You didn't say if the inductors will be used for LC oscillator or just
for filtering.
At 400MHz and FR4, designing inductors is not an insurmountable problem.
All links you've provided are interesting, but for practical reasons
two configuration are widely used at such frequencies: for
oscillators/antennas spiral inductors and for filtering accordeons
inductors. Some software are allowing you simulation (microwave office
if I remember well).
Both types above are require adjustment methodes by short circuiting
spirals or accordeons part at one end (the way is to add top/bottom
stop surfaces in CAD which will create islands in the mask layers so
further you may solder anywhere.

Russians have used such PCB inductor tehnique back in the 75 designing
an 1Ghz vobulator using varactor multiplication and a bunch of
inductances starting from a 10Mhz crystal oscillating with overtone. I
still have one which works but have a defective frequency meter.

A nice software here:
http://rfic.eecs.berkeley.edu/~niknejad/asitic.html

Vasile



On 5/10/07, Gerhard Fiedler <lists@connectionbrazil.com> wrote:
> Hello,
>
> I'm working on a transmitter and receiver in the 400MHz range. The
> inductors in that frequency range are really small (tens of nH) and I
> thought that buying such an inductor may not make much sense. So I looked
> into PCB and air core inductors. Here's what I found so far:
>
> <http://www.educypedia.be/electronics/electroniccalculatorcomp.htm> Lots of
> links to all kinds of calculator sites.
>
> <http://emcsun.ece.umr.edu/new-induct/> Inductor calculations for all kinds
> of geometries, but not PCB spirals.
>
> <http://smirc.stanford.edu/spiralCalc.html> Calculator for integrated
> spiral inductors; may work for PCB inductors also, but I don't know what
> they assume in terms of what's around the conductor.
>
> <http://tinyurl.com/2rn89n> A paper by Marc T. Thompson listing a number of
> formulas for PCB and wire coils.
>
> <http://www.freelists.org/archives/si-list/11-2001/msg00109.html> Steve
> Rogers, who seems to have done some work with PCB inductors, lists a number
> of sources of information and describes some of the potential problems with
> PCB inductors.
>
>
> Has anybody experience with PCB inductors? Or maybe even with a
> formula/calculator that yields realistic results? Are simple air core
> inductors much easier to get right?
>
> Thanks,
> Gerhard
>
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