A simplified calculation method for atmospheric absorption loss in a ground-to-air interference coexistence scenario

Abstract

This invention discloses a simplified calculation method for atmospheric absorption loss in a scenario of coexistence of ground-to-air interference, belonging to the field of satellite communication loss. Specifically, the method involves: First, constructing a visible region on the Earth's surface that constitutes an interference link to the satellite. This visible region is then divided into grids based on latitude and longitude, and the center point of each region is determined. The elevation angle of different regions relative to the satellite is determined based on the positional relationship between each center point and the satellite. Next, three different atmospheric layering models (medium, low, and high) are established based on latitude, covering radio wave signals in the 0-350 GHz frequency band. When a satellite signal passes through different atmospheric layering models, the actual path length through each atmospheric layer in each model is calculated. The absorption loss value of each atmospheric layer is also calculated. Finally, the atmospheric absorption loss values ​​within the 0-350 GHz frequency range for different latitudes and elevation angles are output. This invention improves atmospheric absorption loss efficiency and reduces resource consumption.

Description

Technical Field

[0001] This invention belongs to the field of signal loss in satellite communication, specifically a simplified calculation method for atmospheric absorption loss in a scenario where ground-to-air interference coexists. Background Technology

[0002] With the continuous development of satellite communication technology, the problem of interference coexistence has gradually become an important research area between satellite and ground communication systems.

[0003] In scenarios where satellite and terrestrial communication systems coexist, especially when the frequency bands of satellite communication, 5G and LTE systems overlap or are closely adjacent, satellites are not only subject to interference signals generated by various communication systems on the Earth's surface, but may also be subject to electromagnetic interference from various infrastructure equipment (such as radar, satellite navigation systems, etc.). These interference signals propagate through the atmosphere to the satellite, affecting the satellite's received signals.

[0004] Besides free space loss, atmospheric absorption loss is also a significant component of signal attenuation during signal propagation. Atmospheric absorption loss is caused by the absorption and scattering of electromagnetic waves by gas molecules, particles, and water vapor in the atmosphere. The absorption loss experienced by electromagnetic waves varies significantly across different frequency ranges, especially during the transmission of high-frequency radio waves such as millimeter waves and terahertz waves, where signals encounter more pronounced absorption and attenuation.

[0005] Considering that the signal transmission path from different surface areas to the satellite may be subject to varying degrees of atmospheric absorption and loss, it is necessary to comprehensively consider the meteorological characteristics of different geographical areas and the differences in the actual path length during signal propagation when calculating path loss.

[0006] Atmospheric absorption loss is one of the important factors affecting the quality of satellite communication. Therefore, the simplified modeling and accurate calculation of atmospheric absorption loss, especially in environments with coexisting interference, is of great engineering significance.

[0007] In current satellite and terrestrial IMT systems, the path loss calculation method is typically based on a free-space propagation model and fixed atmospheric absorption loss. This method treats atmospheric absorption loss as a fixed value and cannot accurately reflect the loss experienced by the signal during actual propagation. Especially in wireless communication systems with different frequency bands, such as satellite communication and numerous terrestrial IMT systems, the traditional fixed atmospheric absorption loss model can no longer meet the needs of modern communication simulation.

[0008] In addition, existing atmospheric absorption loss models are often based on the assumption that the signal propagation path is along the zenith (vertical) direction, and calculate the propagation loss of each atmospheric layer by averaging the meteorological parameters of each layer, based on the traditional atmospheric stratification theory. Finally, the propagation losses of each atmospheric layer are superimposed to obtain the total atmospheric absorption loss of the satellite-to-ground link. This approach makes the calculation process extremely slow and consumes a large amount of computing resources when analyzing the propagation loss of large-scale terrestrial communication systems and satellite links.

[0009] The zenith loss-based model also has the problem of only considering the loss of a single frequency band and a specific region of the earth, without taking into account the differences in atmospheric meteorological parameters at different latitudes of the earth. In the face of increasingly complex interference coexistence scenarios, analyzing the signal attenuation of a single frequency band alone cannot accurately reflect the variable loss encountered by the signal in the actual propagation process. Therefore, there is an urgent need for an atmospheric absorption loss estimation method that covers multiple frequency bands.

[0010] The problems or shortcomings of existing technologies are mainly reflected in the following aspects:

[0011] 1) When calculating atmospheric absorption loss, the different paths and elevation angles of different regions on the Earth's surface to the satellite through the atmosphere under the scenario of coexisting interference are often not taken into account, which will result in different degrees of loss. This will lead to the calculation results being not accurate enough and unable to meet the needs of engineering applications.

[0012] 2) When calculating atmospheric absorption loss, atmospheric stratification thickness models are usually considered. Complex stratification thickness models can impose a huge computational burden, which is a significant limitation, especially when rapid estimation and large-scale data processing are required.

[0013] 3) Furthermore, as the Earth's latitude changes, the atmospheric conditions (such as temperature, humidity, and air pressure) in different latitude regions will also vary significantly, and the signal propagation loss will also change accordingly. This change may vary significantly in different latitude regions of the Earth.

[0014] Therefore, researching how to construct a comprehensive model that takes into account the differences in atmospheric and meteorological conditions at different latitudes in order to accurately predict the propagation loss from different regions to satellites is also a problem that current technology urgently needs to solve. Summary of the Invention

[0015] Considering the problems of low efficiency and high resource consumption in calculating atmospheric absorption loss in specific scenarios, this invention proposes a simplified calculation method for atmospheric absorption loss in the scenario of coexistence of ground-to-air interference. This method simplifies the calculation of atmospheric absorption loss from large-scale ground systems to satellites in the scenario of coexistence of interference, and is expected to achieve a balance between calculation accuracy and calculation efficiency in practical engineering applications.

[0016] The simplified calculation method for atmospheric absorption loss based on the coexistence scenario of ground-to-air interference includes the following steps:

[0017] Step 1: Construct a visible area on the Earth's surface that constitutes an interference link to the satellite. Divide the visible area into a grid using longitude and latitude, and determine the center point of each area.

[0018] Based on the input satellite parameters, the visible area on the Earth's surface is identified, and the ocean and uninhabited areas are removed. The remaining visible area is the region that constitutes an interference link to the satellite.

[0019] Step 2: Based on the positional relationship between the center point of each region and the satellite, determine the elevation angle of different regions relative to the satellite;

[0020] The formula for calculating the elevation angle θ is:

[0021]

[0022] R is the Earth's radius; distance is the distance from the satellite to the center of the grid; h FSS This represents the satellite's vertical altitude relative to the Earth's surface.

[0023] Step 3: Establish three different atmospheric stratification models (mid, low, and high) based on latitude, which can cover radio wave signals in the 0-350 GHz frequency band.

[0024] For low latitude regions (0°-22°), the atmosphere consists of eight layers; for mid-latitude regions (22°-45°), the atmosphere consists of nine layers; and for high latitude regions (45°-90°), the atmosphere consists of eight layers.

[0025] Step 4: When the satellite signal passes through different atmospheric layering models, calculate the actual path length through each atmospheric layer of each model;

[0026] For each atmospheric layer in different atmospheric stratification models, the formula for calculating the actual path length is the same:

[0027] l ns (θ) 2 -2Rcos(θ)+R 2 -(R 2 +layers_height(n)) 2 =0

[0028] Among them l ns (θ) represents the actual path length of the nth atmospheric layer in each atmospheric layering model, and layers_height(n) represents the thickness of the corresponding nth atmospheric layer.

[0029] Step 5: Calculate the absorption loss value of each atmospheric layer when the satellite signal passes through the atmospheric layering model;

[0030] The formula for calculating the total atmospheric absorption loss is the same for different atmospheric stratification models:

[0031]

[0032] Among them, A g The atmospheric attenuation γ is calculated by summing the absorption losses generated by each atmospheric layer. n It is a function of the dry air pressure, air temperature, water vapor partial pressure, and radio wave frequency of the nth atmospheric layer in the model; N is the total number of layers in each atmospheric stratification model. For low-latitude atmospheric stratification models, N is 8; for mid-latitude atmospheric stratification models, N is 9.

[0033] Step 6: Output the atmospheric absorption loss values ​​in the 0-350GHz frequency range for regions with different latitudes and elevation angles.

[0034] The advantages of this invention are:

[0035] 1) This invention provides a simplified calculation method for atmospheric absorption loss in a ground-to-air interference coexistence scenario. This method can assess the atmospheric absorption loss of radio wave signals in the 0-350 GHz frequency band, which covers current and future major communication frequency bands and has a wide frequency applicability. The assessment of this frequency band is not only applicable to current 5G and future 6G networks, but also has significant implications for satellite communication, radar, and high-frequency applications (such as large-scale wireless sensor networks). Furthermore, by assessing atmospheric absorption loss of ground systems at different elevation angles, it can effectively provide a more accurate loss calculation method for ground systems in different regions, thereby supporting the rational allocation of system resources and optimizing communication performance in interference coexistence scenarios.

[0036] 2) This invention presents a simplified calculation method for atmospheric absorption loss in scenarios where ground-to-air interference coexists. This method is suitable for rapidly estimating the atmospheric absorption loss of IMT systems-satellites in different ground areas under large-scale interference coexistence scenarios, saving time and computational resources. For complex communication scenarios, especially the joint use of ground-based IMT systems and satellites, the system needs to consider the impact of atmospheric absorption loss on signal strength. Through an efficient model, absorption loss under different environments can be quickly calculated, helping to optimize interference management and spectrum resource allocation. Furthermore, this invention can significantly reduce computational resource consumption and can be widely applied in real-time network planning and deployment.

[0037] 3) This invention presents a simplified calculation method for atmospheric absorption loss in scenarios with coexisting ground-to-air interference. Based on the temperature and pressure distribution patterns of the atmosphere, an atmospheric stratification model is designed. This model reduces errors while approximating atmospheric absorption loss, meeting the error tolerance allowed in practical engineering applications. Atmospheric absorption loss is affected by factors such as temperature, pressure, and humidity. Designing a suitable stratification model can accurately reflect the impact of these factors' changes on signal propagation. By approximating atmospheric stratification characteristics (such as atmospheric conditions at different altitudes) through the model, errors caused by environmental uncertainties can be effectively reduced. This method not only ensures the accuracy of atmospheric absorption loss prediction but also guarantees that the error remains within a reasonable range in engineering applications, thereby ensuring the robustness and reliability of the communication system. Attached Figure Description

[0038] Figure 1 This is a schematic diagram illustrating the interference coexistence scenario between the high-orbit satellite system and the ground-based large-scale mobile communication system used in this invention.

[0039] Figure 2 This is a flowchart of a simplified calculation method for atmospheric absorption loss in a scenario of coexistence of ground-to-air interference, according to the present invention.

[0040] Figure 3 This is a schematic diagram illustrating the temperature distribution relative to geometric height according to the present invention;

[0041] Figure 4 This is a schematic diagram showing the pressure distribution relative to geometric height according to the present invention;

[0042] Figure 5 This is a simplified calculation comparison chart of atmospheric absorption loss under different elevation angles and frequencies in low-latitude regions according to the present invention. Detailed Implementation

[0043] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0044] To improve the performance of satellite communication systems, especially under coexisting interference conditions, a simplified calculation method for atmospheric absorption loss in ground-to-air interference scenarios is proposed. This simplified calculation method, based on different land regions and atmospheric conditions, has significant theoretical and practical value. Specifically, it can not only provide a more accurate reference for the link budget of satellite communication systems, but also help optimize spectrum management and interference suppression strategies, ensuring effective coordination and interference management between different communication systems.

[0045] like Figure 1 As shown, taking the coexistence of high-orbit satellite systems and terrestrial large-scale mobile communication systems as an application scenario, even when a single satellite's beam covers a specific area, it will still be subject to radio wave signal interference from other terrestrial IMT systems within its visible area. First, based on the satellite's orbital position, the visible area of ​​the Earth's surface excluding the ocean can be determined (generally, the ocean area can be approximated as having no IMT system coverage or negligible interference to the satellite). This visible area serves as the total set of areas that constitute interference links to the satellite. The visible area is divided into grids with determined longitude and latitude (the default value of 1° longitude and 1° latitude can balance the requirements of calculation accuracy and computational resource consumption), and the center point of each area is determined. The atmospheric absorption loss value is calculated using the elevation angle, latitude, and distance of this point relative to the satellite. The atmospheric absorption loss of radio wave signals propagated by IMT systems and other devices within this grid area can be approximated by the calculated value at the center point of the area. The differences in atmospheric conditions at different latitudes are mainly caused by factors such as the Earth's heat distribution, airflow patterns, and climate zones, which affect the physical properties of the atmosphere (such as temperature, pressure, and humidity), and consequently lead to different levels of interference with radio wave signals. Therefore, the scenario diagram uses 22° as the boundary between low and mid-latitudes and 45° as the boundary between high and mid-latitudes, thus establishing that the atmospheric absorption loss values ​​in the three different regions of low, mid, and high latitudes are calculated using different atmospheric meteorological elements.

[0046] The simplified calculation method for atmospheric absorption loss in the scenario of coexistence of ground-to-air interference, such as Figure 2 As shown, the specific steps are as follows:

[0047] Step 1: Construct a visible area on the Earth's surface that constitutes an interference link to the satellite. Divide the visible area into a grid using longitude and latitude, and determine the center point of each area.

[0048] Based on the input satellite parameters, the visible area on the Earth's surface is identified, and the ocean and uninhabited areas are removed. The remaining visible area is the region that constitutes an interference link to the satellite.

[0049] Step 2: Based on the positional relationship between the center point of each region and the satellite, determine the elevation angle of different regions relative to the satellite;

[0050] The elevation angle θ is calculated from the relative position of the satellite and the known grid center, using the following formula:

[0051]

[0052] R is the Earth's radius; distance is the distance from the satellite to the center of the grid, calculated by converting the latitude, longitude, and altitude of the grid region and the satellite into a three-dimensional Cartesian coordinate system, with the Earth's center as the origin; h FSS This represents the satellite's vertical altitude relative to the Earth's surface.

[0053] Step 3: Establish three different atmospheric stratification models—medium, low, and high—based on dimensionality, which can cover radio wave signals in the 0-350 GHz frequency band.

[0054] The atmospheric stratification model is confirmed based on the annual reference atmospheric temperature and pressure distribution patterns. At certain specific altitude layers of the atmosphere at different latitudes, the temperature, pressure, and water vapor density are given by corresponding nonlinear functions. The stratification model is determined based on the variation patterns of temperature, pressure, and water vapor density in mid-, low-, and high-latitudes.

[0055] The differences in atmospheric conditions at different latitudes are mainly caused by factors such as the Earth's heat distribution, airflow patterns, and climate zones, which affect the physical properties of the atmosphere (such as temperature, pressure, and humidity), and consequently lead to different levels of interference with radio wave signals. Therefore, the scenario diagram uses 22° as the boundary between low and mid latitudes and 45° as the boundary between high and mid latitudes to establish three different atmospheric layers and calculation models at mid, low, and high latitudes.

[0056] For low-latitude regions (0°-22°), according to ITU-R Recommendation P.835-6, the atmospheric layers are [0,10], [10,15], [15,17], [17,47], [47,52], [52,72], [72,80], and [80,100], in kilometers.

[0057] For mid-latitude regions (22°-45°), atmospheric stratification is represented by [0,10], [10,13], [13,15], [15,17], [17,47], [47,53], [53,72], [72,80], and [80,100], with units in kilometers.

[0058] Atmospheric stratification in high-latitude regions (45°-90°) is represented by [0,10], [10,15], [15,23], [23,48], [48,53], [53,72], [72,79], and [79,100], with units in kilometers.

[0059] Step 4: When the satellite signal passes through different atmospheric layering models, calculate the actual path length through each atmospheric layer of each model;

[0060] For each atmospheric layer in different atmospheric stratification models, the formula for calculating the actual path length is the same:

[0061] l ns (θ) 2 -2Rcos(θ)+R 2 -(R 2 +layers_height(n)) 2 =0

[0062] Among them l ns (θ) represents the actual path length of the signal through the nth atmospheric layer in each atmospheric layering model, and layers_height(n) represents the thickness of the corresponding nth atmospheric layer.

[0063] For low-latitude atmospheric stratification models, there are 8 corresponding values ​​for the actual path length; for mid-latitude atmospheric stratification models, there are 9 corresponding values ​​for the actual path length.

[0064] Step 5: Calculate the absorption loss value of each atmospheric layer when the satellite signal passes through the atmospheric layering model;

[0065] The formula for calculating absorption loss is the same for each atmospheric layer in different atmospheric stratification models; for the ground-to-air propagation path, the earth station's antenna is a transmitting antenna. Accordingly, the calculation for predicting atmospheric attenuation along this path is as follows:

[0066]

[0067] Among them, A g denoted as the atmospheric absorption loss value for each atmospheric stratification model, and N as the total number of strata for each atmospheric stratification model. For low-latitude and high-latitude atmospheric stratification models, N is 8; for mid-latitude atmospheric stratification models, N is 9.

[0068] In the absence of local air temperature, dry air pressure, and water vapor partial pressure profiles relative to altitude (e.g., data from radiosondes), the reference standard atmosphere provided in ITU-R Recommendation P.835-6 may be used. ns (θ) is the actual path length of the signal through the nth atmospheric layer, which depends on the elevation angle and the thickness of the nth atmosphere, and has the following relationship:

[0069]

[0070] Where R is the Earth's radius (6371 km), θ is the elevation angle from the center of different grid regions to the satellite, and h ns Let l be the thickness of the nth layer after atmospheric stratification. By solving this equation N times, we can obtain l based on the thickness of the nth layer and the elevation angle. ns Value range.

[0071] Atmospheric attenuation coefficient γ n The calculation depends on the layered model and is a function of the atmospheric temperature, pressure, and water vapor density of the nth atmospheric layer in that model; the calculation method is as follows:

[0072] γ=γ o +γ w =0.1820f(N″) oxygen (f)+N″ WaterVapour (f) (dB / km)

[0073] Where, γ o and γ w These are the specific attenuation (in dB / km) under dry air (oxygen conditions, nitrogen and non-resonant Debye attenuation caused by air pressure) and water vapor conditions, respectively; f (in GHz) is the frequency, N″. oxygen (f) and N″ WaterVapour (f) is the imaginary part of the complex refractive index related to this frequency:

[0074] N″ Oxygen (f)=∑ i(Oxygen) S i F i +N″ D (f)

[0075] N″ WaterVapour (f)=∑ i(WaterVapour) S i F i

[0076] S i F is the intensity of the i-th oxygen or water vapor spectral line. i It is the shape factor of the oxygen or water vapor spectral line, which is obtained by summing the spectral line data of oxygen decay and water vapor decay.

[0077] Regarding oxygen, Regarding water vapor, The partial pressure of water vapor at any altitude, e (in hPa), can be measured by the water vapor density ρ (in g / m³) at that altitude. 3 The formula is used to calculate the result from the temperature T (in K). a1 and b1 are spectral line coefficients at different frequencies, and p is the dry air pressure (in hPa).

[0078] The calculation of the shape factor for oxygen or water vapor spectral lines follows Where f i It represents the frequency of the oxygen or water vapor spectral line, and Δf is the linewidth: for oxygen, For water vapor Oxygen correction factor For water vapor, the correction factor is 0.

[0079] The key factors for calculating the atmospheric specific attenuation coefficient—water vapor density, atmospheric temperature, and pressure—will be calculated using a stratified method. While the distribution of water vapor in the atmosphere typically varies considerably, it can be approximated by the following formula: The elevation h0 = 2 km, and the water vapor density at standard ground level is ρ0 = 7.5 g / m³. 3 ;

[0080] The specific attenuation coefficient for each layer is calculated using the integral mean of the average water vapor density, i.e.:

[0081]

[0082] The specific attenuation coefficient for each layer is also calculated from the integral average of pressure and temperature, i.e.:

[0083]

[0084] h n This represents the altitude of the nth atmospheric layer after stratification.

[0085] Step 6: Output the atmospheric absorption loss values ​​in the 0-350GHz frequency range for regions with different latitudes and elevation angles.

[0086] Using layer thickness model The calculated atmospheric parameters exhibit complex computational characteristics (where n is the layer number, δ...). n (This refers to the thickness information of the nth layer). Atmospheric absorption loss typically considers atmospheric factors within the 0-100km range, as the concentration of oxygen and water vapor in the atmosphere significantly affects electromagnetic wave propagation within this range. Above 100km, the concentration of oxygen and water vapor decreases sharply, the absorption effect is weak, and it no longer significantly affects the propagation path. Generally, the atmosphere from 0-100km is refined into 922 layers for layer-by-layer calculation, with the layer height increasing exponentially. Analyzing atmospheric absorption loss in large-scale interference scenarios results in extremely high computational resource consumption. Therefore, to improve computational efficiency and reduce time consumption in large-scale simulation scenarios, a simplified atmospheric layering model is established based on the distribution functions of pressure and humidity relative to atmospheric height. For example... Figure 3 and Figure 4 As shown, the curve for the temperature distribution relative to geometric height can be simplified as N linear lines with different slopes, and the change in pressure relative to geometric height can also be approximated as an approximately linear line. The characteristics of the curves for the distribution of atmospheric temperature and pressure relative to geometric height change with different latitudes. Therefore, a layered model that divides the atmosphere into N layers based on mid-, low-, and high latitudes can be used to confirm the information such as temperature, pressure, and water vapor density of each atmospheric layer, thereby simplifying the model.

[0087] To accurately calculate atmospheric transport absorption attenuation, relevant air pressure, water vapor density, and temperature parameters along the propagation path are required. However, due to the extreme difficulty of conducting atmospheric observations, and the limitations of measured data such as small vertical extension range and uneven data distribution at different altitudes, the global annual average reference atmospheric parameters for different latitude regions provided in ITU-R Recommendation P.835-6 are used as the calculation standard.

[0088] The atmospheric stratification model is determined based on the annual reference atmospheric temperature and pressure distribution. At specific altitudes at different latitudes, the temperature, pressure, and water vapor density are given by corresponding nonlinear functions. The stratification model is determined based on the variation patterns of temperature, pressure, and water vapor density in mid-, low-, and high latitudes. The specific attenuation coefficient for each layer is also calculated from the integral mean of pressure and temperature, i.e.

[0089] like Figure 5 The figure shows the theoretical results of simplified calculations of atmospheric absorption loss. It compares atmospheric absorption loss values ​​at different elevation angles in low-latitude regions. The horizontal axis represents radio wave frequency in GHz, and the vertical axis represents the simplified calculated atmospheric absorption loss in dB. As can be seen, the atmospheric absorption loss value at a 90° elevation angle is lower than that at 30° and 60°. This is because the larger the elevation angle, the shorter the actual path length of the ground system relative to the satellite, resulting in a smaller absorption loss. Furthermore, the curve exhibits significant non-linear characteristics. In frequency bands below 10 GHz, the atmospheric absorption loss is relatively small because the size of oxygen and water vapor molecules is much smaller than the wavelength of low-frequency radio waves (molecular scale is in the nanometer range or smaller). When the molecular size is much smaller than the wavelength, the molecules are less likely to absorb the energy of radio waves, resulting in lower absorption loss. As the frequency increases, the atmospheric absorption loss of radio wave signals increases, mainly because the interaction between high-frequency radio waves and gas molecules in the atmosphere (such as oxygen and water vapor) becomes more significant. In certain frequency bands, atmospheric absorption is significantly affected, primarily because atmospheric gas molecules (such as water vapor and oxygen) resonate and absorb electromagnetic waves of specific frequencies. The following are some of the main absorption frequency bands and their reasons:

[0090] The frequency band around 1.22 GHz (water vapor absorption), approximately 20 GHz to 25 GHz, is attenuated primarily because water vapor molecules in the atmosphere resonate with radio waves in this band, absorbing a large amount of energy and resulting in significant signal attenuation. This is suitable for short-range communication, but long-range communication suffers severe signal attenuation. This characteristic is also used to measure atmospheric water vapor content (e.g., in meteorological observations).

[0091] The frequency band around 2.60 GHz (oxygen absorption), approximately 57 GHz to 64 GHz, is primarily due to the strong resonant absorption of radio waves by atmospheric oxygen molecules within this band, resulting in extremely high signal attenuation. Signals in this band can barely propagate beyond 1 kilometer, making it suitable for short-range wireless communication (such as millimeter-wave communication).

[0092] Around 3.118 GHz: another absorption peak for oxygen, with relatively strong absorption, but not as obvious as at 60 GHz.

[0093] The frequency band around 4.183 GHz (strong water vapor absorption), ranging from approximately 180 GHz to 200 GHz, is mainly due to the significant resonant absorption peak of water vapor in this band, resulting in severe signal absorption loss. Communication applications in this band are limited; it is primarily used for meteorological remote sensing and scientific research.

[0094] Around 5.325 GHz: another absorption peak for water vapor, with significant absorption loss.

Claims

1. A simplified calculation method for atmospheric absorption loss in a scenario of coexistence of ground-to-air interference, characterized in that, The specific steps are as follows: Step 1: Construct a visible area on the Earth's surface that constitutes an interference link to the satellite. Divide the visible area into a grid using longitude and latitude, and determine the center point of each area. Step 2: Based on the positional relationship between the center point of each region and the satellite, determine the elevation angle of different regions relative to the satellite; Angle of elevation The calculation formula is: The radius of the Earth; The distance from the satellite to the center of the grid; This refers to the satellite's vertical altitude relative to the Earth's surface. Step 3: Establish three different atmospheric stratification models (mid, low, and high) based on latitude, which can cover radio wave signals in the 0-350 GHz frequency band; For low-latitude regions, the atmosphere consists of eight layers; for mid-latitude regions, the atmosphere consists of nine layers; and for high-latitude regions, the atmosphere consists of eight layers. Step 4: When the satellite signal passes through different atmospheric layering models, calculate the actual path length through each atmospheric layer of each model; For each atmospheric layer in different atmospheric stratification models, the formula for calculating the actual path length is the same: in In each atmospheric stratification model, the first The actual path length of the atmospheric layer. For the corresponding number The thickness of the atmosphere; Step 5: Calculate the absorption loss value of each atmospheric layer when the satellite signal passes through the atmospheric layering model; The formula for calculating the total atmospheric absorption loss is the same for different atmospheric stratification models: in, The atmospheric attenuation is calculated by summing the absorption losses generated by each atmospheric layer. This is the model's first A function of dry air pressure, air temperature, water vapor partial pressure, and radio wave frequency in the atmosphere; The total number of layers for each atmospheric stratification model; Step 6: Output the atmospheric absorption loss values ​​in the 0-350GHz frequency range for regions with different latitudes and elevation angles.

2. The simplified calculation method for atmospheric absorption loss in a scenario of coexistence of ground-to-air interference as described in claim 1, characterized in that, In step one, the visible area of ​​the Earth's surface is confirmed based on the input satellite parameters, and the ocean and uninhabited areas are removed. The remaining visible area is the region that constitutes an interference link to the satellite.

3. The simplified calculation method for atmospheric absorption loss in a scenario of coexistence of ground-to-air interference as described in claim 1, characterized in that, In step one, when dividing the visible area into grids, the visible area is distinguished by 1 degree of longitude and 1 degree of latitude.

4. The simplified calculation method for atmospheric absorption loss in a scenario of coexistence of ground-to-air interference as described in claim 1, characterized in that, In step two, the elevation angle from the grid center to the satellite is used. The elevation angle is used to assess atmospheric absorption loss in this region.

5. The simplified calculation method for atmospheric absorption loss in a scenario of coexistence of ground-to-air interference as described in claim 1, characterized in that, In step three, the atmospheric stratification model is confirmed based on the annual reference atmospheric temperature and pressure distribution patterns. At certain specific altitudes in the atmosphere at different latitudes, the temperature, pressure, and water vapor density are given by corresponding nonlinear functions. The stratification model is determined based on the temperature, pressure, and water vapor density variation patterns in the middle, low, and high latitudes.

6. The simplified calculation method for atmospheric absorption loss in a scenario of coexistence of ground-to-air interference as described in claim 1, characterized in that, In step three, 22° is used as the boundary between low and mid latitudes, and 45° is used as the boundary between high and mid latitudes, thereby establishing three different atmospheric stratification models for the three latitudes.

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