Limit Lines & Keep-Out areas

Restricted areas in the filter characteristic may be shown either by use of limit lines or keep-out areas.
Lines or areas showing the limits of the filter characteristic can be defined and shown together with the S-parameter plots.
This feature gives a fast overview of the filter performance relative to the specifications of the filter.
  • Filter masks are easily defined or removed in the 'Limit Lines' pane below the S-parameter plot area.
  • An unlimited number of masks/lines may be defined
  • Limit lines are only available in the 'dB(S21) dB(S11)' pane
  • A pass/fail indicator is attached to each limit, which gives an instant status of the filter characteristic relative to the requirements.
  • The pass/fail indicators are only dealing with the part of the characteristic, which is visible within the plot window.
    Limits which have a start or stop frequency that falls outside the plot window, will therefore be assigned a grey 'pass' color, which is a warning about that the characteristic may not be passing outside the plot window.
The procedure for defining limits is:
  1. Click the 'Add row' button. This inserts an empty row.
  2. Click in the empty 'Parameter' cell and select the S-parameter, which the limit line is tied to.
  3. Click in the empty 'Selector' cell and chose either the 'above' (>) or 'below' (<) operator.
  4. Fill out the level value (dB) and the frequency range, which the line has to cover.

The line now becomes visible in the plot.


Hints: When a row in the table is selected by the mouse, the corresponding limit line is emphasized. 
The shading of a row may be cleared by pressing 'Add row' and then 'Remove row'.

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