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news and other topics for those interested in RF safety issues.
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What Type of Equipment Do I Need?
Important Questions to Ask Yourself
Equipment needs should be determined by the situations that your organization
faces, the background and availability of your personnel, and your objectives.
Consider how you would answer the following questions:
 | Are all the potential hazards identified? |
| Are the sources of radiation fixed, such as the output of a radio or TV
broadcast station? |
| Are site conditions constantly changing, such as on a rooftop with many
different wireless service providers? |
| Is the primary concern over leaks from industrial process equipment? |
| Does the system use waveguide to conduct high levels of RF energy? |
| Do my personnel have an electronics background? |
| Would my personnel be comfortable with and capable of making RF field
level measurements? Do they have the time to conduct field surveys? |
| Does my organization employ contractors to work in areas with significant
RF field levels? |
| Do my personnel need to work in areas with RF field levels above the
standards? |
Points to Consider
Based on the answers to the questions above, consider the following points:
| RF Survey instruments can provide an accurate
assessment of field levels at a particular location at a particular time.
They do not provide continuous monitoring. A certain level of
expertise and training is needed to use survey equipment properly.
 | Simply checking for leaks near industrial processing equipment requires
limited training. |
| Conducting and documenting surveys at complex antenna sites requires a
knowledge of the equipment, its limitations, the propagation characteristics
of the antenna systems, and concepts such as ground reflections and
reradiating objects. |
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| RF Personal Monitors,
when used properly, provide continuous
monitoring of conditions.
| The training requirements for the proper use of RF personal monitors are
far simpler than those for using survey equipment. |
| All personnel that use RF personal monitors should receive basic RF
safety training. |
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| RF Personal Monitors should not be
used to make measurements! Some models are designed to be isotropic when
the cap is removed. At most, this feature is useful to find a leak.
It should not be used to quantify the leak!. |
| RF Area Monitors solve some problems better
than survey instruments and personal monitors. The simpler area monitors
function much like a smoke detector. They sound an alarm whenever the
field strength increases above a predetermined threshold. The challenge
in using these monitors is locating them so that they properly protect
personnel under all conditions. There are some new, wide area monitoring
systems on the market. These use probes inside weatherproof housings.
These monitors can provide quantitative measurements and a record of site
conditions. Data is collected by the area monitor and sent via phone
lines, either wireless or landline, to a central station where the data is
stored and processed. They can be set to send an alarm notification at
specific field levels. |
| RF Personal Protective Equipment (PPE) is
available in the form of RF protective garments. Personal monitors can
tell you where you cannot go or should not remain, but what if you need to
work in an area with significant RF fields? RF protective garments are
often a good solution to this problem. These garments do provide a
substantial amount of protection—10 dB minimum and often more and work
quite well at frequencies from about 50 MHz and higher. But there are
limitations and cautions, especially at lower frequencies, such as in the AM
radio band. |
| RF PPE Protection is Limited! Putting
on an RF protective garment should not be equated with Clark Kent changing
into his Superman outfit in a phone booth! The manufacturers of these
garments stress that you should know the intensity of the field that you
are entering. Most survey instruments are not usable at these high
field levels, which leaves computer modeling as the most common method to
estimate the field levels. The
conservative, recommended approach is to assume 10 dB of protection—restrict
your work to areas that are no higher than 1000% of the MPE limits. |
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