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T-Mobile· Proposed Base Station (Site No. SF14949)
20041 Bollinger Road· Santa Clara, California
Statement of Hammett & Edison, Inc., Consulting Engineers
The firm of Hammett & Edison, Inc., Consulting Engineers, has been retained on behalf ofT-Mobile,
a personal wireless telecommunications carrier, to evaluate the base station (Site No. SF14949)
proposed to be located at 20041 Bollinger Road in Santa Clara, California, for compliance with
appropriate guidelines limiting human exposure to radio frequency ("RF") electromagnetic fields.
Prevailing Exposure Standards
The U.S. Congress requires that the Federal Communications Commission ("FCC") evaluate its
actions for possible significant impact on the environment. In Docket 93-62, effective October 15,
1997, the FCC adopted the human exposure limits for field strength and power density recommended
in Report No. 86, "Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic
Fields," published in 1986 by the Congressionally chartered National Council on Radiation Protection
and Measurements ("NCRP"). Separate limits apply for occupational and public exposure conditions,
with the latter limits generally five times more restrictive. The more recent Institute of Electrical and
Electronics Engineers ("IEEE") Standard C95.1-1999, "Safety Levels with Respect to Human
Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz," includes nearly identical
exposure limits. A summary of the FCC's exposure limits is shown in F·igure 1. These limits apply
for continuous exposures and are intended to provide a prudent margin of safety for all persons,
regardless of age, gender, size, or health.
The most restrictive limit for exposures of unlimited duration to radio ftequency energy for several
personal wireless services are as follows:
Personal Wireless SeJVice
Personal Communication ("PCS")
Cellular Telephone
Specialized Mobile Radio
most restrictive ftequency range]
ADOTOX. Freauency
1,950 MHz
870
855
30-300
OccuDational Limit
5.00 mW/cm2
2.90
2.85
1.00
Public Limit
1.00 mW/cm2
0.58
0.57
0.20
General Facility Requirements
Base stations typically consist of two distinct parts; the electronic transceivers (also called "radios" or
cabinets") that are connected to the traditional wired telephone lines, and the passive antennas that
send the wireless signals created by the radios out to be received by individual subscriber units. The
transceivers are often located at ground level and are connected to the antennas by coaxial cables
about I inch thick. Because of the short wavelength of the frequencies assigned by the FCC for
wireless services, the antennas require line-of-sight paths for their signals to propagate well and so are
installed at some height above ground. The antennas are designed to concentrate their energy toward
HE HAMMEIT &; EDISON, INC.
CONSULTING ENGINEERS
SAN FRANCISCO
TMSF14949596.1
Page 1 of3
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T-Mobile' Proposed Base Station (Site No. SF14949)
20041 Bollinger Road' Santa Clara, California
the horizon, with very little energy wasted toward the sky or the ground. Along with the low power of
such facilities, this means that it is generally not possible for exposure conditions to approach the
maximum permissible exposure limits without being physically very near the antennas.
Computer Modeling Method
The FCC provides direction for determining compliance in its Office of Engineering and Technology
Bulletin No. 65, "Evaluating Compliance with FCC-Specified Guidelines for Human Exposure to
Radio Frequency Radiation," dated August 1997. Figure 2 attached describes the calculation
methodologies, reflecting the facts that a directional antenna's radiation pattern is not fully fonned at
locations very close by (the "near-field" effect) and that the power level from an energy source
decreases with the square of the distance from it (the "inverse square law"). The conservative nature
of this method for evaluating exposure conditions has been verified by numerous field tests.
Site and Facility Description
Based upon information provided by T-Mobile, including drawings by MSA Architecture and
Planning, Inc., dated June 29, 2005, it is proposed to mount three Andrew Model ADFDI820-6565B-
XDM directional panel antennas on a new 35-foot steel pole to be located near the Tin Tin Market at
20041 Bollinger Road in Santa Clara. The antennas would mounted at an effective height of about
33 feet above ground and would be oriented in pairs with up to 30 downtilt at 1200 spacing, to provide
service in all directions. The maximum effective radiated power in any direction would be
1,200 watts, representing six channels operating simultaneously at 200 watts each. There are reported
no other wireless telecommunications base stations located nearby.
Study Results
For a person anywhere at ground, the maximum ambient RF exposure level due to the proposed
T-Mobile operation is calculated to be 0.0058 mW/cm2, which is 0.58% of the· applicable public
exposure limit. The maximum calculatèd level on the roof of the adjacent building is 3.7% and the
maximum calculated level at the second floor elevation of any nearby building' is 0.97% of the public
exposure limit. It should be noted that these results include several "worst-case" assumptions and
therefore are expected to overstate actual power density levels.
No Recommended Mitigation Measures
Since they are to be mounted on a tall pole, the T-Mobile antennas are not accessible to the general
public, and so no mitigation measures are necessary to comply with the FCC public exposure
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Located at least 90 feet away, based on aerial photographs from Terraserver.
HAMMETT & EDISON, INC.
CONSULTING ENGINEERS
SAN FRANCISCO
1MSF\4949596.\
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T-Mobile. Proposed Base Station (Site No. SF14949)
20041 Bollinger Road· Santa Clara, California
guidelines. It is presumed that T-Mobile will, as an FCC licensee, take adequate steps to ensure that
its employees or contractors comply with FCC occupational exposure guidelines whenever work is
required near the antennas themselves.
Conclusion
Based on the information and analysis above, it is the undersigned's professional opinion that the base
station proposed by T-Mobile at 20041 Bollinger Road in Santa Clara, California, will comply with the
prevailing standards for limiting public exposure to radio ftequency energy and, therefore, will not for
this reason cause a significant impact on the environment. The highest calculated level in publicly
accessible areas is much less than the prevailing standards allow for exposures of unlimited duration.
This finding is consistent with measurements of actual exposure conditions taken at other operating
base stations.
Authorship
The undersigned author of this statement is a qualified Professional Engineer, holding California
Registration Nos. E-13026 and M-20676, which expire on June 30, 2007. This work has been carried
out by him or under his direction, and all statements are true and correct of his own knowledge except,
where noted, when data has been supplied by others, which data he believes to be correct.
August 30, 2005
4
P.E.
HE HAMMETT &. EDISON, INC.
mNSULTING ENGINEERS
SAN FRANCISCO
IMSF14949596.1
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