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How to make a lumped inductor?

Posted: Tue 23 Mar 2021, 17:11
by asdf
Hi,
It looks like making lumped resistor and capacitor is easy because it's a piece of conductor or insulator between plates but inductor is not as straightforward.
Does anyone know how to make a lumped inductor (something like e.g. 0402 smd chip) in a possible simple way? I imagine this could be a 1D wire between caps, surrounded with a piece of magnetic but what shape (cylinder, box, toroid?) and permability (formula?) should it be?

I'd like to use it for antenna matching network.

Re: How to make a lumped inductor?

Posted: Wed 31 Mar 2021, 21:47
by thorsten
I don't think that SMD inductors (with any reasonable value) do exist. Please correct me if I'm wrong. Theoretically something like this would be possible in a numerical tool but I would not see the point if it does not exist in the real world.
As far as a matching network goes I recommend to use a circuit calculator like Qucs for this job and not a FDTD full wave simulation software.

regards
Thorsten

Re: How to make a lumped inductor?

Posted: Thu 01 Apr 2021, 10:01
by asdf
Yes, they do exist, eg 0402 smd inductors murata LQG15 (https://ds.murata.co.jp/simsurfing/rfin ... arinfo=com)
SMD inductors are used in RF, eg matching networks of filters, eg Rigol SA 1st LO filter
https://www.flickr.com/photos/eevblog/8 ... 115219155/

Currently I do simulation in qucs using touchstone files from measurements or simulations, so it's mostly sufficient. It's also better for lumped networks because I can use touchstone file from components manufacturers for each L or C while openEMS has not lumped touchstone components.

One thing that qucs can't do is a layout (I'd be interested to see how layout can degrade some lumped filter + matching network characteristics).

Re: How to make a lumped inductor?

Posted: Sat 03 Apr 2021, 23:53
by rml
thorsten wrote:
Wed 31 Mar 2021, 21:47
I don't think that SMD inductors (with any reasonable value) do exist. Please correct me if I'm wrong.
Hi all,
several years ago there was already a similar discussion here ;)

viewtopic.php?f=3&t=86&p=556