How do I measure EMI intensity at particular frequency?

I would like to figure out how to measure an EMI intensity at a particular frequency.

 

But all E-field (or H-field) meter only measures the intensity at any frequency. (or at least based on my understanding)

 

Is there a way to measure this intensity at a particular frequency?

 

Seems like all meter utilizes an inductor to measure the induced voltage from change in flux to measure the magnetic field.

But how would I isolate it to measure a particular frequency?

Thank you in advance.

You can get a spectrum analyzer (including handheld version) which show you the dBm at a specific frequency. For example check out the Seeed Studio RF Explorer Handheld Spectrum Analyzer.