As I live in North America, my initial hypothesis is that I'm picking the 60Hz from my house's power line.
But, to my understanding, my body can't be a 60Hz antenna (1/4 wave antenna length for 60Hz is ~1250 km.)

I feel like my understanding of "indirect" coupling is incomplete.
Could somebody help me?

  • 2
    \$\begingroup\$ You are assuming a far field model. In a house, the 60 Hz is all around you, it is a near field issue. \$\endgroup\$
    – Mattman944
    Commented May 24, 2020 at 17:03
  • \$\begingroup\$ Have you connected it to grounded or ungrounded outlet? The effect will be amplified if your scope has a grounded mains input, but it is connected to ungrounded outlet. \$\endgroup\$
    – Justme
    Commented May 24, 2020 at 18:15

2 Answers 2


You're picking up near field effects, which is a different mechanism than normal electromagnetic radiation.

See also: Designing 60hz antenna to detect electric field

  • \$\begingroup\$ thanks for pointing me in a good direction. To be honest, I'm still not sure how those two are related, but at least I'm not using far-field equations to guide my research anymore. \$\endgroup\$
    – gbt
    Commented Jun 4, 2020 at 14:26

You and the mains AC lines make a capacitor, not especially many farads, but still well measurable as you have seen on the screen of your oscilloscope. The AC lines do not radiate especially strong 60Hz radiowaves because they are far too short and too near the ground, so the fields mainly fluctuate around them. But that's enough for capacitive connection. As you have seen.


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