Technical Notes

Characteristic Impedance
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.

Where: - Characteristic Impedance
  D - Inside diameter of the outer conductor (inches)
  O - Diameter of the inner conductor (inches)
  - Dielectric constant

Voltage Standing Wave Ratio (VSWR)
VSWR is the ratio of the maximum and adjacent minimum wave, expressed in terms of reflection coefficient.

VWSR is a real number; a value 1.0 implies a perfectly matched load.

 Insertion Loss
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.

Where: CL - Conductor Loss (dB) L - Conductor length (inches)
  - Characteristic Impedance (Ohms) - Dielectric constant
  D - Inside diameter of the outer conductor (inches) - Dielectric constant
  O - Diameter of the inner conductor (inches) f - Frequency (Hz)

 2. Dielectric Losses

Where: DL - Dielectric Loss (dB)
  - Loss tangent
  C - Velocity of propagation
  L - Conductor length (inches)
  f - Frequency (Hz)

 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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