In Below graph

  1. Why Vertical line are so unequal distributed.
  2. In you see in the graph d1 and d2 both are 10 Mhz. But their vertical line area is different why?
  3. In X axis it takes 170Mhz (30Mhz to 200Mhz,200Mhz-30Mhz=170Mhz) to Cover the Half of graph , but in other it cover 800Mhz ( 200Mhz to 1000Mhz, 1000Mhz-200Mhz=800Mhz). How?

enter image description here

  • \$\begingroup\$ The horizontal scale is logarithmic, not linear. Logarithmic scale is normally used for frequency response since it expands the low frequency region, which would otherwise be compressed into a narrow window. \$\endgroup\$
    – Chu
    Aug 9, 2015 at 9:37
  • 1
    \$\begingroup\$ 1) Because it's a log plot. 2) Because it's a log plot. 3) Because it's a log plot. But why is it a log plot? Because a linear plot giving the same level of detail around 40MHz (10MHz/cm on my screen) would be about 1 metre long. \$\endgroup\$
    – user16324
    Aug 9, 2015 at 10:18
  • \$\begingroup\$ The vertical scale is logarithmic too, because it's in dB. The lowest division is only 0.3 microVolt, while the top division is 3 mV. So you have a log-log plot, and natural responses, 1st order, 2nd order etc, tend to form straight lines. \$\endgroup\$
    – tomnexus
    Aug 9, 2015 at 17:16

1 Answer 1


That's what they call a logarithmic scale


multiples have the same distance on a logarithmic scale eg: doubling: the distance 30 to 60 matches the distance 40 to 80 and 100 to 200 etc.

logarithmic scales are useful where arithmetic ratios are more significant than arithmetic differences.


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