Circularly polarized antenna and communication equipment

Abstract

The present invention provides a circularly polarized antenna, comprising: a radiation layer, a feeding layer, a reflecting layer and a supporting part, wherein the feeding layer is arranged between the radiation layer and the reflecting layer; the supporting part is arranged between the reflecting layer and the radiation layer; the radiation layer comprises a first feeding point, an equiangular spiral antenna, a first Archimedean spiral antenna and a second Archimedean spiral antenna; the second end of the equiangular spiral antenna is connected to the second end of the first feeding point, the third end of the equiangular spiral antenna is correspondingly connected to the first end of the first Archimedean spiral antenna, the fourth end of the equiangular spiral antenna is correspondingly connected to the second end of the first Archimedean spiral antenna, the third end of the first Archimedean spiral antenna is connected to the first end of the second Archimedean spiral antenna, and the fourth end of the first Archimedean spiral antenna is connected to the second end of the second Archimedean spiral antenna.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a circularly polarized antenna and communication equipment. Background Art

[0002] As modern electronic devices tend to be miniaturized and integrated, the miniaturization of antennas, which are the front end of communications, has also become a research focus.

[0003] The planar spiral antenna in the existing technology has the problems of large size, high profile and insufficient efficiency. Due to the particularity of its application scenarios, the satellite-borne antenna needs to have a low profile, high efficiency and cover multiple frequency bands. The traditional method of using multiple narrowband antennas makes the entire system appear crowded. Summary of the invention

[0004] The present invention provides a circular polarization antenna and communication equipment to solve the problems of large size, high cross-section and insufficient efficiency of a planar spiral antenna.

[0005] According to a first aspect of the present invention, a circularly polarized antenna is provided, comprising: a radiation layer, a feeding layer, a reflection layer and a support portion, wherein the feeding layer is arranged between the radiation layer and the reflection layer to achieve communication connection between the reflection layer and the radiation layer; the support portion is arranged between the reflection layer and the radiation layer to fix and isolate the reflection layer and the radiation layer; the reflection layer comprises an artificial magnetic conductor AMC;

[0006] The radiation layer includes a first feeding point, an equiangular spiral antenna, a first Archimedean spiral antenna and a second Archimedean spiral antenna; the equiangular spiral antenna, the first Archimedean spiral antenna and the second Archimedean spiral antenna are arranged in a spiral direction from the center to the outer ring, the first end of the equiangular spiral antenna is connected to the first end of the first feeding point, the second end of the equiangular spiral antenna is connected to the second end of the first feeding point, the third end of the equiangular spiral antenna is connected to the first end of the first Archimedean spiral antenna, the fourth end of the equiangular spiral antenna is connected to the second end of the first Archimedean spiral antenna, the third end of the first Archimedean spiral antenna is connected to the first end of the second Archimedean spiral antenna, and the fourth end of the first Archimedean spiral antenna is connected to the second end of the second Archimedean spiral antenna;

[0007] The reflective layer is used to receive signals; the feeder layer is used to transmit the signals of the reflective layer to the radiation layer; and the radiation layer is used to receive and emit the signals transmitted by the feeder layer.

[0008] Optionally, the equiangular spiral antenna includes a first equiangular spiral antenna body and a second equiangular spiral antenna body, and the first equiangular spiral antenna body and the second equiangular spiral antenna body are distributed in a spiral manner from a starting end to an outside.

[0009] Optionally, the first Archimedean spiral antenna includes a first Archimedean spiral antenna body and a second Archimedean spiral antenna body, and the first Archimedean spiral antenna body and the second Archimedean spiral antenna body are distributed in a spiral manner from a starting end to an outside.

[0010] Optionally, the second Archimedean spiral antenna includes a third Archimedean spiral antenna body and a fourth Archimedean spiral antenna body, and the third Archimedean spiral antenna body and the fourth Archimedean spiral antenna body are wavy and distributed in a spiral manner from a starting end to an outside.

[0011] Optionally, the equiangular spiral antenna body includes a self-complementary equiangular spiral antenna, the first Archimedean spiral antenna includes a self-complementary Archimedean spiral antenna, and the second Archimedean spiral antenna includes a sinusoidally loaded Archimedean spiral antenna.

[0012] Optionally, a growth rate α0 of the helical line of the equiangular spiral antenna is 0.15, and a growth rate α1 of the helical line of the first Archimedean spiral antenna and the second Archimedean spiral antenna is 0.6.

[0013] Optionally, the reflective layer also includes a first dielectric substrate, a Jerusalem patch unit, a metal floor and a second feeding point; the Jerusalem patch unit is evenly distributed on the upper surface of the first dielectric substrate, the metal floor is arranged on the lower surface of the first dielectric substrate, and the first feeding point and the second feeding point are on the same vertical line.

[0014] Optionally, the feeding layer includes a gradient planar balun, a first end of the gradient planar balun is connected to the first feeding point, a second end of the gradient planar balun is connected to the second feeding point, and the gradient planar balun is distributed in a bent shape between the reflective layer and the radiation layer.

[0015] Optionally, the feeding layer further includes a coaxial connector, which connects the second end of the gradient planar balun with the second feeding point.

[0016] Optionally, the radiation layer further includes a second dielectric substrate, and the equiangular spiral antenna, the first Archimedean spiral antenna, and the second Archimedean spiral antenna are all arranged on an upper surface of the second dielectric substrate.

[0017] Optionally, the dielectric constant of the first dielectric substrate and the second dielectric substrate is 3.66, the loss tangent is 0.004, and the thickness is 1.5-2 mm.

[0018] Optionally, the first feeding point also includes a radiation resistor, and the first end and the second end of the equiangular spiral antenna are connected to the radiation resistor.

[0019] Optionally, the artificial magnetic conductor AMC is a 5*5 AMC array.

[0020] According to a second aspect of the present invention, there is provided a communication device, comprising the first aspect and the optional circularly polarized antenna thereof.

[0021] The circularly polarized antenna and communication equipment provided by the present invention realize the low-profile characteristics of the circularly polarized antenna by adopting an artificial magnetic conductor AMC. Due to the zero reflection phase characteristics of the artificial magnetic conductor AMC within a specific frequency range, the radiation layer adopts a composite planar spiral antenna, and different antennas can meet the signal transmission needs of different frequency bands, thereby achieving high efficiency and covering multiple frequency bands.

[0022] In a preferred embodiment, the miniaturization of the balun cross-section height is achieved by bending the tapered planar balun, further realizing the low-profile characteristics of the circularly polarized antenna, and the tapered planar balun can still maintain good performance after multiple bendings.

[0023] In addition, the patch unit in the artificial magnetic conductor AMC adopts the Jerusalem patch unit. The Jerusalem patch unit has no vias, which reduces the difficulty of processing. At the same time, it has more design parameters than the conventional patch unit, which facilitates the optimization of design. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 Schematic diagram of the structure of the circularly polarized antenna described in one embodiment of the present invention Figure 1 ;

[0026] Figure 2 Schematic diagram of the structure of the circularly polarized antenna described in one embodiment of the present invention Figure 2 ;

[0027] Figure 3Schematic diagram of the structure of the circularly polarized antenna described in one embodiment of the present invention Figure 3 ;

[0028] Figure 4 Schematic diagram of the structure of the circularly polarized antenna described in one embodiment of the present invention Figure 4 ;

[0029] Figure 5 Schematic diagram of the structure of the circularly polarized antenna described in one embodiment of the present invention Figure 5 ;

[0030] Figure 6 is the simulation result of the circularly polarized antenna described in one embodiment of the present invention Figure 1 ;

[0031] Figure 7 is the simulation result of the circularly polarized antenna described in one embodiment of the present invention Figure 2 ;

[0032] Figure 8 is the simulation result of the circularly polarized antenna described in one embodiment of the present invention Figure 3 ;

[0033] Fig. 9 is the simulation result of the circularly polarized antenna described in one embodiment of the present invention Figure 4 ;

[0034] Fig.10 is the simulation result of the circularly polarized antenna described in one embodiment of the present invention Figure 5 ;

[0035] FIG. 11( a ) is a simulation result of a circularly polarized antenna according to an embodiment of the present invention. Figure 6 ;

[0036] FIG. 11( b ) is a simulation result of a circularly polarized antenna according to an embodiment of the present invention. Figure 7 ;

[0037] FIG. 12( a ) is a simulation result of a circularly polarized antenna according to an embodiment of the present invention. Figure 8 ;

[0038] FIG. 12( b ) is a simulation result of a circularly polarized antenna according to an embodiment of the present invention. Figure 9 ;

[0039] FIG. 13( a ) is a simulation result of a circularly polarized antenna according to an embodiment of the present invention. Figure 10 ;

[0040] FIG. 13( b ) is a simulation result of a circularly polarized antenna according to an embodiment of the present invention. Figure 10 one;

[0041] FIG. 14( a ) is a simulation result of a circularly polarized antenna according to an embodiment of the present invention. Figure 10 two;

[0042] FIG. 14( b ) is a simulation result of a circularly polarized antenna according to an embodiment of the present invention. Figure 10 three;

[0043] Fig.15 Comparison of simulation and measured results of the circularly polarized antenna described in one embodiment of the present invention Figure 1 ;

[0044] Fig.16 Comparison of simulation and measured results of the circularly polarized antenna described in one embodiment of the present invention Figure 2 ;

[0045] FIG. 17( a ) is a comparison of simulation and measured results of a circularly polarized antenna according to an embodiment of the present invention. Figure 3 ;

[0046] FIG. 17( b ) is a comparison of simulation and measured results of a circularly polarized antenna according to an embodiment of the present invention. Figure 4 ;

[0047] FIG. 18( a ) is a comparison of simulation and measured results of a circularly polarized antenna according to an embodiment of the present invention. Figure 5 ;

[0048] FIG. 18( b ) is a comparison of simulation and measured results of a circularly polarized antenna according to an embodiment of the present invention. Figure 6 ;

[0049] FIG. 19( a ) is a comparison of simulation and measured results of a circularly polarized antenna according to an embodiment of the present invention. Figure 7 ;

[0050] FIG. 19( b ) is a comparison of simulation and measured results of a circularly polarized antenna according to an embodiment of the present invention. Figure 8 ;

[0051] FIG. 20( a ) is a comparison of simulation and measured results of a circularly polarized antenna according to an embodiment of the present invention. Figure 9 ;

[0052] FIG. 20( b ) is a comparison of simulation and measured results of a circularly polarized antenna according to an embodiment of the present invention. Figure 10 .

[0053] Description of reference numerals:

[0054] 1-Radiation layer;

[0055] 101-first feeding point;

[0056] 102-Conformal helical antenna;

[0057] 103-The first Archimedean spiral antenna;

[0058] 104-Second Archimedean spiral antenna;

[0059] 105-radiation resistance;

[0060] 106- a second dielectric substrate;

[0061] 2-Feeding layer;

[0062] 201-Gradient plane balun;

[0063] 3-Reflection layer;

[0064] 301-first dielectric substrate;

[0065] 302-Jerusalem patch unit;

[0066] 303-Metal floor;

[0067] 304-second feeding point;

[0068] 4-Supporting part. DETAILED DESCRIPTION

[0069] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0070] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0071] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0072] Before filing this application, the applicant has conducted sufficient research on the structure of circularly polarized antennas and found that in the prior art, the radiation layer of the circularly polarized antenna only uses Archimedean spirals or equiangular spirals. Since the growth rate of Archimedean spirals is relatively slow, if only Archimedean spiral antennas are used, during actual processing and testing, too many Archimedean spiral antennas will result in large conductor losses and low antenna radiation efficiency. If only equiangular spirals are used, since the angles of the equiangular spirals are in an exponential relationship, the equiangular spirals will expand quickly and the terminal reflection current will be large, resulting in poor axial ratio, standing wave and other performance in the low frequency band.

[0073] In view of this, the present invention proposes a circularly polarized antenna, which adopts an equiangular spiral antenna at the center of the radiation layer and an Archimedean spiral at the periphery, which not only avoids the spiral line from being too long, but also ensures that the terminal current is gradually reduced to 0 and can meet the signal transmission of different frequency bands.

[0074] Regarding the solution of the present invention, the specific description is as follows:

[0075] Please refer to Figure 1 The present invention provides a circularly polarized antenna, comprising: a radiation layer 1, a feeding layer 2, a reflection layer 3 and a supporting portion 4, wherein the feeding layer 2 is arranged between the radiation layer 1 and the reflection layer 3 to achieve a communication connection between the reflection layer 3 and the radiation layer 1; the supporting portion 4 is arranged between the reflection layer 3 and the radiation layer 1 to fix and isolate the reflection layer 3 and the radiation layer 1; the reflection layer 3 comprises an artificial magnetic conductor AMC.

[0076] The radiation layer 1 includes a first feeding point 101, an equiangular spiral antenna 102, a first Archimedean spiral antenna 103 and a second Archimedean spiral antenna 104; the equiangular spiral antenna 102, the first Archimedean spiral antenna 103 and the second Archimedean spiral antenna 104 are arranged in a spiral direction from the center to the outer ring, the first end of the equiangular spiral antenna 102 is connected to the first end of the first feeding point 101, the second end of the equiangular spiral antenna 102 is connected to the second end of the first feeding point 101, the third end of the equiangular spiral antenna 102 is correspondingly connected to the first end of the first Archimedean spiral antenna 103, the fourth end of the equiangular spiral antenna 102 is correspondingly connected to the second end of the first Archimedean spiral antenna 103, the third end of the first Archimedean spiral antenna 103 is connected to the first end of the second Archimedean spiral antenna 104, and the fourth end of the first Archimedean spiral antenna 103 is connected to the second end of the second Archimedean spiral antenna 104.

[0077] Specifically, the reflective layer 3 is used to receive signals; the feed layer 2 is used to transmit the signals of the reflective layer 3 to the radiation layer 1, and the radiation layer 1 is used to receive and emit the signals transmitted by the feed layer 2.

[0078] In one example, the support portion 4 includes a plurality of nylon screws.

[0079] Of course, the present invention is not limited thereto, and support portions 4 made of other materials are within the protection scope of the present invention.

[0080] In the above scheme, a composite planar spiral antenna is used in the radiation layer, and different antennas can meet the signal transmission needs of different frequency bands, thereby achieving high efficiency and covering multiple frequency bands.

[0081] In addition, by adopting the artificial magnetic conductor AMC, the low profile characteristic of the circularly polarized antenna is achieved due to the zero reflection phase characteristic of the artificial magnetic conductor AMC in a specific frequency range.

[0082] For radiation layer, please refer to Figure 2 The equiangular spiral antenna 102 includes a first equiangular spiral antenna body and a second equiangular spiral antenna body, and the first equiangular spiral antenna body and the second equiangular spiral antenna body are distributed in a spiral manner from a starting end to an outside; the first Archimedean spiral antenna 103 includes a first Archimedean spiral antenna body and a second Archimedean spiral antenna body, and the first Archimedean spiral antenna body and the second Archimedean spiral antenna body are distributed in a spiral manner from a starting end to an outside; the second Archimedean spiral antenna 104 includes a third Archimedean spiral antenna body and a fourth Archimedean spiral antenna body, and the third Archimedean spiral antenna body and the fourth Archimedean spiral antenna body are wavy and distributed in a spiral manner from a starting end to an outside.

[0083] In a specific embodiment, the equiangular spiral antenna 102 includes a self-complementary equiangular spiral antenna, the first Archimedean spiral antenna 103 includes a self-complementary Archimedean spiral antenna, and the second Archimedean spiral antenna 104 includes a sinusoidally loaded Archimedean spiral antenna.

[0084] Specifically, the curve equation of the sinusoidally loaded Archimedean spiral antenna is as follows:

[0085] x(t)=r+a(t+bsin(ct))*cos(t);

[0086] y(t)=r+a(t+bsin(ct))*sin(t).

[0087] In another preferred embodiment, the growth rate α0 of the helical line of the equiangular helical antenna 102 is 0.15, and the growth rate α1 of the helical lines of the first Archimedean spiral antenna 103 and the second Archimedean spiral antenna 104 is 0.6.

[0088] In other preferred implementations, the number of turns N0 of the equiangular spiral antenna 102 is 1.5, and the inner diameter r0 is 3.2 mm; the number of turns N1 of the first Archimedean spiral antenna 103 is 5, and the number of turns N2 of the second Archimedean spiral antenna 104 is 4.

[0089] In one example, the overall diameter of the radiation layer 1 is 100 mm.

[0090] In a specific embodiment, the radiation layer 1 further includes a second dielectric substrate 106 , and the equiangular spiral antenna 102 , the first Archimedean spiral antenna 103 , and the second Archimedean spiral antenna 104 are all disposed on an upper surface of the second dielectric substrate 106 .

[0091] For details, please refer to Figure 5 The first feeding point 101 also includes a radiation resistor 105, and the first end and the second end of the equiangular spiral antenna 102 are connected to the radiation resistor 105.

[0092] For the performance of composite planar helical antennas in the radiating layer, please refer to Figure 6-Figure 9 , Figure 6-Figure 9 : is a simulation result diagram of the radiation layer. Specifically, the commercial electromagnetic simulation software HFSS is used to simulate the composite planar spiral antenna, and only lumped port feeding is used to verify the performance of the designed antenna.

[0093] in, Figure 6 is the reflection coefficient S of the composite planar helical antenna 11 The simulation results are shown in Figure 2. Figure 6 It can be seen that within the design frequency band, the antenna’s S 11 Both are below -11dB, which is beneficial to the subsequent matching of the gradient planar balun and the artificial magnetic conductor AMC. At the same time, it can be seen that the planar spiral antenna loaded with a sine curve (that is, the second Archimedean spiral antenna) still maintains a good standing wave at low frequency, indicating that loading a sine curve can improve the low-frequency performance.

[0094] Figure 7 The axial ratio simulation diagram of the composite planar helical antenna is shown in Figure 2. Figure 7It can be seen that within the designed frequency band, the axial ratio of the composite helical antenna is below 3dB, and it can be used as the radiator of the circularly polarized antenna; among them, the sudden increase in the axial ratio in the low-frequency band in the figure is because the terminal has no sharpening operation or loading resistance, etc., which results in a small amount of reflected current, affecting the traveling wave current distribution of the antenna arm.

[0095] Figure 8 is a schematic diagram of the real part of the characteristic impedance of the composite planar spiral antenna, Figure 8 It can be seen that the entire impedance curve first decreases and then increases, and the change is relatively gentle within the required frequency band. In one example, the port impedance of the subsequent balun balanced end can be set to 120Ω, and then optimized and adjusted. In addition, due to the sudden increase in impedance at low frequencies, the matching of the entire antenna is affected, causing the current distribution on the spiral arm of the composite helical antenna to present a part of the standing wave component, so the reflection coefficient and axial ratio of the antenna are deteriorated outside the frequency band.

[0096] Fig. 9 is the curve of the axial gain of the composite planar helical antenna changing with frequency, Fig. 9 It can be seen that the gain of the antenna gradually increases with the frequency, which is in line with the principle of an actual planar spiral antenna. Within the required frequency band, the gain of the antenna is basically above 3.5dBi. Since the composite planar spiral antenna does not have a reflector or AMC structure at this time, the composite planar spiral antenna is a bidirectional radiation structure.

[0097] In the above scheme, the number of antenna circles in the radiation layer is not too dense to avoid increasing transmission loss and stray loss, and the current path is extended to reduce current reflection at the terminal, thereby changing the low-frequency performance of the antenna; in terms of performance, the composite planar spiral antenna has an S11 of less than -10dB and an axial ratio of less than 3dB within the required frequency band of 1.4GHz to 2.1GHz, which meets the design index requirements of the circularly polarized antenna.

[0098] In addition, since the composite planar helical antenna loads the radiation resistor at the distal region (i.e., the first feeding point), the number of turns of the helical wire is reduced while ensuring that the low-frequency performance is not deteriorated, and ultimately the overall size of the radiation layer is reduced by 20%.

[0099] For the feed layer, please refer to Figure 3 The feeding layer 2 includes a gradient planar balun 201, a first end of the gradient planar balun 201 is connected to the first feeding point 101, a second end of the gradient planar balun 201 is connected to the second feeding point 304, and the gradient planar balun 201 is distributed in a bent shape between the reflective layer 3 and the radiation layer 1.

[0100] In a preferred implementation, the feed layer 2 further includes a coaxial connector, and the coaxial connector connects the second end of the gradient planar balun 201 and the second feeding point 304 .

[0101] In a specific embodiment, the gradient planar balun is continuously bent and chamfered, and finally spliced ​​to achieve a reduction in the profile height of the balun, specifically, from more than 50 mm to less than 20 mm. In order to facilitate subsequent overall installation and fixation, the input end of the gradient planar balun is below the first dielectric substrate.

[0102] For the performance of the tapered planar balun, please refer to Fig.10 , Fig.10 is the simulation result diagram of the reflection coefficient of the gradient plane balun, Fig.10 It can be seen that even if the gradient planar balun introduces multiple reflection signals after multiple bends, the reflection coefficient S11 of the balun after multiple bends still maintains good performance within the required frequency band, meeting the requirements of the feeding part of the composite planar helical antenna.

[0103] For the reflective layer 3, please refer to Figure 4 The reflective layer 301 also includes a first dielectric substrate 301, a Jerusalem patch unit 302, a metal floor 303 and a second feeding point 304; the Jerusalem patch unit 302 is evenly distributed on the upper surface of the first dielectric substrate 301, the metal floor 303 is arranged on the lower surface of the first dielectric substrate 301, and the first feeding point 101 and the second feeding point 304 are on the same vertical line.

[0104] In one embodiment, the dielectric constant of the first dielectric substrate 301 and the second dielectric substrate 106 is 3.66, the loss tangent is 0.004, and the thickness is 1.5-2 mm, for example, 1.524 mm.

[0105] Specifically, the artificial magnetic conductor AMC structure array is laminated and pressed together to ultimately achieve a thickness of about 2 mm.

[0106] In another embodiment, the artificial magnetic conductor AMC is a 5*5 AMC array.

[0107] In other embodiments, modeling and simulation are performed through the Floquet port in HFSS, and the influencing factors are analyzed in combination with parameters, and finally the parameter values ​​of the artificial magnetic conductor AMC are obtained, as shown in Table 1.

[0108] Table 1 AMC unit parameter values

[0109]

[0110] Among them, taking the plane rectangular coordinate system as an example, the parameter Cell is the length of the artificial magnetic conductor AMC in the Y-axis direction, the parameter W1 is the length of the metal floor in the Y-axis direction, the parameter W2 is the length of the metal floor in the X-axis direction, and the parameter Wslot is the length of the slot in the Y-axis direction.

[0111] In the above scheme, the patch unit in the artificial magnetic conductor AMC adopts the Jerusalem patch unit. The Jerusalem patch unit has no vias, which reduces the difficulty of processing. At the same time, it has more design parameters than the conventional patch unit, which is convenient for optimizing the design.

[0112] Regarding the performance of the reflection layer, please refer to FIG. 11( a ) and FIG. 11( b ). FIG. 11 shows the reflection coefficient S of the artificial magnetic conductor AMC. 11 As shown in Figure 11, the resonant frequency of the artificial magnetic conductor AMC is around 1.75 GHz, and the bandwidth of the zero reflection phase adopts the standard of -90° to 90°, that is, 1.68 GHz to 1.82 GHz. In the required frequency band, the maximum return loss is less than 0.4 dB, that is, the electromagnetic waves are almost all reflected back, and there is almost no transmitted wave.

[0113] Regarding the performance of the circularly polarized antenna, please refer to Figures 12 to 20. Figures 12 to 14 are simulation diagrams showing the effects of the number of turns of the spiral arms of the composite planar spiral antenna, the distance between the radiation layer and the reflection layer, and the size of the loaded radiation resistance on the performance of the antenna.

[0114] 12(a) and 12(b) are curves showing the effect of the number of turns N2 of the spiral arm of the second Archimedean spiral antenna. As shown in FIG. 12(a) and FIG. 12(b), the number of turns N2 of the sinusoidal loading has an effect on S 11 The impact is not significant, that is, the radiation resistance and the number of turns N2 can already meet the performance of the antenna, but the number of turns N2 has a greater impact on the axial ratio, that is, although the method of loading the zigzag arm can improve the characteristics of the reflection coefficient, the introduced parasitic capacitance and inductance will have a greater impact on the axial ratio. Therefore, the value of the number of turns N2 should be paid attention to during the optimization process.

[0115] 13(a) and 13(b) are S when the distance H between the radiation layer and the reflection layer changes from 16 mm to 24 mm. 11 As well as the AR curve. Since the artificial magnetic conductor AMC has a zero reflection phase characteristic, if it is too close to the antenna, it will be coupled with each other, affecting the radiation of the entire antenna. Therefore, the spatial phase difference will cause the reflected wave to be superimposed on the forward radiation wave. As can be seen from Figure 13 (a) and Figure 13 (b), H is proportional to S 11The influence of is relatively weak, and it mainly affects the circular polarization axial ratio. As shown in Figure 13(b), whether H is too large or too small, the axial ratio will deteriorate. Therefore, appropriate parameters should be selected during simulation.

[0116] FIG. 14( a ) and FIG. 14( b ) show the magnitude of the radiation resistance R with respect to S 11 Since R is located at the end of the spiral arm of the composite planar spiral antenna, the size of R has little effect on the input impedance of the antenna. The main purpose of the radiation resistance R is to absorb the residual current and the current coupled to the spiral arm. Therefore, it mainly affects the circular polarization axis ratio. As shown in Figure 14 (a) and Figure 14 (b), it mainly affects the high-frequency part, so the high-frequency part can be considered during optimization.

[0117] Fig.15 is the reflection coefficient S 11 Comparison chart of simulation and measured results; Fig.15 It can be seen that the relative bandwidth of the antenna's impedance bandwidth simulation result is 50%, and the measured bandwidth is 100%. The bandwidth of 1.4GHz to 2.1GHz meets the index requirements, and the measured results are slightly better than the simulation results. This shows that the antenna has good impedance matching performance.

[0118] Fig.16 The comparison chart of the simulation results and test results of the circular polarization axis ratio of the antenna in the 1.4GHz to 2.1GHz frequency band is shown in Figure 1. Fig.16 It can be seen that the simulation and test results are both less than 3dB, meeting the circular polarization index requirements, and the test curve is basically consistent with the simulation curve.

[0119] Figures 17(a) and 17(b) are curves showing the variation of circular polarization axial gain and radiation efficiency with frequency. The helical antenna of the present application is right-hand circular polarization. As shown in Figure 17(a), within the target frequency band of 1.4 to 2.1 GHz, the simulated right-hand circular polarization gain fluctuates within the range of 5dBi to 7.2dBi, and the overall trend of the tested circular polarization gain is relatively consistent, but the tested gain is relatively low. As shown in Figure 17(b), the variation trend of the measured efficiency curve is relatively consistent with the simulation curve, and ultimately, within the entire frequency band, the efficiency is higher than 70%.

[0120] Figures 18(a), 18(b), 19(a), 19(b), 20(a) and 20(b) respectively show the right-hand circular polarization radiation patterns of the antenna at 1.4GHz, 1.8GHz and 2.1GHz, and intuitively compare the simulation and test curves. According to the measured simulation curves of the main frequency point radiation patterns in the above six figures, it can be clearly found that the test curve and the simulation curve are basically consistent in the upper half space, and the lower half space has a smaller right-hand polarized electromagnetic wave component, so the measured error is different from the simulation; in addition, since the test cable is connected to the back end of the antenna, it will also affect the test results.

[0121] In the specific embodiment, within the entire target frequency band (i.e., 1.4 GHz to 2.1 GHz), the test results of the composite planar spiral antenna are basically consistent with the simulation results, which shows the feasibility of the antenna design and the accuracy of the processing. However, there are still some differences, which are caused by four aspects: simulation error, test error, processing error and assembly error.

[0122] Specifically, since this patent designs a low-profile broadband antenna, some simulation convergence and air box settings will be affected; secondly, the test environment has some losses introduced by test cables, the jitter of the test cables causes the maximum radiation direction to shift, the insertion losses of various connectors, errors caused by human measurements, and the antenna designed in this application spans the L and S frequency bands. The speaker needs to be replaced during testing, which will also affect the test results of the boundary points; secondly, the limitation of processing accuracy leads to certain differences from the simulation model, and the parameters of the dielectric substrate used in the processing will also be different from the simulation; during the final assembly, the amount of solder will also affect the performance of the antenna.

[0123] In summary, in terms of the performance of the circularly polarized antenna provided by the present invention, within the required frequency band of 1.4 GHz to 2.1 GHz, the S11 of the circularly polarized antenna is less than -10 dB, the axial ratio is less than 3 dB, the efficiency is greater than 70%, and the gain is greater than 5 dBi, which meets the requirements of the design indicators.

[0124] The present invention also provides a communication device, comprising the circularly polarized antenna mentioned above.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A circularly polarized antenna, characterized in that: include: A radiation layer, a feed layer, a reflective layer and a support portion, wherein the feed layer is arranged between the radiation layer and the reflective layer to achieve communication connection between the reflective layer and the radiation layer; The support portion is disposed between the reflective layer and the radiation layer to fix and isolate the reflective layer and the radiation layer; the reflective layer includes an artificial magnetic conductor AMC; The radiation layer includes a first feeding point, an equiangular spiral antenna, a first Archimedean spiral antenna and a second Archimedean spiral antenna; the equiangular spiral antenna, the first Archimedean spiral antenna and the second Archimedean spiral antenna are arranged in a spiral direction from the center to the outer ring, the first end of the equiangular spiral antenna is connected to the first end of the first feeding point, the second end of the equiangular spiral antenna is connected to the second end of the first feeding point, the third end of the equiangular spiral antenna is connected to the first end of the first Archimedean spiral antenna, the fourth end of the equiangular spiral antenna is connected to the second end of the first Archimedean spiral antenna, the third end of the first Archimedean spiral antenna is connected to the first end of the second Archimedean spiral antenna, and the fourth end of the first Archimedean spiral antenna is connected to the second end of the second Archimedean spiral antenna; The equiangular spiral antenna body comprises a self-complementary equiangular spiral antenna, the first Archimedean spiral antenna comprises a self-complementary Archimedean spiral antenna, and the second Archimedean spiral antenna comprises a sinusoidally loaded Archimedean spiral antenna; The first feeding point also includes a radiation resistor, and the first end and the second end of the equiangular spiral antenna are connected to the radiation resistor; The reflective layer is used to receive signals; the feeder layer is used to transmit the signals of the reflective layer to the radiation layer, and the radiation layer is used to receive and emit the signals transmitted by the feeder layer; The reflective layer also includes a first dielectric substrate, a Jerusalem patch unit, a metal floor and a second feeding point; the Jerusalem patch unit is evenly distributed on the upper surface of the first dielectric substrate, the metal floor is arranged on the lower surface of the first dielectric substrate, and the first feeding point and the second feeding point are on the same vertical line.

2. The circularly polarized antenna according to claim 1, characterized in that: The equiangular spiral antenna comprises a first equiangular spiral antenna body and a second equiangular spiral antenna body, wherein the first equiangular spiral antenna body and the second equiangular spiral antenna body are distributed in a spiral manner from a starting end to an outside.

3. The circularly polarized antenna according to claim 1, characterized in that: The first Archimedean spiral antenna includes a first Archimedean spiral antenna body and a second Archimedean spiral antenna body, and the first Archimedean spiral antenna body and the second Archimedean spiral antenna body are distributed in a spiral manner from a starting end to an outside.

4. The circularly polarized antenna according to claim 1, characterized in that: The second Archimedean spiral antenna includes a third Archimedean spiral antenna body and a fourth Archimedean spiral antenna body. The third Archimedean spiral antenna body and the fourth Archimedean spiral antenna body are wavy and distributed in a spiral manner from a starting end to an outside.

5. The circularly polarized antenna according to claim 1, characterized in that: The growth rate α0 of the helical line of the equiangular spiral antenna is 0.15, and the growth rate α1 of the helical line of the first Archimedean spiral antenna and the second Archimedean spiral antenna is 0.

6.

6. The circularly polarized antenna according to claim 1, characterized in that: The feeding layer includes a gradient planar balun, a first end of the gradient planar balun is connected to the first feeding point, a second end of the gradient planar balun is connected to the second feeding point, and the gradient planar balun is distributed in a bent shape between the reflection layer and the radiation layer.

7. The circularly polarized antenna according to claim 6, characterized in that: The feeding layer further includes a coaxial connector, which connects the second end of the tapered planar balun with the second feeding point.

8. The circularly polarized antenna according to claim 7, characterized in that: The radiation layer further includes a second dielectric substrate, and the equiangular spiral antenna, the first Archimedean spiral antenna and the second Archimedean spiral antenna are all arranged on the upper surface of the second dielectric substrate.

9. The circularly polarized antenna according to claim 8, characterized in that: The dielectric constant of the first dielectric substrate and the second dielectric substrate is 3.66, the loss tangent is 0.004, and the thickness is 1.5-2 mm.

10. The circularly polarized antenna according to claim 1, characterized in that: The artificial magnetic conductor AMC is a 5*5 AMC array.

11. A communication device, characterized in that: The circularly polarized antenna comprises the circularly polarized antenna described in any one of claims 1 to 10.

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