A phased array antenna transmit loop self-excitation detection and exclusion method

Abstract

The application provides a phased array antenna transmitting loop self-excitation detection and elimination method, the detection method comprising the following steps: setting the phased array antenna to a full-array transmitting inner calibration mode; connecting a spectrum analyzer to an input end of a second radio frequency power divider, disconnecting a radio frequency connection between a transmitting output port of a TR component and an antenna unit; connecting the transmitting output port of the TR component and the antenna unit; confirming a radio frequency leakage signal magnitude introduced from a low frequency input port; and confirming a radio frequency leakage signal magnitude introduced from a radio frequency input port. The method of the application does not need to rely on special electromagnetic compatibility testers and equipment, does not need to increase additional costs, and can quickly find a node of the transmitting loop self-excitation by using a spectrum analyzer.

Description

Technical Field

[0001] This invention belongs to the field of phased array antennas and relates to a method for detecting and eliminating self-excitation in the transmitting loop of a phased array antenna. Background Technology

[0002] Phased array antennas are a core component of phased array systems. With technological advancements, the cost and weight requirements for two-dimensional active phased array antennas have become extremely stringent, but electromagnetic compatibility (EMC) has become even more critical, directly impacting their usability and usability. Among the most common RF compatibility issues for phased array antennas is self-oscillation in the transmit loop caused by a combination of electromagnetic leakage within the system and backward radiation. Therefore, quickly detecting the location of electromagnetic leakage in a phased array antenna and identifying key points in the loop is of significant practical importance for detecting and eliminating self-oscillation in the transmit loop.

[0003] As the functional and performance requirements of phased array antennas become increasingly demanding, the integration density within a limited space is also increasing, leading to stricter requirements on the weight of individual units. To further reduce the weight per unit area and the overall weight of the phased array antenna, technologies such as lightweight integrated networks, highly integrated TR components, and flexible printed circuit boards are being employed.

[0004] Electromagnetic compatibility testing of phased array antennas is conducted in accordance with GJB151B-2013 and GJB1389A-2005. However, due to limitations in the space and testing methods of the electromagnetic compatibility test laboratory, it is difficult to conduct tests on electromagnetic leakage of large-size phased array antennas. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for detecting self-excitation in a phased array antenna transmit loop. The phased array antenna transmit loop includes a first radio frequency power divider and M transmit amplification chain groups. Each transmit amplification chain group includes transmit amplification chains A1, A2, ..., AN connected in sequence. Each transmit amplification chain AN in each transmit amplification chain group includes multiple TR components, and each TR component is connected to a corresponding antenna element. The connection of the amplification chain group includes radio frequency connections and low-frequency connections, where M is a positive integer greater than or equal to 1, and N is a positive integer greater than or equal to 2. The method includes the following steps:

[0006] Set the phased array antenna to full-array transmission internal calibration mode. At this time, the output terminals of the transmission amplifier chain AN and the second RF power divider in each transmission amplifier chain group are connected, and no excitation signal is applied to the transmission input port of the phased array antenna. The parameters of the second RF power divider and the first RF power divider are the same.

[0007] Connect the spectrum analyzer to the input of the second RF power divider, and disconnect the RF connection between the TR component's transmit output port and the antenna unit. At this time, the calibration master port output signal on the spectrum analyzer is P2.

[0008] Connect the TR component's transmit output port and the antenna unit, the connection including RF connection and low frequency connection; shield the RF leakage signal introduced by the RF input port of each transmit amplifier chain group; connect an adjustable RF attenuator between transmit amplifier chain A1 and transmit amplifier chain A2 in each transmit amplifier chain group; when the attenuation of each adjustable RF attenuator increases from 0 to x1, the calibration total port output signal P1 = P2 on the spectrum analyzer;

[0009] Shield the RF leakage signal introduced by the low frequency input port of each transmit amplifier chain. Connect an adjustable RF attenuator to the input port of transmit amplifier chain A1 in each transmit amplifier chain. When the attenuation of each adjustable RF attenuator increases from 0 to x2, the calibration port output signal P3 = P2 on the spectrum analyzer.

[0010] The attenuation values ​​x1 and x2 are the RF leakage signal values ​​introduced by the low-frequency input port and the RF leakage signal values ​​introduced by the RF input port, respectively.

[0011] Furthermore, the specific operation of the RF leakage signal introduced by the RF input port of the shielded transmit amplifier chain is as follows: a matching load is connected to the RF input port of the transmit amplifier chain A1 in each transmit amplifier chain group.

[0012] Furthermore, the specific operation of preventing radio frequency leakage signals introduced by the low-frequency input port of the shielded transmit amplifier chain is as follows: a matching load is connected to the radio frequency input port of the transmit amplifier chain A1 in each transmit amplifier chain group, and an S-layer anti-surge sleeve is added to the outside of the low-frequency cable of the low-frequency input port of the transmit amplifier chain A1 in each transmit amplifier chain group; S is a positive integer greater than 1.

[0013] Furthermore, the value of S is determined by the transmit calibration signal output from the calibration port of the spectrum analyzer. That is, when there is no self-excitation at the output of the calibration port of the spectrum analyzer, it indicates that the shielding of the S-layer anti-wave sleeve is effective.

[0014] A method for eliminating self-excitation in a phased array antenna transmitting loop, wherein the elimination method is implemented according to the above detection method, specifically: improving the shielding performance of the low-frequency cable on the low-frequency input port by x1, and improving the overall shielding performance of the RF cable on the RF input port of the transmitting amplifier chain A1 and the first RF power divider connected to the RF cable by x2.

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

[0016] (1) The phased array antenna can be tested and judged by itself during the commissioning stage after installation. It does not require a special electromagnetic compatibility test laboratory, nor does it require special electromagnetic compatibility test personnel and equipment. It can be completed through the internal calibration function of the phased array antenna itself, through the full array internal calibration mode, which greatly saves the development cost.

[0017] (2) It is highly operable. By using an adjustable RF attenuator, the RF signal levels introduced at the two inputs of the amplifier chain can be quantitatively obtained.

[0018] (3) It is highly instructive and avoids blindly searching for leakage sources across the entire array. It can quickly find the entry point of the self-excitation loop and quickly locate the weak point of the radio frequency shield by searching for the leakage point. It provides direction and means for solving the self-excitation of the phased array antenna transmission loop.

[0019] (4) It has strong applicability and is applicable to various types of phased array antennas, which has important practical significance for the development of phased array antennas. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the phased array antenna transmission loop according to an embodiment of the present invention. Detailed Implementation

[0021] This application addresses the challenges of electromagnetic compatibility (EMC) testing of phased array antennas, which are often hampered by limitations in laboratory space and testing methods, particularly the difficulty in implementing testing for large-size phased array antennas and electromagnetic leakage. It proposes a method for detecting and eliminating self-oscillation in the phased array antenna's transmit loop. By reducing link loss in the transmit loop, the method detects poor shielding in the RF and low-frequency links, thereby improving the shielding performance of these links and eliminating loop self-oscillation, ultimately enhancing the phased array antenna's performance.

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0023] This embodiment provides a method for detecting self-excitation in a phased array antenna transmit loop. The phased array antenna transmit loop includes a first radio frequency power divider and M transmit amplification chain groups. Each transmit amplification chain group includes transmit amplification chains A1, A2, ..., AN connected in sequence. Each transmit amplification chain AN in each transmit amplification chain group includes multiple TR components, and each TR component is connected to a corresponding antenna element. The connection of the amplification chain group includes radio frequency connection and low frequency connection, where M is a positive integer greater than or equal to 1, and N is a positive integer greater than or equal to 2.

[0024] The detection method includes the following steps:

[0025] Set the phased array antenna to full-array transmission internal calibration mode. At this time, the output terminals of the transmission amplifier chain AN and the second RF power divider in each transmission amplifier chain group are connected, and no excitation signal is applied to the transmission input port of the phased array antenna. The parameters of the second RF power divider and the first RF power divider are the same.

[0026] Connect the spectrum analyzer to the input of the second RF power divider, and disconnect the RF connection between the TR component's transmit output port and the antenna unit. At this time, the calibration master port output signal on the spectrum analyzer is P2.

[0027] Connect the TR component's transmit output port and the antenna unit, the connection including RF connection and low frequency connection; shield the RF leakage signal introduced by the RF input port of each transmit amplification chain group, and connect an adjustable RF attenuator between transmit amplification chain A1 and transmit amplification chain A2 of each transmit amplification chain group. When the attenuation of the adjustable RF attenuator increases from 0 to x1, the calibration total port output signal P1 = P2 on the spectrum analyzer.

[0028] Shield the RF leakage signal introduced by the low frequency input port of each transmit amplifier chain. Connect an adjustable RF attenuator to the input port of transmit amplifier chain A1 in each transmit amplifier chain. When the attenuation of the adjustable RF attenuator increases from 0 to x2, the calibration output signal P3 = P2 on the spectrum analyzer.

[0029] The attenuation values ​​x1 and x2 are the RF leakage signal values ​​introduced by the low-frequency input port and the RF leakage signal values ​​introduced by the RF input port, respectively.

[0030] x1 and x2 are the RF leakage levels introduced from the RF input port and the low-frequency input port, respectively. They can guide phased array antenna engineers to optimize the shielding improvement of RF leakage.

[0031] The specific operation to prevent the RF leakage signal introduced by the RF input port of the shielded transmit amplifier chain is as follows: a matching load is connected to the RF input port of the transmit amplifier chain A1 in each transmit amplifier chain group.

[0032] The specific operation to prevent RF leakage signals introduced by the low-frequency input port of the shielded transmit amplifier chain is as follows: a matching load is connected to the RF input port of the transmit amplifier chain A1 in each transmit amplifier chain group, and an S-layer anti-surge sleeve is added to the outside of the low-frequency cable of the low-frequency input port of the transmit amplifier chain A1 in each transmit amplifier chain group; S is a positive integer greater than 1; the value of S is determined by the transmit calibration signal output by the calibration port of the spectrum analyzer, that is, when there is no self-excitation at the output of the calibration port of the spectrum analyzer, it indicates that the shielding with the S-layer anti-surge sleeve is effective.

[0033] This embodiment also provides a method for eliminating self-excitation in the transmitting loop of a phased array antenna. The elimination method is implemented according to the above detection method, specifically by: improving the shielding performance of the low-frequency cable on the low-frequency input port by x1, and improving the overall shielding performance of the RF cable on the RF input port of the transmitting amplifier chain A1 and the first RF power divider connected to the RF cable by x2.

[0034] To facilitate public understanding, a preferred embodiment will be used to further illustrate the technical solution of the present invention in detail below.

[0035] As attached Figure 1 As shown, a certain phased array antenna contains 32 transmit and receive channels (i.e., Figure 1 The TR component and 32 antenna elements in the array were observed to have a normal output spectrum at the calibration port during full-array transmission calibration test.

[0036] Without RF excitation at the transmit input port: 1. When the TR output port and the antenna unit are disconnected, the spectrum analyzer shows that the calibration port output only has noise floor and the spectrum is normal; 2. When the TR output port and the antenna unit are connected by a cable, the spectrum analyzer shows that there are two self-excited frequency points in the calibration port output working frequency band, with a maximum amplitude of 0dBm.

[0037] The entire transmission loop consists of two transmission amplification chain groups. Each transmission amplification chain group is divided into two stages: transmission amplification chain A1 and transmission amplification chain A2. Individual tests of transmission amplification chain A1 and transmission amplification chain A2 showed no self-oscillation phenomenon, which confirms that the loop is self-oscillating.

[0038] Analyze the causes of self-excitation, such as Figure 1 As shown, each transmit amplification chain consists of transmit amplification chain A1 and transmit amplification chain A2. The fact that transmit amplification chains A1 and A2 alone do not exhibit self-oscillation proves that the gain of either transmit amplification chain A1 or A2 is insufficient to cause self-oscillation; only cascading the two together can induce self-oscillation. It is necessary to locate the source of RF signal leakage and the entry point for the leaked RF signal into the loop. From... Figure 1 As can be seen, the transmitter amplifier chain A1 has only one RF input port and one low-frequency input port, which are the leaked RF signal inputs.

[0039] First, confirm the magnitude of the RF leakage signal introduced from the low-frequency input port:

[0040] To shield the RF leakage signal introduced by the RF input port of the transmit amplifier chain, at the RF input port of each transmit amplifier chain A1 ( Figure 1 When a matching load is connected at point 1 and the RF input port is closed, a self-excited signal with a maximum amplitude of 0dBm is observed at the output of the calibration port from the spectrum analyzer.

[0041] Between the output port of the transmitting amplifier chain A1 and the input port of the transmitting amplifier chain A2 ( Figure 1 An adjustable RF attenuator is connected at point 2 in the middle. Starting from 0dB, the attenuation is gradually increased. When it increases to 11dB, the self-excited signal level is -4dBm. When it increases to 12dB, the self-excited signal disappears. Therefore, the RF leakage signal introduced from the low-frequency input port is 12dB.

[0042] Secondly, confirm the magnitude of the RF leakage signal introduced from the RF input port:

[0043] To shield the radio frequency leakage signal introduced by the low-frequency input port of the transmit amplifier chain, the radio frequency input port of the transmit amplifier chain A1 ( Figure 1 Connect a matching load at point 1, and add an S-layer (S is a positive integer greater than 1) anti-surge sleeve to the low-frequency cable of the low-frequency input port of the transmitting amplifier chain A1. The value of S is determined by observing the transmitting calibration signal output by the calibration port of the spectrum analyzer. When no self-excitation is observed at the output of the calibration port of the spectrum analyzer, it indicates that the shielding of the S-layer anti-surge sleeve is effective.

[0044] Remove the matching load connected to the RF input port of the transmitter amplifier chain A1, and simultaneously connect the RF input port of the transmitter amplifier chain A1 and the RF cable ( Figure 1 An adjustable RF attenuator is connected at point 1. The attenuator is gradually increased from 0dB. When it reaches 20dB, the self-excited signal disappears. Therefore, the RF leakage signal introduced from the RF input port is 20dB.

[0045] After locating the RF signal input point, the system searches forward along both the RF link and the low-frequency link. On the RF link, the RF cable and the first RF power divider are found; on the low-frequency link, the low-frequency cable is found. Therefore, from the above steps, it can be concluded that the leakage RF signal level entering from the RF input port needs to be reduced by more than 20dB, and the RF signal level introduced from the low-frequency power supply link needs to be reduced by more than 12dB. Before the transmit amplification chain A1 are the RF cable and the first RF power divider; therefore, the overall shielding performance of the RF cable and the first RF power divider needs to be improved by more than 20dB, and the shielding performance of the low-frequency cable needs to be improved by more than 12dB. In this embodiment, the RF cable shielding performance is >100dB, and the first RF power divider shielding performance is <60dB; therefore, the shielding performance of the first RF power divider needs to be improved to >80dB.

[0046] The main effects of this invention are:

[0047] (1) The phased array antenna can be tested and judged by itself during the commissioning stage after installation. It does not require a special electromagnetic compatibility test laboratory, nor does it require special electromagnetic compatibility test personnel and equipment. It can be completed through the internal calibration function of the phased array antenna itself, through the full array internal calibration mode, which greatly saves the development cost.

[0048] (2) It is highly operable. By using an adjustable RF attenuator, the RF signal levels introduced at the two inputs of the amplifier chain can be quantitatively obtained.

[0049] (3) It is highly instructive and avoids blindly searching for leakage sources across the entire array. It can quickly find the entry point of the self-excitation loop and quickly locate the weak point of the radio frequency shield by searching for the leakage point. It provides direction and means for solving the self-excitation of the phased array antenna transmission loop.

[0050] (4) It has strong applicability and is applicable to various types of phased array antennas, which has important practical significance for the development of phased array antennas.

[0051] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0052] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0053] In the several embodiments provided in this application, it should be understood that the disclosed systems and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0054] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0055] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0056] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0057] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for detecting self-excitation in a phased array antenna transmit loop, wherein the phased array antenna transmit loop includes a first radio frequency power divider and M transmit amplification chain groups, each transmit amplification chain group including sequentially connected transmit amplification chains A1, A2, ..., AN, and each transmit amplification chain AN in each transmit amplification chain group includes multiple TR components, each TR component being connected to a corresponding antenna element; the connections of the amplification chain groups include radio frequency connections and low-frequency connections, wherein... M is a positive integer greater than or equal to 1, and N is a positive integer greater than or equal to 2. The method is characterized by the following steps: Set the phased array antenna to full-array internal calibration mode. At this time, the output terminals of the transmit amplifier chain AN and the second RF power divider in each transmit amplifier chain are connected, and no excitation signal is applied to the transmit input port of the phased array antenna. The parameters of the second RF power divider and the first RF power divider are the same. Connect the spectrum analyzer to the input terminal of the second RF power divider and disconnect the RF connection between the transmit output port of the TR component and the antenna element. At this time, the calibration master port output signal on the spectrum analyzer is P2. Connect the TR component's transmit output port and the antenna unit, the connection including RF connection and low frequency connection; shield the RF leakage signal introduced by the RF input port of each transmit amplification chain group; connect an adjustable RF attenuator between transmit amplification chain A1 and transmit amplification chain A2 of each transmit amplification chain group; when the attenuation of each adjustable RF attenuator increases from 0 to x1, the calibration total port output signal P1=P2 on the spectrum analyzer. Shield the RF leakage signal introduced by the low frequency input port of each transmit amplifier chain group. Connect an adjustable RF attenuator to the input port of transmit amplifier chain A1 in each transmit amplifier chain group. When the attenuation of each adjustable RF attenuator increases from 0 to x2, the output signal P3 of the calibration port on the spectrum analyzer is P2. The attenuation values ​​x1 and x2 are the RF leakage signal values ​​introduced by the low-frequency input port and the RF leakage signal values ​​introduced by the RF input port, respectively.

2. The phased array antenna transmit loop self-excitation detection method according to claim 1, characterized in that, The specific operation to introduce the RF leakage signal into the RF input port of the shielded transmit amplifier chain is as follows: connect a matching load to the RF input port of the transmit amplifier chain A1 of each transmit amplifier chain.

3. The phased array antenna transmit loop self-excitation detection method according to claim 1, characterized in that, The specific operation to prevent the radio frequency leakage signal introduced by the low-frequency input port of the shielded transmit amplifier chain is as follows: a matching load is connected to the radio frequency input port of the transmit amplifier chain A1 of each transmit amplifier chain, and an S-layer anti-wave sleeve is added to the outside of the low-frequency cable of the low-frequency input port of the transmit amplifier chain A1 of each transmit amplifier chain; S is a positive integer greater than 1.

4. The phased array antenna transmit loop self-excitation detection method according to claim 3, characterized in that, The value of S is determined by the transmit calibration signal output from the calibration port of the spectrum analyzer. That is, when there is no self-excitation at the output of the calibration port of the spectrum analyzer, it indicates that the shielding of the S-layer anti-wave sleeve is effective.

5. A method for eliminating self-excitation in the transmitting loop of a phased array antenna, characterized in that, The exclusion method is implemented according to the detection method of any one of claims 1-4, specifically by: improving the shielding performance of the low-frequency cable on the low-frequency input port by x1, and improving the overall shielding performance of the RF cable on the RF input port of the transmit amplifier chain A1 and the first RF power divider connected to the RF cable by x2.

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