Google returned a large number of hits in response
to the term

spiral inductance

Of these,

http://www.csgnetwork.com/spiralcoilinduccalc.html

is a javascript programme, which you can see by doing
a view source, and if necessary reverse engineer back
to the equations

Stewart G3YSX


Talbot Andrew wrote:

Sorry if this is somewhat off topic, but I am looking for the design
equations for spiral inductors printed on PCB material, with or without a
groundplane.   I vaguely remember seeing some equations in one of the
freebie RF magazines a few years ago, but can't find it.  A web search has
not pointed at anything useful - yet.

I need to design some bandpass filters in the 300MHz and 600 to 800MHz

ranges and want something more repeatable than bits of silver plated wire.

Can anyone lay their hands on the design equations ?

Tnx
Andy  G4JNT

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