Does anyone know where I can find some basic info on this? I have to use this horrible part, 100-ohm 5%, as a 'lumped element' in a microstrip circuit (power divider) for a school lab experiment, though it'll be anything but lumped. Having 15mm+ leads, soldering to microstrip stubs, and it being a thin film resistor (inductive trim lines) got me to make up this model:
solder C_series solder
joint |-------||--------| joint
------???---nnnn--------| |---nnnn-------???--------
/ L_stub1 | |--nnnn----/\/\/--| L_stub2 | \
Z0 \ C_stub1 === L_Rtrim R C_stub2 === / Z0
/ | | \
--------------------------------------------------------------------
The solder joint effect is unknown (some C and L to GND) and probably not reproducible, so it's the first thing I'd like to ignore. Next, the axial leads were treated as transmission lines, but they are each only 10% of a wavelength, and symmetric, which isn't a great argument but one I'll use to ignore them, anyway. The series capacitance is likely tiny and leads to a very high frequency pole, so it disappears. The Z0's are the microstrips (characteristic impedance).
Leaving this:
---------nnnn----/\/\/---------
/ L_Rtrim R \
Z0 \ / Z0
/ \
-------------------------------
Does it look familiar, or have I simplified it too much? Do you know what to expect for (trimmed helical thin film in resistor) inductance?
Even my microwave book (Pozar) doesn't have this crud... must be too close to 'real life'.
