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Old 20-10-2010, 10:35 AM
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bojan
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Quote:
Originally Posted by CraigS View Post
The duration of the pulse (~1ms) is a function of the circuit tuning parameters. The physical size/geometry of the components, whilst related, doesn't directly correlate with the pulse duration. I'm not clear on what you're saying here.

Can you explain ?

Cheers
Of course

What you are talking about is ideal circuit, with lumped elements - meaning, the component properties (capacitance, inductance, resistance etcetera ) are concentrated in infinitely small spaces.

However (what is often ignored by non-RF people) when you move to higher frequencies (or the size of the circuit becomes comparable to the 1/4 wavelength of the frequencies involved) we are dealing with circuit with distributed parameters.
In other words, the things become much more complicated, and the circuit components are no more simple - for example, you may find a capacitor is actually a weird combination of number of capacitances, inductances and resistors.. all that can be sometimes modelled by equivalent schematic, or, what is more practical, we just take s-parameters of the component, valid for certain frequency range, and we are not bothered with actual physical component (black box approach).

So, the duration of 1ms in a circuit 300km size is VERY significant. The circuit will behave completely different from small PCB on the bench, even if values are the same.

Last edited by bojan; 20-10-2010 at 11:11 AM.
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