I read with interest your feature story on the proliferation of cell phone antennas and concerns with public health expressed by neighbors in the immediate area surrounding them ["Antenna Invasion," July 23]. As both a cell phone user and an expert in the field of radio and antennas, I am dismayed by the inability of the writer to separate scientific facts from ignorance.
First, my qualifications. I am an electrical engineer and was first licensed by the FCC to operate and maintain broadcast transmitters in 1959 (First Class Radiotelephone). After graduating from the University of Cincinnati in 1964 (BSEE), where my undergraduate thesis was on transmitting antennas, I worked briefly for Motorola's two-way-radio division and taught at DeVry for five years, including courses on antenna systems. I have since made my living designing sound systems for public places, among them Wrigley Field, the United Terminal at O'Hare, Northwestern's Ryan Field, the Old Town School of Folk Music, and the Jazz Showcase. I was recently elected a Fellow of the Audio Engineering Society. I also consult on electromagnetic compatibility (EMC) and am vice-chair of the Audio Engineering Society Standards Committee's working group on EMC. EMC is, in essence, the science of understanding and limiting the interference between electronic equipment, as well as other undesired effects.
The concerns raised with respect to possible dangers posed to the public health of cell phone towers are completely without merit and have no scientific basis. I have appended an excerpt from a Frequently Asked Questions document on the Federal Communications Commission's (FCC) Web site to this letter. I find it to be entirely sound from a scientific point of view. For the benefit of your readers, I will summarize its essence in less technical (but no less correct) terms than the FCC has used.
(1) The cell phone antennas used in populated areas (as opposed to those on remote mountaintops) are very special types of antennas that concentrate their energy in a very narrow beam directed straight out from the antenna. These antennas are so directional that nearly all of the energy is confined to approximately five degrees or so of vertical angle. The energy at angles below that beam is far less than in the main beam. Putting some numbers to it, if there were 100 watts in the main beam, there would typically be less than 20 watts at five degrees below the main beam, 5 watts ten degrees below it, and much less than one watt escaping in the direction of people below the antenna! Very similar (but larger and far more powerful) antennas on Sears Tower and the Hancock building are used to transmit television signals. Both the cell antennas and the TV antennas "beam over the heads" of those close by to reach users at far greater distances.
(2) As energy radiates outward from any antenna, it spreads out over an increasingly wider area, and its strength falls off twice as fast as the distance from it (mathematically, as the square of the distance). That means that the strength of the energy at 100 feet from the antenna is 1/100th of the energy at 10 feet, the energy at 320 feet is 1/1000th the energy at ten feet, and so on.
(3) A typical cell phone transmits about one-tenth of a watt average power, but in pulses of about one watt, and it is very close to the body of the person using it. So a cell phone user is getting a far larger dose of energy from a cell phone than he or she would from a transmitting antenna.
(4) Scientific studies appear to have failed to convincingly show a link between even this level of radiation and public health, but the FCC has adopted relatively conservative (that is, in favor of the public health) guidelines to protect the public safety anyway, as well they should. (Note that my competence is not in the field of medicine, so here I am only citing what I have read in scientifically solid publications.)
Quoting from the FCC Web site, "Measurements made near typical cellular and PCS installations, especially those with tower-mounted antennas, have shown that ground-level power densities are thousands of times less than the FCC's limits for safe exposure. In fact, in order to be exposed to levels at or near the FCC limits for cellular or PCS frequencies an individual would essentially have to remain in the main transmitting beam (at the height of the antenna) and within a few feet from the antenna. This makes it extremely unlikely that a member of the general public could be exposed to RF levels in excess of these guidelines due to cellular or PCS base station transmitters."
As I read the FCC's document, a person would not even be in danger if they were on a building 100 feet away from the antenna and directly in line with it (that is, at the same elevation). This is entirely consistent with my understanding of how these antennas and systems work. If I were on the receiving end I would be concerned only if that antenna was pointed at my living space, at the same elevation, and right next door. Incidentally, because most electronic equipment is deficient in its ability to reject interference from radio transmitters, including cell phones, I would be far more concerned with interference to my consumer electronics equipment than with any health issues. But the whole thing is really much ado about nothing--no cell phone company is going to point an antenna at a building--such an antenna wouldn't be effective, because the building would block its signal from those cell phone users it was intended to serve!
One final point. I have considerable technical competence in professional audio and acoustics, as well as in radio systems. My wife is a scientist working in the pharmaceutical industry. It is painfully common for us to see technical issues within our fields of expertise covered in the general press by journalists who are completely unqualified to report on them. There is far more to journalism than getting everyone's name right and reporting conflicting points of view on an issue without regard to the validity or technical accuracy of those points of view. It is irresponsible and unprofessional of you, or for any publication, to report on an issue without reasonable competence on the subject, both on the part of the authors and the editors, or without peer review by those who are technically competent. I've been an avid reader of the Reader since its inception, and I would be the last to say that you're worse than average in this regard--I've read plenty of incompetent "journalism" on technical topics in publications as diverse as the New York Times, the Wall Street Journal, Consumer Reports, and the Chicago Tribune.
Audio Systems Group, Inc.