Agilent Fieldfox N9912a help

[axh]

I recently came across one of these but it doesn't seem to be performing as expected. I don't know much about them but it isn't showing the same VSWR for an antenna as other test equipment. With no antenna connected at all, the attached picture is what's shown. Just wondering if the equipment is faulty or if I'm doing something wrong. When I left it on for a while, it seemed to come good and show roughly what I expected as the VSWR for the antenna (2.4g/5g wifi antenna) but for the majority of the time it's on, the VSWR plot for an antenna seems to have these strange parabolas added to it. Apologies in advance if this is a stupid question, still learning!

[eb4fbz]

Have you calibrated it properly?

[TheSteve]

That certainly doesn't look good. But a cal has been performed - and if it wasn't done properly it can cause nearly any result.