A method for measuring insertion loss of radome samples

Abstract

The present invention discloses a method for measuring the insertion loss of a radome sample. The method first calculates the Y factor of the ratio of the normalized noise power output by the system when a standard gain horn is placed with a normal temperature load and points to the clear sky zenith direction, i.e., the calibration Y factor; then, the Y factor of the ratio of the normalized noise power output by the system when a standard gain horn is placed with a normal temperature load and the radome sample is placed and points to the clear sky zenith direction, i.e., the Y factor to be measured; finally, the insertion loss of the radome sample is calculated from the measured calibration Y factor and the Y factor to be measured. The method of the present invention is simple and feasible, and has promotion and application value.

Description

Technical Field

[0001] The invention relates to the field of electrical performance measurement of radome samples and can be used for measuring insertion loss of radome samples. Background Art

[0002] The radome is a covering or structure placed on the antenna to protect the antenna from its physical environment. It has good electromagnetic wave penetration characteristics in terms of electrical properties, and can withstand the effects of harsh external environments in terms of mechanical properties. The radome sample is a flat plate with a single-layer dielectric structure or a sandwich structure made of the same material, under the same production conditions, and through a certain molding process as the actual radome production. The electrical performance measurement of the radome sample is mainly to verify whether the radome profile structure designed based on material parameters conforms to the theoretical design. It can also provide a basis for the design of high-performance radomes by measuring samples of materials with different characteristics. Therefore, it is very important to measure the insertion loss of the radome sample.

[0003] The traditional methods for measuring the insertion loss of radome samples are: free space power ratio method and waveguide transmission method. The free space power ratio method determines the insertion loss of the radome sample by measuring the amount of power received by the system when there is or is not a radome sample between the transmitting antenna and the receiving antenna; the waveguide transmission method determines the insertion loss of the radome sample by measuring the amount of signal power transmitted by the system when there is or is not a radome sample to be tested in the waveguide bracket. The traditional method of measuring the insertion loss of radome samples has the following limitations:

[0004] 1. In the traditional free space power ratio method, the transmitting antenna and the receiving antenna are required to meet the far-field test distance conditions, which places great demands on the size of the radome sample. In addition, the ground reflection and multiple reflections of the environment affect the measurement accuracy of the insertion loss of the radome sample.

[0005] 2. The traditional free space power ratio method is not suitable for measuring antenna cover samples with small insertion loss;

[0006] 3. In the traditional waveguide transmission method, the radome sample is required to be precisely processed according to the cross-sectional dimensions of the waveguide, so the processing of the radome sample is complicated; in addition, different frequency bands require different waveguide measurement systems, so the system for measuring broadband radome samples by the waveguide transmission method is relatively complicated. Summary of the invention

[0007] The purpose of the present invention is to avoid the shortcomings of the above-mentioned background technology and propose a method for measuring the insertion loss of a radome sample. The method does not need to know the normal temperature load noise temperature and the low noise amplifier noise temperature, and only needs to measure the Y factor to calculate the insertion loss of the radome sample. The measurement method is simple and convenient, and the measurement accuracy is high.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for measuring the insertion loss of a radome sample comprises the following steps:

[0010] (1) Measurement and calibration of the Y factor: Point the standard gain horn toward the clear sky zenith, place a normal temperature load at the mouth of the standard gain horn, and let the system receive the blackbody radiation noise of the normal temperature load. Use a spectrum analyzer to measure the normalized noise power output by the system, and use N load The unit is dBm / Hz. Then remove the normal temperature load of the standard gain horn, point the standard gain horn toward the clear sky zenith, receive the sky noise, and use a spectrum analyzer to measure the normalized noise power output by the system, expressed as N sky The unit is dBm / Hz; the calibration Y factor is calculated by the following formula:

[0011]

[0012] Where:

[0013] Y D - calibration Y factor;

[0014] N load —Normalized noise power output by the system when the standard gain bell mouth is placed at normal temperature load, dBm / Hz;

[0015] N sky —The normalized noise power output by the system when the standard gain horn points to the clear sky zenith and there is no radome sample at the horn mouth, dBm / Hz;

[0016] (2) Measure the Y factor to be measured: point the standard gain horn toward the clear sky zenith, place the radome sample at the mouth of the standard gain horn, and use a spectrum analyzer to measure the normalized noise power output by the system. sky-sample The unit is dBm / Hz. The Y factor to be measured is calculated by the following formula:

[0017]

[0018] Where:

[0019] Y X —Y factor to be measured;

[0020] N sky-sample —The normalized noise power output by the system when the standard gain horn points to the clear sky zenith and there is a radome sample at the horn mouth, dBm / Hz;

[0021] (3) Calculate the insertion loss of the radome sample: Calculate the insertion loss of the radome sample in decibels using the following formula based on the measured calibration Y factor and the Y factor to be measured:

[0022]

[0023] Complete the insertion loss measurement of the radome sample.

[0024] Furthermore, the specific method of step (1) is:

[0025] Establish a test system, point the standard gain horn toward the clear sky zenith, place a normal temperature load at the mouth of the standard gain horn, and let the system receive the blackbody radiation noise of the normal temperature load. Set the state parameters of the spectrum analyzer. If the noise power is measured, the RF attenuation of the spectrum analyzer is set to 0dB. Use the noise measurement function of the spectrum analyzer to measure the normalized noise power output by the system, and use N load express;

[0026] Then, the normal temperature load of the standard gain horn is removed, and the standard gain horn is pointed toward the clear sky zenith to receive the sky noise. The normalized noise power output by the system is measured with a spectrum analyzer, and N is used to represent the power of the system. sky express;

[0027] The magnitude of the calibration Y factor is calculated from the measured normalized noise power.

[0028] Furthermore, the specific method of step (2) is:

[0029] After completing the measurement in step (1), the standard gain horn is pointed toward the clear sky zenith, and the antenna cover sample is placed at the mouth of the standard gain horn to receive the sky noise. The measurement state parameters of the spectrum analyzer are kept unchanged, and the noise power of the spectrum analyzer is used to measure the power. The normalized noise power of the measurement system output is measured and expressed as N. sky-sample express;

[0030] The normalized noise power N of the bell mouth at normal temperature load is measured by step (1). load and the normalized noise power N measured in step (2) sky-sample Calculate the size of the Y factor to be measured.

[0031] Furthermore, the normal temperature load is made of microwave absorbing material, and its size is larger than the mouth size of a standard gain horn.

[0032] Furthermore, the size of the radome sample is larger than the aperture size of a standard gain horn.

[0033] Furthermore, the measurement of the normalized noise power output by the system is performed under clear sky conditions.

[0034] Compared with the background technology, the present invention has the following advantages:

[0035] 1. When measuring the insertion loss of the radome sample, this method does not need to know the load noise temperature at room temperature and the low noise amplifier noise temperature. It only needs to measure the Y factor to calculate the insertion loss of the radome sample. Therefore, the measurement method is simple and convenient with high measurement accuracy.

[0036] 2. By measuring the Y factor technique, the common error of normalized noise power measurement can be eliminated;

[0037] 3. This method can eliminate the influence of multiple reflections in traditional methods when measuring the insertion loss of radome samples;

[0038] 4. This method is suitable for measuring the insertion loss of any antenna cover sample and has good promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the measurement principle of the present invention. DETAILED DESCRIPTION

[0040] A method for measuring the insertion loss of a radome sample comprises the following steps: firstly, a standard gain horn is pointed toward the clear sky zenith, a normal temperature load is placed at the mouth of the standard gain horn, and the normalized noise power output by the system is measured by a spectrum analyzer; then, the normal temperature load at the mouth of the standard gain horn is removed, the standard gain horn is pointed toward the clear sky zenith, and the normalized noise power output by the system is measured by a spectrum analyzer, and a Y factor of the ratio of the normal temperature load at the mouth of the standard gain horn to the normalized noise power output by the system when the normal temperature load is placed at the mouth of the standard gain horn and the horn is pointed toward the clear sky zenith is calculated, and the Y factor is called a calibration Y factor; then, a radome sample to be measured is placed at the mouth of the standard gain horn, and the normalized noise power output by the system is measured by a spectrum analyzer, and the Y factor of the ratio of the normal temperature load at the mouth of the standard gain horn to the normalized noise power output by the system when the radome sample is placed and the horn is pointed toward the clear sky zenith is calculated, and the Y factor is called a Y factor to be measured; finally, the insertion loss of the radome sample is calculated based on the measured calibration Y factor and the Y factor to be measured.

[0041] Specifically, the method comprises the following steps:

[0042] (1) Measure and calibrate the Y factor. Point the standard gain horn toward the clear sky zenith, place a normal temperature load at the mouth of the standard gain horn, and let the system receive the blackbody radiation noise of the normal temperature load. Use a spectrum analyzer to measure the normalized noise power output by the system, and use N load The unit is dBm / Hz. Then remove the normal temperature load of the standard gain horn, point the standard gain horn toward the clear sky zenith, receive the sky noise, and use a spectrum analyzer to measure the normalized noise power output by the system, expressed as N sky The unit is dBm / Hz. Use the following formula to calculate the calibration Y factor:

[0043]

[0044] Where:

[0045] Y D - calibration Y factor;

[0046] N load —Normalized noise power output by the system when the standard gain bell mouth is placed at normal temperature load, dBm / Hz;

[0047] N sky —The normalized noise power output by the system when the standard gain horn points to the clear sky zenith and there is no radome sample at the horn mouth, dBm / Hz.

[0048] (2) Measure the Y factor to be measured. The standard gain horn is pointed toward the clear sky zenith, and the radome sample is placed at the mouth of the standard gain horn. Use a spectrum analyzer to measure the normalized noise power output by the system, and use N sky-sample The unit is dBm / Hz. Use the following formula to calculate the Y factor to be measured:

[0049]

[0050] Where:

[0051] Y X —Y factor to be measured;

[0052] N sky-sample —The normalized noise power output by the system when the standard gain horn points to the clear sky zenith and there is a radome sample at the horn mouth, dBm / Hz.

[0053] (3) Calculate the insertion loss of the radome sample. Based on the measured calibration Y factor and the Y factor to be measured, calculate the insertion loss of the radome sample expressed in decibels using the following formula:

[0054]

[0055] The calibration Y factor measurement method in step (1) is as follows: establish a test system, point the standard gain horn toward the clear sky zenith, place a normal temperature load at the mouth of the standard gain horn, and the system receives the black body radiation noise of the normal temperature load. Reasonably set the state parameters of the spectrum analyzer. For example, in the noise power measurement, the RF attenuation of the spectrum analyzer should be set to 0 dB. Use the noise measurement function of the spectrum analyzer to measure the size of the normalized noise power output by the system, and use N load Then remove the normal temperature load of the standard gain horn, point the standard gain horn toward the clear sky zenith, receive the sky noise, and use a spectrum analyzer to measure the normalized noise power output by the system, expressed as N skyThe magnitude of the calibration Y factor is calculated from the measured normalized noise power.

[0056] The method for measuring the Y factor to be measured in step (2) is as follows: after completing the measurement in step (1), the standard gain horn is pointed to the direction of the clear sky zenith, the antenna cover sample is placed at the mouth of the standard gain horn, and the sky noise is received. The measurement state parameters of the spectrum analyzer are kept unchanged, and the noise measurement power of the spectrum analyzer is used to measure the normalized noise power output by the system, and N is used to measure the normalized noise power of the system output by N. sky-sample The normalized noise power N of the bell mouth under normal temperature load is measured by step (1). load and the normalized noise power N measured in step (2) sky-sample Calculate the size of the Y factor to be measured.

[0057] Among them, the normal temperature load is usually made of microwave absorbing material, and its size should be larger than the size of the standard gain horn mouth surface.

[0058] In this method, the size of the radome sample to be tested should be larger than the aperture size of the standard gain horn. In addition, the measurement of normalized noise power should be carried out under clear weather conditions.

[0059] Here is a more specific example:

[0060] Reference Figure 1 The test system consists of a radome sample, a standard gain horn, a normal temperature load, a low noise amplifier, a RF test cable and a spectrum analyzer. The low noise amplifier used in the measurement should have high gain, low noise and good stability.

[0061] In the specific embodiment, the size of the antenna cover sample to be tested is 50cm×50cm, and the operating frequency range is 3.4GHz~4.2GHz. The test frequency is 4GHz. The steps of the antenna cover sample insertion loss measurement method are as follows:

[0062] Step 1: Measure and calibrate the Y factor. Point the standard gain horn toward the clear sky zenith, place a normal temperature load at the mouth of the standard gain horn, and let the system receive the blackbody radiation noise of the normal temperature load. Use a spectrum analyzer to measure the normalized noise power output by the system, and use N load The unit is dBm / Hz. Then remove the normal temperature load of the standard gain horn, point the standard gain horn toward the clear sky zenith, receive the sky noise, and use a spectrum analyzer to measure the normalized noise power output by the system, expressed as N sky The unit is dBm / Hz. Use the following formula to calculate the calibration Y factor:

[0063]

[0064] In the embodiment, the standard gain horn points to the clear sky zenith direction, the standard gain horn mouth is placed with a normal temperature load, the system receives the black body radiation noise of the normal temperature load, and the normalized noise power N output by the system is measured by a spectrum analyzer. load The normal temperature load of the standard gain horn is then removed, and the standard gain horn is pointed toward the clear sky zenith to receive sky noise. The normalized noise power N output by the system is measured using a spectrum analyzer. sky is -120.8dBm / Hz. The calibration Y factor is:

[0065] Y D =10 (-115.2+120.8) / 10 =3.631

[0066] Step 2: Measure the Y factor to be measured. The standard gain horn is pointed to the clear sky zenith, and the radome sample is placed at the mouth of the standard gain horn. Use a spectrum analyzer to measure the normalized noise power output by the system, and use N sky-sample The unit is dBm / Hz. Use the following formula to calculate the Y factor to be measured:

[0067]

[0068] In the embodiment, the standard gain horn is pointed to the clear sky zenith direction, the radome sample is placed at the mouth of the standard gain horn, and the normalized noise power N output by the system is measured by a spectrum analyzer. sky-sample is -120.4dBm / Hz. The Y factor to be measured is:

[0069] Y X =10 (-115.2+120.4) / 10 =3.311

[0070] Step 3: Calculate the insertion loss of the radome sample. Using the measured calibrated Y factor and the Y factor to be measured, calculate the insertion loss of the radome sample in decibels using the following formula.

[0071]

[0072] The insertion loss of the radome sample in the embodiment is:

[0073]

[0074] In summary, the present invention does not need to know the normal temperature load noise temperature and the low noise amplifier noise temperature, and only needs to measure the Y factor to calculate the insertion loss of the antenna cover sample. Therefore, the measurement method is simple and convenient, with high measurement accuracy, and has promotion and application value.

Claims

1. A method for measuring the insertion loss of a radome sample, characterized in that: The following steps are involved: (1) Measurement and calibration of the Y factor: Point the standard gain horn toward the clear sky zenith, place a normal temperature load at the mouth of the standard gain horn, and let the system receive the blackbody radiation noise of the normal temperature load. Use a spectrum analyzer to measure the normalized noise power output by the system, and use N load The unit is dBm / Hz. Then remove the normal temperature load of the standard gain horn, point the standard gain horn toward the clear sky zenith, receive the sky noise, and use a spectrum analyzer to measure the normalized noise power output by the system, expressed as N sky The unit is dBm / Hz; the calibration Y factor is calculated by the following formula: Where: Y D - calibration Y factor; N load —Normalized noise power output by the system when the standard gain bell mouth is placed at normal temperature load, dBm / Hz; N sky —The normalized noise power output by the system when the standard gain horn points to the clear sky zenith and there is no radome sample at the horn mouth, dBm / Hz; (2) Measure the Y factor to be measured: point the standard gain horn toward the clear sky zenith, place the radome sample at the mouth of the standard gain horn, and use a spectrum analyzer to measure the normalized noise power output by the system. sky-sample The unit is dBm / Hz. The Y factor to be measured is calculated by the following formula: Where: Y X —Y factor to be measured; N sky-sample —The normalized noise power output by the system when the standard gain horn points to the clear sky zenith and there is a radome sample at the horn mouth, dBm / Hz; (3) Calculate the insertion loss of the radome sample: Calculate the insertion loss of the radome sample in decibels using the following formula based on the measured calibration Y factor and the Y factor to be measured: Complete the insertion loss measurement of the radome sample.

2. The method for measuring the insertion loss of a radome sample according to claim 1, characterized in that: The specific method of step (1) is: Establish a test system, point the standard gain horn toward the clear sky zenith, place a normal temperature load at the mouth of the standard gain horn, and let the system receive the blackbody radiation noise of the normal temperature load. Set the state parameters of the spectrum analyzer. If the noise power is measured, the RF attenuation of the spectrum analyzer is set to 0dB. Use the noise measurement function of the spectrum analyzer to measure the normalized noise power output by the system, and use N load express; Then, the normal temperature load of the standard gain horn is removed, and the standard gain horn is pointed toward the clear sky zenith to receive the sky noise. The normalized noise power output by the system is measured with a spectrum analyzer, and N is used to represent the power of the system. sky express; The magnitude of the calibration Y factor is calculated from the measured normalized noise power.

3. The method for measuring the insertion loss of a radome sample according to claim 2, characterized in that: The specific method of step (2) is: After completing the measurement in step (1), the standard gain horn is pointed toward the clear sky zenith, and the antenna cover sample is placed at the mouth of the standard gain horn to receive the sky noise. The measurement state parameters of the spectrum analyzer are kept unchanged, and the noise power of the spectrum analyzer is used to measure the power. The normalized noise power of the measurement system output is measured and expressed as N. sky-sample express; The normalized noise power N of the bell mouth at normal temperature load is measured by step (1). load and the normalized noise power N measured in step (2) sky-sample Calculate the size of the Y factor to be measured.

4. The method for measuring the insertion loss of a radome sample according to claim 3, characterized in that: The normal temperature load is made of microwave absorbing material, and its size is larger than the mouth size of the standard gain horn.

5. The method for measuring the insertion loss of a radome sample according to claim 3, characterized in that: The size of the radome sample is larger than the aperture size of a standard gain horn.

6. The method for measuring the insertion loss of a radome sample according to claim 3, characterized in that: The measurements of the normalized noise power at the system output are performed under clear sky conditions.

Images