Out-of-band self-decoupling dipole antenna based on hollow cylindrical resonator loading and self-decoupling system

Abstract

The invention discloses an out-of-band self-decoupling dipole antenna based on hollow cylindrical resonator loading, which comprises a radiation dipole, a hollow cylindrical resonator, a feed coaxial line and a balun, and is characterized in that the radiation dipole comprises a first dipole arm and a second dipole arm which are arranged along the same linear direction, the first dipole arm is connected with the top end of an inner conductor, and the second dipole arm is connected with the top end of an outer conductor; the second dipole arm is connected with the position, corresponding to the first dipole arm, of the side wall of the outer conductor, the balun is formed by two sets of top grooves formed in the upper portion of the outer conductor along the two sides perpendicular to the arrangement direction of the radiation dipole, the hollow cylindrical resonator is arranged on the outer side of the outer conductor in a sleeving mode, and the hollow cylindrical resonator, the inner conductor and the outer conductor are coaxially arranged. Partition structures are arranged at the positions, corresponding to the two sets of top grooves, of the hollow cylindrical resonator. According to the invention, the problem of serious mutual coupling of different-frequency antenna units placed in a close range at a high frequency band is solved, the structure of a low-frequency antenna is not changed, the introduction of extra insertion loss is avoided, and the efficiency of the high-frequency antenna is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave antennas, and particularly to an out-of-band self-decoupling dipole antenna and a self-decoupling system based on a hollow cylindrical resonator loading. Background Art

[0002] Multi-band common-aperture antennas can meet the working requirements of different frequency bands of the system. However, with the increasing requirements for high integration and miniaturization of multi-system integration devices, the distance between different-frequency antenna elements is too close, resulting in the deterioration of the isolation between different-frequency unit ports, and further reducing the system performance of multi-functional devices. Compared with orthogonally polarized elements, the mutual coupling between co-polarized different-frequency elements is more serious. Therefore, solving the mutual coupling problem between closely placed co-polarized different-frequency ports is the key to realizing high-integration, miniaturized multi-functional devices.

[0003] The mutual coupling between co-polarized different-frequency elements is mainly reflected in the high-frequency band. When the high-frequency element is excited, the high-order modes of the low-frequency element structure will be excited, resulting in a decrease in the isolation of the high-frequency band ports. The existing methods for improving the isolation of co-polarized different-frequency unit ports in the high-frequency band are mainly divided into three categories: one is to cascade a filter or a decoupling network at the back end of the antenna. This method requires additional design of the filter or decoupling structure, inevitably introducing additional losses; the second is to load lumped elements on the low-frequency element. This method requires cutting the antenna and reasonably selecting the value of the lumped element; the third is to design a new low-frequency element with frequency selection characteristics. This method can effectively solve the mutual coupling problem between different-frequency elements, but the unit structure form of the low-frequency antenna is limited. In summary, it is necessary to propose a method for decoupling closely placed different-frequency antennas without changing the structure of the low-frequency antenna, and at the same time avoid introducing additional insertion losses to ensure the efficiency of the high-frequency band antenna. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, an object of the present invention is to provide an out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator loading, which solves the serious mutual coupling problem of different-frequency antenna elements placed closely in the high-frequency band, and at the same time can not change the structure of the low-frequency antenna, avoid introducing additional insertion losses, and ensure the efficiency of the high-frequency band antenna.

[0005] In a first aspect, an out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator loading is proposed by the present invention, which includes a radiating dipole, a hollow cylindrical resonator, a coaxial feeder, and a balun. The radiating dipole includes a dipole arm 1 and a dipole arm 2 arranged along the same straight line direction. The coaxial feeder includes an inner conductor and an outer conductor insulated from each other outside the inner conductor. The dipole arm 1 is connected to the top end of the inner conductor, and the dipole arm 2 is connected to the side wall of the outer conductor at a position corresponding to the dipole arm 1. The balun is formed by two sets of top slots opened on both sides of the upper part of the outer conductor along a direction perpendicular to the radiating dipole. The hollow cylindrical resonator is sleeved outside the outer conductor, and the hollow cylindrical resonator, the inner conductor, and the outer conductor are coaxially arranged. The hollow cylindrical resonator is provided with a partition structure at positions corresponding to the two sets of top slots.

[0006] Preferably, the hollow cylindrical resonator includes a cylindrical surface 1 and a cylindrical surface 2 formed by the partition structure. The top end of the cylindrical surface 1 is connected to the side wall of the outer conductor through a ring section 1, and the top end of the cylindrical surface 2 is connected to the side wall of the outer conductor through a ring section 2. The distances from the ring section 1 and the ring section 2 to the radiating dipole are equal and less than the length of the top slot.

[0007] Preferably, the width of the partition structure is not less than the width of the top slot.

[0008] Preferably, the heights of the cylindrical surface 1 and the cylindrical surface 2 are equal and both are 0.25λ0, where λ0 is the free space wavelength corresponding to the out-of-band frequency to be decoupled.

[0009] Preferably, the sizes of the cylindrical surface 1 and the cylindrical surface 2 are adjusted according to the decoupling frequency band, and there is a height difference between the cylindrical surface 1 and the cylindrical surface 2.

[0010] Preferably, the materials of the cylindrical surface 1, the cylindrical surface 2, the ring section 2, and the ring section 1 are all copper.

[0011] In a second aspect, a self-decoupling system proposed by the present invention includes any one of the above-mentioned out-of-band self-decoupling dipole antennas based on a hollow cylindrical resonator loading. The self-decoupling system further includes a high-frequency dipole, which is arranged parallel to the radiating dipole. The distance between the high-frequency dipole and the radiating dipole is da. When da = 0.21λ0 and da = 0.1λ0, when the ratio of the out-of-band suppression frequency of the high-frequency dipole to the operating frequency of the radiating dipole is close to 1.3, the in-band reflection coefficient of the dipole is less than -10 dB, and the out-of-band suppression is greater than 20 dB.

[0012] The beneficial effects in the present invention are:

[0013] (1) Compared with the traditional three - type heterogenous frequency decoupling scheme, the present invention introduces a hollow cylindrical resonator outside the feeding balun structure, achieving a simpler structure, without introducing additional insertion loss, and without the need to damage the radiation structure of the low - frequency unit, avoiding the errors existing in the lumped elements in the array design, and being applicable to different - structured low - frequency radiation units fed by a balun;

[0014] (2) The present invention can simply achieve heterogenous frequency decoupling for different frequency ratios or broadband by adjusting the length and loading position of the hollow cylindrical resonator;

[0015] (3) The decoupling scheme based on the hollow cylindrical resonator proposed by the present invention can be applicable to the case of non - fixed element spacing. When the element spacing changes, it still has a good decoupling effect;

[0016] (4) For the out - of - band self - decoupling dipole antenna based on the loading of the hollow cylindrical resonator of the present invention, the hollow cylindrical resonator and the feeding coaxial balun can be integrally formed, having the advantages of small error, low cost, short processing cycle, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the drawings:

[0018] Figure 1 is a schematic structural diagram of an out - of - band self - decoupling dipole antenna based on the loading of a hollow cylindrical resonator proposed by the present invention;

[0019] Figure 2 is an exploded view of the hollow cylindrical resonator and the feeding coaxial line proposed by the present invention;

[0020] Figure 3 is a schematic structural diagram of the self - decoupling system proposed by the present invention;

[0021] Figure 4 is a top view of the self - decoupling system proposed by the present invention;

[0022] Figure 5 is a front view of the out - of - band self - decoupling dipole antenna based on the loading of a hollow cylindrical resonator proposed by the present invention;

[0023] Figure 6 is a graph of the simulation results of S - parameters when the hollow cylindrical resonators are of equal height in Embodiment II proposed by the present invention;

[0024] Figure 7 is a graph of the simulation results of S - parameters when the hollow cylindrical resonators have an asymmetric height in Embodiment III proposed by the present invention;

[0025] Figure 8 is a normalized far - field radiation two - dimensional pattern of the two ports in Embodiment II proposed by the present invention at 2.35 GHz (left) and 3.14 GHz (right);

[0026] Figure 9 The simulation result diagram of the S parameters of the antenna in Embodiment 2 proposed by the present invention at different element spacings;

[0027] Figure 10 The schematic diagram of the structural dimensions of the I-shaped radiation dipole in Embodiment 4 proposed by the present invention;

[0028] Figure 11 The simulation result diagram of the S parameters of Embodiment 4 proposed by the present invention;

[0029] Figure 12 The normalized far-field radiation two-dimensional pattern of the two ports of Embodiment 4 proposed by the present invention at 2.35 GHz (left) and 3.14 GHz (right).

[0030] In the figure: 1 - radiation dipole, 2 - hollow cylindrical resonator, 3 - feeding coaxial line, 4 - balun, 5 - high-frequency dipole;

[0031] 11 - dipole arm one, 12 - dipole arm two;

[0032] 21 - cylinder one, 22 - cylinder two, 23 - ring section two, 24 - ring section one;

[0033] 31 - inner conductor, 32 - outer conductor, 33 - top slot. Specific implementation manner

[0034] Embodiment 1:

[0035] Referring to Figure 1 and Figure 2 , a dipole antenna with out-of-band self-decoupling loaded by a hollow cylindrical resonator includes a radiation dipole 1, a hollow cylindrical resonator 2, a feeding coaxial line 3 and a balun 4. The radiation dipole 1 includes a dipole arm one 11 and a dipole arm two 12 arranged along the same straight line direction. The feeding coaxial line 3 includes an inner conductor 31 and an outer conductor 32 which is arranged outside the inner conductor 31 and insulated from each other. The dipole arm one 11 is connected to the top end of the inner conductor 31, and the dipole arm two 12 is connected to the side wall of the outer conductor 32 at a position corresponding to the dipole arm one 11. The balun 4 is formed by two groups of top slots 33 opened on both sides of the upper part of the outer conductor 32 along the direction perpendicular to the radiation dipole 1. The hollow cylindrical resonator 2 is sleeved outside the outer conductor 32, and the hollow cylindrical resonator 2, the inner conductor 31 and the outer conductor 32 are coaxially arranged. The hollow cylindrical resonator 2 is provided with a partition structure at positions corresponding to the two groups of top slots 33.

[0036] Referring to Figure 1 , Figure 2 and Figure 5, the hollow cylindrical resonator 2 includes a cylindrical surface one 21 and a cylindrical surface two 22 formed by a partition structure. The top end of the cylindrical surface one 21 is connected to the side wall of the outer conductor 32 through a first ring section 24, and the top end of the cylindrical surface two 22 is connected to the side wall of the outer conductor 32 through a second ring section 23. The distances from both the first ring section 24 and the second ring section 23 to the length of the radiating dipole 1 are d and less than the length h3 of the top slot 33; the width of the partition structure is not less than the width of the top slot 33.

[0037] Refer to Figure 1 and Figure 2 , the heights of the cylindrical surface one 21 and the cylindrical surface two 22 are equal and both are near 0.25λ0, where λ0 is the free space wavelength corresponding to the out-of-band frequency to be decoupled.

[0038] The sizes of the cylindrical surface one 21 and the cylindrical surface two 22 are adjusted according to the decoupling frequency band, and there is a height difference between the cylindrical surface one 21 and the cylindrical surface two 22.

[0039] The materials of the cylindrical surface one 21, the cylindrical surface two 22, the second ring section 23 and the first ring section 21 are all copper.

[0040] Embodiment 2:

[0041] Refer to Figure 3 , Figure 4 and Figure 5 , a self-decoupling system includes any one of the above solutions of the out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator loading. The self-decoupling system further includes a high-frequency dipole 5, the high-frequency dipole 5 is arranged in parallel with the radiating dipole 1, and the distance between the high-frequency dipole 5 and the radiating dipole 1 is da.

[0042] In this embodiment, the total length L of the high-frequency dipole 5 H is 43 mm, the width w is 1 mm, and the vertical spacing da from the low-frequency radiating dipole is 20 mm.

[0043] The total length of the radiating dipole 1 is 55 mm and the width is 1 mm. The target high-frequency band to be decoupled in this embodiment is 3.125 GHz. According to the correspondence between the height of the hollow cylinder and the out-of-band frequency to be decoupled, the heights of the two hollow cylinders 31 of the hollow cylindrical resonator 2 are set to h1 = h2 = 23 mm. The inner radius of the second ring section 23 and the first ring section 24 is 1.9 mm and the outer radius is 3 mm. This size is optimized through actual practice to achieve the impedance matching of the antenna. The distance d between the second ring section 23 and the first ring section 24 and the low-frequency radiating dipole 1 is 3 mm. The length h2 of the top slot 33 of the coaxial outer conductor 32 is 12 mm and the width is 1 mm.

[0044] The simulation results show that the operating frequency range of the low-frequency radiation dipole 1 is 2.28 - 2.41 GHz, and the reflection coefficient within the band is less than -10 dB. The operating frequency range of the high-frequency dipole 5 as the high-frequency verification dipole is 2.97 - 3.29 GHz, and the reflection coefficient within the band is less than -10 dB. The isolation degree between ports within the operating frequency range of the high-frequency verification dipole is greater than 21 dB, which is 10 dB higher than the case without loading the hollow cylindrical resonator 2, while the port isolation degree within the operating frequency of the low-frequency radiation dipole 1 remains basically unchanged (greater than 16.2 dB). In addition, the loading of the hollow cylindrical resonator 2 also increases the total efficiency of the high-frequency verification dipole by 0.1.

[0045] Embodiment 3:

[0046] The height of the hollow cylindrical resonator 2 further adopts an asymmetric height configuration structure, and the cylindrical sections with different heights correspond to different resonant frequencies, thereby generating an effect of suppressing coupling at multiple frequency points. Among them, the height h1 of the first cylindrical surface 22 is 23 mm, and the height h2 of the second cylindrical surface 22 is 26 mm. The annular structure parameters of the first annular section 24 and the second annular section 23 are optimized to an outer radius of 4 mm. The remaining structural parameters are consistent with the operating parameters in the above embodiments.

[0047] The simulation results show that this optimized structure shifts the operating frequency range of the low-frequency radiation dipole 1 down to 2.06 - 2.15 GHz, and the reflection coefficient S within the passband 11 remains below -10 dB. The operating bandwidth of the high-frequency verification dipole still remains in the range of 2.97 - 3.29 GHz, and the reflection coefficient within the band remains unchanged. Within the operating frequency band of the high-frequency verification dipole, the isolation degree between ports is stably maintained above 21 dB. The port isolation degree within the operating frequency of the low-frequency radiation dipole 1 is increased to 19.8 dB. In particular, in the region outside the bandwidth of the low-frequency radiation dipole 1, the port isolation degree S 21 shows a significant improvement, and the overall isolation degree between ports remains above 19.26 dB, achieving enhanced isolation in a wide frequency band. The design parameter of the asymmetric height difference Δh = h2 - h1 = 3 mm of the hollow cylindrical resonator 2 is verified by experiments to be the key factor for optimizing the isolation degree.

[0048] The working principle of the present invention is described in detail as follows:

[0049] The length of the radiating dipole 1 is close to half a wavelength. When it is loaded with a center feed, the main radiation mode is the dipole mode of half a wavelength. The top slot 33 of the outer conductor 32 of the coaxial cable forms a balun 4 to achieve balanced feeding of the two arms of the radiating dipole 1. However, at the same time, this balun 4 also causes the frequency of the higher-order modes on the radiating dipole 1 to shift downwards. Therefore, when the low-frequency radiating dipole 1 and the high-frequency verification dipole are placed in parallel, if the high-frequency verification dipole is excited, an induced current will be generated on the low-frequency radiating dipole 1. When the resonance frequency of the higher-order mode on the low-frequency radiating dipole 1 is close to the operating frequency of the high-frequency verification dipole, the port isolation of the two antennas will deteriorate within the operating frequency band of the high-frequency verification dipole.

[0050] The length of the hollow cylindrical resonator 2 is approximately equal to one-quarter wavelength. The upper ring section 23 and the first ring section 24 of it are connected to the upper part of the outer conductor 32 of the feeding coaxial cable 3 to form a short circuit. If the structural dimensions of the hollow cylindrical resonator 2 are reasonably selected, for the higher-order modes, the hollow cylindrical resonator 2 seen from the bottom of the top slot 33 can be equivalent to two parallel-resonant open loads, thus effectively suppressing the high-frequency current induced on the low-frequency radiating dipole 1, and then realizing the improvement of the port isolation between the parallel-placed low-frequency radiating dipole 1 and the high-frequency verification dipole in the high-frequency band.

[0051] See Figure 6 , which gives the comparison of the port S parameters of the antenna in the second embodiment of the present invention and the isolation between the two ports before and after loading the hollow cylindrical resonator 2. It can be seen from the simulation results that in this embodiment, by loading the hollow cylindrical resonator 2, the isolation between the ports within the operating frequency range of the high-frequency verification dipole is greater than 21 dB, which is 10 dB higher than the case without loading the hollow cylindrical resonator 2. The port isolation within the operating frequency of the low-frequency radiating dipole 1 is not greatly affected by the hollow cylindrical resonator 2.

[0052] See Figure 7 , which gives the simulation results of the S parameters when the hollow cylinder has an asymmetric height configuration in the third embodiment. The simulation results show that the isolation between the ports of the low-frequency radiating dipole 1 and the high-frequency verification dipole generally remains above 19.26 dB. By adopting the asymmetric height configuration, the effect of suppressing coupling is generated at multiple frequency points, and finally a wider frequency band is covered. It can be compared with the Figure 6 symmetric structure configuration in, and the decoupling frequency band of the high-frequency verification dipole is broadened.

[0053] See Figure 8 , where the curves with the lower triangle and square symbols are the main polarization radiation patterns in the E-plane and H-plane respectively, and the other two lines are the cross-polarization far-field patterns. It can be seen from the main polarization radiation patterns that in the second embodiment of the present invention, after loading the hollow cylindrical resonator 2, the radiation patterns of both the low-frequency radiating dipole 1 and the high-frequency verification dipole can achieve good omnidirectional radiation.

[0054] See Figure 9 , where the curves with square, circular and triangular symbols are the S-parameters of the low-frequency radiation dipole 1 and the high-frequency verification dipole at the distances da = 10 mm, da = 15 mm and da = 20 mm (i.e., da = 0.1λ0, da = 0.16λ0, da = 0.21λ0) respectively. The in-band reflection coefficients of the dipoles at different distances are all less than -10 dB. From the coupling coefficient S 21 , it can be seen that the loaded hollow cylindrical resonator 2 in the second embodiment has different degrees of coupling suppression effects on the parallel dipoles with different distances, and the isolation degree between ports is greater than 20 dB.

[0055] Embodiment 4:

[0056] Compared with the second embodiment, in the structure of the out-of-band self-decoupling dipole antenna loaded with a hollow cylindrical resonator in this embodiment, only the metal arm structure of the radiation dipole 1 changes, and other basic parameters are the same as those in the first embodiment. The specific working parameters are described as follows:

[0057] The radiation structure of the radiation dipole 1 is an I-shaped structure, with an arm length of 40 mm, the lengths of both side branches are 10 mm, and the arm width is 1 mm.

[0058] The simulation results show that the operating frequency range of the radiation dipole 1 is 2.29 - 2.42 GHz, the in-band reflection coefficient is less than -10 dB, the operating frequency range of the high-frequency verification dipole is 3.04 - 3.37 GHz, and the in-band reflection coefficient is less than -10 dB. The isolation degree between ports within the operating frequency range of the high-frequency verification dipole is greater than 20 dB, which is 10 dB higher than that without loading the hollow cylindrical resonator 2, while the isolation degree between ports within the operating frequency of the low-frequency radiation dipole 1 remains basically unchanged (greater than 17 dB). In addition, the loading of the hollow cylindrical resonator 2 also increases the total efficiency of the high-frequency verification dipole by 0.1.

[0059] See Figure 11 , which shows the comparison of the port S-parameters of the antenna in this embodiment 4 and the isolation degree between the two ports before and after loading the hollow cylindrical resonator 2. It can be seen from the simulation results that in this embodiment, by loading the hollow cylindrical resonator 2, the isolation degree between ports within the operating frequency range of the high-frequency verification dipole is greater than 20 dB, which is 10 dB higher than that without loading the hollow cylindrical resonator 2, and the isolation degree between ports within the operating frequency of the low-frequency radiation dipole 1 is not greatly affected by the hollow cylindrical resonator 2.

[0060] See Figure 12, where the curves with the triangular and square symbols are the main polarization radiation patterns of the E-plane and H-plane respectively, and the other two lines are the cross-polarization far-field patterns. It can be seen from the main polarization radiation patterns that in the fourth embodiment, after loading the hollow cylindrical resonator 2, the patterns of the low-frequency radiation dipole 1 and the high-frequency verification dipole can both achieve good omnidirectional radiation.

Claims

1. An out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator loading, characterized in that: The invention comprises a radiating dipole (1), a hollow cylindrical resonator (2), a feeding coaxial line (3) and a balun (4); the radiating dipole (1) comprises a dipole arm 1 (11) and a dipole arm 2 (12) arranged along the same straight line direction; the feeding coaxial line (3) comprises an inner conductor (31) and an outer conductor (32) arranged outside the inner conductor (31) and insulated from each other; the dipole arm 1 (11) is connected to the top end of the inner conductor (31); the dipole arm 2 (12) is connected to the outer conductor (31); 2) is connected at a position corresponding to the dipole arm one (11), the balun (4) is formed by two groups of top grooves (33) opened on both sides of the upper part of the outer conductor (32) perpendicular to the setting direction of the radiation dipole (1), the hollow cylindrical resonator (2) is sleeved on the outside of the outer conductor (32), the hollow cylindrical resonator (2), the inner conductor (31) and the outer conductor (32) are coaxially arranged, and the hollow cylindrical resonator (2) is provided with a partition structure at the position corresponding to the two groups of top grooves (33).

2. The out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator loading according to claim 1, characterized in that: The hollow cylindrical resonator (2) comprises a first cylindrical surface (21) and a second cylindrical surface (22) formed by the partition structure, the top of the first cylindrical surface (21) being connected to the side wall of the outer conductor (32) via a first ring segment (24), the top of the second cylindrical surface (22) being connected to the side wall of the outer conductor (32) via a second ring segment (23), the lengths of the first ring segment (24) and the second ring segment (23) being equal to each other from the radiating dipole (1) and being less than the length of the top groove (33).

3. The out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator loading according to claim 2, characterized in that: The width of the partition structure is not less than the width of the top groove (33).

4. The out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator loading according to claim 3, characterized in that: The heights of the first cylindrical surface (21) and the second cylindrical surface (22) are equal and are both 0.25λ0, wherein λ0 is the free space wavelength corresponding to the out-of-band frequency to be decoupled.

5. The out-of-band self-decoupling dipole antenna based on hollow cylindrical resonator loading according to claim 3, characterized in that: The sizes of the first cylinder (21) and the second cylinder (22) are adjusted according to the decoupling frequency band, and there is a height difference between the first cylinder (21) and the second cylinder (22).

6. The out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator loading according to claim 2, characterized in that: The materials of the cylindrical surface 1 (21), cylindrical surface 2 (22), ring segment 2 (23) and ring segment 1 (21) are all copper.

7. A self-decoupling system, characterized in that: The invention comprises an out-of-band self-decoupling dipole antenna based on a hollow cylindrical resonator as described in any one of items 1 to 6, wherein the self-decoupling system also includes a high-frequency dipole (5), wherein the high-frequency dipole (5) is arranged in parallel with the radiating dipole (1), and the distance between the high-frequency dipole (5) and the radiating dipole (1) is da. When da=0.21λ0 and da=0.1λ0, when the ratio of the out-of-band suppression frequency of the high-frequency dipole (5) to the operating frequency of the radiating dipole (1) is close to 1.3, the dipole in-band reflection coefficient is less than -10dB, and the out-of-band suppression is greater than 20dB.

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