Novel three-frequency-band common-caliber antenna

Abstract

A novel three-frequency-band common-caliber antenna comprises a dielectric plate, a frequency selection surface, a low-frequency dipole antenna, an intermediate-frequency dipole antenna, a high-frequency dipole antenna, a Y-shaped feed branch knot and a metal floor. Two LC resonant circuits are introduced into the frequency selective surface, so that the frequency selective surface has a dual-band band-pass characteristic, the transmission coefficient at the frequency bands of 3.3-3.8 GHz and 4.6-4.9 GHz is greater than-0.5 dB, and electromagnetic waves are almost transmitted from a port 1 to a port 2; the FSS and the low-frequency dipole antenna are fused, so that the low-frequency dipole antenna has the electromagnetic transparent characteristic in a middle frequency band and a high frequency band, electromagnetic waves can be spread without shielding, and the far-field pattern of the middle-frequency dipole antenna and the far-field pattern of the high-frequency dipole antenna are basically kept consistent with independent radiation; according to the intermediate-frequency dipole antenna, the miniaturization of the antenna is realized by bending a dipole arm to prolong a current path; the three frequency band antennas are placed in the same aperture, and can work normally; according to the invention, under the condition of not additionally increasing the space occupation area of the base station antenna equipment, the signal coverage of multiple network systems can be realized, and the situation of shortage of base station site resources can be relieved.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a novel three-band common aperture antenna. Background Art

[0002] With the rapid development of modern wireless communication systems, a large number of high-tech and product innovations have promoted the rapid development of contemporary society. As an important part of the wireless communication system, the radiation performance of the antenna directly affects the working performance of the communication system. Therefore, the demand for antennas is becoming more and more stringent, requiring not only the antenna to be miniaturized in size, but also to be multifunctional. The common aperture antenna allows communication or radar systems with different polarizations, different frequency bands, and different bandwidths to work within the same antenna aperture. This greatly reduces the space required for the antenna system and effectively utilizes the space size, which is especially important for equipment with strict space constraints.

[0003] When antennas of multiple frequency bands are installed simultaneously in a limited space, there is often a large electromagnetic coupling between them, which leads to mutual interference caused by coupling and ultimately affects the various electrical properties of the antenna, such as deteriorating the S parameter characteristics of the base station antenna (such as poor antenna impedance matching and reduced antenna frequency isolation) and causing distortion of the antenna radiation pattern. Distortion of the radiation pattern will seriously affect the coverage capability of the antenna and even make it unable to work normally. How to reasonably solve the mutual coupling of antennas with different functions is a difficult and key problem to be solved in the design of co-aperture antennas. Otherwise, the advantages of co-aperture antennas will be lost and the limited space cannot be fully utilized. The document [HE D, YU Q, CHEN Y, et al. Dual-Band Shared-Aperture Base Station Antenna Array With Electromagnetic Transparent Antenna Elements [J]. IEEE Transactions on Antennas and Propagation, 2021, 69(9): 5596-5606.] discloses a co-aperture antenna, which only realizes a dual-band co-aperture antenna with a coverage frequency band of 1.7-2.7 GHz and 3.3-3.8 GHz, and cannot achieve coverage of the 5G high-frequency band. The document [HE D, CHEN Y, YANG SA Low-Profile Triple-Band Shared-Aperture Antenna Array for 5G Base Station Applications[J]. IEEE Transactions on Antennas and Propagation, 2022, 70(4): 2732-2739.] discloses a co-aperture antenna. Through a stacked design, the frequency selective surface is located between the low-frequency antenna and the high-frequency antenna, which increases the profile height of the entire antenna system and is not conducive to installing the co-aperture antenna in a limited space. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a new type of three-band co-aperture antenna. In view of the radiation shielding problem of low-frequency dipole antenna when antennas of different frequency bands are in the co-aperture state, the directional diagram of medium and high frequency dipole antennas is conformal by realizing structural multiplexing of frequency selective surface and low-frequency dipole antenna, thereby suppressing the strong coupling between antennas of different frequency bands and preventing the deterioration of antenna performance, thereby ensuring the radiation range of the antenna; the three-band co-aperture antenna of the present invention can integrate base station antennas of three different frequency bands in a limited space, achieving extremely high integration, and multiple frequency bands of low, medium and high frequency antennas can work normally under the same aperture surface; thereby realizing the setting of high and low frequency networking, miniaturization and strong applicability.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A novel three-band co-aperture antenna includes a plurality of arranged co-aperture antenna subarrays, each of which includes a metal floor 19 and a low-frequency dipole antenna 5 arranged in the middle of the metal floor 19; an intermediate frequency dipole antenna 9 and a high frequency dipole antenna 15 are respectively arranged at the four corners of the metal floor 19 around the low-frequency dipole antenna 5, and the intermediate frequency dipole antenna 9 is located on one side of the low-frequency dipole antenna 5, and the high frequency dipole antenna 15 is located on the other side of the low-frequency dipole antenna 5.

[0007] The low-frequency dipole antenna 5 comprises a first dielectric plate 1, wherein two orthogonal first Y-type feeding branches 6 are printed in the middle of the upper surface of the first dielectric plate 1, and a first jumper 7 is used at the intersection of the two first Y-type feeding branches 6 to avoid topological crossing; orthogonal frequency selective surface units 4 are printed at the four corners of the lower surface of the first dielectric plate 1, and two pairs of frequency selective surface units 4 are used as dipole arms to realize structural multiplexing to form a ±45° dipole antenna; a first coaxial feed line 8 is connected between the low-frequency dipole antenna 5 and the metal floor 19, wherein one end of the shielding layer of the first coaxial feed line 8 is connected to the low-frequency dipole antenna 5, and the other end is connected to the metal floor 19, one end of the inner core of the first coaxial feed line 8 is connected to the first Y-type feeding branch 6, and the other end is connected to the feed source to realize coupled feeding.

[0008] The intermediate frequency dipole antenna 9 includes a second dielectric plate 2, and two orthogonal second Y-type feeding branches 10 are printed on the upper surface of the second dielectric plate 2, and the intersection of the two second Y-type feeding branches 10 is isolated by a second jump bridge 11; orthogonal curved dipole arms 21 are printed on the lower surface of the second dielectric plate 2, and two pairs of curved dipole arms 21 form a ±45° dipole antenna; a second coaxial feed line 12 is connected between the intermediate frequency dipole antenna 9 and the metal floor 19, one end of the shielding layer of the second coaxial feed line 12 is connected to the intermediate frequency dipole antenna 9, and the other end is connected to the metal floor 19, one end of the inner core of the second coaxial feed line 12 is connected to the second Y-type feeding branch 10, and the other end is connected to the feed source to realize coupled feeding.

[0009] The high-frequency dipole antenna 15 includes a third dielectric plate 3, and two orthogonal third Y-type feeding branches 16 are printed on the upper surface of the third dielectric plate 3, and the intersection of the two third Y-type feeding branches 16 is isolated by a third jump bridge 17; orthogonal rectangular dipole arms 22 are printed on the lower surface of the third dielectric plate 3, and two pairs of rectangular dipole arms 22 form a ±45° dipole antenna; a third coaxial feed line 18 is connected between the high-frequency dipole antenna 15 and the metal floor 19, one end of the shielding layer of the third coaxial feed line 18 is connected to the high-frequency dipole antenna 15, and the other end is connected to the metal floor 19, one end of the inner core of the third coaxial feed line 18 is connected to the third Y-type feeding branch 16, and the other end is connected to the feed source to realize coupled feeding.

[0010] A fixed base 13 is provided at the bottom of the intermediate frequency dipole antenna 9 and the high frequency dipole antenna 15 and on the metal floor 19. The fixed base 13 is covered with copper metal on the top and bottom. A metal through hole 14 is etched on the fixed base 13 to realize the connection between the coaxial feeder and the metal floor 19.

[0011] The first dielectric plate 1 , the second dielectric plate 2 , and the third dielectric plate 3 are all made of Rogers 4003 plate.

[0012] The material of the fixing base 13 is FR4.

[0013] The three-band common aperture antenna operates in the sub-6G band of the base station, covering the n77-n79 band, wherein the low frequency operates in the 1.7-2.7GHz band; the medium frequency antenna operates in the 3.3-3.8GHz band; and the high frequency antenna operates in the 4.6-4.9GHz band.

[0014] The frequency selective surface unit 4 includes two LC resonant circuits, which realize bandpass characteristics in the medium and high frequency bands; wherein the period P of the frequency selective surface unit 4 is 25 mm, and the width W of the outermost rectangular patch is 1 = 1.5 mm, the gap between the outermost rectangular patches 1= 0.5 mm, the width W of the cross-shaped gap etched in the center of the inner rectangular patch 3 = 1.3 mm, and the length L of the inner rectangular patch 1 =19.4 mm.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] When three traditional dipole antennas of different frequency bands are radiating under the same aperture, since the electrical size of the low-frequency dipole antenna is larger than that of the high-frequency dipole antenna, when the high-frequency dipole antenna radiates, a high-frequency induced current will exist in the low-frequency dipole antenna. When the scattered field of the low-frequency dipole antenna is superimposed on the radiation field of the high-frequency dipole antenna, the radiation pattern of the high-frequency dipole antenna will be distorted.

[0017] The three-band common aperture antenna disclosed in the present invention first designs a dual-band pass frequency selective surface 4 so that it exhibits passband characteristics in the 3.3-3.8GHz and 4.6-4.9GHz frequency bands, and its transmission coefficient is greater than -0.5dB. The frequency selective surface is integrated with the low-frequency dipole antenna so that the low-frequency antenna serves as both a radiation subject and a frequency selective surface. It exhibits low scattering characteristics in the medium and high frequency bands, so that medium and high frequency electromagnetic waves can be transmitted without obstruction, thereby achieving the function of pattern conformality in both frequency bands of 3.3-3.8GHz and 4.6-4.9GHz. The zenith gain and beam width of the medium and high frequency dipole antenna patterns are consistent with those when radiated alone, so that the three-band antenna can work normally under the same aperture surface. At the same time, the medium-frequency dipole antenna realizes a miniaturized design by bending the dipole arm to extend the current path, which is conducive to subsequent array design. At the same time, the three-band common aperture antenna of the present invention has good port isolation characteristics, and its port isolation is greater than 20dB.

[0018] In summary, the present invention aims to solve the radiation shielding problem of low-frequency dipole antennas when antennas of different frequency bands are in the same aperture state. The frequency selective surface and the low-frequency dipole antenna are used to realize structural multiplexing to achieve conformal alignment of the directional patterns of medium- and high-frequency dipole antennas, thereby suppressing the strong coupling between antennas of different frequency bands and preventing the deterioration of antenna performance, thereby ensuring the radiation range of the antenna. The three-band common aperture antenna of the present invention can integrate base station antennas of three different frequency bands in a limited space, achieving an extremely high level of integration, and multiple frequency bands of low, medium, and high-frequency antennas can all work normally under the same aperture surface. This enables the design of high- and low-frequency networking, miniaturization, and strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a three-dimensional diagram of the three-frequency common aperture antenna in the present invention.

[0020] Figure 2 It is a top view of the frequency selective surface unit 4 in the present invention.

[0021] Figure 3 (a) is the lower surface of the first dielectric plate 1 of the low-frequency dipole antenna of the present invention, Figure 3 (b) is the upper surface of the first dielectric plate 1 of the low-frequency dipole antenna of the present invention.

[0022] Figure 4 (a) is the lower surface of the second dielectric plate 2 of the intermediate frequency dipole antenna in the present invention, Figure 4 (b) is the upper surface of the second dielectric plate 2 of the intermediate frequency dipole antenna in the present invention.

[0023] Figure 5 (a) is the lower surface of the third dielectric plate 3 of the high frequency dipole antenna of the present invention, Figure 5 (b) is the upper surface of the third dielectric plate 3 of the high frequency dipole antenna of the present invention.

[0024] Figure 6 It is the S parameter curve of the frequency selective surface unit 4 in the present invention.

[0025] Figure 7 This is a comparison of the radiation patterns of the intermediate frequency antenna at a typical frequency of 3.5 GHz in the present invention, where: Figure 7 (a) is the E-plane directional diagram, Figure 7 (b) is the H-plane direction diagram.

[0026] Figure 8 It is the reflection coefficient curve of the intermediate frequency antenna in the present invention.

[0027] Fig. 9 This is the isolation curve of the intermediate frequency antenna port in the present invention.

[0028] Fig.10 This is a comparison of the radiation patterns of the high-frequency antenna of the present invention at a typical frequency of 4.8 GHz, where: Fig.10 (a) is the E-plane directional diagram, Fig.10 (b) is the H-plane direction diagram.

[0029] Fig.11 It is the reflection coefficient curve of the high frequency antenna in the present invention.

[0030] Fig.12 This is the isolation curve of the high-frequency antenna port in the present invention.

[0031] Fig.13 It is the radiation pattern of the low frequency antenna at typical frequency points of the present invention.

[0032] Fig.14 It is the reflection coefficient curve of the low-frequency antenna in the present invention.

[0033] Fig.15This is the gain curve of the low-frequency antenna in the present invention.

[0034] As shown in the figure: 1. first dielectric plate; 2. second dielectric plate; 3. third dielectric plate; 4. frequency selective surface unit; 5. low frequency dipole antenna; 6. first Y-type feeding branch; 7. first jump bridge; 8. first coaxial feed line; 9. intermediate frequency dipole antenna; 10. second Y-type feeding branch; 11. second jump bridge; 12. second coaxial feed line; 13. fixed base; 14. metal through hole; 15. high frequency dipole antenna; 16. third Y-type feeding branch; 17. third jump bridge; 18. third coaxial feed line; 19. metal floor; 21. curved dipole arm; 22. rectangular dipole arm. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] The three-band common aperture antenna of the present invention mainly works in sub-6G, mainly covering the n77-n79 frequency band. The low-frequency antenna works at 1.7-2.7GHz, and has low scattering characteristics in the medium and high frequency bands; the medium-frequency antenna works at 3.3-3.8GHz; the high-frequency antenna works at 4.6-4.9GHz. Antennas of three different frequency bands work in the same aperture plane to form a stacked topology structure. All three maintain good impedance matching, and the radiation characteristics are almost the same as when radiating separately.

[0037] like Figure 1 A novel three-band co-aperture antenna includes a plurality of arranged co-aperture antenna subarrays, each of which includes a metal floor 19 and a low-frequency dipole antenna 5 arranged in the middle of the metal floor 19; an intermediate frequency dipole antenna 9 and a high frequency dipole antenna 15 are respectively arranged at the four corners of the metal floor 19 around the low-frequency dipole antenna 5, and the intermediate frequency dipole antenna 9 is located on one side of the low-frequency dipole antenna 5, and the high frequency dipole antenna 15 is located on the other side of the low-frequency dipole antenna 5.

[0038] The low-frequency dipole antenna 5 comprises a first dielectric plate 1, wherein two orthogonal first Y-type feeding branches 6 are printed in the middle of the upper surface of the first dielectric plate 1, and a first jumper 7 is used at the intersection of the two first Y-type feeding branches 6 to avoid topological crossing; orthogonal frequency selective surface units 4 are printed at the four corners of the lower surface of the first dielectric plate 1, and two pairs of frequency selective surface units 4 are used as dipole arms to realize structural multiplexing to form a ±45° dipole antenna; a first coaxial feed line 8 is connected between the low-frequency dipole antenna 5 and the metal floor 19, wherein one end of the shielding layer of the first coaxial feed line 8 is connected to the low-frequency dipole antenna 5, and the other end is connected to the metal floor 19, one end of the inner core of the first coaxial feed line 8 is connected to the first Y-type feeding branch 6, and the other end is connected to the feed source to realize coupled feeding.

[0039] The intermediate frequency dipole antenna 9 includes a second dielectric plate 2, and two orthogonal second Y-type feeding branches 10 are printed on the upper surface of the second dielectric plate 2, and the intersection of the two second Y-type feeding branches 10 is isolated by a second jump bridge 11; orthogonal curved dipole arms 21 are printed on the lower surface of the second dielectric plate 2, and two pairs of curved dipole arms 21 form a ±45° dipole antenna; a second coaxial feed line 12 is connected between the intermediate frequency dipole antenna 9 and the metal floor 19, one end of the shielding layer of the second coaxial feed line 12 is connected to the intermediate frequency dipole antenna 9, and the other end is connected to the metal floor 19, one end of the inner core of the second coaxial feed line 12 is connected to the second Y-type feeding branch 10, and the other end is connected to the feed source to realize coupled feeding.

[0040] The high-frequency dipole antenna 15 includes a third dielectric plate 3, and two orthogonal third Y-type feeding branches 16 are printed on the upper surface of the third dielectric plate 3, and the intersection of the two third Y-type feeding branches 16 is isolated by a third jump bridge 17; orthogonal rectangular dipole arms 22 are printed on the lower surface of the third dielectric plate 3, and two pairs of rectangular dipole arms 22 form a ±45° dipole antenna; a third coaxial feed line 18 is connected between the high-frequency dipole antenna 15 and the metal floor 19, one end of the shielding layer of the third coaxial feed line 18 is connected to the high-frequency dipole antenna 15, and the other end is connected to the metal floor 19, one end of the inner core of the third coaxial feed line 18 is connected to the third Y-type feeding branch 16, and the other end is connected to the feed source to realize coupled feeding.

[0041] A fixed base 13 is provided at the bottom of the intermediate frequency dipole antenna 9 and the high frequency dipole antenna 15 and on the metal floor 19. The fixed base 13 is covered with copper metal on the top and bottom. A metal through hole 14 is etched on the fixed base 13 to realize the connection between the coaxial feeder and the metal floor 19.

[0042] The first dielectric plate 1 , the second dielectric plate 2 , and the third dielectric plate 3 are all made of Rogers 4003 plate.

[0043] The material of the fixing base 13 is FR4.

[0044] The three-band common aperture antenna operates in the sub-6G band of the base station, covering the n77-n79 band, wherein the low frequency operates in the 1.7-2.7GHz band; the medium frequency antenna operates in the 3.3-3.8GHz band; and the high frequency antenna operates in the 4.6-4.9GHz band.

[0045] The three-band common aperture antenna is composed of 1 low-frequency antenna, 1×2 medium-frequency antennas, and 1×2 high-frequency antennas, forming a stacked topology layout. The three different frequency band antennas can achieve good impedance matching and stable gain curves in their operating frequency bands, and the radiation pattern is basically consistent with that when radiating alone.

[0046] Figure 2 The schematic diagram of the structure of the unit 4 of the frequency selective surface is given. It is evolved from the basic aperture type frequency selective surface, and two LC resonant circuits are introduced to achieve the bandpass characteristics in the medium and high frequency bands. The period of the frequency selective surface is P = 25 mm, and the width of the outermost rectangular patch is W 1 =1.5mm, the gap between patches 1 = 0.5 mm, the width W of the cross-shaped gap etched in the center of the inner rectangular patch 3 = 1.3 mm, and the length of the inner rectangular patch L 1 =19.4 mm.

[0047] Figure 3 A schematic diagram of the low-frequency antenna is given, and it can be seen that Figure 2 It is composed of a 2×2 frequency selective surface unit, forming a pair of dipole antennas with ±45° polarization. The fusion design of the low-frequency antenna and the frequency selective surface makes it both the radiating body of the low-frequency antenna and the frequency selection function. The size of the low-frequency antenna is basically the same as that of the frequency selective surface.

[0048] Figure 4 A schematic diagram of an intermediate frequency antenna is given. The intermediate frequency antenna achieves a miniaturized design by bending the dipole arm to extend the current path. The intermediate frequency antenna is printed under the second dielectric plate 2. The material of the second dielectric plate 2 is Rogers 4003 with a thickness of H. 1 =0.5 mm, width W 4 = 30 mm. The length of the medium frequency dipole arm L 2 =13 mm, width W 5 = 1.2 mm, the length of the folded portion of the bent dipole arm is L 3 = 2.3 mm. The second Y-shaped feeding branch 10 is printed on the second dielectric plate 2. The length of the feeding branch L 4 =2.45 mm, L 5= 2.3 mm. The inner core of the second coaxial line 12 is connected to the second Y-shaped feeding branch 10, and the outer core of the coaxial line is connected to the dipole arm. Meanwhile, the unit spacing of the intermediate frequency dipole antenna is 60 mm.

[0049] Figure 5 A schematic diagram of a high-frequency antenna is given. The high-frequency antenna is a pair of orthogonal dipole antennas that achieve ±45° polarized radiation. The high-frequency antenna is printed below the third dielectric plate 3. The material of the dielectric plate (3) is Rogers 4003, with a thickness of H. 2 =0.5 mm, width W 6 = 30 mm. The length of the high frequency dipole arm is L 6 =12.5 mm, width W 7 = 1 mm. The third Y-shaped feeding branch 16 is printed on the third dielectric plate 3. The length of the feeding branch L 7 =5.3 mm. The inner core of the third coaxial line 18 is connected to the third Y-shaped feeding branch 16, and the outer core of the coaxial line is connected to the high-frequency dipole antenna. At the same time, the unit spacing of the high-frequency dipole antenna is 55 mm.

[0050] Figure 6 It is the S parameter curve of the frequency selective surface in the present invention. It can be observed that it has a bandpass characteristic in the 3.3-3.8 GHz and 4.6-4.9 GHz frequency bands. In the working frequency band, its transmission coefficient S21 is less than -0.5 dB, which is in a fully transparent state, and the electromagnetic wave can be transmitted from port 1 to port 2 without obstruction.

[0051] Figure 7 The figure is a comparison of the directional patterns of the IF antenna at a typical frequency of 3.5 GHz in the present invention. Scheme 1, Scheme 2, and Scheme 3 are respectively the IF antenna radiates alone, the IF antenna is under a traditional dipole antenna, and the IF antenna is under a low scattering dipole antenna. Figure 7 (a) It can be observed that compared with state 1, the gain in the zenith direction of state 2 decreases significantly, the right side of the radiation pattern is squeezed, the beam width becomes narrower, and the coverage range becomes narrower. Figure 7 (b) It can be observed that compared with state 1, the gain in the zenith direction of state 2 decreases significantly, while the backward radiation energy increases. When the IF antenna is below the low-scattering dipole antenna, the radiation pattern is basically the same as when it radiates alone.

[0052] Figure 8 This is the reflection coefficient curve of the intermediate frequency antenna in the present invention. It can be seen that the reflection coefficient of the intermediate frequency antenna in the working frequency band of 3.3-3.8 GHz is less than -10 dB, and the impedance matching is good. Fig. 9 The port isolation curve of the intermediate frequency antenna shows that its isolation is less than -20dB in the working frequency band, and the port coupling between antennas is small.

[0053] Fig.10 This is a comparison of the directional patterns of the intermediate frequency antenna in the present invention at a typical frequency of 4.8 GHz. Fig.10 (a) It can be observed that compared with state 1, the right side of the directivity pattern in state 2 is squeezed, the beam width is narrowed, and the coverage range is narrowed. Fig.10 (b) It can be observed that the backward radiation energy of the pattern in state 2 increases compared with that in state 1. When the IF antenna is under the low-scattering dipole antenna, the pattern is basically consistent with that when it radiates alone, thus achieving pattern conformality.

[0054] Fig.11 This is the reflection coefficient curve of the intermediate frequency antenna in the present invention. It can be seen that the reflection coefficient of the intermediate frequency antenna in the working frequency band of 4.6-4.9 GHz is less than -10 dB, and the impedance matching is good. Fig.12 The port isolation curve of the intermediate frequency antenna shows that its isolation is less than -20dB in the working frequency band, and the port coupling between antennas is small.

[0055] Fig.13 This is the directional diagram of the low-frequency antenna of the present invention at the 2.2 GHz frequency point, and the zenith gain is 8 dBi, which is basically consistent with the single radiation; Fig.14 This is the reflection coefficient curve of the low-frequency antenna. In the 1.7-2.7GHz operating frequency band, the reflection coefficient is less than -10dB, and the impedance matching is good.

[0056] Fig.15 is the gain curve of the low-frequency antenna. For the low-frequency antenna, the medium and high-frequency antennas will also interfere with it. This is mainly because the feeding structure is equivalent to a top-loaded monopole mode. The vibrator arm of the high-frequency antenna is equivalent to capacitor loading, which makes the resonant frequency of the monopole antenna resonate in the low-frequency band. The radiation field of the top-loaded monopole antenna is superimposed on the radiation field of the low-frequency antenna itself, causing the radiation pattern of the low-frequency antenna to be distorted. By extending the grounding method, the frequency band where the high-frequency antenna generates common-mode interference is moved out of the working frequency band of the low-frequency antenna, allowing the low-frequency antenna to maintain a stable gain curve within the working frequency band. Fig.15 It can be seen that the gain curve of the low-frequency antenna is maintained near 8dBi, and the low-frequency antenna has a stable gain curve.

[0057] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. The novel three-band common aperture antenna according to claim 1, characterized in that: The invention comprises a plurality of arranged common-aperture antenna subarrays, each of which comprises a metal floor (19) and a low-frequency dipole antenna (5) arranged in the middle of the metal floor (19); a medium-frequency dipole antenna (9) and a high-frequency dipole antenna (15) are respectively arranged at four corners of the metal floor (19) around the low-frequency dipole antenna (5), and the medium-frequency dipole antenna (9) is located on one side of the low-frequency dipole antenna (5), and the high-frequency dipole antenna (15) is located on the other side of the low-frequency dipole antenna (5).

2. The novel three-band common aperture antenna according to claim 1, characterized in that: The low-frequency dipole antenna (5) comprises a first dielectric plate (1), wherein two orthogonal first Y-type feeding branches (6) are printed in the middle of the upper surface of the first dielectric plate (1), and a first jump bridge (7) is used at the intersection of the two first Y-type feeding branches (6) to avoid topological intersection; orthogonal frequency selective surface units (4) are printed at the four corners of the lower surface of the first dielectric plate (1), and two pairs of frequency selective surface units (4) are used as dipole arms to realize structural multiplexing to form a ±45° dipole antenna; a first coaxial feed line (8) is connected between the low-frequency dipole antenna (5) and the metal floor (19), one end of the shielding layer of the first coaxial feed line 8 is connected to the low-frequency dipole antenna (5), and the other end is connected to the metal floor (19); one end of the inner core of the first coaxial feed line (8) is connected to the first Y-type feeding branch (6), and the other end is connected to the feed source to realize coupled feeding.

3. The novel three-band common aperture antenna according to claim 1, characterized in that: The intermediate frequency dipole antenna (9) comprises a second dielectric plate (2), the upper surface of the second dielectric plate (2) being printed with two orthogonal second Y-shaped feeding branches (10), the intersection of the two second Y-shaped feeding branches (10) being isolated by a second jumper (11); the lower surface of the second dielectric plate (2) being printed with orthogonal curved dipole arms (21), the two pairs of curved dipole arms (21) forming a ±45° dipole antenna; A second coaxial feeder (12) is connected between the intermediate frequency dipole antenna (9) and the metal floor (19); one end of the shielding layer of the second coaxial feeder (12) is connected to the intermediate frequency dipole antenna (9), and the other end is connected to the metal floor (19); one end of the inner core of the second coaxial feeder (12) is connected to the second Y-type feeding branch (10), and the other end is connected to the feed source to realize coupled feeding.

4. The novel three-band common aperture antenna according to claim 1, characterized in that: The high-frequency dipole antenna (15) comprises a third dielectric plate (3), the upper surface of which is printed with two orthogonal third Y-type feeding branches (16), the intersection of the two third Y-type feeding branches (16) being isolated by a third jump bridge (17); the lower surface of the third dielectric plate (3) is printed with orthogonal rectangular dipole arms (22), the two pairs of rectangular dipole arms (22) forming a ±45° dipole antenna; a third coaxial feeder (18) is connected between the high-frequency dipole antenna (15) and the metal floor (19), one end of the shielding layer of the third coaxial feeder (18) is connected to the high-frequency dipole antenna (15), and the other end is connected to the metal floor (19); one end of the inner core of the third coaxial feeder (18) is connected to the third Y-type feeding branch (16), and the other end is connected to a feed source, so as to realize coupled feeding.

5. The novel three-band common aperture antenna according to claim 1, characterized in that: The bottom of the intermediate frequency dipole antenna 9 () and the high frequency dipole antenna (15) and the metal floor (19) are provided with a fixed base (13), the upper and lower parts of the fixed base (13) are covered with copper metal, and a metal through hole (14) is etched on the fixed base (13) to realize the connection between the coaxial feed line and the metal floor (19).

6. The three-band common aperture antenna according to claim 1, characterized in that: The first dielectric plate (1), the second dielectric plate (2) and the third dielectric plate (3) are all made of Rogers 4003 plate.

7. The novel three-band common aperture antenna according to claim 5, characterized in that: The material of the fixed base (13) is FR4.

8. The three-band common aperture antenna according to claim 1, characterized in that: The three-band common aperture antenna operates in the sub-6G band of the base station, covering the n77-n79 band, wherein the low frequency operates in the 1.7-2.7GHz band; the medium frequency antenna operates in the 3.3-3.8GHz band; and the high frequency antenna operates in the 4.6-4.9GHz band.

9. The three-band common aperture antenna according to claim 1, characterized in that: The frequency selective surface unit (4) comprises two LC resonant circuits, and the LC resonant circuits realize bandpass characteristics in the medium and high frequency bands; wherein the period P of the frequency selective surface unit (4) is 25 mm, the width W1 of the outermost rectangular patch is 1.5 mm, the spacing Gap1 between the outermost rectangular patches is 0.5 mm, the width W3 of the cross-shaped gap etched in the center of the inner rectangular patch is 1.3 mm, and the length L1 of the inner rectangular patch is 19.4 mm.

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