February 2007

RF Safety: New Tools Provide Peace of Mind
By Robert Johnson, Director of Instrument Products, Narda Safety
Test Solutions

The issue of whether or not nonionizing (RF) radiation can be hazardous to your health has always been fraught with emotion, as “experts” attempt to inform the unwashed that there either is or is not something to worry about. You don’t have to be a cynic to notice that people with the most to gain financially are generally the least worried and those with no financial agenda (generally from academia) the most cautious. The dialog between evangelists from both camps has become (pardon the pun) heated to the point of near fisticuffs and slurs of one’s manhood. Other than the obvious damage caused by heating (as in microwave ovens) there remains no clear answer as to what insidious damage occurs at lower levels of exposure, and if it does, how long it takes and at what level.

However, one thing has become very clear: With more than 2 billion mobile phones in service throughout the world, the issue of RF safety has taken a back seat (no more puns, I promise) to the issue of people driving while talking, dialing, looking up contacts, text messaging, etc. - and even most recently riding bicycles while doing so (a ban was proposed and soundly trounced in New Jersey). Governments are, logically enough, concerned more with the tangible and more easily remedied threat of people killing each other on the highway while chewing the fat than whether there might, at some time, be some health damage from the mobile phone having become an appendage to the ears of virtually half the humans on Earth.

As a leading manufacturer of RF radiation safety test equipment, Narda is “viewpoint agnostic” as it concerns the potential dangers of electromagnetic radiation. We have read the studies, we know most of the major players in both camps, and we respect (most) of their opinions. We also recognize that it is far easier to dismiss something as intangible as RF radiation effects than it is to wave off obvious causes of harm, and that a cavalier attitude is not synonymous with safety. So we concentrate on making measurements of electric and magnetic fields as easy and accurate as possible so that people owning equipment that generates EM fields, people who work near them, and people who inadvertently come near them can be as well informed and safe as possible.

Perhaps the most important recent development in measurement technology is the ability to “overlay” the results of field measurement on applicable standards to see if the measured levels exceed accepted limits. It has only been within the last few years that, thanks to signal processing, computer, and antenna technology, that this has been achievable. The first instrument to offer such capability is Narda’s SRM-3000.

The impact of this is more significant than it might appear on first inspection. The Federal Communications Commission has decreed that any emitter contributing 5% or more to the total emissions radiated at a site is responsible for ensuring it is in compliance, and if it is not to become part of the solution. However, the FCC and transmitter operators wishing to comply with its rules have been hamstrung when attempting to monitor and evaluate the radiation levels from the multi-transmitter sites prevalent today. This was because evaluating each emitter required all other emitters at the site to be turned off.

Consider the difficulty of this. No doubt you can picture a broadcast tower, water tower, or some other platform in your area than is covered with antennas of various sorts, serving companies that transmit over a wide array of frequencies. If there are 25 at this site (for example), imagine trying to get 24 of them to shut down while someone measures the radiation from the remaining emitter. The FCC can do it, but you don’t want that, and if you try....well, carry a big stick.

The SRM-3000 narrowband measurement system captures the spectrum in question, displays it spectrum analyzer fashion - but provides values of these emissions (if you choose to) as a percentage of the standard applicable at their operating frequencies. This means that measurements at collocated sites can be made in almost “drive-by” fashion, without disrupting operation (and, as an aside, without anyone knowing you’re there).

This is good news for everyone, although it does remove the last remaining excuse for not being in compliance with FCC guidelines. The FCC can become more active in enforcement, and site owners and system operators can be more comfortable in knowing they are in compliance and if not, what their contribution to the total radiation is at the site.
Even better news is that Narda and several of its first customers for the SRM-3000 found that sites that look like massive violators sometimes are not, and are well within FCC limits. It is provided a level of assurance to people in several communities who expected the worst. The SRM-3000 and its probe are precision instruments, accurate to very narrow tolerances, and calibrated to known standards, so the results are verifiable.

So in short, while the answer to the question of RF safety remains elusive, the tools to measure levels that have been set into safety standards have been significantly improved in terms of their utility in the collocated transmitter environments that are the norm today. Their use by the FCC and the small but dedicated group of consultants who travel the continent every year to evaluate specific emissions environments and recommend and implement solutions should go a long way toward making the intangible world of RF radiation safety more tangible for everyone.

Narda Safety Test Solutions
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