A cheap tester from Amazon.
Discussion
I'd be using a TinySA, which is a cheap tester I got off Amazon. That doesn't rule out you having a useful tool.
I'm curious about your test protocol. There is a specific affect I want to rule out that is usually the thing people are seeing in bad demonstrations of objects like this.
Ever seen the musical instrument called a theremin, the only instrument you can play without touching? Here is a bit about how it works to explain. No antenna is a perfect match for the wavelength of the signal. So you send a signal into the antenna, which is a dead end of wired conductors. Depending on the match of antenna to signal, some signal goes out into the air and some bounces off the end of the antenna right back into the input. That ratio of emitted power to reflected power is called VSWR. Moving your hand around in the field of an antenna changes its VSWR reading.
Usually we output that ratio to a screen and use it to tune antennas to make them more effective. Or you could convert that information about the VSWR of an antenna into noise and you get the theremin.
I told you all that to say this. If you wave that object near the meter as your way of testing you were really testing your hands effect on the meter, not the object. Basically a boring theremin.
To answer what I think you'll ask next also. This works because you are a ball of saltwater and saltwater reflects EMF very well. Remember, you are measuring the changes in power reflected back rather than emitted. So the theremin by itself is proof EMF is safe to be around if you understand that noise is the energy that bounced off of you.
Wild that you can bend and manipulate RF waves at will like that using only your body and mind. Like a magic superpower you didn't know you had. This is why I say the secrets of science are far cooler and wonderful than the myths.
I think you talked me into talking myself into making a theremin.