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Technical Notes |
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Characteristic Impedance
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The Characteristic Impedance of a coaxial transmission line is a function of the ratio of the inner and outer conductor diameters and the dielectric constant of the insulating medium.
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Where:
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- Characteristic Impedance
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D
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- Inside diameter of the outer conductor (inches)
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O
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- Diameter of the inner conductor (inches)
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- Dielectric constant
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Voltage Standing Wave Ratio (VSWR)
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VSWR is the ratio of the maximum and adjacent minimum wave, expressed in terms of reflection coefficient.
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VSWR is a real number; a value 1.0 implies a perfectly matched load.
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Insertion Loss
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The composite Insertion Loss of a transmission line is determined by the loss associated with the inner and outer conductor, the dielectric medium and characteristic impedance mismatches.
1. Conductor Loss is a function of transmission line dimensions and materials.
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Where:
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CL
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- Conductor Loss (dB)
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L
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- Conductor length (inches)
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- Characteristic Impedance (Ohms)
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- Dielectric constant
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D
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- Inside diameter of the outer conductor (inches)
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- Dielectric constant
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O
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- Diameter of the inner conductor (inches)
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f
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- Frequency (Hz)
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2. Dielectric Losses.
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Where:
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DL
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- Dielectric Loss (dB)
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- Loss tangent
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C
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- Velocity of propagation
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L
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- Conductor length (inches)
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f
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- Frequency (Hz)
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3. Mismatch Loss is a function of reflected energy due to deviations from the characteristic impedance of the transmission line system.
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Alpha Center
351 Irving Drive, Oxnard, CA 93030, USA
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