id love to know more about how that works. :)

Its basically a microstripline edge coupled filter. It is microstripline because the substrate does not sandwich the circuital path. The electrical signal travels along the input where it creates an induced field and thus an induced signal on the next strip, and so on. The even and odd mod impedances of the strips determine the magnitude and phase of the signal output in relation to the input, thus making it a bandpass filter with a center at 5GHz. Theres a lot of info online about microstripline edge coupled filters.

This reminds me I need to make a mixer for my 20GHz oscillator... >.<

You sure 20 Gigahertz and not MHz? That seems pretty high.

20MHz is ewwy... Yes its 20GHz its a big aluminum/stainless-steal/brass brick with three SMA connections on it. I should take a picture of it sometime. Its a TCXO. I'm thinking about combining it with 144MHz IF to create a 20GHz transceiver. (I'm also a licensed amateur radio operator.)

Oh, OK, that makes sense then. I thought this was for your GPS and I couldnt think of a reason for a 20GHz oscillator for a GPS set up.

*nods* Yuuup!