Partial disk 36GHz passive component

Question

Partial disk 36GHz passive component

logbook (Electrical)

(OP)

3 Dec 04 14:45

I have just seen an interesting planar structure on a microwave mixer (Agilent AMMC-3040) which operates up to 36GHz. The structure looks like metalisation in the shape of a sector of one sixth of a circular disk (ie 60 degrees worth of a circular disk, 180 degrees being half a circular disk), with the input going to the centre of the circular disk. At a lower frequency this would be a lumped capacitor, but it looks like a distributed line of some type with the capacitance increasing and the inductance decreasing with distance from the feed point.

Can anybody suggest a link to what this structure is or does?

biff44 (Electrical) · Answer 1 · 2004-12-03 15:14:05

Most likely is a quarter wave radial stub, and there is a diode between it and the input line (but it is too small to see). Radial stub gives a fairly broadband short circuit.

logbook (Electrical) · Answer 2 · 2004-12-03 18:11:33

Biff,
"radial stub" is the key technical phrase here. Just giving it a name has unleashed the power of Google onto the problem. I found the exact structure on the Integrated Engineering Software web page.

http://www.integratedsoft.com/products/singula/examplesradialstub.asp

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Partial disk 36GHz passive component