CN113161752A - Circularly polarized back cavity slot antenna - Google Patents
Circularly polarized back cavity slot antenna Download PDFInfo
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- CN113161752A CN113161752A CN202110390019.1A CN202110390019A CN113161752A CN 113161752 A CN113161752 A CN 113161752A CN 202110390019 A CN202110390019 A CN 202110390019A CN 113161752 A CN113161752 A CN 113161752A
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- H—ELECTRICITY
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- H—ELECTRICITY
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Abstract
The invention provides a circularly polarized cavity-backed slot antenna, which comprises: the tuning cavity comprises a first panel, a second panel opposite to the first panel and a side wall connected between the first panel and the second panel, the first panel is provided with a radiation gap, the radiation gap is of a porous structure, the second panel is provided with a feed gap, the feed cavity is connected to the side of the second panel, which is far away from the first panel, the feed cavity surrounds the feed gap, the feed cavity is connected with a coaxial feed terminal, the inner side of the side wall is connected with two disturbing pieces, each disturbing piece is provided with an inward reflecting surface, an included angle is formed between the reflecting surface and the length direction of the feed gap, and the first panel, the second panel, the side wall and the reflecting surface jointly surround to form a resonant cavity. The antenna of the scheme has a simple structure, and can simultaneously have the characteristics of high AR bandwidth and wide AR beam width.
Description
Technical Field
The invention belongs to the technical field of communication equipment, and particularly relates to a circularly polarized cavity-backed slot antenna.
Background
A Circularly Polarized (CP) antenna can reduce polarization mismatch and multipath interference and is widely applied to positioning, navigation, satellite and radar wireless communication systems.
The CP slot antenna unit based on the degenerate mode generally has a problem of narrow Axial Ratio (AR) bandwidth, and therefore, in the related art, a slot array is designed to obtain a wide AR bandwidth, wherein a feed network of the slot array brings broadband characteristics. As another important characteristic of CP antennas, a wide AR beamwidth is generally required to extend the coverage. However, in the related art, except at a narrow AR bandwidth, the AR beamwidth of the CP slot antenna is reportedly obtainable only at the center frequency.
Therefore, on the one hand, the AR beamwidth and AR bandwidth of the related CP slot antenna are relatively narrow, and on the other hand, although the broadband AR bandwidth can be improved by using the slot array, they have a problem that the AR beamwidth is narrow due to the large size of the antenna.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a circularly polarized cavity-backed slot antenna, which has the characteristics of simple antenna structure, high AR bandwidth and wide AR beam width.
To solve the above technical problem, the present invention is implemented as follows, and a circularly polarized cavity-backed slot antenna includes: the tuning cavity body, the feeding cavity body and the disturbing piece are all made of metal materials, the tuning cavity body comprises a first panel, a second panel opposite to the first panel and a side wall connected between the first panel and the second panel, the first panel is provided with a radiation gap, the radiation gap is of a hole-shaped structure with a smooth edge, the second panel is provided with a feeding gap, the feeding cavity body is connected to the side of the second panel, which is far away from the first panel, the feeding cavity body surrounds the feeding gap, the feeding cavity body is connected with a coaxial feeding terminal, a central feeding line of the coaxial feeding terminal extends into the feeding cavity body, the inner side of the side wall is connected with two disturbing pieces, the disturbing piece is provided with an inward reflecting surface, and an included angle is formed between the reflecting surface and the length direction of the feeding gap, the first panel, the second panel, the side wall and the reflecting surface jointly enclose to form a resonant cavity.
Further, the first panel and the second panel are parallel to each other;
the centers of the two disturbing pieces are symmetrically distributed around the feed gap, and the symmetric center is the center of the feed gap; the reflective surface is perpendicular to the first panel.
Further, the included angle between the reflecting surface and the length direction of the feed gap is 30-60 degrees.
Furthermore, the radiation gap is circular, and the center of the radiation gap is opposite to the center of the feed gap.
Further, the ratio of the diameter of the radiation slot to the length of the feed slot is 0.6-1.2; the ratio of the length of the feed slot to the width of the feed slot is between 2 and 10.
Furthermore, the radiation gap is oval, the center of the radiation gap is opposite to the center of the feed gap, and an included angle is formed between the long axis direction of the radiation gap and the length direction of the feed gap.
Further, the long axis direction of the radiation slot is perpendicular to the length direction of the feed slot, the ratio of the long axis diameter of the radiation slot to the short axis diameter of the radiation slot is 1.05-3, the ratio of the long axis diameter of the radiation slot to the length of the feed slot is 0.8-2, and the ratio of the length of the feed slot to the width of the feed slot is 2-10.
Further, the central feed line is parallel to the plate surface of the second panel, and the central feed line is perpendicular to the length direction of the feed gap.
Further, the ratio of the length of the central feeder line extending into the feeding cavity to the length of the feeding gap is 0.3-0.8.
Further, the first panel and the second panel are square with the same width, and the distance between the first panel and the second panel is smaller than the width of the first panel.
Compared with the prior art, the circularly polarized back cavity slot antenna has the beneficial effects that:
signals can be fed in from the feed gap through the feed cavity and the coaxial feed terminal, two degenerate cavity modes facing CP radiation can be generated through the two disturbing pieces, and the smooth hole-shaped radiation gap can radiate the signals. The antenna has the advantages of simple structure, stable radiation gain and directional diagram, higher AR bandwidth and wider AR beam width.
Drawings
Fig. 1 is a schematic structural diagram of a circularly polarized cavity-backed slot antenna according to a first implementation manner in the embodiment of the present invention: (a) a three-dimensional view; (b) a top view in the XY plane; (c) a side view of the XZ plane;
fig. 2 is a schematic structural diagram of a circularly polarized cavity-backed slot antenna according to a second implementation manner in the embodiment of the present invention: three-dimensional view (up); top view of XY plane (bottom left); side view of XZ plane (bottom right);
fig. 3 shows simulation results of the circularly polarized cavity-backed slot antenna according to the first implementation with (Lt 12mm) and without (Lt 0 mm);
fig. 4 is the electric field distribution of the first implementation of the circularly polarized cavity-backed slot antenna: (a) an electric field distribution of 3.68 ghz; (b) an electric field distribution of 3.78 ghz; (c) electric field distribution at t-0 at 3.75 GHz; (d) electric field distribution at T ═ T/4 at 3.75 GHz;
FIG. 5 is a parametric study of resonator dimensions: (a) the influence of a and b; (b) c;
fig. 6 shows the amplitude ratio and the phase difference between Ex and Ey of the circularly polarized cavity-backed slot antenna according to the first implementation mode under the conditions of different sizes of the perturbation elements Lt and the radiation slot R: (a) an amplitude ratio; (b) phase difference;
fig. 7 simulates AR of the circularly polarized cavity-backed slot antenna of the first implementation under the conditions of different sizes of the perturbation element Lt and the radiation slot R;
fig. 8 is an AR of a second implementation of a circularly polarized cavity-backed slot antenna with different sized radiating slots;
fig. 9 shows the electric field directions in the radiation slot of the circularly polarized cavity-backed slot antenna of the second implementation when T is 0 and T is T/4: (a) and (b)3.4 GHz; (c) and (d)3.5 GHz; (e) and (f)3.6 GHz;
fig. 10 is a circularly polarized cavity-backed slot antenna of the second implementation: (a) the ratio of the amplitudes of Ex and Ey in the XZ plane and YZ plane of 3.5ghz and (b) the phase difference as a function of θ;
fig. 11 simulates the AR beamwidth at 3.5ghz for a second implementation of a circularly polarized cavity-backed slot antenna;
fig. 12 is a graph of feed gap parameters versus impedance matching: (a) length Lf and (b) width Wf;
fig. 13 is a comparison of the circularly polarized cavity-backed slot antenna of the second implementation (solid line and graphic-backed line) and the circularly polarized cavity-backed slot antenna of the first implementation (dotted line and graphic-backed line): (a) | S11| and axial ratio; (b) the gain and aperture efficiency achieved;
fig. 14 is a sample photograph of a second implementation of a circularly polarized cavity-backed slot antenna: (a) full view, (b) top view;
fig. 15 is the measurement (Measured) and simulation (Simulated) results of the circularly polarized cavity-backed slot antenna of the second implementation: (a) s11 and efficiency; (b) gain and axial ratio, where TE denotes total efficiency and AE denotes aperture efficiency;
fig. 16 is a measured (Mea.) and simulated (Sim.) radiation patterns at different frequencies for a second implementation of a circularly polarized cavity-backed slot antenna: (a) at 3.4 GHz; (d) at 3.5 GHz; (g) (ii), (h) and (i) at 3.6 GHz;
fig. 17 shows measured (Mea.) and simulated (Sim.) AR beamwidths at different frequencies for the second implementation of the circularly polarized cavity-backed slot antenna: (a) at 3.4 GHz; (b) at 3.5 GHz; (c) at 3.6 GHz.
In the drawings, each reference numeral denotes: 1. tuning the cavity; 11. a radiation gap; 12. a feed gap; 13. A side wall; 2. a feed cavity; 21. a coaxial feed terminal; 211. a central feed line; 3. a disturbing piece.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example (b):
in this embodiment, with reference to fig. 1-2, there is provided a circularly polarized cavity-backed slot antenna, comprising: the tuning cavity body 1, the feed cavity body 2 and the disturbing piece 3 are all made of metal materials, the tuning cavity body 1 comprises a first panel, a second panel opposite to the first panel and a side wall 13 connected between the first panel and the second panel, the first panel is provided with a radiation gap 11, the radiation gap 11 is of a smooth-edge hole-shaped structure, the second panel is provided with a feed gap 12, the feed cavity body 2 is connected to the side of the second panel, which is far away from the first panel, the feed cavity body 2 surrounds the feed gap 12, the feed cavity body 2 is connected with a coaxial feed terminal 21, a central feed line 211 of the coaxial feed terminal 21 extends into the feed cavity body 2, the inner side of the side wall 13 is connected with two disturbing pieces 3, the disturbing piece 3 is provided with an inward reflecting surface, an included angle is formed between the reflecting surface and the length direction of the feed gap 12, and the first panel, the second panel, the feed cavity body 2 and the disturbing piece 3 are all made of metal materials, The side wall 13 and the reflecting surface together enclose a resonant cavity.
Signals can be fed from the feed slot 12 through the feed cavity 2 and the coaxial feed terminal 21, two degenerate cavity modes facing the CP radiation can be generated through the two perturbators 3, and the smooth hole-like structure of the radiation slot 11 can radiate the signals. The antenna has the advantages of simple structure, stable radiation gain and directional diagram, higher AR bandwidth and wider AR beam width.
In the present embodiment, the first panel and the second panel are parallel to each other; the first panel and the second panel are squares with the same width, and the distance between the first panel and the second panel is smaller than the width of the first panel; the two disturbing pieces 3 are centrally and symmetrically distributed around the feed gap 12, and the symmetric center is the center of the feed gap 12; the reflecting surface is vertical to the first panel; the angle between the reflecting surface and the length of the feed slot 12 is between 30 and 60. Specifically, in the present embodiment, the tuning cavity 1 is a cuboid structure as a whole, so that the inside of the tuning cavity 1 is a cuboid cavity, the disturbing component 3 is a triangular prism with an isosceles right triangle cross section, the two disturbing components 3 are respectively disposed at two opposite corner positions in the tuning cavity 1, and two faces of the disturbing component 3 are respectively attached to the wall surface of the side wall 13, the disturbing component 3 can be integrally formed with the side wall 13, the disturbing component 3 can also be formed separately from the side wall 13 and connected to the side wall 13 by welding or bonding, the feeding gap 12 is a rectangular hole, the length direction of the feeding gap 12 is parallel to one side of the first panel, the center of the feeding gap 12 is directly opposite to the center of the second panel, so that the included angle between the reflection surface and the length direction of the feeding gap 12 is 45 °, by such a structure, CP radiation can be realized, that two modes can be generated by the disturbing component 3, the two modes can generate CP radiation, and a higher AR bandwidth and a wider AR beam width can be obtained, for the TE101 mode and the TE011 mode, respectively. It should be understood that the foregoing detailed description is only a preferred embodiment, and in some embodiments, the shape of the tuning cavity 1 may be adaptively adjusted, for example, the first panel and the second panel of the tuning cavity 1 are both rectangular, so that the tuning cavity 1 has a rectangular shape with unequal length, width, height and size as a whole; in some embodiments, the first and second panels have the same contour size, and may be circular, regular pentagonal, regular hexagonal, regular heptagonal, etc., so that the tuning cavity 1 may have a cylindrical shape, a regular pentagonal prism shape, a regular hexagonal prism shape, a regular heptagonal prism shape, etc. as a whole; in some embodiments, the perturbation elements 3 may not be arranged around the feed slot 12 in a central symmetry manner, as long as the reflecting surfaces of the two perturbation elements 3 and the length direction of the feed slot 12 are ensured to have an included angle, and the two reflecting surfaces are parallel to each other, and the included angle between the reflecting surface and the length direction of the feed slot 12 may be 30 °, 35 °, 40 °, 45 °, 50 °, 55 °, 60 °, and so on.
In the present embodiment, the center feed line 211 is parallel to the plate surface of the second panel, and the center feed line 211 is perpendicular to the length direction of the feed slot 12; the ratio of the length of the central feed line 211 extending into the feed cavity 2 to the length of the feed slot 12 is in the range 0.3-0.8.
In this embodiment, two implementations of the circularly polarized cavity-backed slot antenna are provided.
With reference to fig. 1, in a first implementation:
the radiation slot 11 is circular, and the center of the radiation slot 11 is opposite to the center of the feed slot 12; the ratio of the diameter of the radiating slot 11 to the length of the feed slot 12 is between 0.6 and 1.2, e.g. 0.7, 0.8, 0.9, 1.0, 1.1, etc.; the ratio of the length of the feed slot 12 to the width of the feed slot 12 is in the range of 2-10, e.g. 3, 4, 5, 6, 7, 8, 9, etc.
Specifically, in this implementation, the length a of the cavity of the tuning cavity 11 is 60mm, the width b of the cavity of the tuning cavity 11 is 60mm, the height c of the cavity of the tuning cavity 11 is 50mm, the length p of the cavity of the feeding cavity 2 is 50mm, the width q of the cavity of the feeding cavity 2 is 22mm, the height s of the cavity of the feeding cavity 2 is 20mm, the radius R of the radiation slot 11 is 17mm, the right-angle side length l of the cross section of the perturbation element 3 is 12mm, the length Lf of the feeding slot 12 is 36mm, the width Wf of the feeding slot 12 is 8mm, the distance Dp between the center feeding line 211 and the second panel is 6mm, the length Lp of the center 211 extending into the feeding cavity 2 is 18mm, the thickness t1 of the first panel is 2mm, and the thickness t2 of the second panel is 2 mm.
In this implementation, the cavity parameters of the tuning cavity 1 may be adaptively set for operating waves (wavelength λ) of different operating frequencies, and preferably, the length a of the cavity of the tuning cavity 1 is 0.75 λ, the width b of the cavity of the tuning cavity 1 is 0.75 λ, and the height c of the cavity of the tuning cavity 1 is 0.62 λ.
It should be understood that the above parameters of the antenna of this implementation are only exemplary and preferred, and in practical applications, each of the above parameters may be adjusted adaptively, and in the case where the tuning cavity 1 and the feeding cavity 2 are both rectangular parallelepiped structures, the length a of the inner cavity of the tuning cavity 1 may be selected from 20mm to 150mm, such as 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65 mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm, and so on, and the ratio of the size of the rest parameters to the length a of the inner cavity of the tuning cavity 1 may be varied up and down, and the ratio of the up and down variation may be between 0% and 50%, such as 5%, 10%, or so on, 15%, 20%, 25%, 30%, 35%, 40%, 45%, etc., taking the length a of the inner cavity of the tuning cavity 1 as 120mm, and the height c of the inner cavity of the tuning cavity 1 as 10%, where c may be set to 120 × 50/60 (1+ 10%) -110 mm, and other parameters may be adaptively set according to this manner, which is not described herein again.
With reference to fig. 2, in a second implementation:
the radiation slot 11 is oval, the center of the radiation slot 11 is opposite to the center of the feed slot 12, and an included angle is formed between the long axis direction of the radiation slot 11 and the length direction of the feed slot 12. Preferably, the long axis direction of the radiation slot 11 is perpendicular to the length direction of the feed slot 12, and the ratio of the long axis diameter of the radiation slot 11 to the short axis diameter of the radiation slot 11 is 1.05-3, such as 1.10, 1.20, 1.40, 1.60, 1.80, 2.00, 2.20, 2.40, 2.60, 2.80, etc.; the ratio of the major axis diameter of the radiating slot 11 to the length of the feed slot 12 is in the range of 0.8-2 and the ratio of the length of the feed slot 12 to the width of the feed slot 12 is in the range of 2-10, e.g. 3, 4, 5, 6, 7, 8, 9, etc.
Specifically, in this implementation, the length a of the cavity of the tuning cavity 1 is 60mm, the width b of the cavity of the tuning cavity 1 is 60mm, the height c of the cavity of the tuning cavity 1 is 50mm, the length p of the cavity of the feeding cavity 2 is 50mm, the width q of the cavity of the feeding cavity 2 is 22mm, the height s of the cavity of the feeding cavity 2 is 20mm, the major axis diameter Ly of the radiation slot 11 is 57mm, the minor axis diameter Lx of the radiation slot 11 is 57mm, the right-angle side length Lt of the cross section of the perturbation 3 is 22mm, the length Lf of the feeding slot 12 is 45mm, the width Wf of the feeding slot 12 is 12mm, the distance Dp between the center 211 and the second panel is 9mm, the length Lp of the center 211 extending into the feeding cavity 2 is 16mm, the thickness t1 of the first panel is 2mm, and the thickness t 2mm of the second panel is 2 mm.
In this implementation, the cavity parameters of the tuning cavity 1 may be adaptively set for operating waves (wavelength λ) of different operating frequencies, and preferably, the length a of the cavity of the tuning cavity 1 is 0.75 λ, the width b of the cavity of the tuning cavity 1 is 0.75 λ, and the height c of the cavity of the tuning cavity 1 is 0.62 λ.
It should be understood that the above parameters of the antenna of this implementation are only exemplary and preferred, and in practical applications, each of the above parameters may be adjusted adaptively, and in the case where the tuning cavity 1 and the feeding cavity 2 are both rectangular parallelepiped structures, the length a of the inner cavity of the tuning cavity 1 may be selected from 20mm to 150mm, such as 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65 mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm, and so on, and the ratio of the size of the rest parameters to the length a of the inner cavity of the tuning cavity 1 may be varied up and down, and the ratio of the up and down variation may be between 0% and 50%, such as 5%, 10%, or so on, 15%, 20%, 25%, 30%, 35%, 40%, 45%, etc., taking the length a of the inner cavity of the tuning cavity 1 as 120mm, and the height c of the inner cavity of the tuning cavity 1 as 10%, c may be set to 120 × 50/60 (1-10%) -90 mm, and other parameters may be adaptively set according to this manner, which is not described herein again.
The following design analysis is carried out on the circularly polarized cavity-backed slot antenna of the scheme:
fig. 1 shows the structure of the proposed circularly polarized cavity-backed slot antenna, in which cavity modes TE101 and TE011 are used to obtain CP radiation. Their original resonance frequencies are calculated by equations (1) and (2), respectively:
v represents the wave velocity in free space, and a, b and c are the length, width and height of the cavity of the tuning cavity 1, respectively. Since TE101 and TE011 modes are considered a pair of degenerate modes and are likely to be used to design CP antennas under appropriate perturbations, their original frequencies are set to be the same, i.e., a-b.
The perturbation element 3 generates perturbation to the cavity mode TE101, thereby generating a new cavity mode TE 011. These two modes have orthogonal field distributions, which can be used to achieve CP radiation with appropriate perturbation. Fig. 3 shows simulated | S11| and Axial Ratio (AR) without perturbation 3(Lt 0mm) and with perturbation 3(Lt 12 mm). It can be seen that when Lt is 0mm, only a single mode (TE101 mode) is excited. The frequency difference between the simulation result (3.68ghz) and the calculation result (3.93ghz) is due to the loading effect of the feed slot 12 and the radiation slot 11. Under the action of the perturbation 3(Lt ═ 12mm), another mode, namely TE011 mode, is generated. It can be seen that the TE101 mode is still resonant at its original frequency of 3.68ghz, while the TE011 mode is resonant at the higher frequency of 3.78 ghz. Their electric field distributions are shown in fig. 4(a) and (b), respectively; as shown in fig. 4(c) and (d), these two modes produce CP radiation at about 3.75GHz because they have the same amplitude and 90 ° phase difference. The AR bandwidth in fig. 3 reaches about 1.0%.
As can be seen from equation (1), the cavity size affects the resonant frequency of the cavity modes, and thus the impedance band and the AR band operating frequency of the antenna. To understand this, the effect of cavity size on the antenna is shown in fig. 5. It can be seen that the operating frequency of the antenna gradually decreases with increasing size of the resonant cavity, which is consistent with the results obtained from equation (1).
Improvements in AR bandwidth
We then discuss the improvement of AR bandwidth. The result shows that under the action of two degenerate modes and one antenna unit, the AR bandwidth can be improved without introducing an additional feed network or a coupling structure.
Ideal CP radiation with AR ═ 1 is obtained under the conditions of Ex ═ Ey and ═ Ex ═ Ey ═ 90 °, where Ex and Ey are the two electric field components from which the CP wave is obtained. To obtain a wider AR bandwidth, two requirements should be met:
a) the amplitude ratio Ex/Ey is approximately equal to 1 over a wide frequency range.
b) The phase difference is equal to about 90 ° in the same frequency range as required for (a).
In such a CP slot antenna, the main perturbation is caused by the perturber 3 and the radiating slot 11. Their effect on the amplitude ratio and phase difference of Ex and Ey is shown in fig. 6. Fig. 6(a) shows that increasing Lt alone (case 1 to case 2) and increasing R alone (case 1 to case 3) cannot improve the AR bandwidth because they both result in an amplitude ratio exceeding 3 db. Increasing Lt and R simultaneously (case 1 to case 4 to case 5) can broaden the bandwidth with amplitude ratio around ± 3 dB. Fig. 6(b) also shows that the simultaneous increase of Lt and R can widen the bandwidth with a phase difference around 90 ° (90 ° ± 15 °). Therefore, the simultaneous increase of Lt and R can surely satisfy the requirements of (a) and (b), thereby widening the AR bandwidth.
Fig. 7 shows simulated AR for different dimensions of perturber 3 and radiation slot 11. It can be seen that the AR bandwidth increases when Lt and R increase simultaneously. The 3db AR bandwidth ranges from 3.73 to 3.9ghz, and is 4.5% wider than the original 1.0% for Lt 22 and R21. Previous analysis of AR bandwidth improvement was based on a circular radiation slit 11. To further increase the AR bandwidth, the circular radiation slit 11 is replaced by an elliptical radiation slit 11, as shown in fig. 8. The elliptical radiation slit 11 has different diameters in the x-axis and the y-axis, and produces different perturbations to the two degenerate modes, possibly widening the AR bandwidth. Fig. 8 shows the effect of increasing the y-axis diameter (Ly) while keeping the x-axis diameter (Lx) constant. It can be seen that the AR bandwidth increases from 4.5% to 10.3% as Ly increases from 42mm to 58 mm. To more clearly understand the working mechanism, fig. 9 shows the electric field directions on the radiation slits 11 at different periods and different frequencies. It can be seen that the electric fields at 3.4GHz, 3.5GHz and 3.6GHz are all 90 deg. out of phase between adjacent quarter-cycle instances.
AR beamwidth analysis
Then, the performance of the AR beamwidth is given. Fig. 10 shows the Ex and Ey amplitude ratios and phase differences in the XZ plane and YZ plane as a function of theta. The amplitude ratio of the XZ plane in the angle range of-74 degrees to +74 degrees is within +/-2 dB, the amplitude ratio in the angle range of-80 degrees to +80 degrees is within +/-3 dB, and the phase difference in the angle range of-85 degrees to +85 degrees is between 90 degrees and 100 degrees. The amplitude ratio of a YZ plane in an angle range of-70 degrees to +70 degrees is within +/-2 dB, the amplitude ratio in an angle range of-82 degrees to +82 degrees is within +/-3 dB, and the phase difference in an angle range of-86 degrees to +86 degrees is between 89 degrees and 94 degrees. Therefore, as can be understood from fig. 11, the proposed CP antenna can widen the relevant AR beam width. The 3db AR beamwidths for the XZ plane and YZ plane are 156 ° and 160 °, respectively. Intrinsic factors of wide AR beamwidth are: (1) a single resonant cavity introduces a relatively small antenna size, so that a wide radiation beam width can be kept; (2) the back cavity acts as a finite ground plane, reshaping the radiation patterns on the E-plane and H-plane and then making the two radiation modes more similar.
Impedance matching
After the radiation performance of the antenna is determined, the input impedance of the antenna is also determined. In order to obtain a good impedance match, the impedance of the feed structure should be matched to the input impedance of the antenna. In such an antenna, the impedance of the feed structure is mainly affected by the dimensions of the feed slot 12, feed cavity 2 and central feed line 211 protruding into the feed cavity 2. Two main parameters are investigated here, namely the length (Lf) and the width (Wf) of the feed slot 12. As can be seen from fig. 12, the increase in Lf and Wf both produce good impedance matching at the desired frequency band.
Comparison of wideband and narrowband antennas
A comparison of a wideband (elliptical radiating slot 11) and narrowband (circular radiating slot 11) CP slot antenna is shown in fig. 13. The Impedance Bandwidth (IBW) and AR bandwidth (ARBW) increased from 2% and 1.0% to 18.7% and 10.3%, respectively. Enhanced bandwidth is obtained without increasing antenna size (conversely, decreasing antenna size due to a decrease in operating frequency) or complicating the antenna structure. In addition, the realized gain is increased by 1db, and the aperture efficiency is improved from 57-59 percent to 78-88 percent.
Results of the experiment
After the CP slot antenna is designed, a prototype machine is manufactured, and experimental verification is carried out. A photograph of the antenna is shown in fig. 14. Fig. 15 shows the measurement and simulation results as a function of frequency. The bandwidth measured at 3.45ghz (3.29-3.62ghz) was 9.5% and was slightly narrower than the 10.3% bandwidth at the simulated 3.5ghz (3.32-3.68 ghz). The antenna has a flat in-band gain of 7.65 + -0.15 dbic due to the use of two similar degenerate cavity modes. The measured total efficiency is 93% -97%, while the simulated total efficiency is 98% -99.5%, both of which have very low power consumption. At 3.3ghz, the pore efficiency is greater than 70%, the peak efficiency is 91%, and the simulated pore efficiency is greater than 78%.
Fig. 16 shows the radiation patterns at 3.4GHz, 3.5GHz and 3.6GHz in the plane of 0 °, 45 ° and 90 ° indicating that the measured co-polarization (LHCP) is almost the same as simulated and that the measured cross-polarization (RHCP) is better than-20 dB. We can also see that the co-polarization at these three frequencies is almost the same, indicating that the radiation pattern is stable over the operating band. As shown in fig. 17, the AR beamwidths of the CP slot antenna at three planes indicate that the proposed antenna has a wide AR beamwidth over a wide frequency range. The 3db-AR beamwidths of the XZ and YZ planes, 3.4ghz, 3.5ghz, and 3.6ghz, are each greater than 140, and the diagonal plane 3db-AR beamwidths are each greater than 120. The detailed results of the measured AR beamwidth are shown in table one.
Table one: 3dB axial ratio beam width under different frequencies
Conclusion
According to the circularly polarized cavity-backed slot antenna, the triangular prism-shaped disturbing piece 3 is introduced, and two degenerate cavity modes TE101 and TE011 facing CP radiation are generated by the disturbing piece 3. By appropriate variation of the dimensions of the perturber 3 and the radiating slot 11, it has been demonstrated that the proposed CP slot antenna achieves an AR bandwidth of about 10.3% on the basis of a single pair of degenerate modes, wider than the initial 1%. This work leads to a new idea that degenerate modes can also be used to obtain wider AR bandwidths without introducing ultra-wideband feeding networks or coupling structures. The single-cavity and back-cavity antenna structure can simultaneously obtain wider AR beam width and enhanced AR bandwidth. Finally, an antenna prototype is manufactured and tested, and the result shows that the actually measured AR wave beam width exceeds 140 degrees, and the AR bandwidth is 9.5 percent. In addition, the slot antenna also has the advantages of high radiation efficiency, high aperture efficiency, stable gain, stable radiation pattern and the like.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A circularly polarized cavity-backed slot antenna, comprising: the tuning cavity body (1), the feed cavity body (2) and the disturbing piece (3) are all made of metal materials, the tuning cavity body (1), the feed cavity body (2) and the disturbing piece (3) are made of metal materials, the tuning cavity body (1) comprises a first panel, a second panel opposite to the first panel and a side wall (13) connected between the first panel and the second panel, the first panel is provided with a radiation gap (11), the radiation gap (11) is of a hole-shaped structure with smooth edges, the second panel is provided with a feed gap (12), the feed cavity body (2) is connected to the side of the second panel, which is far away from the first panel, the feed cavity body (2) surrounds the feed gap (12), the feed cavity body (2) is connected with a coaxial feed terminal (21), and a central feed line (211) of the coaxial feed terminal (21) extends into the feed cavity body (2), the inner side of the side wall (13) is connected with two disturbing pieces (3), the disturbing pieces (3) are provided with inward reflecting surfaces, an included angle is formed between the reflecting surfaces and the length direction of the feed gap (12), and the first panel, the second panel, the side wall (13) and the reflecting surfaces jointly enclose to form a resonant cavity.
2. The circularly polarized cavity-backed slot antenna of claim 1, wherein the first and second panels are parallel to each other;
the two disturbing pieces (3) are centrally and symmetrically distributed around the feed gap (12), and the symmetric center is the center of the feed gap (12); the reflective surface is perpendicular to the first panel.
3. The circularly polarized cavity-backed slot antenna of claim 2, wherein the angle between the reflecting surface and the length of the feed slot (12) is between 30 ° and 60 °.
4. The circularly polarized cavity-backed slot antenna of claim 2, characterized in that the radiating slot (11) is circular, and the center of the radiating slot (11) and the center of the feed slot (12) are aligned.
5. The circularly polarized cavity-backed slot antenna according to claim 4, characterized in that the ratio of the diameter of the radiating slot (11) to the length of the feed slot (12) is between 0.6 and 1.2; the ratio of the length of the feed slot (12) to the width of the feed slot (12) is between 2 and 10.
6. The circularly polarized cavity-backed slot antenna according to claim 2, wherein the radiating slot (11) has an elliptical shape, the center of the radiating slot (11) is opposite to the center of the feeding slot (12), and an included angle is formed between the long axis direction of the radiating slot (11) and the length direction of the feeding slot (12).
7. The circularly polarized cavity-backed slot antenna according to claim 6, wherein the long axis direction of the radiation slot (11) is perpendicular to the length direction of the feed slot (12), the ratio of the long axis diameter of the radiation slot (11) to the short axis diameter of the radiation slot (11) is 1.05-3, the ratio of the long axis diameter of the radiation slot (11) to the length of the feed slot (12) is 0.8-2, and the ratio of the length of the feed slot (12) to the width of the feed slot (12) is 2-10.
8. The circularly polarized cavity-backed slot antenna according to any of claims 1 to 7, wherein the central feed line (211) is parallel to the second panel plane, and the central feed line (211) is perpendicular to the length direction of the feed slot (12).
9. The circularly polarized cavity-backed slot antenna of claim 8, wherein the ratio of the length of the central feed line (211) extending into the feed cavity (2) to the length of the feed slot (12) is in the range of 0.3-0.8.
10. The circularly polarized cavity-backed slot antenna of claim 8, wherein the first and second panels are square with the same width, and wherein the distance between the first and second panels is less than the width of the first panel.
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| WO2024001837A1 (en) * | 2022-06-27 | 2024-01-04 | 华为技术有限公司 | Electronic device |
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