Radiofrequency Radiation Source Lab and Instrumentation

Dana Stahl, MS, CIH

Instructor & Content Manager, Continuing Education Programs

Environmental and Occupational Health Sciences, University of Washington (UW DEOHS)

  • 1 Mhz= 106 Hz
  • 1 GHz -109 Hz

Exercise 1: The Hairdryer/Router/RF Source (This will take several people):

  • One person to operate the hair dryer
  • One person to hold shielding materials (metal, or wood)
  • One person to operate the Extech
  • One person to operate the EMDEX
  • Recorders for each instrument
  • Someone to measure distances

Instructions:(record results in table below)

  • Turn the hair dryer/router/source on. Take measurements next to the source and 2 feet in front the source.
  • Place shield in front of the source and record measurements at one foot and two feet from the source. Take measurements using the following for shields:
  • Metal
  • Wood
  • Person
  • Place shield behind the source and take measurements at one foot behind.

Hairdryer/Source
Distance (ft) / Instrument 1 / Instrument 2 / Barrier / Reflector
1 / none / none
2 / none / none
1 / Metal / none
2 / Metal / none
1 / Wood / none
2 / Wood / none
1 / Person / none
2 / Person / none
1 / none / Metal
Router
Distance (ft) / Instrument / Barrier / Reflector
2 / none / none
2 / Metal / none
2 / none / Metal
2 / Wood / none
2 / none / Wood
2 / Person / none
2 / none / Person
  1. Do your measurements reflect the inverse square law for distance? Why or why not?
  2. How does placement of the different types of shields in front of or behind the source change your measurements and potential exposure to personnel?
  3. Compare exposures to the ACGIH TLV.Are hairdressers exposed above the TLV?

Exercise 2: The Microwave

US standards state that a microwave oven cannot emit more than 5mW/cm2 (or 1 mW/cm2 on initial purchase). Use the instruments to determine if microwaves in the building meet this standard. The procedure to measure microwave emissions is:

  • Set Power on High
  • Place 275 ml of cool water (in a coffee cup or glass beaker) in the center of the microwave.
  • Set the timer for 3 minutes. If the water boils, pour it out and replace it.
  • Move the meter slowly (to avoid picking up static discharge) and take measurements around the door seal, the window, and at vents.

You may also take measurements with the second instrument (look in the area near the power cord)

Microwave
Instrument 1 / Instrument 2
*Background level: 0.001 uW/cm^2
  1. Do the microwaves you tested fall within the acceptable standards for leakage?
  2. How would you communicate the results of your microwave survey to building occupants?