I'm trying to determine a SMA to IPEX adapter impedance using a LCR meter following SQRT(L/C) . I'm a hobbiest, and do not have access to expensive impedance measuring equipment. I've had success with this on standard size coax cables but the not with the smaller IPEX to SMA cables, like in the picture below. I've tested 3 different "Chinese" brands which are supposed to be 50ohm but I'm receiving values in the range of 140-170 ohms. I'm following the procedure laid out here . Am I doing something wrong? Assuming the impedance is in the range of 150ohms, can I assume that signal loss is negligable since these connectors are extremely short?

 

I am really not sure if you will be able to measure that. The adapters are very short when compared to the coaxial cable shown in the procedure you linked, thus an accurate measurement with a regular LCR will be quite daunting. You would need to verify your procedure with a well known quality brand adapter to have a ballpark of results.