RadioBanter - View Single Post

March 23rd 06, 05:11 PM posted to rec.radio.amateur.antenna

wrote:

A two-terminal network that transforms impedance, now there's a
concept!

(My opinion follows, please correct me. Dang, I should put that in my
sig.)

In reality, there is no such thing as a two terminal network, unless
one of those terminals is grounded. For all other cases, there is an
unavoidable implied ground terminal that covers all the stray
capacitance of the device.

So the bug catcher coil is recognized as a 3 terminal device, with
ground being the third terminal. It can be modeled as a pi, T or
transmission line structure, as long as you want to understand what to
quantify it at only one frequency (or a narrow band), and the choice
is arbitrary. If you are concerned with modeling a large frequency
range (that goes well past the first self resonance), one of those
models (or a more complicated one) will be superior.