A method for measuring EIRP of high-power large reflector antenna

Abstract

The application discloses a method for measuring EIRP of a high-power large reflector antenna, and relates to the technical field of reflector antenna performance measurement. The method comprises the following steps: firstly, measuring the near-zone power density of a to-be-measured antenna at different distances in a radiation near-field area of the to-be-measured antenna; then, calculating an axial near-zone power density correction factor at the different distances according to a mouth-face field distribution function of the to-be-measured reflector antenna; calculating the size of EIRP of the to-be-measured antenna according to the measured near-zone power density at the different distances and the axial near-zone power density correction factor; and finally, performing arithmetic average on the measured EIRP at the different distances to determine the size of EIRP of the high-power large reflector antenna. The method is simple and feasible, and has popularization and application values.

Description

Technical Field

[0001] This invention relates to the technical field of performance measurement of reflector antennas, and is particularly applicable to the measurement of EIRP (equivalent isotropic radiated power) of high-power large reflector antennas. Background Technology

[0002] With the rapid development of radar technology, deep space exploration technology, and satellite communication, reconnaissance, and jamming technology, high-power large reflector antennas have been widely used. The EIRP (Emitting Input Reduction Ratio) of a high-power large reflector antenna characterizes the transmission capability of a ground station antenna system. It is equal to the product of the antenna's transmit power and transmit gain (expressed in decibels as the sum of transmit power and transmit gain). EIRP is one of the important technical indicators of a ground station antenna system, and accurate measurement of the ground station antenna's EIRP is crucial. Traditional methods for measuring the EIRP of ground station antennas include the far-field indirect method and the far-field direct method. The far-field indirect method involves measuring the antenna's transmit power and transmit gain separately to determine the EIRP. The far-field direct method involves measuring the signal power level received by a standard gain antenna from the signal transmitted by the antenna under test and using the far-field power transfer equation to calculate the ground station antenna's EIRP. The primary condition for far-field antenna measurement is that the distance between the transmitting and receiving antennas meets the far-field test distance condition, i.e., R ≥ 2D. 2 / λ (R is the distance between the transmitting and receiving antennas, D is the aperture of the antenna under test, and λ is the operating wavelength). Measuring the EIRP of high-power, large reflector antennas using traditional methods has the following limitations:

[0003] 1. In traditional far-field measurement methods, the distance between the transmitting and receiving antennas must meet the far-field test distance requirements. For EIRP measurements of large reflector antennas, it is difficult to meet these requirements. For example, a 34-meter dual-reflector antenna in the X-band at a frequency of 7.5 GHz has a minimum far-field test distance of 57.8 km. Clearly, measuring the EIRP of large reflector antennas using traditional far-field methods is virtually impossible.

[0004] 2. In traditional far-field measurement methods, due to the limitation of antenna installation height, multiple reflections from the ground and the test environment have a significant impact on the measurement results;

[0005] 3. In the traditional far-field indirect method for measuring EIRP, a high-power measurement system and an antenna transmit gain test system need to be established. Therefore, the test system is complex and the measurement efficiency and accuracy are low. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology by proposing a method for measuring the EIRP of a high-power large reflector antenna. This invention does not require meeting the far-field test distance condition of the antenna; it can complete the EIRP measurement of the antenna under test within the near-field region of the antenna, greatly reducing the test distance requirement between the transmitting and receiving antennas, thereby overcoming the limitation of far-field test distance in traditional measurement methods.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for measuring the EIRP of a high-power large reflector antenna includes the following steps:

[0009] (1) Measure the near-field power density at different distances, specifically as follows:

[0010] Within the near-field region of the antenna under test, standard gain horns are sequentially placed at different distances, with the distance R from the standard gain horn to the aperture of the antenna under test satisfying the following condition: At a distance R i At this point, adjust the antenna under test to align with and polarize the standard gain horn axis. Use a spectrum analyzer to measure the signal power level received by the standard gain horn. m (R i () indicates that the unit is dBm; the near-field power density at different distances is calculated using the following formula:

[0011]

[0012] In the formula:

[0013] PD(R i —The antenna under test is at a distance R i Near-field power density at dBW / m 2 ;

[0014] λ—Operating wavelength, in meters;

[0015] P m (R i —The antenna under test is at a distance R i The signal power level measured by the spectrum analyzer, in dBm;

[0016] L RF —RF cable loss between standard gain speaker and spectrum analyzer, dB;

[0017] G SGH —The gain of a standard gain speaker, in dBi;

[0018] N—positive integer, N≥3;

[0019] (2) Calculate the axial near-field power density correction factor, specifically as follows:

[0020] Based on the aperture field distribution function of the antenna under test, the test distance, and the antenna aperture, the axial near-field power density correction factor of the antenna under test is calculated using the following formula:

[0021]

[0022] In the formula:

[0023] PDCF(R i —The antenna under test is at a distance R i Axial near-field power density correction factor at the location;

[0024] f(x) — the aperture field distribution function of the antenna under test;

[0025] β i —Distance factor,

[0026] x — A variable used to normalize the aperture radius of the antenna under test

[0027] j—imaginary unit;

[0028] (3) Calculate the EIRP of the antenna under test, specifically as follows:

[0029] The EIRP of the antenna under test is calculated using the following formula, based on the measured near-field power density at different distances and the corresponding axial near-field power density correction factor:

[0030]

[0031] In the formula:

[0032] EIRP—Equivalent Isotropic Radiated Power of the Antenna Under Test, dBW;

[0033] A—Aperture area of ​​the antenna under test, in m² 2 ;

[0034] Complete the measurement of the high-power large reflector antenna EIRP.

[0035] Further, the method for measuring the near-field power density at different distances in step (1) is as follows: In an outdoor antenna test field, install the antenna under test and a standard gain horn, requiring the distance between the standard gain horn and the antenna under test to meet the near-field distance condition. At this time, the distance between the antenna under test and the standard gain horn is represented by R1. Adjust the axes of the antenna under test and the standard gain horn to align, and match the antenna polarization. The transmitter transmits a high-power single-carrier radio frequency signal, which is transmitted through the antenna feeder, transmitted by the antenna under test, propagates through free space, and is received by the standard gain horn. The signal power level received by the standard gain horn is measured using a spectrum analyzer. Then, turn off the transmitter's radio frequency output, move the standard gain horn to R2 along the direction away from the axis of the antenna under test, adjust the axes of the antenna under test and the standard gain horn to align, and match the antenna polarization. Turn on the transmitter's radio frequency output switch, transmit a high-power single-carrier radio frequency signal, which is transmitted through the antenna feeder, transmitted by the antenna under test, propagates through free space, and is received by the standard gain horn. The signal power level received by the standard gain horn is measured using a spectrum analyzer. This process is repeated until the standard gain horn reaches R2. N At the location, the signal power level received by the standard gain horn is measured using a spectrum analyzer; based on the measured signal power level received by the standard gain horn, the near-field power density at different distances is calculated.

[0036] Further, the method for calculating the axial near-field power density correction factor in step (2) is as follows: After completing the measurement in step (1), turn off the RF output of the transmitter, and calculate the axial near-field power density correction factor based on the aperture field distribution function of the antenna under test, the antenna aperture and the distances R1, R2, ..., R from the aperture of the antenna under test. N The magnitude of the axial near-field power density correction factor at different test distances was calculated using numerical integration.

[0037] Furthermore, the distance R between the antenna under test and the standard gain horn satisfies the near-field distance condition, i.e. The selected test distances R1, R2, ..., R N All are within the near-field region of the antenna under test and satisfy R1. <R2<·····<R N .

[0038] Furthermore, near-field power density measurements at different distances should be conducted in an environment with light winds, clear skies, open space, and no obstacles or electromagnetic interference.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] 1. This method measures the EIRP of a high-power large reflector antenna without requiring the antenna to meet the far-field test distance condition. The EIRP measurement of the antenna under test can be completed within the near-field region of the antenna, which greatly reduces the test distance requirement between the transmitting and receiving antennas, thus overcoming the limitation of far-field test distance in traditional measurement methods.

[0041] 2. This method effectively reduces the impact of multiple reflections from the ground and the testing environment on the measurement results, thus improving the accuracy of EIRP measurement. When measuring antenna EIRP in outdoor sites, multiple reflections from the ground and the testing environment are unavoidable due to limitations in antenna installation height and testing distance. This method reduces the influence of multiple reflections from the ground and the testing environment by changing the testing distance, measuring the EIRP at different distances, and then arithmetically averaging the EIRP values ​​at different distances.

[0042] 3. This method is suitable for EIRP measurement of reflector antennas with different power and aperture, and has universality. Therefore, this invention has good promotion and application value. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the measurement principle of the present invention. Detailed Implementation

[0044] A method for measuring the energy intensity resistance (EIRP) of a high-power large reflector antenna includes the following steps: First, the near-field power density of the antenna under test is measured at different distances within its radiation near-field region. Then, based on the aperture field distribution function of the antenna under test, the axial near-field power density correction factor at different distances is calculated. The EIRP of the antenna under test is calculated using the measured near-field power densities at different distances and the axial near-field power density correction factor. Finally, the EIRP measured at different distances is arithmetically averaged to determine the magnitude of the EIRP of the high-power large reflector antenna.

[0045] The method specifically includes the following steps:

[0046] (1) Near-field power density measurement at different distances. In the near-field region of the antenna under test, the distance from the aperture of the antenna under test is R, and R satisfies the near-field distance condition. Install a standard gain horn, align the antenna under test with the axis of the standard gain horn, and perform polarization matching. Use a spectrum analyzer to measure the signal power level received by the standard gain horn. m (R1) represents the unit in dBm; then, the standard horn is installed sequentially at R2, ..., R in the near-field region of the antenna under test. N At each location, the signal power level received by the standard gain speaker was measured using a spectrum analyzer, and the result was measured using P... m (R2), ... P m (RN () indicates that the unit is dBm; the near-field power density at different distances is calculated using the following formula:

[0047]

[0048] In the formula:

[0049] PD(R i —The antenna under test is at a distance R i Near-field power density at dBW / m 2 ;

[0050] λ—Operating wavelength, in meters;

[0051] P m (R i —The antenna under test is at a distance R i The signal power level measured by the spectrum analyzer, in dBm;

[0052] L RF —RF cable loss between standard gain speaker and spectrum analyzer, dB;

[0053] G SGH —The gain of a standard gain speaker, in dBi;

[0054] N—positive integer, N≥3.

[0055] (2) Calculation of Axial Near-Field Power Density Correction Factor. Given the aperture field distribution function of the antenna under test, the test distance, and the antenna aperture, the axial near-field power density correction factor of the antenna under test is calculated using the following formula:

[0056]

[0057] In the formula:

[0058] PDCF(R i —The antenna under test is at a distance R i Axial near-field power density correction factor at the location;

[0059] f(x) — the aperture field distribution function of the antenna under test;

[0060] β i —Distance factor,

[0061] x — A variable used to normalize the aperture radius of the antenna under test;

[0062] j — Imaginary unit.

[0063] (3) Calculation of EIRP of the antenna under test. The EIRP of the antenna under test is calculated using the following formula based on the measured near-field power density at different distances and the corresponding axial near-field power density correction factor:

[0064]

[0065] In the formula:

[0066] EIRP—EIRP of the antenna under test, dBW;

[0067] A—Aperture of the antenna under test, in m² 2 .

[0068] The method for measuring near-field power density at different distances in step (1) is as follows: In an outdoor antenna test field, install the antenna under test and a standard gain horn. The distance between the standard gain horn and the antenna under test must meet the near-field distance condition. At this time, the distance between the antenna under test and the standard gain horn is represented by R1. Adjust the axes of the antenna under test and the standard gain horn to align and match the antenna polarization. The transmitter emits a high-power single-carrier radio frequency signal, which is transmitted through the antenna feeder, emitted by the antenna under test, propagates through free space, and is received by the standard gain horn. The signal power level received by the standard gain horn is measured using a spectrum analyzer. Then, turn off the transmitter's radio frequency output and move the standard gain horn to R2 along the direction away from the axis of the antenna under test. Adjust the axes of the antenna under test and the standard gain horn to align and match the antenna polarization. Turn on the transmitter's radio frequency output switch and emit a high-power single-carrier radio frequency signal, which is transmitted through the antenna feeder, emitted by the antenna under test, propagates through free space, and is received by the standard gain horn. The signal power level received by the standard gain horn is measured using a spectrum analyzer. This process is repeated until the standard gain horn reaches R2. N Similarly, a spectrum analyzer is used to measure the signal power level received by the standard gain speaker. Based on the measured signal power level received by the standard gain speaker, the near-field power density at different distances is calculated.

[0069] The calculation method for the axial near-field power density correction factor in step (2) is as follows: After completing the measurement in step (1), turn off the RF output of the transmitter. Based on the aperture field distribution function of the antenna under test, the antenna aperture and the distances R1, R2, ..., R from the aperture of the antenna under test are calculated. N The magnitude of the axial near-field power density correction factor at different test distances was calculated using numerical integration.

[0070] The distance R between the antenna under test and the standard gain horn satisfies the near-field distance condition, i.e. The selected test distances R1, R2, ..., R N All are within the near-field region of the antenna under test and satisfy R1. <R2<·····<RN .

[0071] Near-field power density measurements at different distances should be conducted in an environment with light winds, clear skies, open space, and no obstacles or electromagnetic interference.

[0072] Figure 1 This is a schematic diagram illustrating the measurement principle of this method. The test system consists of a transmitter, a transmit feed line, a standard gain horn, an antenna under test (AUT), an RF test cable, and a spectrum analyzer. This method measures the near-field power density of the AUT at different distances within its radiation near-field region. Then, based on the aperture field distribution function of the AUT, the axial near-field power density correction factor is calculated at different distances. The AUT's energy level per unit area (EIRP) is calculated using the measured near-field power densities at different distances and the axial near-field power density correction factor. Finally, the arithmetic mean of the measured EIRPs at different distances is taken to determine the EIRP of the high-power, large reflector antenna.

[0073] In this specific embodiment, the antenna under test is a satellite communication jamming ground station. The antenna type is a Cassegrain dual-reflector antenna with an aperture D = 15m, an operating frequency range of 5.925GHz to 6.425GHz, and linear polarization. The standard gain horn is a C-band horn with a gain of 20.1dBi at 6GHz; the RF cable loss between the standard gain horn and the spectrum analyzer is 10dB. The measurement steps for the EIRP of the antenna under test are as follows:

[0074] Step 1: Near-field power density measurement at different distances. Within the near-field region of the antenna under test, the distance from the aperture of the antenna under test is R, and R satisfies the near-field distance condition. Install a standard gain horn, align the antenna under test with the axis of the standard gain horn, and perform polarization matching. Use a spectrum analyzer to measure the signal power level received by the standard gain horn. m (R1) represents the unit in dBm; then, the standard horn is installed sequentially at R2, ..., R in the near-field region of the antenna under test. N At each location, the signal power level received by the standard gain speaker was measured using a spectrum analyzer, and the result was measured using P... m (R2), ... P m (R N The value is represented by () and the unit is dBm; the near-field power density at different distances is calculated using the following formula.

[0075]

[0076] In this embodiment, the test frequency was 6 GHz, and the test distances within the near-field region of the antenna under test were 450 m, 460 m, and 470 m. The signal power levels received by the standard gain horn were measured using a spectrum analyzer to be 13.05 dBm, 14.10 dBm, and 13.30 dBm, respectively. The near-field power density at different distances was calculated using the following formula:

[0077]

[0078]

[0079]

[0080] Step 2: Calculation of Axial Near-Field Power Density Correction Factor. Given the aperture field distribution function of the antenna under test, the test distance, and the antenna aperture, the axial near-field power density correction factor of the antenna under test is calculated using the following formula:

[0081]

[0082] In this embodiment, the test distances are R1 = 450m, R2 = 460m, R3 = 470m, the antenna aperture diameter is D = 15m, the antenna aperture distribution function is a circular aperture tapered distribution, and the aperture field distribution function is f(x) = 1 - x. 2 The correction factor for the axial near-field power density of the antenna under test at different distances, calculated using the numerical integration method, is as follows:

[0083]

[0084]

[0085]

[0086] Step 3: Calculation of EIRP of the antenna under test. Using the measured near-field power density at different distances and the corresponding axial near-field power density correction factor, the EIRP of the antenna under test is calculated using the following formula:

[0087]

[0088] In this embodiment, the antenna aperture area A = 176.71 m² 2 The operating wavelength λ = 0.05m. Based on the measured near-field power density at different distances and the axial near-field power density correction factor, the EIRP of the antenna under test is calculated as follows:

[0089]

[0090] This invention eliminates the need to meet far-field test distance requirements, enabling EIRP measurements of the antenna under test within the near-field region. This significantly reduces the required test distance between the transmitting and receiving antennas, overcoming the limitations of traditional far-field test distances. This method effectively reduces the impact of multiple reflections from the ground and the test environment on the measurement results, improving EIRP measurement accuracy. When measuring antenna EIRP outdoors, multiple reflections from the ground and the test environment are unavoidable due to limitations in antenna height and test distance. This method reduces the influence of multiple reflections from the ground and the test environment by varying the test distance, measuring the EIRP at different distances, and then arithmetically averaging the EIRP values ​​at these different distances.

[0091] In summary, this method is suitable for EIRP measurement of reflector antennas with different power and aperture, and has versatility, making it valuable for promotion and application.

Claims

1. A method for measuring the EIRP of a high-power large reflector antenna, characterized in that, Includes the following steps: (1) Measure the near-field power density at different distances, specifically as follows: Within the near-field region of the antenna under test, standard gain horns are sequentially placed at different distances, with the distance R from the standard gain horn to the aperture of the antenna under test satisfying the following condition: At a distance R i At this point, adjust the antenna under test to align with and polarize the standard gain horn axis. Use a spectrum analyzer to measure the signal power level received by the standard gain horn. m (R i () indicates that the unit is dBm; the near-field power density at different distances is calculated using the following formula: In the formula: PD(R i —The antenna under test is at a distance R i Near-field power density at dBW / m 2 ; λ—Operating wavelength, in meters; P m (R i —The antenna under test is at a distance R i The signal power level measured by the spectrum analyzer, in dBm; L RF —RF cable loss between standard gain speaker and spectrum analyzer, dB; G SGH —The gain of a standard gain speaker, in dBi; N—positive integer, N≥3; (2) Calculate the axial near-field power density correction factor, specifically as follows: Based on the aperture field distribution function of the antenna under test, the test distance, and the antenna aperture, the axial near-field power density correction factor of the antenna under test is calculated using the following formula: In the formula: PDCF(R i —The antenna under test is at a distance R i Axial near-field power density correction factor at the location; f(x) — the aperture field distribution function of the antenna under test; β i —Distance factor, x — A variable used to normalize the aperture radius of the antenna under test j—imaginary unit; (3) Calculate the EIRP of the antenna under test, specifically as follows: The EIRP of the antenna under test is calculated using the following formula, based on the measured near-field power density at different distances and the corresponding axial near-field power density correction factor: In the formula: EIRP—Equivalent Isotropic Radiated Power of the Antenna Under Test, dBW; A—Aperture of the antenna under test, in m² 2 ; Complete the measurement of the high-power large reflector antenna EIRP.

2. The method for measuring the EIRP of a high-power large reflector antenna according to claim 1, characterized in that, The method for measuring the near-field power density at different distances in step (1) is as follows: In an outdoor antenna test field, install the antenna under test and a standard gain horn. The distance between the standard gain horn and the antenna under test must meet the near-field distance condition. At this time, the distance between the antenna under test and the standard gain horn is represented by R1. Adjust the axes of the antenna under test and the standard gain horn to align and match the antenna polarization. The transmitter transmits a high-power single-carrier radio frequency signal, which is transmitted through the antenna feeder, transmitted by the antenna under test, propagates through free space, and is received by the standard gain horn. The signal power level received by the standard gain horn is measured using a spectrum analyzer. Then, turn off the transmitter's RF output and move the standard gain horn to R2 along a direction away from the axis of the antenna under test. Adjust the axes of the antenna under test and the standard gain horn to align and match their polarization. Turn on the transmitter's RF output switch to transmit a high-power single-carrier RF signal. The signal is transmitted through the antenna feeder, transmitted by the antenna under test, propagates in free space, and is received by the standard gain horn. Use a spectrum analyzer to measure the signal power level received by the standard gain horn. Repeat this process until the standard gain horn is at R2. N At the location, the signal power level received by the standard gain horn is measured using a spectrum analyzer; based on the measured signal power level received by the standard gain horn, the near-field power density at different distances is calculated.

3. The method for measuring the EIRP of a high-power large reflector antenna according to claim 2, characterized in that, The method for calculating the axial near-field power density correction factor in step (2) is as follows: After completing the measurement in step (1), turn off the RF output of the transmitter. Based on the aperture field distribution function of the antenna under test, the antenna aperture and the distances R1, R2, ..., R from the aperture of the antenna under test are calculated. N The magnitude of the axial near-field power density correction factor at different test distances was calculated using numerical integration.

4. The method for measuring the EIRP of a high-power large reflector antenna according to claim 3, characterized in that, The distance R between the antenna under test and the standard gain horn satisfies the near-field distance condition, i.e. The selected test distances R1, R2, ..., R N All are within the near-field region of the antenna under test and satisfy R1. <R2<·····<R N .

5. The method for measuring the EIRP of a high-power large reflector antenna according to claim 1, characterized in that, Near-field power density measurements at different distances should be conducted in an environment with light winds, clear skies, open space, and no obstacles or electromagnetic interference.

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