Patent ID: 11959952
Assignee: BEIJING ORIENT INSTITUTE OF MEASUREMENT AND TEST
Field: Measurement (Instruments)
Classification: CPC G  Y | IPC G  H

Claim 0:
1. A construction method of an anechoic chamber, comprising:
determining a reflectivity equation of the anechoic chamber;
determining, according to the reflectivity equation of the anechoic chamber, sizes of a top surface, trapezoid surfaces and rectangular surfaces of the anechoic chamber, determining a number of edges of the top surface, a number of the trapezoid surfaces and a number of the rectangular surfaces; and
splicing the top surface, the trapezoid surfaces and the rectangular surfaces to construct the anechoic chamber;
wherein the determining a reflectivity equation of the anechoic chamber comprises:
taking a center of a ring surrounded by the rectangular surfaces as an origin of a spherical coordinate system, taking a radius of the ring surrounded by the rectangular surfaces as an x-axis, and taking a height direction as a z-axis to construct the spherical coordinate system;
determining a radius of a bottom of a mirror monocone in the anechoic chamber, and determining a height of the anechoic chamber, the radius of the ring surrounded by the rectangular surfaces and a thickness of an absorbing material; wherein the top surface comprises a relevant area and an irrelevant area, the irrelevant area is a part of the top surface covered by a projection of the mirror monocone on the top surface along the height direction, and the relevant area is a part of the top surface that is not covered by the projection of the mirror monocone on the top surface along the height direction;
taking a vertical plane passing through a center of the anechoic chamber and passing through a radius of the top surface as a reference plane, recording a projection of a vertex of the ring surrounded by the rectangular surfaces on the reference plane as a point A, recording a projection of an intersection of a radius of the top surface and a boundary between the relevant area and the irrelevant area on the reference plane as a point C, recording a projection of a connection position between each of the rectangular surfaces and each of the trapezoid surfaces on the reference plane as a point D, recording a projection of a connection position between each of the trapezoid surfaces and the top surface on the reference plane as a point E, recording a projection of an end point of the absorbing material of one of the rectangular surfaces on the reference plane as a point D1, and the end point of the absorbing material of the rectangular surface being located on a side of a contact surface connected with the rectangular surface and proximate to one of the trapezoid surfaces; and recording a projection of an end point of the absorbing material of the top surface on the reference surface as a point E1, and the end point of the absorbing material of the top surface being located on a side of a contact surface connected with the top surface and proximate to the one of the trapezoid surfaces; and
wherein the reflectively equation of the anechoic chamber is expressed as follows:, R
     T
    
    =
    
     
      
       ∫
       
        θ
        A
       
       
        θ
        C
       
      
      
       
        
         ❘
         "\[LeftBracketingBar]"
        
        S
        
         ❘
         "\[RightBracketingBar]"
        
       
       ⁢
       
        
         R
         l
        
        (
        
         α
         ⁡
         (
         θ
         )
        
        )
       
       ⁢
       ds
      
     
     =
     
      
       
        
         ∫
         
          θ
          A
         
         
          θ
          
           D
           ⁢
           1
          
         
        
        
         
          
           ❘
           "\[LeftBracketingBar]"
          
          S
          
           ❘
           "\[RightBracketingBar]"
          
         
         ⁢
         
          
           R
           l
          
          (
          
           α
           ⁡
           (
           θ
           )
          
          )
         
         ⁢
         ds
        
       
       +
       
        
         ∫
         
          θ
          
           D
           1
          
         
         
          θ
          
           E
           ⁢
           1
          
         
        
        
         
          
           ❘
           "\[LeftBracketingBar]"
          
          S
          
           ❘
           "\[RightBracketingBar]"
          
         
         ⁢
         
          
           R
           l
          
          (
          
           α
           ⁡
           (
           θ
           )
          
          )
         
         ⁢
         ds
        
       
       +
       
        
         ∫
         
          θ
          
           E
           1
          
         
         
          θ
          C
         
        
        
         
          
           ❘
           "\[LeftBracketingBar]"
          
          S
          
           ❘
           "\[RightBracketingBar]"
          
         
         ⁢
         
          
           R
           l
          
          (
          
           α
           ⁡
           (
           θ
           )
          
          )
         
         ⁢
         ds
        
       
      
      =
      
       
        
         5
         
          12
          ⁢
          π
         
        
        [
        
         
          
           ∫
           
            θ
            A
           
           
            θ
            
             D
             ⁢
             1
            
           
          
          
           
            
             2
             ⁢
             π
             ⁢
             
              ρ
              2
             
             ⁢
             
              sec
              2
             
             ⁢
             θ
             ⁢
               
             
              
               R
               l
              
              (
              
               α
               ⁡
               (
               θ
               )
              
              )
             
            
            
             ρ
             2
            
           
           ⁢
           d
           ⁢
           θ
          
         
         +
         
          
           ∫
           
            θ
            A
           
           
            θ
            
             D
             ⁢
             1
            
           
          
          
           
            
             2
             ⁢
             π
             ⁢
             
              ρ
              2
             
             ⁢
             
              sec
              3
             
             ⁢
             θ
             ⁢
               
             
              
               R
               l
              
              (
              
               α
               ⁡
               (
               θ
               )
              
              )
             
            
            
             
              ρ
              2
             
             (
             
              
               tan
               ⁢
                 
               θ
              
              -
              
               k
               s
              
             
             )
            
           
           ⁢
           d
           ⁢
           θ
          
         
         +
         
          
           ∫
           
            θ
            
             E
             1
            
           
           
            θ
            C
           
          
          
           
            
             2
             ⁢
             π
             ⁢
             
              ρ
              2
             
             ⁢
             
              
               R
               l
              
              (
              
               α
               ⁡
               (
               θ
               )
              
              )
             
            
            
             
              ρ
              2
             
             ⁢
               
             cos
             ⁢
               
             θ
             ⁢
               
             sin
             ⁢
               
             θ
            
           
           ⁢
           d
           ⁢
           θ
          
         
        
        ]
       
       =
       
        
         
         
          
           5
           6
          
          [
          
           
            
             ∫
             
              θ
              A
             
             
              θ
              
               D
               ⁢
               1
              
             
            
            
             
              sec
              2
             
             ⁢
             θ
             ⁢
               
             
              
               R
               l
              
              (
              
               α
               ⁡
               (
               θ
               )
              
              )
             
             ⁢
             d
             ⁢
             θ
            
           
           +
          
         
         
        
        ⁢
        
         
         
          
           
            ∫
            
             θ
             A
            
            
             θ
             
              D
              ⁢
              1
             
            
           
           
            
             
              sec
              3
             
             ⁢
             θ
             ⁢
             
              
               R
               l
              
              (
              
               α
               ⁡
               (
               θ
               )
              
              )
             
             ⁢
             d
             ⁢
             θ
            
            
             (
             
              
               tan
               ⁢
                 
               θ
              
              -
              
               k
               s
              
             
             )
            
           
          
          +
          
           
            ∫
            
             θ
             
              E
              1
             
            
            
             θ
             C
            
           
           
            
             
              
               R
               l
              
              (
              
               α
               ⁡
               (
               θ
               )
              
              )
             
             ⁢
             d
             ⁢
             θ
            
            
             cos
             ⁢
               
             θ
             ⁢
               
             sin
             ⁢
               
             θ
            
           
          
         
        
       
      
     
    
   
   ]
  
  ;
 

wherein θA represents an incident angle of the point A in the spherical coordinate system, θC represents an incident angle of the point C in the spherical coordinate system, θD1 represents an incident angle of the point D1 in the spherical coordinate system, θE1 represents an incident angle of the point E1 in the spherical coordinate system, |S| represents an incident power density of an electromagnetic wave, Rl(α(θ)) represents a linear power dimensional transformation of a reflectivity of the absorbing material expressed as a function of an incident angle α, ks represents an equation of a straight line {right arrow over (D1E1)} in the spherical coordinate system, and ρ represents a radius of a cylindrical coordinate system converted from the spherical coordinate system.