Large carrier antenna test system and method

Abstract

The invention relates to the technical field of antenna testing, and discloses a large carrier antenna testing system and method.The testing system comprises a testing link and a wave absorbing screen, and the wave absorbing screen is arranged in the middle of the testing link and used for absorbing mirror reflection from the ground; the wave-absorbing screen comprises a wave-absorbing material layer and a supporting frame, and the wave-absorbing material layer is arranged on the supporting frame. The wave-absorbing screen is adopted to reduce multipath reflection, the optical fiber link replaces part of radio frequency cable links to reduce link loss, the signal receiving level of the test system is increased, and it is guaranteed that the test system can reflect the real performance of a tested piece to a greater extent.

Description

Technical Field

[0001] This invention relates to the field of antenna testing technology, and in particular to a large carrier antenna testing system and method. Background Technology

[0002] As a transceiver front-end component of a radio system, the antenna plays a crucial role in the electromagnetic propagation field. Antenna amplitude and phase pattern performance are important indicators of an antenna. After the antenna is designed and manufactured, its electrical performance, such as its amplitude and phase patterns, needs to be tested and evaluated.

[0003] For single-unit antennas, current antenna testing technologies and systems can generally meet testing requirements. However, antennas typically need to operate on large carrier platforms, such as aircraft, automobiles, and ships. When antennas are installed on large carriers like aircraft and automobiles, their performance is affected by the carrier, resulting in a certain degree of degradation. The specific extent of this degradation needs to be determined through testing methods and systems. Therefore, research on antenna testing on large carriers is necessary.

[0004] Once the antenna is mounted on an aircraft platform, its large size necessitates the construction of a massive anechoic chamber to ensure the quiet zone requirements of the device under test (DUT) and to accommodate its installation and rotation. Furthermore, the large size of the DUT necessitates a significant far-field distance. For example, with an effective antenna aperture of 2m after mounting, the required far-field distance at 2GHz is at least 53m, and this distance will be even greater for frequencies above 2GHz. This will further increase the required anechoic chamber size and cost.

[0005] Far-field testing can effectively overcome the above problems, but traditional far-field testing has certain limitations: 1) Multiple path interference in the external field The actual field environment is quite complex, with numerous multipath effects from ground reflections, tree reflections, and other sources. This can lead to significant errors in field test results, and may even prevent the antenna pattern from being accurately measured. Particularly for low-frequency antenna installation testing, the superimposed environmental influences from the ground cause substantial distortion in the antenna pattern, making it difficult to reflect the true performance of the antenna after installation.

[0006] 2) The link loss of the field test system is relatively large. A typical far-field test system mainly consists of a vector network analyzer, a power amplifier, RF cables, and a transmitting antenna, such as... Figure 1 As shown.

[0007] According to the far-field distance formula ,in The wavelength corresponding to the highest test frequency is given, and D represents the size of the device under test (DUT). After the antenna is mounted, the DUT size is considered within the entire carrier platform. Since the carrier size is generally large, taking an effective antenna aperture of 2m after mounting as an example, the required far-field distance at 2GHz is 50m. This leads to increased spatial and link attenuation, especially at 18GHz, where spatial attenuation is approximately 91.5dB at a 50m transmit / receive distance. Furthermore, traditional far-field testing requires RF cables for RF signal transmission, and the path loss introduced by these cables at a 50m transmit / receive distance is unacceptable for the test system.

[0008] like Figure 2 As shown, commonly used testing methods employ instruments and equipment such as signal generators, spectrum analyzers, power amplifiers, RF cables, and transmitting antennas. The signal generator and power amplifier enhance the link signal, and the signal generator can be placed directly at the transmitting antenna, avoiding signal attenuation via the transmission-to-reception cable. However, this method cannot obtain antenna phase information; it can only test antenna amplitude information. Summary of the Invention

[0009] To address the issues of severe multipath interference and low received signal levels during traditional field testing of large carrier antennas, this invention proposes a testing system and method for large carrier antennas. This system employs an absorbing screen to reduce multipath reflections, replaces some RF cable links with fiber optic links to reduce link loss, and increases the received signal level of the testing system, ensuring that the testing system can reflect the true performance of the device under test to a greater extent.

[0010] The technical solution adopted in this invention is as follows: A large carrier antenna testing system includes a test link and an absorbing screen. The absorbing screen is located in the middle of the test link and is used to absorb mirror reflections from the ground. The absorbing screen includes an absorbing material layer and a support frame, with the absorbing material layer disposed on the support frame.

[0011] Furthermore, the width and height of the absorbing screen are adjusted according to the test link transmission and reception parameters, which include the installation height of the transmitting and receiving antennas, the beamwidth of the transmitting antenna, and the transmission and reception distance; the type of absorbing material of the absorbing screen is adjusted according to the test frequency band.

[0012] Furthermore, the placement point of the absorbing screen is determined based on the Fresnel reflection zone, and the placement point includes the physical light reflection point of the test link.

[0013] Furthermore, the wave-absorbing screen also includes rollers, which are disposed at the bottom of the support frame.

[0014] Furthermore, the test link includes a vector network analyzer, a photoelectric converter transmitter, an optical fiber, a photoelectric converter receiver, a power amplifier, and a transmitting antenna connected in sequence.

[0015] Furthermore, the vector network analyzer is capable of transmitting radio frequency signals and transmitting them to the transmitter of the photoelectric converter via a radio frequency cable.

[0016] Furthermore, the photoelectric converter transmitter can convert the radio frequency signal emitted by the vector network analyzer into an optical signal and transmit it to the photoelectric converter receiver via optical fiber.

[0017] Furthermore, the photoelectric conversion receiver can convert the optical signal emitted by the photoelectric converter transmitter into a radio frequency signal, and transmit it to the power amplifier for amplification via a radio frequency cable before entering the transmitting antenna.

[0018] Furthermore, the transmitting antenna can convert the amplified radio frequency signal from the power amplifier into electromagnetic waves and transmit them. The device under test receives the transmitted electromagnetic waves, converts them into radio frequency signals, transmits them to the vector network analyzer, and obtains the corresponding amplitude and phase data of the device under test through the vector network analyzer.

[0019] A method for testing large carrier antennas, comprising: A radio frequency signal is emitted by a vector network analyzer, and the radio frequency signal is transmitted to the transmitter of the photoelectric converter via a radio frequency cable; The radio frequency signal is converted into an optical signal by the transmitter of the photoelectric converter, and the optical signal is transmitted to the receiver of the photoelectric converter through optical fiber. The optical signal is converted into a radio frequency signal by the receiving end of the photoelectric converter. The radio frequency signal is transmitted to the power amplifier for amplification via the radio frequency cable, and then enters the transmitting antenna. The radio frequency signal is converted into an electromagnetic wave by a transmitting antenna and transmitted. The device under test receives the electromagnetic wave and converts it into a radio frequency signal. The amplitude and phase data of the device under test are obtained by testing with a vector network analyzer.

[0020] The beneficial effects of this invention are as follows: 1. This invention uses a wave-absorbing screen to absorb mirror reflections from the ground, which can effectively reduce the influence of ground multipath reflections and improve the testing accuracy of large carrier antennas in the field, especially in improving the antenna test pattern distortion problem during low-frequency testing.

[0021] 2. This invention replaces part of the RF cable link with an optical fiber link to reduce link loss, increase the received signal level of the test system, and ensure that the test system can reflect the true performance of the device under test to a greater extent. Since the optical fiber link is almost unrestricted by the transmission and reception distance, it can minimize link loss, significantly improve the received level of the large carrier antenna field test system, improve the signal-to-noise ratio of the test system, and at the same time, it can stably acquire amplitude and phase test information.

[0022] In summary, this invention can effectively reduce the influence of multipath propagation in complex field testing environments, reduce test link loss, increase the test link receiving level, obtain stable amplitude and phase test data, and realize effective testing of antenna amplitude and phase patterns after antenna installation. It also has high practicality and reliability. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a classic far-field testing system.

[0024] Figure 2 This is a schematic diagram of an existing fiber optic link.

[0025] Figure 3 This is a schematic diagram of the wave-absorbing screen structure of Embodiment 1 of the present invention.

[0026] Figure 4 This is a schematic diagram of the wave-absorbing screen absorbing ground reflections according to Embodiment 1 of the present invention.

[0027] Figure 5 This is a schematic diagram of an optical fiber link according to Embodiment 1 of the present invention.

[0028] Figure 6 This is a schematic diagram of a large carrier antenna testing system according to Embodiment 2 of the present invention. Detailed Implementation

[0029] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] Example 1 Current antenna testing mostly employs field testing methods. The field environment is complex, with numerous multipath interferences from ground reflections, tree reflections, and random vehicles or pedestrians. This leads to significant errors in field test results, and may even prevent the antenna radiation pattern from being accurately determined. Among the many multipath interference factors in the field, ground reflection is the primary influencing factor.

[0031] Based on this, this embodiment provides a large carrier antenna testing system, including a test link and an absorbing screen, wherein the absorbing screen is set in the middle of the test link to absorb the image reflection from the ground, thereby reducing the influence of ground multipath reflection and improving the testing accuracy of large carrier antennas in the field.

[0032] like Figure 3As shown, the wave-absorbing screen includes wave-absorbing material, a support frame, and pulleys, with the pulleys facilitating quick position adjustment.

[0033] Preferably, the width and height of the absorbing screen are designed based on factors such as the installation height of the transmitting and receiving antennas, the beamwidth of the transmitting antenna, and the transmission and reception distance. Specifically, assuming the transmitting and receiving antennas are at the same height, if the height is H (in meters), the transmission and reception distance is L (in meters), and the half-power beamwidth of the transmitting antenna is W (in degrees), then the width and height of the absorbing screen are generally designed to be L / 2*tan(W / 2) and H / 2, respectively. For cases where the transmitting antenna beamwidth is narrow, the height and width of the absorbing screen can be appropriately changed according to the actual situation.

[0034] Preferably, the type of absorbing material on the absorbing screen depends on the test frequency band. When testing low-frequency antennas, it is necessary to use absorbing materials with a higher height (e.g., high-specification absorbing materials of not less than 0.7m) to ensure good absorbing performance.

[0035] Preferably, the placement of the absorbing screen is primarily determined by the Fresnel reflection zone. In actual testing, a direct, simple, and effective placement method can refer to the principle of specular reflection, placing the absorbing screen at the physical light reflection point of the test link, such as... Figure 4 As shown, the physical light reflection point is basically consistent with the calculated Fresnel reflection zone.

[0036] Preferably, such as Figure 5 As shown, the test link includes a vector network analyzer, a photoelectric converter transmitter, an optical fiber, a photoelectric converter receiver, a power amplifier, and a transmitting antenna connected in sequence.

[0037] More preferably, the receiving end of the photoelectric converter has a built-in amplification unit, which can compensate for signal loss during the photoelectric signal conversion process, and at the same time appropriately increase the link signal to ensure the signal strength for long-distance signal transmission.

[0038] like Figure 5 As shown, the signal transmission process of the test link includes: the vector network analyzer transmits a radio frequency (RF) signal, which is transmitted to the transmitter of the optoelectronic converter via an RF cable. The transmitter converts the RF signal into an optical signal, which is then transmitted over a long distance via optical fiber to the receiver. The receiver converts the optical signal back into an RF signal and transmits it to the power amplifier via an RF cable. The RF signal is amplified by the power amplifier and then enters the transmitting antenna. The transmitting antenna converts the RF signal into an electromagnetic wave and transmits it. The device under test (DUT) receives the emitted electromagnetic wave, converts it back into an RF signal, and transmits it to the vector network analyzer. The vector network analyzer then tests and obtains the corresponding amplitude and phase data of the DUT, completing the signal transmission of the entire test link.

[0039] It should be noted that during the entire signal transmission process of the test link, the photoelectric converter and optical fiber replaced the long cables in the traditional link, effectively reducing signal attenuation in the link and improving the received signal level of the test link. The optical fiber link is almost unrestricted by the transmission and reception distance, which can minimize link loss, significantly improve the received level of the large carrier antenna field test system, improve the signal-to-noise ratio of the test system, and at the same time, it can stably acquire amplitude and phase test information.

[0040] Accordingly, this embodiment also provides a method for testing large carrier antennas, including: transmitting radio frequency (RF) signals through a vector network analyzer, the RF signals being transmitted to the transmitter of an optoelectronic converter via an RF cable; converting the RF signals into optical signals through the transmitter of the optoelectronic converter, the optical signals being transmitted to the receiver of the optoelectronic converter via an optical fiber; converting the optical signals into RF signals through the receiver of the optoelectronic converter, the RF signals being transmitted to a power amplifier via an RF cable for amplification, and then entering the transmitting antenna; converting the RF signals into electromagnetic waves and transmitting them through the transmitting antenna, the device under test (DUT) receiving the electromagnetic waves and converting them into RF signals, and obtaining the amplitude and phase data of the DUT through a vector network analyzer.

[0041] Example 2 This embodiment is based on embodiment 1: like Figure 6 As shown, this embodiment provides a large-scale carrier antenna testing system, including a test link and an absorbing screen. In this embodiment, the antenna under test 1 is mounted on the fuselage of a 1:1 scale aircraft model 2. The aircraft model 2 is fixed on a turntable 3, which is fixed on a concrete test tower 4. The transmitting antenna 5 is mounted on the operating platform of an elevator 6. The transmitting and receiving distance L can be freely adjusted by the self-moving elevator 6. The height of the transmitting antenna 5 is adjusted by the hydraulic arm of the elevator 6 so that the transmitting antenna 5 and the device under test 1 are at the same height. The test computer 8, turntable 3, vector network analyzer 9, and switch 16 are connected by a network cable 7. The photoelectric converter transmitter 11 and photoelectric converter receiver 12 are connected by an optical fiber 10 to reduce link loss. The remaining instruments and equipment are connected by an RF cable 13, wherein the photoelectric converter receiver 12, power amplifier 15, and transmitting antenna 5 are connected sequentially by the RF cable 13. The absorbing screen 14 is placed between the elevator 6 and the concrete test tower 4 to absorb ground-reflected signals.

[0042] Specifically, in this embodiment, the transmission and reception distance is 50m. The absorbing screen 14 is placed about 25m away from the transmitting antenna 5. The absorbing screen 8 is 4 meters high and 12 meters wide, and is composed of 700mm conical absorbing material, which can effectively absorb ground reflected signals and reduce the influence of multipath on antenna pattern testing.

[0043] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

[0044] It should be noted that, for the sake of simplicity, the foregoing method embodiments are described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

Claims

1. A large carrier antenna testing system, characterized in that, It includes a test link and an absorbing screen. The absorbing screen is located in the middle of the test link and is used to absorb mirror reflections from the ground. The absorbing screen includes an absorbing material layer and a support frame. The absorbing material layer is disposed on the support frame.

2. The large carrier antenna testing system according to claim 1, characterized in that, The width and height of the absorbing screen are adjusted according to the test link transmission and reception parameters, which include the installation height of the transmitting and receiving antennas, the beamwidth of the transmitting antenna, and the transmission and reception distance; the type of absorbing material of the absorbing screen is adjusted according to the test frequency band.

3. The large carrier antenna testing system according to claim 1, characterized in that, The placement point of the absorbing screen is determined according to the Fresnel reflection zone, and the placement point includes the physical light reflection point of the test link.

4. The large carrier antenna testing system according to claim 1, characterized in that, The wave-absorbing screen also includes rollers, which are located at the bottom of the support frame.

5. A large carrier antenna testing system according to claim 1, characterized in that, The test link includes a vector network analyzer, a photoelectric converter transmitter, an optical fiber, a photoelectric converter receiver, a power amplifier, and a transmitting antenna connected in sequence.

6. A large carrier antenna testing system according to claim 5, characterized in that, The vector network analyzer can emit radio frequency signals and transmit them to the transmitter of the photoelectric converter via a radio frequency cable.

7. A large carrier antenna testing system according to claim 6, characterized in that, The photoelectric converter transmitter can convert the radio frequency signal emitted by the vector network analyzer into an optical signal and transmit it to the photoelectric converter receiver via optical fiber.

8. A large carrier antenna testing system according to claim 7, characterized in that, The photoelectric conversion receiver can convert the optical signal emitted by the photoelectric converter transmitter into a radio frequency signal, and transmit it to the power amplifier for amplification through the radio frequency cable before entering the transmitting antenna.

9. A large carrier antenna testing system according to claim 8, characterized in that, The transmitting antenna can convert the amplified radio frequency signal from the power amplifier into electromagnetic waves and transmit them. The device under test receives the transmitted electromagnetic waves, converts them into radio frequency signals, transmits them to the vector network analyzer, and obtains the corresponding amplitude and phase data of the device under test through the vector network analyzer.

10. A testing method for a large carrier antenna, characterized in that, include: A radio frequency signal is emitted by a vector network analyzer, and the radio frequency signal is transmitted to the transmitter of the photoelectric converter via a radio frequency cable; The radio frequency signal is converted into an optical signal by the transmitter of the photoelectric converter, and the optical signal is transmitted to the receiver of the photoelectric converter through optical fiber. The optical signal is converted into a radio frequency signal by the receiving end of the photoelectric converter. The radio frequency signal is transmitted to the power amplifier for amplification via the radio frequency cable, and then enters the transmitting antenna. The radio frequency signal is converted into an electromagnetic wave by a transmitting antenna and transmitted. The device under test receives the electromagnetic wave and converts it into a radio frequency signal. The amplitude and phase data of the device under test are obtained by testing with a vector network analyzer.

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