A slide rule for fast calculation of electromagnetic wave free space attenuation

Abstract

The present invention discloses a slide rule for rapidly calculating the free space attenuation of electromagnetic waves, belonging to the technical field of measuring equipment, comprising a base, a distance scale fixedly arranged on the base, a transparent reading plate fixedly arranged on the distance scale, and a frequency scale and an attenuation value scale movably arranged on the base, the frequency scale and the attenuation value scale slide in linkage, and a frequency pointer is arranged on the transparent reading plate. The present invention can rapidly calculate the attenuation value of a signal, meeting the effectiveness of electronic warfare.

Description

Technical Field

[0001] The invention relates to the technical field of measuring equipment, in particular to a slide rule for rapidly calculating the free space attenuation of electromagnetic waves. Background Art

[0002] When performing reconnaissance or jamming missions, airborne combat personnel of electronic warfare aircraft need to quickly and accurately grasp the battlefield electromagnetic situation and target radiation source information. Among them, the transmission power of the target radiation source is an important information data, an important indicator reflecting the target type and state of the radiation source, and the basic data for combat personnel to adjust the receiver sensitivity and dynamic range. It is also an important information that is indispensable for formulating reconnaissance and jamming plans. According to the signal link transmission theory, the signal transmission power can be calculated by the signal receiving power and the signal attenuation in the link. The signal receiving power can be directly measured, while the signal attenuation in the link transmission needs to be calculated according to the formula. However, the process is complicated and time-consuming, which reduces work efficiency and does not meet the real-time and urgency requirements of combat personnel in performing tasks.

[0003] The patent document with publication number CN 109283388 A discloses a measuring device and a measuring method for the attenuation of electromagnetic wave frequency with propagation distance. The device includes an electromagnetic wave signal generating device, a multi-level electromagnetic wave transmission channel and a signal processing device. The electromagnetic wave signal generating device generates a single-frequency electromagnetic wave signal source. After amplification, the single-frequency electromagnetic wave signal source is transmitted to the multi-level electromagnetic wave transmission channel in one way and transmitted to the signal processing device in another way. The multi-level electromagnetic wave transmission channel transmits the input electromagnetic wave signal in multiple levels and outputs it to the signal processing device. The signal processing device draws a dynamic Lissajous figure according to the two electromagnetic wave signals received, measures the phase angle accumulation value of the electromagnetic wave signal frequency according to the number of flips and position shape of the Lissajous figure, calculates the attenuation of the electromagnetic wave signal frequency according to the phase angle accumulation value, and converts the relative change of the electromagnetic wave signal frequency attenuation into the relative change of the electromagnetic wave wavelength based on the redshift relationship. However, the patent document focuses on the measurement and calculation of the attenuation of the electromagnetic wave frequency with the propagation distance, and fails to solve the timeliness problem of obtaining the free space attenuation value of electromagnetic waves in electronic warfare.

[0004] The patent document with publication number CN 109036036 A discloses an experimental device and method for the attenuation and redshift of electromagnetic wave frequency with propagation distance based on the Chen Shouyuan effect. The experimental device includes a signal generation module, an electromagnetic wave propagation channel and a signal detection module; the signal generation module is used to generate electromagnetic waves with set frequency and amplitude, and the electromagnetic waves reach the signal detection module through the electromagnetic wave propagation channel. The signal detection module observes the attenuation of the electromagnetic wave frequency with propagation distance by measuring the frequency of the electromagnetic waves; wherein the sound source position of the electromagnetic wave generated by the signal generation module, the electromagnetic wave propagation channel and the measurement point position of the signal detection module remain relatively static. However, this patent document is used for electromagnetic wave frequency attenuation and redshift experiments, and cannot quickly calculate the attenuation value of electromagnetic waves in free space. Summary of the invention

[0005] In view of this, the present invention aims at the deficiencies of the prior art and provides a slide rule for quickly calculating the free space attenuation of electromagnetic waves, which can quickly calculate the attenuation value of a signal, quickly obtain the transmission power of the signal, and improve the efficiency of electronic warfare work.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a slide rule for quickly calculating the free space attenuation of electromagnetic waves, comprising a base, a distance scale fixedly arranged on the base, a transparent reading plate fixedly arranged on the distance scale, and a frequency scale and an attenuation value scale movably arranged on the base, the frequency scale and the attenuation value scale slide in conjunction, and a frequency pointer is provided on the transparent reading plate.

[0007] Furthermore, the distance scale includes a first scale and a second scale arranged in parallel on the base, the attenuation value scale is located between the first scale and the second scale, the frequency scale is located on one side of the first scale, and the frequency scale is connected to the attenuation value scale by a connecting rod.

[0008] Furthermore, the scale display range of the first scale is 10 to 2000 m, the reference length of the first scale is 5 cm with a length of 10 to 100 m, and the scale determination formula of the first scale is:

[0009]

[0010] Where: S1 is the display distance, in meters;

[0011] d1 is the actual distance between the scale corresponding to a certain distance value S and the "0 point" on the ruler, in cm.

[0012] Furthermore, the scale display range of the second scale is 1 to 200 km, the reference length of the second scale is 5 cm for a length of 1 to 10 km, and the scale determination formula of the second scale is:

[0013]

[0014] Where: S2 is the displayed distance, in km;

[0015] d2 is the actual distance between the scale corresponding to a certain distance value S and the "0 point" on the ruler, in cm.

[0016] Furthermore, the scale display range of the frequency scale is 0.1 GHz to 20 GHz, the reference length of the frequency scale is 5 cm with a length of 0.1 GHz to 1 GHz, and the scale determination formula of the frequency scale is:

[0017]

[0018] Where: f is the frequency value, in GHz;

[0019] d3 is the actual distance between the scale corresponding to a certain frequency value f and the "0 point" on the scale, in cm.

[0020] Furthermore, the attenuation value scale is provided with an upper scale and a lower scale, the upper scale corresponds to the first scale, the lower scale corresponds to the second scale, the range of the upper scale is 0 to 130 dB, the range of the lower scale is 40 to 170 dB, the minimum scale of the upper scale and the lower scale is 1 dB, and the actual length of each scale is 0.25 cm.

[0021] Furthermore, pads are provided at the lower parts of both ends of the first scale and the second scale, fixing plates are provided at the upper parts of both ends of the first scale and the second scale, and the first scale and the second scale are fixed to the base by bolts.

[0022] Furthermore, a baffle is provided on the upper portion of the base outside the frequency scale, and two sides of the transparent reading plate are respectively fixed to the second scale and the baffle by bolts.

[0023] Furthermore, the transparent reading board is a plexiglass board, and the frequency pointer, as well as unit information of the distance scale, frequency scale and attenuation value scale are engraved on the transparent reading board.

[0024] When electromagnetic waves propagate in space, the power of the signal will weaken as the propagation distance increases, and the degree of signal attenuation is related to the frequency of the signal. According to the signal link transmission theory, the attenuation of electromagnetic wave signals propagating in space can be calculated in a computer by establishing a corresponding mathematical model. The computer of the electronic warfare mission system is installed with software with this function. The software calculation method can meet the measurement accuracy. Therefore, existing technicians mostly use this electronic calculation method, for example, the publication number is CN 109283388 A patent document discloses a device and method for measuring the attenuation of electromagnetic wave frequency with propagation distance. The device includes an electromagnetic wave signal generating device, a multi-level electromagnetic wave transmission channel and a signal processing device. The electromagnetic wave signal generating device generates a single-frequency electromagnetic wave signal source. After amplification, the single-frequency electromagnetic wave signal source is transmitted to the multi-level electromagnetic wave transmission channel in one path and to the signal processing device in another path. The multi-level electromagnetic wave transmission channel transmits the input electromagnetic wave signal in multiple stages and outputs it to the signal processing device. The signal processing device draws a dynamic Lissajous figure based on the two electromagnetic wave signals received, measures the phase angle accumulation value of the electromagnetic wave signal frequency based on the number of flips and position shape of the Lissajous figure, calculates the attenuation of the electromagnetic wave signal frequency based on the phase angle accumulation value, and converts the relative change of the electromagnetic wave signal frequency attenuation into the relative change of the electromagnetic wave wavelength based on the redshift relationship.

[0025] This prior art provides an electronic measuring device and method that can meet the requirements of accurate measurement of electromagnetic wave attenuation values. Moreover, compared with speed, industry insiders pay more attention to the accuracy of calculation, so it is easy to think of using electronic calculation methods. Using mechanical structures to measure electromagnetic wave attenuation is not easy for existing technicians to think of.

[0026] In order to satisfy both accuracy and timeliness of calculation, the inventor of the present application creatively designed a slide rule and set high-precision scale lines for the slide rule based on scientific calculation methods, thus solving the problem of poor timeliness of traditional electronic calculation of electromagnetic wave attenuation values. This technical solution is not easy for existing technicians to think of and implement.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The slide rule for rapidly calculating the free-space attenuation of electromagnetic waves of the present invention is made according to the relationship between the attenuation of electromagnetic waves and the propagation distance and the signal frequency. A distance scale is fixedly arranged on a base, and a frequency scale and an attenuation value scale slide in linkage. By sliding the frequency scale, the signal frequency is aligned with the frequency pointer, and the attenuation value at a certain distance can be observed. The calculation reading is fast, and the problem that it takes a long time to calculate the attenuation value by manually inputting the parameters of the signal into the computer when using software for calculation in the traditional way is solved, and the timeliness of electronic warfare can be met.

[0029] The present invention determines the parameter range according to the signal frequency and the meaningful propagation distance in the actual use environment, and reflects the parameters for calculating the signal attenuation in the form of scales on the slide rule, so that the signal attenuation can be quickly calculated. The slider of the slide rule is moved according to the known parameters, and the signal attenuation can be intuitively displayed in the result area. The use of this tool can help combat support personnel save calculation time, quickly obtain the transmission power of the signal, greatly improve efficiency, and have significant military benefits.

[0030] In addition, the present invention selects 0.1GHz to 20GHz as the frequency measurement range of the slide rule according to the actual frequency measurement requirements. This frequency range basically covers the electromagnetic wave signals that electronic warfare aircraft need to deal with on the battlefield, including ultra-short wave radio communication signals, ground long-range warning radar signals, ground and sea search radar signals, weapon system guidance radar signals, and airborne fire control radar signals. The frequency band can meet actual needs.

[0031] In addition, the present invention selects a measurement range of 10 meters to 200 kilometers based on the actual link distance, which can meet the distance requirement between the actual aircraft and the radiation source when the electronic warfare aircraft is in combat. In order to shorten the length of the slide rule and take into account the logarithmic relationship between the scale value and the actual distance value, the greater the distance, the tighter the interval between the scales. The link distance scale is designed as an upper and lower segmented structure, the upper section is a scale with m as the unit, and the lower section is a scale with km as the unit, which greatly enhances the convenience of carrying and operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the present invention;

[0033] Figure 2 It is a scale schematic diagram of the frequency scale of the present invention;

[0034] Figure 3 is a schematic diagram of the scale of the first scale in an embodiment of the present invention;

[0035] Figure 4 is a schematic diagram of the scale of the second scale in an embodiment of the present invention;

[0036] Figure 5 is a schematic diagram of the scale of the attenuation value scale of the present invention;

[0037] Figure 6 is a graph showing the relationship between the frequency value and the real scale distance of the frequency scale in an embodiment of the present invention;

[0038] Figure 7 is a diagram showing the relationship between the displayed distance and the actual scale distance of the first scale in an embodiment of the present invention;

[0039] Figure 8 is a schematic diagram of the structure of Embodiment 3 of the present invention;

[0040] Among them, 1-base, 3-transparent reading plate, 4-frequency scale, 5-attenuation value scale, 6-frequency pointer, 7-pad, 8-fixed plate, 9-baffle, 21-first scale, 22-second scale. DETAILED DESCRIPTION

[0041] In order to better understand the present invention, the content of the present invention is further clearly set forth in conjunction with the embodiments below, but the protection content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are provided in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0042] Embodiment 1

[0043] like Figure 1 As shown, a slide rule for quickly calculating the free space attenuation of electromagnetic waves includes a base 1, a distance scale fixedly arranged on the base 1, a transparent reading plate 3 fixedly arranged on the distance scale, and a frequency scale 4 and an attenuation value scale 5 movably arranged on the base 1, the frequency scale 4 and the attenuation value scale 5 slide in conjunction with each other, and a frequency pointer 6 is provided on the transparent reading plate 3.

[0044] Specifically, the distance scale includes a first scale 21 and a second scale 22 which are arranged in parallel on the base 1, the attenuation value scale 5 is located between the first scale 21 and the second scale 22, the frequency scale 4 is located on one side of the first scale 21, the frequency scale 4 is connected to the attenuation value scale 5 through a connecting rod, a gap is left between the bottom of the first scale 21 and the base, and the connecting rod crosses the gap.

[0045] Embodiment 2

[0046] like Figures 2 to 7 As shown, the slide rule for quickly calculating the free space attenuation of electromagnetic waves in the embodiment of the present invention is different from the first embodiment in that: the scale display range of the first scale is 10 to 2000 m, the reference length of the first scale is 5 cm with a length of 10 to 100 m, and the scale determination formula of the first scale is:

[0047]

[0048] Where: S1 is the display distance, in meters;

[0049] d1 is the actual distance between the scale corresponding to a certain distance value S and the "0 point" on the ruler, in cm.

[0050] The scale display range of the second scale is 1 to 200 km, the reference length of the second scale is 5 cm for a length of 1 to 10 km, and the scale determination formula of the second scale is:

[0051]

[0052] Where: S2 is the displayed distance, in km;

[0053] d2 is the actual distance between the scale corresponding to a certain distance value S and the "0 point" on the ruler, in cm.

[0054] The scale display range of the frequency scale is 0.1 GHz to 20 GHz, the reference length of the frequency scale is 5 cm with a length of 0.1 GHz to 1 GHz, and the scale determination formula of the frequency scale is:

[0055] d3=5log2 10f / log2 10

[0056] Where: f is the frequency value, in GHz;

[0057] d3 is the actual distance between the scale corresponding to a certain frequency value f and the "0 point" on the scale, in cm.

[0058] The attenuation value scale is provided with an upper scale and a lower scale, the upper scale corresponds to the first scale, the lower scale corresponds to the second scale, the range of the upper scale is 0 to 130 dB, the range of the lower scale is 40 to 170 dB, the minimum scale of the upper scale and the lower scale is 1 dB, and the actual length of each scale is 0.25 cm.

[0059] When electromagnetic waves propagate in space, the power of the signal will weaken as the propagation distance increases, and the degree of signal attenuation is related to the frequency of the signal. According to the signal link transmission theory, the propagation loss of electromagnetic waves in space can be calculated using the following formula:

[0060] L = (4π) 2 f 2 d 2 / c 2

[0061] in:

[0062] d is the propagation distance, in meters;

[0063] f is the signal frequency, in Hz;

[0064] c is the speed of light.

[0065] In the field of electronic warfare, signal attenuation is usually described in dB, so the formula is converted to dB, and the unit of distance d is km, and the unit of frequency f is MHz. The conversion result is:

[0066] L(dB)=32.44+20log 10 d+20log 10 f

[0067] in:

[0068] d is the propagation distance in km;

[0069] f is the signal frequency in MHz.

[0070] According to the formula, the attenuation of the signal can be calculated based on the frequency of the signal and the distance between the signal source and the receiver. The attenuation value of the signal propagating in free space has a linear relationship with the common logarithm of the distance and the common logarithm of the frequency. When the frequency or distance is a fixed value, the attenuation value of the signal will also change linearly by changing the other parameter.

[0071] If you want to calculate the attenuation of a specified frequency signal, you only need to move the frequency scale so that the frequency pointer indicates the specified frequency value, and then find the current propagation distance on the distance scale. The attenuation value in the attenuation scale corresponding to the current distance in the middle of the distance scale is the attenuation value of electromagnetic wave propagation at the current frequency and distance.

[0072] According to the attenuation value calculation formula, the attenuation of electromagnetic waves will increase significantly with the increase of signal frequency, so the calculation accuracy in the low frequency band should be higher than that in the high frequency band. According to the calculated scale value data, as the frequency increases, the actual scale distance of the same frequency interval becomes significantly smaller, which is not conducive to engineering implementation. Therefore, considering the constraints of both actual needs and engineering implementation, the scale on the actual slide rule has higher accuracy in the low frequency band, and the accuracy decreases as the frequency increases. Based on the considerations of engineering implementation and portability, the length of 5cm from 0.1GHz to 1GHz was finally selected as the reference length for the scale. The actual position of the scale values ​​of all other parameters on the slide rule is calculated based on this reference. Under this condition, combined with the attenuation value calculation formula, the following formula for determining the scale distance of the frequency scale can be derived:

[0073] d3=5log2 10f / log2 10

[0074] in:

[0075] f is the frequency value, in GHz;

[0076] d3 is the actual distance between the scale corresponding to a certain frequency value f and the "0 point" (0.1GHz scale) on the scale, in cm.

[0077] The actual distance between two adjacent scales:

[0078] Δd3=d 32 -d 31 =5log2 10f 32 / log2 10-5log2 10f 31 / log2 10

[0079] d 32 and d 31 is the distance between two adjacent scales and the zero point, f 32 and f 31 are two adjacent frequency values.

[0080] According to the above two formulas, the positions of all scales on the frequency scale can be determined. The specific scale calculation results are shown in Appendix 1. The frequency scale made based on this calculation result is shown in Figure 2 , the relationship between the scale distance and frequency is shown in Figure 6 .

[0081] The conversion method between the distance scale and the actual length on the slide rule is consistent with the conversion method of frequency. The relationship between distance and attenuation is consistent with the relationship between frequency and attenuation. In order to shorten the length of the slide rule and take into account the logarithmic relationship between the scale value and the actual distance value, the greater the distance, the closer the interval between the scales. The link distance scale is designed as an upper and lower segmented structure. The upper section is a scale in m, and the lower section is a scale in km. According to the reference length of the frequency scale, it can be determined that the reference length of the upper distance scale is 5 cm for 10 meters to 100 meters, with 10 meters as the starting scale, and the reference length of the lower distance scale is 5 cm for 1 kilometer to 10 kilometers, with 1 kilometer as the starting scale. Combined with the attenuation value calculation formula, the following formula for determining the distance scale scale can be derived:

[0082]

[0083]

[0084] S1 and S2 are displayed distances in m and km respectively;

[0085] d1 is the actual distance between the scale corresponding to a certain distance value S1 of the first scale and the "0 point" (10 meters) on the scale, and the unit is cm.

[0086] d2 is the actual distance between the scale corresponding to a certain distance value S2 of the second scale and the "0 point" (1 km) on the scale, in cm.

[0087] The actual distance between two adjacent scales:

[0088]

[0089]

[0090] According to the above four formulas, the positions of all scales on the link distance scale can be determined. The specific scale calculation results are shown in Appendix 2. The distance scale made based on this calculation result is shown in Figure 3 and Figure 4 , the relationship between the scale distance and frequency is shown in Figure 7 .

[0091] According to the attenuation value calculation formula, the attenuation value is linearly related to the common logarithm of the frequency and link distance. Because the frequency and distance scales are both logarithmically variable, the scale values ​​on the attenuation scale change evenly and linearly. The signal frequency scale is selected to have a length of 5 cm from 0.1 GHz to 1 GHz as the reference length of the scale. At the same time, the reference length of the link distance scale is selected to be 5 cm from 10 meters to 100 meters. Under this condition, the value of each scale on the attenuation scale can be easily calculated. The specific values ​​are shown in Appendix 3. At the same time, in order to correspond to the upper and lower segmented structure of the link distance scale, the attenuation value scale is also designed as an upper and lower two-segment structure, see Figure 5 .

[0092] After completing the calculation of the signal attenuation value and determining the range of the frequency scale, distance scale, attenuation scale, and scale value, the plane diagram of the slide rule was designed according to the function of the slide rule. The pointer above the frequency scale indicates the frequency value of the current signal. The frequency scale can be moved left and right as needed to select the frequency value. The distance scales in the middle are in "meters" and "kilometers" respectively, and the corresponding distance can be selected according to the spatial distance. In the middle of the distance scale is the attenuation scale. The attenuation scale and the frequency scale are linked structures. When the frequency scale moves left and right, the attenuation scale also moves with it, so that the attenuation of signals of different frequencies at different distances can be read.

[0093] Embodiment 3

[0094] like Figure 8As shown, a slide rule for quickly calculating the free space attenuation of electromagnetic waves includes a base 1, a distance scale fixedly arranged on the base 1, a transparent reading plate 3 fixedly arranged on the distance scale, and a frequency scale 4 and an attenuation value scale 5 movably arranged on the base 1, the frequency scale 4 and the attenuation value scale 5 slide in conjunction with each other, and a frequency pointer 6 is provided on the transparent reading plate 3.

[0095] Specifically, the distance scale includes a first scale 21 and a second scale 22 which are arranged in parallel on the base 1, the attenuation value scale 5 is located between the first scale 21 and the second scale 22, the frequency scale 4 is located on one side of the first scale 21, the frequency scale 4 is connected to the attenuation value scale 5 through a connecting rod, a gap is left between the bottom of the first scale 21 and the base, and the connecting rod crosses the gap.

[0096] The scale display range of the first scale 21 is 10 to 2000 m, the reference length of the first scale is 5 cm with a length of 10 to 100 m, and the scale determination formula of the first scale is:

[0097]

[0098] Where: S1 is the display distance, in meters;

[0099] d1 is the actual distance between the scale corresponding to a certain distance value S and the "0 point" on the ruler, in cm.

[0100] The scale display range of the second scale 22 is 1 to 200 km, the reference length of the second scale is 5 cm for a length of 1 to 10 km, and the scale determination formula of the second scale is:

[0101]

[0102] Where: S2 is the displayed distance, in km;

[0103] d2 is the actual distance between the scale corresponding to a certain distance value S and the "0 point" on the ruler, in cm.

[0104] The scale display range of the frequency scale 4 is 0.1 GHz to 20 GHz. The reference length of the frequency scale is 5 cm in the range of 0.1 GHz to 1 GHz. The scale determination formula of the frequency scale is:

[0105] d3=5log2 10f / log2 10

[0106] Where: f is the frequency value, in GHz;

[0107] d3 is the actual distance between the scale corresponding to a certain frequency value f and the "0 point" on the scale, in cm.

[0108] The attenuation value scale 5 is provided with an upper scale and a lower scale, the upper scale corresponds to the first scale, and the lower scale corresponds to the second scale, the range of the upper scale is 0-130dB, the range of the lower scale is 40-170dB, the minimum scale of the upper scale and the lower scale is 1dB, and the actual length of each scale is 0.25cm.

[0109] The slide rule for quickly calculating the free-space attenuation of electromagnetic waves in the embodiment of the present invention is different from the first and second embodiments in that pads 7 are provided at the lower parts of both ends of the first scale 21 and the second scale 22, fixing plates 8 are provided at the upper parts of both ends of the first scale 21 and the second scale 22, and the first scale 21 and the second scale 22 are fixed to the base by bolts.

[0110] A baffle plate 9 is provided on the upper part of the base 1 outside the frequency scale 4, and two sides of the transparent reading plate 3 are respectively fixed to the second scale 22 and the baffle plate 9 by bolts.

[0111] The transparent reading board is a plexiglass board, and the frequency pointer, as well as unit information of the distance scale, frequency scale and attenuation value scale are engraved on the transparent reading board.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

[0113] Schedule 1

[0114]

[0115]

[0116] Schedule 2

[0117]

[0118]

[0119] Schedule 3

[0120]

[0121]

Claims

1. A slide rule for rapidly calculating the free-space attenuation of electromagnetic waves, characterized in that: It comprises a base, a distance scale fixedly arranged on the base, a transparent reading plate fixedly arranged on the distance scale, and a frequency scale and an attenuation value scale movably arranged on the base, the frequency scale and the attenuation value scale slide in linkage, and a frequency pointer is arranged on the transparent reading plate; The distance scale comprises a first scale and a second scale arranged in parallel on the base, the attenuation scale is located between the first scale and the second scale, the frequency scale is located on one side of the first scale, and the frequency scale is connected to the attenuation scale through a connecting rod; The scale display range of the first scale is 10 to 2000 m, the reference length of the first scale is 5 cm for a length of 10 to 100 m, and the scale determination formula of the first scale is: Where: S1 is the display distance, in meters; d1 is the actual distance between the scale corresponding to a certain distance value S and the "0 point" on the scale, in cm; The scale display range of the second scale is 1 to 200 km, the reference length of the second scale is 5 cm for a length of 1 to 10 km, and the scale determination formula of the second scale is: Where: S2 is the displayed distance, in km; d2 is the actual distance between the scale corresponding to a certain distance value S and the "0 point" on the ruler, in cm.

2. The slide rule for rapidly calculating electromagnetic wave free space attenuation as claimed in claim 1, characterized in that: The scale display range of the frequency scale is 0.1 GHz to 20 GHz, the reference length of the frequency scale is 5 cm with a length of 0.1 GHz to 1 GHz, and the scale determination formula of the frequency scale is: d3=5log210f / log210 Where: f is the frequency value, in GHz; d3 is the actual distance between the scale corresponding to a certain frequency value f and the "0 point" on the scale, in cm.

3. The slide rule for rapidly calculating electromagnetic wave free space attenuation as claimed in claim 1, characterized in that: The attenuation value scale is provided with an upper scale and a lower scale, the upper scale corresponds to the first scale, the lower scale corresponds to the second scale, the range of the upper scale is 0 to 130 dB, the range of the lower scale is 40 to 170 dB, the minimum scale of the upper scale and the lower scale is 1 dB, and the actual length of each scale is 0.25 cm.

4. The slide rule for rapidly calculating electromagnetic wave free space attenuation as claimed in claim 1, characterized in that: Pads are disposed at the lower parts of both ends of the first scale and the second scale, fixing plates are disposed at the upper parts of both ends of the first scale and the second scale, and the first scale and the second scale are fixed to the base by bolts.

5. The slide rule for rapidly calculating electromagnetic wave free space attenuation as claimed in claim 4, characterized in that: A baffle is provided on the upper part of the base, located outside the frequency scale, and two sides of the transparent reading plate are respectively fixed to the second scale and the baffle by bolts.

6. The slide rule for rapidly calculating electromagnetic wave free space attenuation as claimed in claim 5, characterized in that: The transparent reading board is a plexiglass board, and the frequency pointer, as well as unit information of the distance scale, frequency scale and attenuation value scale are engraved on the transparent reading board.

Images