Ground electromagnetic compatibility test method for airborne very-low-frequency ultra-long antenna system

Abstract

The invention belongs to the technical field of aircraft system-level electromagnetic compatibility, and relates to a very-low-frequency ultra-long towed antenna ground verification test method. By adopting an equivalent mode, a test mode of the towed antenna needing to be released in a full state is improved into a mode of combining small-proportion release with the simulated matched load, the antenna radiation efficiency and the test result accuracy are ensured, meanwhile, the period required by the test is effectively shortened, manpower and material resources are effectively reduced, and smooth development of model development is ensured.

Description

Technical Field

[0001] The invention belongs to the field of aircraft system-level electromagnetic compatibility design verification, and relates to a ground electromagnetic compatibility test method for an airborne very low frequency ultra-long antenna system. Background Art

[0002] In order to achieve airborne VLF communication capabilities, it is necessary to install VLF communication antennas on the aircraft. Due to the long wavelength of VLF, to ensure antenna performance, the antenna size generally ranges from several hundred meters to several thousand meters. Take the foreign E-6A "submarine communication relay" as an example. It is equipped with a "TACAMO" system and equipped with dual towed antennas, with a long antenna of 7,925 meters and a short antenna of 1,220 meters. When not in use, the towed antenna is stored inside the fuselage and released by a winch when in use.

[0003] The VLF communication system installed on a certain aircraft also uses a dual-trailer antenna, with the short antenna being more than 1,000 meters long and the long antenna being more than 4,000 meters long. Due to the long antennas, when conducting ground tests and verifications, if all the antennas are deployed, a large area will be required, which is difficult to achieve.

[0004] In order to verify the electromagnetic compatibility of the system on the ground after installing a very low frequency ultra-long antenna on an aircraft, an equivalent test method for ultra-long towed antenna system was proposed through theoretical analysis and verification. Summary of the invention

[0005] The present invention provides a ground electromagnetic compatibility test method for an airborne very low frequency ultra-long antenna system, which can effectively avoid the problem of a large site and a large amount of engineering required for a ground test of an ultra-long antenna, and can ensure the test effect, effectively saving the period, manpower and material resources required for the ground test.

[0006] Compared with the prior art, the beneficial effect of the present invention is that it has been shown through electromagnetic compatibility tests and practical engineering applications that the adopted test method effectively saves the resources required for the test, the test data is consistent with the actual performance of the full-release state in the air, and the test data has high credibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Schematic diagram of the aerial release of the VLF dual towed antenna system;

[0008] Figure 2 This is a schematic diagram of the layout of the very low frequency dual-towed antenna system during ground testing. DETAILED DESCRIPTION

[0009] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0010] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0011] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0012] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0013] Combined with Figure 2 The long antenna is led out from the belly of the aircraft for 100 meters, and the short antenna is led out from the tail of the aircraft for 100 meters. The ends of the short antenna and the long antenna are connected to the high and low potential ends of the simulated matching load respectively. The non-uniform half-wave dipole antenna with asymmetrical excitation and variable radius is normalized and equivalent to a typical closed antenna radiation loop with the help of simulated matching load.

[0014] The two antennas form a square with a side length of approximately 50 meters. The aircraft and the simulated matching load are located at the two diagonal positions of the square, and the sides are kept vertical as much as possible to minimize the coupling of electromagnetic waves in space. To ensure safety and avoid electromagnetic influence between the external environment and the airborne very low frequency communication system, more than 2 meters of space is reserved around the aircraft and antennas.

[0015] Both the long antenna and the short antenna are exposed metal conductors, and the peak operating voltage at the output end of the tuning device is relatively high. Therefore, after the ground antenna is released, it needs to be raised by an antenna bracket. The bracket height is: 2-3m, and the bracket-to-ground insulation requirement is not less than 15kV.

[0016] The surface of the bracket should be passivated to prevent the antenna from being damaged when it is retracted or extended during joint tuning, which will affect the antenna performance.

[0017] The antenna bracket should be highly stable to prevent electric shock accidents caused by the bracket falling to the ground. To ensure safety, it is recommended that the short antenna be insulated.

[0018] The antenna bracket should have a portable disassembly function so that the bracket and antenna can be removed in time before it rains.

[0019] After the aircraft is parked at the test site, the long antenna is extended 100 meters from the belly of the aircraft, and the short antenna is extended 100 meters from the tail of the aircraft. The ends of the short antenna and the long antenna are connected to the high and low potential ends of the simulated matching load respectively. The two antennas form a square with a side length of approximately 50 meters. The antenna is raised by 2.5 meters through a wooden bracket. After the arrangement is completed, the test is carried out according to the normal procedure.

[0020] The above-mentioned embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that the above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the art can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna system, characterized in that: include: Lead the long antenna out from the belly of the aircraft by L meters, and the short antenna out from the tail of the aircraft by L meters. The ends of the short antenna and the long antenna are respectively connected to the high potential and low potential ends of the simulated matching load to form a ring-shaped transmitting loop. Place the two antennas and the simulated matching load on the support frame to form a square with a side length of L / 2 meters, and the aircraft and the simulated matching load are located at two diagonal positions of the square respectively; The aircraft applies an excitation signal to the short antenna, and together with the long antenna forms an electrical circuit that performs the antenna function, completing the conversion and radiation of very low frequency current into electromagnetic waves; electromagnetic compatibility tests are conducted, and the antenna radiation effect test equipment in the aircraft cabin obtains the test results.

2. The ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna system according to claim 1 is characterized in that: The method further comprises: The antenna radiation effect detection equipment obtains the signal emission intensity generated by the dual antenna radiation system formed by the long antenna and the short antenna, and determines whether the emission intensity meets the electromagnetic compatibility requirements.

3. The ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna system according to claim 1 is characterized in that: L is determined based on the wavelength of the typical operating frequency of the airborne very low frequency hypercommunication system.

4. The ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna system according to claim 1 is characterized in that: L is 100 meters.

5. The ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna system according to claim 1 is characterized in that: The height of the support frame is 2-3 meters.

6. The ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna system according to claim 1 is characterized in that: The resistance value of the simulated matching load is determined according to the remaining lengths of the long antenna and the short antenna, and the shell of the simulated matching load is grounded.

7. The ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna system according to claim 1 is characterized in that: The bracket is made of insulating material, and the insulation requirement of the bracket to the ground is not less than 15kV.

8. The ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna system according to claim 1 is characterized in that: The signal strength sent by the aircraft through the extra-long antenna system is the maximum transmit power of the device.

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