davem – Page 15 – Dave McGlone

Filtering – Part 4

davem / 13 Nov 2017

I left Part 3 indicating the Butterworth filter was superior in amplitude response and the Bessel in group delay response.… Read the rest

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Quotes

davem / 4 Nov 2017

“The significant problems we face can not be solved at the same level of thinking we were at when we created them”… Read the rest

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2nd-Order Passive Filters – Coax

davem / 28 Oct 2017

The basic model of a coax cable is that of a 2nd-order passive low-pass filter. Here I describe forms of analysis, the relation… Read the rest

Maxwell

Maxwell’s Equations 2

davem / 27 Oct 2017

Use the vector identity: $\nabla \cdot \left( \nabla \times \overline{A} \right) = 0$

From this:

(1) $\begin{equation*} \nabla \cdot \left( \nabla \times \overline{E} \right) = 0 = -\left( \nabla \cdot \frac{\partial B}{\partial t} \right) = -\frac{\partial}{\partial t} \left(\nabla \cdot \overline{B} \right) \rightarrow \nabla \cdot \overline{B} = 0 \end{equation*}$

Following this method:

(2) $\begin{equation*} \nabla \cdot \left( \overline{J} + \frac{\partial D}{\partial t} \right) = \nabla \cdot \overline{J} + \nabla \cdot \frac{\partial \overline{D}}{\partial t} = \nabla \cdot \overline{J} + \frac{\partial}{\partial t} \left( \nabla \cdot \overline{D} \right) \end{equation*}$