Antipodal Vivaldi antenna array loaded with pi-shaped coupling network

Abstract

The invention relates to the technical field of antennas, and discloses an antipodal Vivaldi antenna array loaded with a pi-shaped coupling network and a coupling utilization verification method in order to solve the problem that the number of structures for coupling utilization through the network is small. The antenna array comprises a pi-shaped coupling network and at least two array elements of an antipodal Vivaldi antenna array, wherein the at least two array elements are connected through the pi-shaped coupling network; the pi-shaped coupling network is provided with a first port, a second port, a third port, a fourth port, a fifth port and a sixth port, the first port, the second port, the third port and the fourth port are used for connecting array elements, and a main transmission path between the third port and the fourth port is a transmission line with characteristic impedance of Z3; the fifth port and the sixth port are arranged on the transmission line with the characteristic impedance of Z3, and the transmission line with the characteristic impedance of Z3 is cut into three sections with the electrical lengths of theta3, theta4 and theta5 respectively. By adopting the antenna array, the active bandwidth of the antipodal Vivaldi antenna array can be improved.

Description

Technical Field

[0001] This application relates to the technical field of antennas, and more specifically, to an antipodal Vivaldi antenna array loaded with a π-shaped coupling network and a coupling utilization verification method. Background Art

[0002] When designing a broadband phased array antenna, usually, an antenna element with broadband characteristics is first designed, and then arrayed in a certain way, and means to compensate or weaken the mutual coupling effect are adopted to avoid too much deterioration of the broadband performance of the array. However, this method is difficult to further expand the bandwidth and scanning range of the phased array antenna. Although antennas with larger sizes can meet the broadband requirements of phased array antennas, they will cause many disadvantages such as narrow beam scanning range, high antenna profile height, large volume, and large weight. Therefore, it is necessary to study the coupling utilization technology for phased array antennas to achieve breakthroughs in characteristics such as wide operating frequency bands and wide-angle beam scanning. Currently, the common coupling utilization structures are mainly space parasitic structures, and there are few structures for network coupling utilization.

[0003] The antipodal Vivaldi antenna can be used as the basic unit of a phased array antenna, breaking through the bandwidth limitation caused by the traditional Vivaldi feeding structure, and can greatly improve the operating bandwidth of the antenna. By loading a network coupling utilization structure, its bandwidth can be further expanded.

[0004] Currently, there are few structures for coupling utilization through networks. Therefore, it is necessary to study the application of network structures in broadband antennas. Summary of the Invention

[0005] To solve the above problems, the present invention provides an antipodal Vivaldi antenna array loaded with a π-shaped coupling network and a coupling utilization verification method, which can improve the active bandwidth of the antipodal Vivaldi antenna array through the π-shaped coupling network.

[0006] To achieve the above object, according to the first aspect of the present invention, there is provided an antipodal Vivaldi antenna array loaded with a π-shaped coupling network, the antenna array comprising:

[0007] a π-shaped coupling network and at least two array elements of the antipodal Vivaldi antenna array connected by the π-shaped coupling network;

[0008] The π-shaped coupling network has a first port, a second port, a third port, a fourth port, a fifth port, and a sixth port. The first port, the second port, the third port, and the fourth port are used to connect array elements. The main transmission path between the third port and the fourth port is a transmission line with a characteristic impedance of Z3. The fifth port and the sixth port are arranged on the transmission line with a characteristic impedance of Z3, and the transmission line with a characteristic impedance of Z3 is cut into three segments with electrical lengths of θ3, θ4, and θ5 respectively. The branch transmission path between the first port and the fifth port is a transmission line with a characteristic impedance of Z1 and an electrical length of θ1. The branch transmission path between the second port and the sixth port is a transmission line with a characteristic impedance of Z2 and an electrical length of θ2.

[0009] The total admittance matrix of the antipodal Vivaldi antenna array loaded with the π-shaped coupling network is:

[0010]

[0011] where K = (k 11 - k 31 )(k 22 - k 42 ) - (k 41 - k 21 )(k 32 - k 12 ), k l,m represents the coefficient between the l-th port and the m-th port, l = 1, 2, 3, 4, m = 1, 2, I I and V I are the current and voltage of the total port I respectively, I II and V II are the current and voltage of the total port II respectively, I I = I1 = -I3, I II = I2 = -I4, V I = V1 - V3, V II = V2 - V4, I l and V l are the current and voltage at the l-th port respectively.

[0012] Furthermore, the array element is an unbalanced-fed antenna with a single feeder or a balanced-fed antenna with two arms.

[0013] Furthermore, the voltage and current at the fifth port are related to the voltage and current at the first port and the third port, and satisfy:

[0014]

[0015] Furthermore, the voltage and current at the sixth port are related to the voltage and current at the fifth port, and satisfy:

[0016]

[0017] Furthermore, the voltages and currents at the second and fourth ports are both related to the voltages and currents at the sixth port, and satisfy:

[0018]

[0019] Furthermore, the admittance matrix of the π-shaped coupling network is:

[0020]

[0021] Furthermore, the total admittance matrix of the antipodal Vivaldi antenna array loaded with the π-shaped coupling network is the sum of the admittance matrix of the π-shaped coupling network and the admittance matrix of the antipodal Vivaldi antenna array without the π-shaped coupling network loaded.

[0022] Furthermore, the total admittance matrix of the antipodal Vivaldi antenna array loaded with the π-shaped coupling network satisfies:

[0023]

[0024] where Y l,n represents the mutual admittance between the l-th port and the n-th port, n = 1, 2, 3, 4.

[0025] Furthermore, the relationship between V1, V2, V3 and V4 and I I and I II satisfies:

[0026]

[0027] According to the second aspect of the present invention, there is also provided a coupling utilization verification method, which is applied to the above-mentioned antipodal Vivaldi antenna array loaded with the π-shaped coupling network, and includes:

[0028] According to the conversion relationship between the admittance matrix and the scattering matrix, calculate the S matrix corresponding to the total admittance matrix. The S matrix includes the reflection coefficient S 11 of the total port I and the transmission coefficient S 21 between the total port I and II;

[0029] According to the S matrix, determine the coupling utilization condition as:

[0030] S llactive = S 11 + S 21

[0031]

[0032] According to the coupling utilization condition, judge whether the coupling between the array elements can be utilized.

[0033] Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0034] (1) A contra-Vivaldi antenna array loaded with a π-shaped coupling network provided by the present invention realizes an improvement in the active bandwidth of the contra-Vivaldi antenna array through the π-shaped coupling network, and expands the application of the network structure in the bandwidth expansion of the antenna array.

[0035] (2) By using a coupling utilization verification method for a contra-Vivaldi antenna array loaded with a π-shaped coupling network provided by the present invention, it can be determined whether the coupling between array elements can be utilized, thereby verifying the feasibility of the design method of the π-shaped coupling network. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a schematic structural diagram of a π-shaped coupling network in a contra-Vivaldi antenna array loaded with a π-shaped coupling network provided by an embodiment of the present application;

[0038] Figure 2 It is a schematic diagram of the S-parameters and phase differences of a binary original antenna array provided by an embodiment of the present application;

[0039] Figure 3 It is a schematic structural diagram of a binary E-plane contra-Vivaldi antenna array loaded with a π-shaped coupling network provided by an embodiment of the present application;

[0040] Figure 4 It is a schematic diagram of the S-parameters and phase differences of a binary antenna array loaded with a π-shaped coupling network provided by an embodiment of the present application;

[0041] Figure 5 It is a schematic diagram of the gains of a binary antenna array with and without a π-shaped coupling network loaded provided by an embodiment of the present application;

[0042] Figure 6 It is a normalized radiation pattern of a binary antenna array with and without a π-shaped coupling network loaded provided by an embodiment of the present application;

[0043] Figure 7 It is a schematic diagram of the active S-parameters and phase differences of an eight-element antenna array loaded with a π-shaped coupling network provided by an embodiment of the present application;

[0044] Figure 8 Schematic diagram of the gain of the eight - element antenna array with unloaded and loaded π - shaped coupling networks provided by the embodiments of the present application;

[0045] Figure 9 Normalized radiation pattern of the eight - element antenna array with loaded π - shaped coupling network provided by the embodiments of the present application. Detailed implementation manners

[0046] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to 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. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] In one embodiment, a loaded antipodal Vivaldi antenna array with a π - shaped coupling network is provided, which includes a π - shaped coupling network and at least two array elements of the antipodal Vivaldi antenna array connected by the π - shaped coupling network.

[0048] As Figure 1 shown, the π - shaped coupling network is a four - port network with a first port, a second port, a third port, and a fourth port. It can be connected to unbalanced - feed antennas with only a single feeder or to balanced - feed antennas with two arms. The π - shaped coupling network is composed of transmission lines. For simplicity of design, the main transmission path between the third port (i.e., port 3) and the fourth port (i.e., port 4) is a transmission line with a characteristic impedance of Z3, and is intercepted by the (Z1, θ1) section connected to the first port (i.e., port 1) and the (Z2, θ2) section connected to the second port (i.e., port 2) into three sections with electrical lengths of θ3, θ4, and θ5 respectively.

[0049] Two virtual ports are set: a fifth port (i.e., port 5) and a sixth port (i.e., port 6). Ports 5 and 6 are set on the transmission line with a characteristic impedance of Z3. The branch transmission path between port 1 and port 5 is a transmission line with a characteristic impedance of Z1 and an electrical length of θ1, and the branch transmission path between port 2 and port 6 is a transmission line with a characteristic impedance of Z2 and an electrical length of θ2.

[0050] Parameters matrix is used to analyze and deduce the characteristics of the loaded antipodal Vivaldi antenna array with a π - shaped coupling network. I l and V l are the current and voltage at the l - th port respectively, where l = 1, 2, 3, 4. First, the voltage and current at port 5 are related to the voltage and current at ports 1 and 3, and satisfy:

[0051]

[0052] The voltage and current at port 6 are related to the voltage and current at port 5 and satisfy:

[0053]

[0054] Similarly, the voltage and current at ports 2 and 4 are both related to the voltage and current at port 6 and satisfy:

[0055]

[0056] Therefore, the transmission matrix A between ports 1 to 4 c is:

[0057]

[0058]

[0059] For the transmission matrix A c Using the unified block method for representation, we get:

[0060]

[0061] Wherein,

[0062] Referring to the conversion formula of the two-port network, the admittance matrix of the π-shaped coupling network can be obtained as:

[0063]

[0064] Connect the π-shaped coupling network to the original antipodal Vivaldi antenna array, and determine the admittance matrix Y of the antenna array above the connection point a . Thus, the total admittance matrix of the antenna array loaded with the coupling network (i.e., loaded with the π-shaped coupling network model) can be obtained as Y = Y c + Y a , that is:

[0065]

[0066] Wherein, Y l,n represents the mutual admittance between the l-th port and the n-th port, n = 1, 2, 3, 4.

[0067] By combining port 1 and 3 into the total port I of the loaded π-shaped coupling network model, and combining port 2 and 4 into the total port II, the four-port network can be simplified into a two-port network, then there is I I = I1 = -I3, I II = I2 = -I4, V I= V1 - V3, V II = V2 - V4. Through the above current relationship I I = I1 = -I3, I II = I2 = -I4 and formula (7), solving the four - element system of equations, we can obtain the relationships between V1, V2, V3 and V4 and I I and I II Since the coefficient k l,m (m = 1, 2) between the l - th port and the m - th port is relatively complex, it can be simplified to:

[0068]

[0069] Combining the above voltage relationships V I = V1 - V3, V II = V2 - V4, we can obtain the relationships between V I and V II and I I and I II Therefore, the total admittance matrix of the model is:

[0070]

[0071] where K = (k 11 - k 31 )(k 22 - k 42 )-(k 41 - k 21 )(k 32 - k 12 ).

[0072] Then, according to the conversion relationship between the admittance matrix and the scattering matrix, calculate the S - matrix corresponding to the total admittance matrix (i.e., the S - matrix of the antipodal Vivaldi antenna array loaded with a π - shaped coupling network). The S - matrix includes the reflection coefficient S 11 of the total port I and the transmission coefficient S 21 between the total ports I and II; and according to the S - matrix, determine the coupling utilization condition as:

[0073] S llactive = S 11 + S 21 (10)

[0074]

[0075] According to the coupling utilization condition, judge whether the coupling between array elements can be utilized.

[0076] For the practical application of the proposed π-shaped coupling network in the array, in one embodiment, the dual array is designed first. Specifically, the case of a 2×1 dual array is considered first. Taking the E-plane dual antipodal Vivaldi antenna array as an example, the spacing between the antenna elements is d = 42 mm (0.48λ l ), and at this time, the s sides of the upper radiation arm of element 1 and the lower radiation arm of element 2 are facing and overlapping. The active reflection coefficient and coupling utilization condition of the dual antenna array are shown in formulas (9) and (10) respectively. The S parameters and phase differences of the dual original antenna array (i.e., the dual antenna array without the loaded π-shaped coupling network) are as Figure 2 shown. When element 1 and element 2 work independently, their lower operating frequencies are 3.24 GHz and 3.3 GHz respectively. Since the single antenna will have beam offset in the high-frequency band and there is a certain degree of splitting of the main lobe, the upper operating frequency of the element is determined to be 13 GHz. Figure 2 (b) is the phase difference of port 1, Figure 2 (c) is the phase difference of port 2. Calculate the coupling utilization condition, as Figure 2 (b) and 2(c) shown. Near the lower operating frequency, the phase differences are within the boundary values, so the coupling can be utilized. Therefore, the active operating frequency bands of elements 1 and 2 are 2.88 - 13 GHz and 2.85 - 13 GHz respectively. Part of the coupling is utilized, but the extended bandwidth is still limited. At the same time, it can be found from the figure that there are some phase differences that do not meet the coupling utilization condition in the high-frequency band. This part of the coupling results in an active reflection coefficient higher than its corresponding reflection coefficient. However, since the reflection coefficient itself is low at high frequencies, its active reflection coefficient still meets the requirement of being lower than -10 dB. This also further shows that the coupling utilization condition can effectively judge whether the coupling between elements can be utilized.

[0077] By loading the π-shaped coupling network as Figure 3 shown, where Figure 3 (b) is the front structure of the coupling network, Figure 3 (c) is the back structure of the coupling network, the operating bandwidth of the antipodal Vivaldi antenna array can be further extended to the low frequency. The main transmission path of the π-shaped coupling network is directly connected to the two lower radiation arms of the antipodal Vivaldi antenna array, and the two branch paths are connected to the transmission line led out by the upper radiation arm via metallized vias. The specific structural dimensions in the figure are: l1 = 7.5 mm, l2 = 6.5 mm, l3 = 8.5 mm, l4 = 6.5 mm, l5 = 3 mm, l6 = 4 mm, l7 = 11.5 mm. According to the design process of the π-shaped coupling network, the admittance matrix Y c of the coupling network can be obtained first. Select the frequency 2 GHz as the typical frequency.

[0078]

[0079] Meanwhile, the admittance matrix Y of the original antipodal Vivaldi antenna array at the four connection points a is as follows:

[0080]

[0081] According to the above derivation process, the final scattering matrix can be obtained as:

[0082]

[0083] Therefore, at 2 GHz, the active reflection coefficient of element 1 can be calculated as -11.85 dB, and the phase difference is 113.5°, which is within the boundary values (111.7°, 248.3°); while the active reflection coefficient of element 2 is calculated as -16.33 dB, and the phase difference is 149.5°, which is within the boundary values (112.7°, 247.3°), indicating that the coupling is utilized.

[0084] Figure 4 The S-parameters and phase differences of the antenna array with the introduced π-shaped coupling network are given. Among them, Figure 4 (b) is the phase difference of port 1, Figure 4 (c) is the phase difference of port 2. At 2 GHz, the active reflection coefficients of elements 1 and 2 are -11.26 dB and -18.02 dB respectively, and the phase differences are 114.5° and 172.5°. The boundary values are (105.8°, 254.2°) and (107.8°, 252.2°), which are consistent with the calculated values, verifying the correctness of the π-shaped coupling network design. The lower limit operating frequencies corresponding to the reflection coefficients of elements 1 and 2 lower than -10 dB are 3.12 GHz and 3.16 GHz respectively. From the phase differences of ports 1 and 2, it can be found that the coupling within the frequency bands of 1.34 - 2.04 GHz, 2.3 - 3.24 GHz, and 1.28 - 3.9 GHz satisfies the coupling utilization conditions, so it can be used for the expansion of the active bandwidth. The active operating frequency band of element 1 is 1.58 - 13 GHz (8.23:1), and the active operating frequency band of element 2 is 1.53 - 13 GHz (8.50:1). Therefore, the common active operating frequency band of the array is 1.58 - 13 GHz (8.23:1). Compared with the antenna array without the loaded π-shaped coupling network, the active operating bandwidth is expanded by 37.6%.

[0085] Figure 5 and Figure 6 give the gains and normalized radiation patterns of the two-element antenna arrays without and with the loaded π-shaped coupling network. From Figure 5 and Figure 6 it can be seen that the π-shaped coupling network mainly improves the performance at low frequencies, such as Figure 5As shown, the gain within 1.66 - 2.1 GHz has increased significantly, while having less impact on the radiation in the medium and high frequency bands. The gain variation range across the entire frequency band is 1.9 - 12.3 dBi. Figure 6 are the normalized radiation patterns of the two - element antenna array with and without the loaded π - shaped coupling network. Among them, Figure 6 (a), 6(c), 6(e), 6(g) are the E - plane patterns at 2 GHz, 4 GHz, 8 GHz, and 12 GHz respectively. Figure 6 (b), 6(d), 6(f), 6(h) are the H - plane patterns at 2 GHz, 4 GHz, 8 GHz, and 12 GHz respectively. From Figure 6 (a) and (c), it can be seen that the E - plane pattern beams of the two - element array are relatively wide at 2 GHz and 4 GHz. When the number of array elements is further increased, it can be applied to wide - angle beam scanning.

[0086] In one embodiment, the π - shaped coupling network is extended to an 8×1 eight - element E - plane antipodal Vivaldi antenna array for verification. Due to the large number of array elements, the edge element 1, the middle element 4, and the sub - edge element 7 are selected as typical elements for research. Figure 7 shows the active reflection coefficient and port phase difference of the antenna array with the loaded π - shaped coupling network. Among them, Figure 7 (b) is the phase difference of port 1. Figure 7 (c) is the phase difference of port 4. Figure 7 (d) is the phase difference of port 7. The π - shaped coupling network of the eight - element antenna array is obtained by extending and further optimizing the coupling network of the two - element array. From Figure 7 the phase differences of ports 1, 4, and 7 in (b) - 7(d), it can be seen that the coupling at low frequencies can also be used to expand the bandwidth. Specifically, the available coupling frequency bands for element 1 are 1.36 - 3.78 GHz, for element 4 are 1.46 - 3.66 GHz, and for element 7 are 1.48 - 2.42 GHz and 2.74 - 3.9 GHz. These available coupling frequency bands lower the active lower - limit frequencies of element 1, element 4, and element 7 to 1.86 GHz, 1.73 GHz, and 1.71 GHz respectively. Therefore, the common operating frequency band of the antenna array is 1.86 - 13 GHz (6.99:1). Although the active reflection coefficient of elements 1 and 7 increases at some frequency points within this frequency band, it is always lower than - 9 dB (VSWR < 2.1), meeting the impedance - matching requirements.

[0087] Figure 8The gains of the eight - element array without the loaded π - shaped coupling network and the loaded π - shaped coupling network are given. In the range of 1.86 - 2.2 GHz, the gain of the antenna array with the loaded π - shaped coupling network is higher than that without loading, further verifying the effectiveness of the coupling network in expanding the bandwidth. The in - band gain variation range is 8.0 - 18.7 dBi. Due to the limitation of the element spacing, the scanning ability of the antenna array at high frequencies is limited. Therefore, only the E - plane scanning patterns at 2 GHz and 4 GHz are given, as Figure 9 shown. At 2 GHz (as shown in Figure 9 (a)), the antenna array can be scanned within the range of ±60°, and the gain variation is within 2.3 dB, and the cross - polarization level is below - 25 dB; at 4 GHz (as shown in Figure 9 (b)), the antenna array can be scanned within the range of ±45°, and the gain variation is within 2.7 dB, and the cross - polarization level is below - 24 dB, indicating that the antenna array has good wide - angle scanning ability at low frequencies.

[0088] In the above - mentioned embodiment, for the antipodal Vivaldi antenna array, combined with the structural characteristics of the dual - radiation arms of its elements, a four - port π - shaped coupling network is proposed to connect adjacent elements of the antenna array. Through the π - shaped coupling network, the active operating bandwidth of the antipodal Vivaldi antenna array is improved. And, the design focuses on the low - frequency band, expanding the active operating bandwidths of the one - dimensional two - element and eight - element E - plane arrays to 8.23:1 and 6.99:1 respectively, and improving the scanning performance of the eight - element array at low frequencies.

[0089] In the above - mentioned embodiments, the descriptions of each embodiment have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0090] The above - mentioned are only exemplary embodiments of the present disclosure and should not be used to limit the scope of the present disclosure. That is, any equivalent changes and modifications made according to the teachings of the present disclosure still fall within the scope covered by the present disclosure. Those skilled in the art will easily think of the implementation schemes of the present disclosure after considering the specification and practicing the disclosure here. This application aims to cover any variations, uses, or adaptive changes of the present disclosure, which follow the general principles of the present disclosure and include the common general knowledge or conventional technical means in the technical field not recorded in the present disclosure. The specification and embodiments are only regarded as exemplary, and the scope and spirit of the present disclosure are defined by the claims.

[0091] The technical features of the above - mentioned embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above - mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0092] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An antipodal Vivaldi antenna array loaded with a π-shaped coupling network, characterized in that: include: A π-shaped coupling network and at least two array elements of an antipodal Vivaldi antenna array connected via the π-shaped coupling network; The π-shaped coupling network has a first port, a second port, a third port, a fourth port, a fifth port and a sixth port, wherein the first port, the second port, the third port and the fourth port are used to connect the array element, the main transmission path between the third port and the fourth port is a transmission line with a characteristic impedance of Z3, the fifth port and the sixth port are arranged on the transmission line with the characteristic impedance of Z3, and the transmission line with the characteristic impedance of Z3 is cut into three sections with electrical lengths of θ3, θ4 and θ5 respectively; the branch transmission path between the first port and the fifth port is a transmission line with a characteristic impedance of Z1 and an electrical length of θ1, and the branch transmission path between the second port and the sixth port is a transmission line with a characteristic impedance of Z2 and an electrical length of θ2; The total admittance matrix of the antipodal Vivaldi antenna array loaded with the π-shaped coupling network is: Where K = (k 11 -k 31 )(k 22 -k 42 )-(k 41 -k 21 )(k 32 -k 12 ), k l,m Represents the coefficient between the lth port and the mth port, l=1,2,3,4, m=1,2,I I and V I are the current and voltage of the total port I, I II and V II are the current and voltage of the total port II, I I =I1=-I3,I II =I2=-I4, V I =V1-V3, V II =V2-V4,I l and V l are the current and voltage at the lth port respectively.

2. The antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in claim 1, characterized in that: The array element is an unbalanced feeding type antenna with a single feed line or a balanced feeding type antenna with two arms.

3. The antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in claim 1, characterized in that: The voltage and current at the fifth port are related to the voltage and current at the first port and the third port, and satisfy:

4. The antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in claim 3, characterized in that: The voltage and current at the sixth port are related to the voltage and current at the fifth port and satisfy:

5. The antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in claim 4, characterized in that: The voltage and current at the second port and the fourth port are both related to the voltage and current at the sixth port and satisfy:

6. The antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in claim 5, characterized in that: The admittance matrix of the π-shaped coupling network is:

7. The antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in claim 1, characterized in that: The total admittance matrix of the antipodal Vivaldi antenna array loaded with the π-shaped coupling network is the sum of the admittance matrix of the π-shaped coupling network and the admittance matrix of the antipodal Vivaldi antenna array not loaded with the π-shaped coupling network.

8. The antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in claim 7, characterized in that: The total admittance matrix of the antipodal Vivaldi antenna array loaded with the π-shaped coupling network satisfies: Among them, Y l,n Represents the mutual admittance between the lth port and the nth port, n=1,2,3,4.

9. The antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in claim 8, characterized in that: The V1, V2, V3 and V4 are I and I II The relationship between them satisfies:

10. A coupling utilization verification method, applied to the antipodal Vivaldi antenna array loaded with a π-shaped coupling network as claimed in any one of claims 1 to 9, characterized in that: include: According to the conversion relationship between the admittance matrix and the scattering matrix, the S matrix corresponding to the total admittance matrix is ​​calculated, and the S matrix includes the reflection coefficient S of the total port I 11 and the total transmission coefficient S between ports I and II 21 ; According to the S matrix, the coupling utilization condition is determined as: S llacttive =S 11 +S 21 According to the coupling utilization condition, it is determined whether the coupling between array elements can be utilized.

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