Or perhaps to do with the fact that the impedance will not be free space. The units could perhaps be E field or H field, depending. If it's to do with the actual interference power onto a signal the significance would be a bit specific. Very different from free space interference into an antenna.Merlin3189 said:So, not knowing your context, I wonder whether it is to do with radiation resistance?
The body is only about 2m long, so it is a very inefficient antenna for the long waves associated with ELF and VLF. Therefore it couples very little power out of a passing wave, and the heating effect is small. On the other hand, the body might be exposed to very large electric fields, for instance in the case of a rigger working on a transmitting antenna. Such fields can produce dielectric heating of the body. Very strong magnetic fields are also subject to recommended limits, as adverse effects are thought to occur.Curiousphy said:Why do EMF meters measure ELF and VLF in flux density units but RF in power density units? Is it because ELF/VLF have low power density and high flux density, and RF has high power density and low flux density? They are all EM waves, right? what's driving the difference in measurement units? thanks
EMF meters measure ELF and VLF differently because they operate based on different principles. ELF refers to electromagnetic frequencies that range from 3 to 30 Hz, while VLF refers to frequencies between 3 kHz and 30 kHz. These frequencies have different wavelengths and properties, which require different detection methods.
EMF meters measure ELF and VLF frequencies by using different types of sensors. ELF frequencies are typically measured using a magnetic field sensor, as these frequencies produce a magnetic field that can be easily detected. VLF frequencies, on the other hand, are measured using an electric field sensor, as they produce an electric field that can be easily detected.
Yes, some EMF meters are capable of measuring both ELF and VLF frequencies at the same time. These meters will typically have two sensors, one for measuring magnetic fields and another for measuring electric fields. However, it is important to note that these frequencies may still be measured differently due to their different properties.
While both ELF and VLF frequencies have been linked to potential health risks, the level of risk may differ depending on the specific frequency. For example, ELF frequencies have been associated with increased risk of cancer, while VLF frequencies may impact the nervous system and cause other health effects. Therefore, it is important to consider the specific frequency being measured when assessing potential health risks.
Yes, there are some limitations to using EMF meters for measuring ELF and VLF frequencies. These meters may not be able to accurately measure frequencies outside of their designated range, and they may also be affected by external interference or electronic devices nearby. Additionally, the placement and orientation of the meter can also impact the accuracy of the measurements.