RF Probe and Pigtail

Hey Guys,

I am designing a circuit with a 2.4 GHZ printed antenna, I would like to probe the antenna for S11 parameters without sticking an SMA jack on the PCB. It seems to me that the only way to accomplish this is to put an RF Probe point on the PCB. Can someone direct me to a resource that specifies how to place the probe point?

I would like some information on what the probe point should look like, I suspect this depends greatly on the type of probe that is being used. What types of probes exist? I have heard of the use of pigtails as cheap RF probes but I am not so sure about the details (and pitfalls) of doing this.



Reply to
Brian Chan
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Well, there are plenty of other connectors besides SMA jacks -- MMCX is not uncommon for 2.4GHz stuff. But I'm assuming you didn't want to put *any* connector on the PCB?

Unless you have more money than you know what to do with (in which case you can give, e.g., Cascade Microtech a call), you'll find yourself using just straight 50 ohm coax or FET probes. FET probes are meant more for troubleshooting, however, and this is really the core of your problem: At

2.4GHz, to get accurate *measurements*, you need a mechanically repeatable interface to the board for your signal and ground reference. After that, you need some amount of transmission line (preferably many tens of degrees at a minimum) to de-embed whatever your mechanical interface is... and you need to make yourself a a open/short/through/load (or similar) calibration board with the same amount of transmission line.

Now, if you're just after *relative* measurements (i.e., just trying to find resonances or maixmize return loss, etc.), you probably don't need any of this: Just solder down some short pigtail leads off of a coax cable to your board, and call it good.


Reply to
Joel Kolstad

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