RF RG Anten Kabloları

Receiving success: Draka RF Solution

 10 Figure 1.1: Functional elements of a coaxial cable Figure 1.2: Electromagnetic field pattern for the TEM mode in a coaxial cable Outer conductor Dielectric Inner conductor Electric field Magnetic field

 11 fc = cut-off frequencyC = speed of light in vacuum r = relative permittivity of dielectric d = diameter of inner conductorD = inner diameter of outer conductor L = Inductance per unit lengthR = Resistance per unit lengthG = Conductance per unit lengthC = Capacitance per unit length ) ( 2 D d c f r c + = ε π   I V Z =  

 12 j   = imaginary unit used in complex      numbers   = 2 f f    = frequency =  attenuation coefficient per  unit length   =  phase coefficient per unit length

Z  = characteristic impedance = relative permittivity of the dielectric D  =  inner diameter of the outer    conductor, mmd   =  diameter of the inner conductor, mm = attenuation at given frequency      (dB/100 m) 1 = loss coefficient of conductors 2 = loss coefficient of dielectric f   = frequency (MHz) = attenuation, dB/100 m r   = relative permittivity of the dielectric D  = inner diameter of the outer    conductor, mmd  = diameter of the inner conductor, mm 1 = conductivity of the inner     conductor, MS/m 2 = conductivity of the outer     conductor, MS/mtan = dissipation factor of the dielectric f  = frequency, MHz T  = attenuation at temperature T   = attenuation at a temperature     of +20°CT  = Temperature Z = 60 r ln D d  13

Figure 1.4: Basic transmission formulas Figure 1.5: Typical attenuation curves of Draka MRC 50  cable types  14

 15 Figure 1.6: Reflection caused by a change of the impedance    = reflection coefficient Z 1  , Z 2 = values of characteristic impedance RL = return loss of the cableV i   = input voltage V r   = resulting reflected signal Figure 1.7: Resulting reflected signal in a coaxial cable. Table 1.1 shows examples of the relationship between RL and VSWR. Small changes in characteristic impedance RL  VSWR  RL  VSWR  RL  VSWR  RL  VSWR dB    dB    dB    dB  16  1.374  21  1.193  26  1.105  36  1.032 17  1.329  22  1.171  28  1.082  38  1.025 18  1.285  23  1.151  30  1.064  40  1.020 19  1.251  24  1.133  32  1.051  50  1.010 20  1.220  25  1.118  34  1.040  60  1.000

 16 Figure 1.8: Typical structural return loss curve SRL = increase of SRL level, dB  = attenuation coefficient, dB/100m L  = length of the cable, m

 17 VF = Velocity FactorV   = propagation velocity in the        coaxial cable C   = velocity of light in free space = (c/f)VF    = wavelength  V   = propagation velocity in the        coaxial cable C   = velocity of light in free space r C  = CapacitanceZ  = Impedance r    = relative permittivity of the         dielectric

 18 P T   =  average power rating at      temperature Ta P 40   =  average power rating at         ambient temperature 40°C T 1   =  maximum inner conductor     temperature (100°C)

 19 m and n  = any positive integersf 1  and f 2   = transmitter frequencies The order of the intermodulation is (m+n) Figure 1.9: Intermodulation attenuation Figure 1.10: Principle circuit of Transfer impedance a =  inner conductorb  =  outer conductorl  =  effective length

 20 R K    =  transfer impedance U O  =   longitudinal voltage induced in       the inner circuit   =   current in the outer circuit  L   =    effective length of the coaxial  cable Figure 1.11: Typical traces for outer conductors: a = tube; b = foil and braid; c = braid R K = U 0 lI IEC61196-1EN 50289-1-6DIN 47250

 21 cable sheath coupling length L c cable screen tube short circuit terminatingresistor R 1  = Z 1 Figure 1.13: Transfer impedance of an RF cable according to American Military Specification type RG223 Figure 1.14: Screening attenuation of an RF cable according to IEC 61196-1 type 2.7/7.3AF Figure 1.12: Connection of cable elements to the tube

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