A Ground Electromagnetic Compatibility Test Method for Airborne Very Low Frequency Very Long Antenna Systems

Abstract

This invention belongs to the field of aircraft system-level electromagnetic compatibility technology, and relates to a ground verification test method for very low frequency ultra-long towed antennas. This invention improves the testing method from requiring full-state deployment of the towed antenna to a method of small-scale deployment combined with simulated matching loads, by adopting an equivalent approach. This effectively reduces the required testing cycle, manpower, and material resources while ensuring antenna radiation performance and test result accuracy, thus ensuring the smooth progress of model development.

Description

Technical Field

[0001] This 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 Technology

[0002] To achieve airborne very low frequency (VLF) communication capabilities, VLF communication antennas need to be installed on the aircraft. Due to the long wavelength of VLF frequencies, the antenna size typically ranges from several hundred meters to several kilometers to ensure performance. For example, the foreign E-6A "submarine communication relay aircraft" is equipped with the "TACAMO" system, featuring dual towed antennas: a long antenna of 7925 meters and a short antenna of 1220 meters. When not in use, the towed antennas are stored inside the fuselage and deployed via a winch when needed.

[0003] The very low frequency (VLF) communication system installed on a certain aircraft also adopts a dual-towed antenna configuration, with the shorter antenna exceeding 1,000 meters and the longer antenna exceeding 4,000 meters. Due to the length of the antennas, deploying the entire antenna during ground testing and verification would require a large area, making implementation quite challenging.

[0004] To address the issue of ground-based electromagnetic compatibility verification of aircraft systems after the installation of very low frequency (VLF) ultra-long antennas, an equivalent test method for ultra-long towed antenna systems is proposed through theoretical analysis and verification. Summary of the Invention

[0005] This invention provides a ground electromagnetic compatibility test method for airborne very low frequency ultra-long antenna systems, which can effectively avoid the problems of large site and large amount of engineering work required for ground testing of ultra-long antennas, and can ensure the test results, effectively saving the time, manpower and material resources required for ground testing.

[0006] This invention provides a ground electromagnetic compatibility test method for an airborne very low frequency (VLF) very long antenna system, comprising:

[0007] Extend the long antenna L meters from the belly of the fuselage and the short antenna L meters from the tail of the fuselage. Connect the ends of the short antenna and the long antenna to the high and low potential ends of the analog matching load, respectively, to form a loop transmission circuit.

[0008] The two antennas and the simulated matching load are placed on the support frame to form a square with a side length of L / 2 meters, with the aircraft and the simulated matching load located at two opposite corners of the square.

[0009] The aircraft performs electromagnetic compatibility tests by applying an excitation signal to the short antenna, which together with the long antenna forms an electrical circuit to perform the antenna function, thus completing the conversion and radiation of very low frequency current into electromagnetic waves; the antenna radiation effect testing equipment in the aircraft cabin obtains the test results.

[0010] Optionally, the method further includes:

[0011] Antenna radiation effect testing equipment acquires the signal transmission intensity generated by a dual-antenna radiation system formed by a long antenna and a short antenna, and determines whether the transmission intensity meets electromagnetic compatibility requirements.

[0012] Optionally, L is determined based on the wavelength of the typical operating frequency of the airborne very low frequency ultra-low frequency communication system.

[0013] Optional, L is 100 meters.

[0014] Optionally, the height of the support frame is 2-3 meters.

[0015] Optionally, the resistance of the simulated matching load is determined based on the remaining length of the long and short antennas, and the housing of the simulated matching load is grounded.

[0016] Optionally, the bracket is made of insulating material, and the insulation of the bracket to ground is required to be no less than 15kV.

[0017] Optionally, the signal strength transmitted by the aircraft through the ultra-long antenna system is equal to the maximum transmit power of the equipment.

[0018] Compared with the prior art, the beneficial effects of the present invention are that electromagnetic compatibility tests and practical engineering applications have shown that the adopted test method effectively saves the resources required for testing, the test data is consistent with the actual performance under full air discharge conditions, and the test data has high reliability. Attached Figure Description

[0019] Figure 1 A schematic diagram of the low-frequency dual-tow antenna system being launched into the air;

[0020] Figure 2 This is a schematic diagram showing the setup of a low-frequency dual-tow antenna system during ground testing. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0023] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0025] Combined with appendix Figure 2 The long antenna extends 100 meters from the fuselage belly, and the short antenna extends 100 meters from the tail. The ends of the short and long antennas are connected to the high and low potential ends of the simulated matching load, respectively. The asymmetrically excited, radius-variable non-uniform half-wave dipole antenna is normalized and equivalent to a typical closed antenna radiation loop using the simulated matching load.

[0026] The two antennas form a square with sides approximately 50 meters long. The aircraft and the simulated matching load are located at opposite corners of the square, with the sides kept as perpendicular as possible to minimize electromagnetic wave coupling in space. To ensure safety and avoid electromagnetic interference between the external environment and the airborne VLF communication system, a space of at least 2 meters is reserved around the aircraft and antennas.

[0027] Both long and short antennas are exposed metal conductors, and the peak operating voltage at the output of the tuning equipment is relatively high. Therefore, after the ground antenna is deployed, it needs to be raised using an antenna support. The support height should be 2-3m, and the insulation of the support to ground should be no less than 15kV.

[0028] The surface of the bracket should be passivated to prevent damage to the antenna surface during antenna deployment and retraction, which would affect antenna performance.

[0029] The antenna support should be highly stable to prevent it from tipping over and causing electric shock. For safety, it is recommended that short antennas be insulated.

[0030] The antenna bracket should have a portable disassembly function so that the bracket and antenna can be removed in time before it rains.

[0031] After the aircraft was parked at the test site, the long antenna was extended 100 meters from the fuselage belly, and the short antenna was extended 100 meters from the tail. The ends of the short and long antennas were connected to the high and low potential terminals of the simulated matched load, respectively. The two antennas formed a square with approximately 50-meter sides. The antennas were then raised 2.5 meters using wooden supports. After setup, the test was conducted according to normal procedures.

[0032] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be included within the scope of protection of the present invention.

Claims

1. A ground electromagnetic compatibility test method for an airborne very low frequency (VLF) very long antenna system, characterized in that, include: Extend the long antenna L meters from the belly of the fuselage and the short antenna L meters from the tail of the fuselage. Connect the ends of the short antenna and the long antenna to the high and low potential ends of the analog matching load, respectively, to form a loop transmission circuit. The two antennas and the simulated matching load are placed on the support frame to form a square with a side length of L / 2 meters, with the aircraft and the simulated matching load located at two opposite corners of the square. The aircraft performs electromagnetic compatibility tests by applying an excitation signal to the short antenna, which together with the long antenna forms an electrical circuit to perform the antenna function, thus completing the conversion and radiation of very low frequency current into electromagnetic waves; the antenna radiation effect testing equipment in the aircraft cabin obtains the test results.

2. The ground electromagnetic compatibility test method for an airborne very low frequency very long antenna system according to claim 1, characterized in that, The method further includes: Antenna radiation effect testing equipment acquires the signal transmission intensity generated by a dual-antenna radiation system formed by a long antenna and a short antenna, and determines whether the transmission intensity meets electromagnetic compatibility requirements.

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

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

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

6. The ground electromagnetic compatibility test method for an airborne very low frequency very long antenna system according to claim 1, characterized in that, The resistance of the simulated matching load is determined based on the remaining lengths of the long and short antennas, and the housing of the simulated matching load is grounded.

7. The ground electromagnetic compatibility test method for an airborne very low frequency very long antenna system according to claim 1, characterized in that, The support frame is made of insulating material, and the insulation of the support frame to ground is required to be no less than 15kV.

8. The ground electromagnetic compatibility test method for an airborne very low frequency very long antenna system according to claim 1, characterized in that, The signal strength transmitted by the aircraft through the ultra-long antenna system is the maximum transmission power of the equipment.

Images