RF probe for network analyzer measurements
RF probe for network analyzer measurements
(OP)
Hi,
I´m working with small RF amplifiers designed for production. That means that when I have to take lab measurements of intermediate stages, where there are no cables, I have to solder on the PCB coax cables all the time. I was wondering if anybody could advise me on RF probes or something similar to a probe which I can connect to the network analyzer so I can put the signal at any PCB point without soldering a cable. (like an osciloscope probe but for a network analyzer)
Thanks a lot.
I´m working with small RF amplifiers designed for production. That means that when I have to take lab measurements of intermediate stages, where there are no cables, I have to solder on the PCB coax cables all the time. I was wondering if anybody could advise me on RF probes or something similar to a probe which I can connect to the network analyzer so I can put the signal at any PCB point without soldering a cable. (like an osciloscope probe but for a network analyzer)
Thanks a lot.





RE: RF probe for network analyzer measurements
If you just solder on a coax you have added another 50 ohms in shunt at that point in the circuit. If you disconnect the load so you only have one 50 ohm load you then have an open circuit stub driving the open pads and you have changed the load conditions on the amplifier under test. What you want is a coplanar waveguide output so you can make signal and ground connections easily to the amplifier. If nothing else you should be able to get a repeatable measurement, although the absolute accuracy is questionable.
You can get wafer probe stations for microwave circuits. Take a look at those for clues.
RE: RF probe for network analyzer measurements
You turn on the amplifier chain, and you can probe the output power of each stage, minus the 20 dB coupling.
RE: RF probe for network analyzer measurements
Of course, You would have to carefully calibrate it somehow to make sense of the data. Also, you would need some straight lines interstage to mate up with the coupled section.
RE: RF probe for network analyzer measurements
Common is a 3 point probe, it requires you to bring up ground points on both sides of your microstrip line. The 3 pint probe grounds touch these points and the center of the probe is on your transmission line.
At higher frequencies, you need to break your line, test your items, then solder the lines back together.
You could just add the grounds and make measurements on a good unit and record the data as a standard, then compare to the standard.
Tricky measurement if you're winging it. Hard to get the pass fail requirements with the probe some times.
kch