Frequency response calculation of coaxial cables and twin-leads
coordinate system
phase shift display
Start frequency (MHz)
End Frequency (MHz)
Length of cable (m)
Output resistance of generator (Ohm)
Output capacitance of generator (pF)
Input resiztance of receiver (Ohm)
Input capacitance of receiver (pF)
Cable name

Select cable, coordinate system and phase shift display, and enter parameters then press 'compute' button to get result. If output resistance of generator and input resistance of receiver set to 0 then these resistance(s) are automatically corrected to the characteristic impedance of selected cable.

The computational model of this program is as follows. The frequency response is expressed by insertion loss.

  +- Rs -+-o---------------------o-+---+  ^
  |      |                         |   |  |
  G      Cs        cable           Cr  Rr Vr
  |      |                         |   |  |
  +------+-o---------------------o-+---+  -

  G = generator (2Vpp)
  Rs = output resistance of generator (Ohm)
  Cs = output capacitance of generator (pF)
  Rr = input resistance of receiver (Ohm)
  Cr = input capacitance of receiver (pF)
  cable = length of cable (m)

The frequency response is very impotant on almost all situations. But it's value varies with not only cable characteristics but source and load impedance.

This program shows magnitude and phase response as network analyzer. So, we can get results without actual experiments. For example, we can get real feeling of cable's nature by calculating,

  1) efect of impedance mismatch for short length cable.
  2) attenuation for long distance cable.

The frequency response analysis is effective for rather narrow frequency signals. For pulse wave signals, we must evaluate squere wave response or eye-diagram analysis.