjusting the phase difference, which can be implemented by using a rectangular metal parallel double-line structure, and the signal transmission delay can be adjusted by changing the length, so as to meet the required 90° phase difference of circular polarization. The open side refers to the edge region of the planar microstrip magnetic dipole 10 which is not provided with a shorted element, and is used to guide electromagnetic waves to radiate outward.

[0072] Specifically, the first part 21 of the delay line is directly connected to the open side of the first substrate 11, and the second part 31 of the delay line is directly connected to the open side of the second substrate 12, thereby forming a dual-frequency signal transmission path. By directly coupling the delay line with the open side, electromagnetic energy is guided to the radiation region. The open side of the planar microstrip magnetic dipole 10 as the radiation port, the connection position of the delay line directly affects the current distribution, thereby optimizing the coverage of the circularly polarized beam in the end-fire direction.

[0073] The embodiment further proposes that the sum of the length of the delay line along the first direction and the width of the electric dipole with the reverse elongated branch along the first direction is in the range of 26mm-29mm, i.e., the value range of L0 is 26mm-29mm as shown in Figure 4 The value range of the width of the first part 21 of the delay line along the second direction and the width of the second part 31 of the delay line along the second direction is 0.6mm-4.1mm, i.e., the value range of W0 is 0.6mm-4.1mm as shown in Figure 4

[0074] ​Specifically, the sum of the length of the delay line along the first direction and the width of the electric dipole with the reverse elongated branch along the first direction is controlled between 26mm and 29mm, for example, it can be 27.5mm or 28mm. Within this range, the horizontal current component of the electric dipole unit and the vertical current component of the magnetic dipole form an orthogonal relationship, and by adjusting the phase difference introduced by the delay line structure, the 90° phase condition required for circular polarization can be met in two frequency bands respectively.

[0075] The width of the first part 21 of the delay line along the second direction and the width of the second part 31 of the delay line along the second direction are both controlled within the range of 0.6mm-4.1mm, mainly to adjust the amplitude difference between the horizontal component and the vertical component.

[0076] The embodiment further proposes that the length of the first part 22 of the electric dipole along the second direction and the length of the second part 32 of the electric dipole along the second direction are both within the range of 29mm-34mm, that is, as shown in the following formula (1), the value range of L1 is 29mm-34mm. Figure 4 The width of the first part 22 of the electric dipole along the first direction and the width of the second part 32 of the electric dipole along the first direction are both within the range of 3mm-8mm, that is, as shown in the following formula (2), the value range of W1 is 3mm-8mm. Figure 4

[0077] Specifically, the length of the electric dipole is set to cover the half-wavelength resonance condition required for the low frequency band. The width of the electric dipole is configured to ensure uniformity of current distribution while avoiding excessive transverse size causing parasitic resonance, thereby maintaining a stable radiation pattern. By controlling the length and width within a certain range, the dual-frequency resonance and circular polarization performance can be balanced without introducing additional structures.

[0078] The embodiment further proposes that the length of the first part 23 of the reverse elongated branch along the second direction and the length of the second part 33 of the reverse elongated branch along the second direction are both within the range of 13mm-15mm, and the width is within the range of 0.1mm-2mm, that is, as shown in the following formula (3), the value range of L2 is 13mm-15mm, and the value range of W2 is 0.1mm-2mm. Figure 4

[0079] The reverse elongated branch refers to a conductive structure in the electric dipole unit that extends in the opposite direction of the main radiation direction, which can be implemented by a metal sheet. For example, the length controlled within the range of 13mm-15mm is used to provide a horizontal polarization component at high frequency while compensating for the 90° phase difference required for circular polarization, and the width controlled within the range of 0.1mm-2mm can suppress excessive diffusion of low frequency current, thereby balancing the impedance matching and radiation efficiency of the dual frequency band.

[0080] ​​Specifically, the first part 23 of the reverse elongated branch forms an asymmetric structure with the first part 22 of the electric dipole, and the second part 33 of the reverse elongated branch forms a mirror asymmetric structure with the second part 32 of the electric dipole. By setting the length of the reverse elongated branch to 13mm-15mm, a 90° phase difference required for circular polarization in the high frequency band is compensated. At the same time, by compressing the width to the range of 0.1mm-2mm, the parasitic radiation of the low frequency band current on the reverse elongated branch can be reduced, and the vertical polarization component can be avoided to interfere with the circular polarization purity.

[0081] The embodiment further proposes that the length of the planar microstrip magnetic dipole 10 along the second direction is in the range of 95mm-115mm, the width along the first direction is in the range of 38mm-40mm, and the height is in the range of 2.5mm-5mm, i.e., as shown in the following formula (1), the length L is in the range of 95mm-115mm, the width W is in the range of 38mm-40mm, and the height H is in the range of 2.5mm-5mm. Figure 4

[0082] The length of the planar microstrip magnetic dipole 10 refers to the physical size between the two short edges along the electromagnetic wave propagation direction, and by adjusting the length range, effective resonance of the antenna in the dual frequency band can be ensured.

[0083] The width of the planar microstrip magnetic dipole 10 refers to the physical size between the two short edges perpendicular to the propagation direction, which can be realized by microstrip lines or metal layers, and by limiting the width range, the radiation efficiency of the horizontal polarization component can be optimized.

[0084] The height of the planar microstrip magnetic dipole 10 refers to the vertical spacing between the upper and lower planes, which can be realized by dielectric substrates or air layers, and by controlling the height range, the phase matching characteristics of the vertical polarization component can be adjusted. For example, the air dielectric material with a dielectric constant of 1.0006 and a thickness of 4mm is used in the embodiment.

[0085] Specifically, the size parameters of the planar microstrip magnetic dipole 10 are designed in coordination, so that the antenna meets the amplitude balance and phase orthogonal conditions required for circular polarization in the dual frequency band.

[0086] The embodiment further proposes that one end of the feeding coaxial conductor 40 is connected to the first substrate 11, and the other end is connected to the second substrate 12. The distance between the center of the feeding coaxial conductor 40 and the second short circuit element 14 is in the range of 10mm-17.5mm, i.e., as shown in the following formula (2), the distance D is in the range of 10mm-17.5mm. Figure 4

[0087] ​​The coaxial conductor 40 is a coaxial structure used to transmit high-frequency electromagnetic wave signals. Specifically, it can be implemented using a metal tubular structure with coaxially nested inner and outer conductors. The inner conductor passes through the dielectric layer to form a signal transmission path, and the outer conductor is connected to the ground layer to form a loop. This structure, by directly connecting the first substrate 11 and the second substrate 12, can optimize current distribution and enhance dual-band coupling efficiency.

[0088] The center of the power supply coaxial conductor 40 refers to the geometric center point between the inner and outer conductors of the coaxial cable, which is used to ensure the symmetry of the electromagnetic field distribution to maintain the stability of signal transmission.

[0089] Specifically, the inner conductor of the feeding coaxial conductor 40 penetrates the dielectric substrate and is soldered to the first substrate 11, while the outer conductor is connected to the second substrate 12 through a via. When an excitation signal is input from the coaxial port, current is injected into the first substrate 11 through the inner conductor, while the outer conductor and the second substrate 12 form a ground loop, resulting in a symmetrical current path between the upper and lower planes. This cross-layer feeding method can balance the impedance matching of high and low frequency bands and control the current phase difference by adjusting the position of the connection point, ultimately achieving a stable circularly polarized beam in both frequency bands.

[0090] The distance between the center of the feeding coaxial conductor 40 and the second short-circuit element 14 is constrained within a specific range. By adjusting this distance, the electromagnetic coupling strength between the planar microstrip magnetic dipole 10 and the electric dipole unit can be optimized. Within this distance range, the current distribution of the planar microstrip magnetic dipole 10 and the radiation field of the electric dipole unit can achieve phase matching, thereby maintaining the orthogonal field component relationship required for circular polarization in both frequency bands.

[0091] like Figure 5 As shown, Figure 5 The antenna's reflection coefficient performance is shown. From... Figure 5 As can be seen, the impedance bandwidth of the antenna includes: low frequency range from 2.39GHz to 2.52GHz (bandwidth 0.13GHz, 5.30%), and high frequency range from 5.47GHz to 5.83GHz (bandwidth 0.35GHz, 6.19%).

[0092] like Figure 6 As shown, Figure 6 The antenna axial ratio performance is shown. From... Figure 6 As can be seen, the axial bandwidth of the antenna includes: low frequency from 2.30GHz to 2.58GHz (bandwidth 0.28GHz, 11.48%), and high frequency from 5.57GHz to 5.67GHz (bandwidth 0.10GHz, 1.78%).

[0093] like Figure 7 As shown, Figure 7 The antenna gain is shown. From...Figure 7 It can be seen that the gain in the low frequency part is higher than 4dBic, and the average gain in the high frequency part is about 6dBic.

[0094] In combination Figures 9 to 11 , Figures 9 to 11 The antenna directional patterns at 2.46GHz and 5.58GHz are shown. In combination Figures 9 to 11 It can be seen that the left-handed and right-handed gain difference at 90° is greater than 15dB and both are left-handed gain greater than right-handed gain, showing left-handed circular polarization characteristics, the maximum radiation direction is in the positive direction of the Y axis, and the directional pattern has good stability.

[0095] Embodiment two to embodiment four

[0096] Based on embodiment one, embodiment two to embodiment four are comparisons of each planar end-fire dual-frequency circularly polarized antenna with W1 being 3mm, 5mm and 7mm, the specific antenna reflection coefficient performance is shown in Figure 12 , and the specific antenna axial ratio performance is shown in Figure 13 .

[0097] Embodiment five to embodiment eight

[0098] Based on embodiment one, embodiment five to embodiment eight are comparisons of each planar end-fire dual-frequency circularly polarized antenna with different W2 being 0.5mm, 1.0mm, 1.5mm and 2.0mm, the specific antenna reflection coefficient performance is shown in Figure 14 , and the specific antenna axial ratio performance is shown in Figure 15 .

[0099] It can be seen from embodiment two to embodiment eight and in combination Figures 12 to 15 that the electric dipole width W1 and the reverse elongated branch width W2 have an effect on the reflection coefficient and the axial ratio characteristics. From Figure 12 and Figure 13 it can be seen that W1 has certain control ability on the working frequency range of the high frequency band, which can effectively improve the matching of the high frequency, while the impedance characteristics of the low frequency remain basically unchanged. In addition, it has a great influence on the axial ratio of the low frequency and the high frequency. As shown in Figure 14 and Figure 15 , adjusting W2 can effectively control the reflection coefficient amplitude of the low frequency band and the working bandwidth range of the high frequency band, while also ensuring the dual-frequency circular polarization function of the antenna.

[0100] Comparative example one

[0101] Based on embodiment one, the difference between embodiment one and comparative example one is that the electric dipole is not provided with a reverse elongated branch, that is, the electric dipole includes the first part 22 of the electric dipole which is reversely arranged in the second direction and the second part 32 of the electric dipole which is arranged in the positive direction of the second direction.

[0102] As shown in Figure 16 As shown in the table, after the introduction of the reverse extension branch, the low frequency center frequency of the antenna is increased, the bandwidth of the small -10dB reflection coefficient is slightly widened, the high frequency center frequency is reduced, and the bandwidth of the small -10dB reflection coefficient is obviously expanded. The low frequency band is adjusted from 2.36GHz-2.46GHz to 2.39GHz-2.52GHz, and the high frequency band is adjusted from 5.72GHz-5.88GHz to 5.47GHz-5.83GHz.

[0103] As shown in Figure 17 As shown in the table, after the introduction of the reverse extension branch, the value of the axial ratio is obviously reduced to below 3dB in both frequency bands, and the effect of dual-frequency circular polarization is achieved.

[0104] As shown in Figure 18 As shown in the table, the presence or absence of the reverse extension branch has little effect on the gain of the low frequency band, and the gain of the high frequency band is basically maintained at about 6dB.

[0105] In the description of the embodiments of the application, it should also be noted that, unless otherwise explicitly specified and limited, if the terms "arrangement", "connection" appear, they should be understood in a broad sense, for example, can be fixedly connected, can also be detachably connected, or integrally connected; can be mechanically connected, can also be electrically connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0106] Obviously, the above embodiments are only examples for clearly illustrating, and are not limited to the implementation. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made. Here, it is not necessary and impossible to enumerate all the implementation. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A planar end-fire dual-band circularly polarized antenna, characterized in that, The application relates to a planar microstrip magnetic dipole (10) with three short-circuit edges and one open-circuit edge, wherein the open-circuit edge is used for radiating energy; the planar microstrip magnetic dipole (10) comprises a first substrate (11), a second substrate (12), a first short-circuit element (13), a second short-circuit element (14) and a third short-circuit element (15); the first substrate (11) and the second substrate (12) are arranged in parallel; the first short-circuit element (13) and the third short-circuit element (15) are arranged on the short edges of the first substrate (11), and the second short-circuit element (14) is arranged on the long edge of the first substrate (11); the first short-circuit element (13), the second short-circuit element (14) and the third short-circuit element (15) are arranged as three short-circuit edges and are used for connecting the first substrate (11) and the second substrate (12); a delay line is arranged along a first direction and is connected with the open-circuit edge; the delay line unit comprises a first part (21) of the delay line and a second part (31) of the delay line; an electric dipole with a reverse elongated branch comprises a first part (22) of the electric dipole arranged in a reverse direction along a second direction, a second part (32) of the electric dipole arranged in a forward direction along the second direction, a first part (23) of the reverse elongated branch arranged in a forward direction along the second direction and a second part (33) of the reverse elongated branch arranged in a reverse direction along the second direction; wherein the first part (22) of the electric dipole and the second part (32) of the electric dipole and the first part (23) of the reverse elongated branch and the second part (33) of the reverse elongated branch are arranged in mirror image about the central axis of the planar microstrip magnetic dipole (10); the width of the first part (23) of the reverse elongated branch along the first direction is smaller than the width of the first part (22) of the electric dipole along the first direction; the width of the second part (33) of the reverse elongated branch along the first direction is smaller than the width of the second part (32) of the electric dipole along the first direction; a feeding coaxial conductor (40) is arranged in the planar microstrip magnetic dipole (10) and is used for generating an excitation signal to excite the electric dipole with the reverse elongated branch to generate a phase difference. The first part (21) of the delay line is connected with the open-circuit edge of the first substrate (11), and the second part (31) of the delay line is connected with the open-circuit edge of the second substrate (12); the length of the delay line along the first direction and the width of the electric dipole with the reverse elongated branch along the first direction are in the range of 26mm-29mm; the width of the first part (21) of the delay line along the second direction and the width of the second part (31) of the delay line along the second direction are in the range of 0.6mm-4.1mm. ​ ​ ​ ​ ​ 2. The planar end-fire dual-band circularly polarized antenna according to claim 1, wherein, ​ 3. The planar end-fire dual-band circularly polarized antenna according to claim 1, wherein, ​ 4. The planar end-fire dual-band circularly polarized antenna according to claim 1, wherein, ​ 5. The planar end-fire dual-band circularly polarized antenna according to claim 1, wherein, The length of the first part (22) of the electric dipole along the second direction and the length of the second part (32) of the electric dipole along the second direction are both in the range of 29mm-34mm; the width of the first part (22) of the electric dipole along the first direction and the width of the second part (32) of the electric dipole along the first direction are both in the range of 3mm-8mm.

6. The planar end-fire dual-band circularly polarized antenna according to claim 1, wherein, The length of the first part (23) of the reverse elongated branch along the second direction and the length of the second part (33) of the reverse elongated branch along the second direction are both in the range of 13mm-15mm; the width of the first part (23) of the reverse elongated branch along the first direction and the width of the second part (33) of the reverse elongated branch along the first direction are both in the range of 0.1mm-2mm.

7. The planar end-fire dual-band circularly polarized antenna according to claim 1, wherein, The length of the planar microstrip magnetic dipole (10) along the second direction is in the range of 95mm-115mm, the width along the first direction is in the range of 38mm-40mm, and the height is in the range of 2.5mm-5mm.

8. The planar end-fire dual-band circularly polarized antenna according to claim 1, wherein, One end of the feeding coaxial conductor (40) is connected to the first substrate (11), and the other end is connected to the second substrate (12).

9. The planar end-fire dual-band circularly polarized antenna according to claim 8, wherein, The distance between the center of the feeding coaxial conductor (40) and the second short circuit element (14) is in the range of 10mm-17.5mm.

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