64 The PCB Design Magazine • October 2017
less, that is, you are making a microwave oven.)
Loss tangent is also referred to with a variety
of terms: tanδ, Tan D, Df. From an SI perspec-
tive, the lower the better, but you must factor in
the cost.
Martyn Gaudion is managing
director of Polar Instruments. To
read his past columns or contact
him, click here.
Figure 7a and 7b: Example of Svensson-Djordjevic modelling, which uses mathematical models of the
substrate to predict the value of TanD and Er over frequency when given a single known frequency input.
TANGENTIAL THOUGHTS: LOSS TANGENT VALUES
