Vallco RF Report.pdf
Verizon Wireless ¥ Proposed Base Station (Site Name ÅVallco COW TempÆ)
19333 Vallco Parkway ¥ Cupertino, California
Statement of Hammett & Edison, Inc., Consulting Engineers
The firm of Hammett & Edison, Inc., Consulting Engineers, has been retained on behalf of Verizon
Wireless, a personal wireless telecommunications carrier, to evaluate the base station (Site Name
ÅVallcoCOWTempÆ) proposed to be located at 19333 Vallco Parkway in Cupertino, California, for
compliance with appropriate guidelines limiting human exposure to radio frequency (ÅRFÆ)
electromagnetic fields.
Executive Summary
Verizon proposes to install directional panel antennas on a tall steel pole to be sited at
19333 Vallco Parkway in Cupertino. The proposed operation will comply with the FCC
guidelines limiting public exposure to RF energy.
Prevailing Exposure Standards
The U.S. Congress requires that the Federal Communications Commission (ÅFCCÆ) evaluate its
actions for possible significant impact on the environment. A summary of the FCCÈs exposure limits
is shown in Figure 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
FCC limit for exposures of unlimited duration to radio frequency energy for several personal wireless
services are as follows:
Wireless Service Frequency Band Occupational Limit Public Limit
22
Microwave (Point-to-Point) 5Ã80 GHz 5.00 mW/cm 1.00 mW/cm
WiFi (and unlicensed uses) 2Ã6 5.00 1.00
BRS (Broadband Radio) 2,600 MHz 5.00 1.00
WCS (Wireless Communication)2,3005.001.00
AWS (Advanced Wireless)2,1005.001.00
PCS (Personal Communication) 1,950 5.00 1.00
Cellular 870 2.90 0.58
SMR (Specialized Mobile Radio) 855 2.85 0.57
700 MHz 700 2.40 0.48
\[most restrictive frequency range\] 30Ã300 1.00 0.20
General Facility Requirements
Base stations typically consist of two distinct parts: the electronic transceivers (also called ÅradiosÆ or
ÅchannelsÆ) 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. A
small antenna for reception of GPS signals is also required, mounted with a clear view of the sky.
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Verizon Wireless ¥ Proposed Base Station (Site Name ÅVallco COW TempÆ)
19333 Vallco Parkway ¥ Cupertino, California
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 the horizon, with
very little energy wasted toward the sky or the ground. 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, ÅEvaluating Compliance with FCC-Specified Guidelines for Human Exposure to
Radio Frequency Radiation,Æ dated August 1997. Figure 2 describes the calculation methodologies,
reflecting the facts that a directional antennaÈs radiation pattern is not fully formed at locations very
close by (the Ånear-fieldÆ effect) and that at greater distances the power level from an energy source
decreases with the square of the distance from it (the Åinverse square lawÆ). 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 Verizon, it is proposed to install three Andrew Model SBNH-
1D6565B directional panel antennas on top of a 55-foot mast on a trailer to be parked at the north end
of the parking lot behind the Apple building located at 19333 Vallco Parkway in Cupertino, near the
bend in Perimeter Road, on the southwest side of Interstate 280. The antennas would employ up to 4¡
downtilt, would be mounted at an effective height of about 55 feet above ground, and would be
oriented at about 120¡ spacing, to provide service in all directions. The maximum effective radiated
power in any direction would be 13,100 watts, representing simultaneous operation at 5,220 watts for
AWS, 5,750 watts for PCS, and 2,130 watts for 700 MHz service; no operation on cellular frequencies
is presently proposed from this site. There are reported no other wireless telecommunications base
stations at the site or nearby.
Study Results
For a person anywhere at ground, the maximum RF exposure level due to the proposed Verizon
2
operation is calculated to be 0.028 mW/cm, which is 2.9% of the applicable public exposure limit.
*
The maximum calculated level at the second-floor elevation of any nearby building is 3.3% of the
public exposure limit. It should be noted that these results include several Åworst-caseÆ assumptions
and therefore are expected to overstate actual power density levels from the proposed operation.
There are no residential buildings located within 1,000 feet radius of the site.
*
The Vallco Shopping Center located at 10123 North Wolfe Road, about 400 feet to the southwest.
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Verizon Wireless ¥ Proposed Base Station (Site Name ÅVallco COW TempÆ)
19333 Vallco Parkway ¥ Cupertino, California
No Recommended Mitigation Measures
Due to their mounting location and height, the Verizon antennas would not be accessible to
unauthorized persons, and so no mitigation measures are necessary to comply with the FCC public
exposure guidelines. It is presumed that Verizon will, as an FCC licensee, take adequate steps to
ensure that its employees or contractors receive appropriate training and 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 undersignedÈs professional opinion that
operation of the base station proposed by Verizon Wireless at19333Vallco Parkway in Cupertino,
California, will comply with the prevailing standards for limiting public exposure to radio frequency
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, 2017. This work has been carried
out 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.
_________________________________
William F. Hammett, P.E.
707/996-5200
September 29, 2016
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FCC Radio Frequency Protection Guide
The U.S. Congress required (1996 Telecom Act) the Federal Communications Commission (ÅFCCÆ)
to adopt a nationwide human exposure standard to ensure that its licensees do not, cumulatively, have
a significant impact on the environment. The FCC adopted the limits from Report No. 86, ÅBiological
Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields,Æ published in 1986 by the
Congressionally chartered National Council on Radiation Protection and Measurements (ÅNCRPÆ).
Separate limits apply for occupational and public exposure conditions, with the latter limits generally
five times more restrictive. The more recent standard, developed by the Institute of Electrical and
Electronics Engineers and approved as American National Standard ANSI/IEEE C95.1-2006, ÅSafety
Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to
300 GHz,Æ includes similar limits. These limits apply for continuous exposures from all sources and
are intended to provide a prudent margin of safety for all persons, regardless of age, gender, size, or
health.
As shown in the table and chart below, separate limits apply for occupational and public exposure
conditions, with the latter limits (in italics and/or dashed) up to five times more restrictive:
Frequency Electromagnetic Fields (f is frequency of emission in MHz)
ApplicableElectricMagneticEquivalent Far-Field
RangeField StrengthField StrengthPower Density
2
(MHz)(V/m)(A/m)(mW/cm)
0.3 Ã1.34614 614 1.63 1.63 100 100
2
1.34 Ã3.0614 823.8/ f 1.63 2.19/ f 100 180/ f
2 2
3.0 Ã301842/ f 823.8/ f 4.89/ f 2.19/ f 900/ f 180/ f
30 Ã30061.4 27.5 0.163 0.0729 1.0 0.2
300 Ã1,500f/300 f/1500
3.54 1.59/106/238
f f f f
1,500 Ã100,000137 61.4 0.364 0.163 5.0 1.0
Exposure
)
2
Density
Power
(mW/cm
Public
(MHz)
Higher levels are allowed for short periods of time, such that total exposure levels averaged over six or
thirty minutes, for occupational or public settings, respectively, do not exceed the limits, and higher
levels also are allowed for exposures to small areas, such that the spatially averaged levels do not
exceed the limits. However, neither of these allowances is incorporated in the conservative calculation
formulas in the FCC Office of Engineering and Technology Bulletin No. 65 (August 1997) for
projecting field levels. Hammett & Edison has built those formulas into a proprietary program that
calculates, at each location on an arbitrary rectangular grid, the total expected power density from any
number of individual radio sources. The program allows for the description of buildings and uneven
terrain, if required to obtain more accurate projections.
FCC Guidelines
Figure 1
ª
RFR.CALC Calculation Methodology
Assessment by Calculation of Compliance with FCC Exposure Guidelines
The U.S. Congress required (1996 Telecom Act) the Federal Communications Commission (ÅFCCÆ) to
adopt a nationwide human exposure standard to ensure that its licensees do not, cumulatively, have a
significant impact on the environment. The maximum permissible exposure limits adopted by the FCC
(see Figure 1) apply for continuous exposures from all sources and are intended to provide a prudent
margin of safety for all persons, regardless of age, gender, size, or health. Higher levels are allowed for
short periods of time, such that total exposure levels averaged over six or thirty minutes, for
occupational or public settings, respectively, do not exceed the limits.
Near Field
Prediction methods have been developed for the near field zone of panel (directional) and whip
(omnidirectional) antennas, typical at wireless telecommunications base stations, as well as dish
(aperture) antennas, typically used for microwave links. The antenna patterns are not fully formed in
the near field at these antennas, and the FCC Office of Engineering and Technology Bulletin No. 65
(August 1997) gives suitable formulas for calculating power density within such zones.
mW
S
2
For a panel or whip antenna, power density, in /cm,
=
0.116P
mW
S
net
2
and for an aperture antenna, maximum power density , in /cm,
=
max
2
h
where= half-power beamwidth of the antenna, in degrees, and
BW
P= net power input to the antenna, in watts,
net
D= distance from antenna, in meters,
h= aperture height of the antenna, in meters, and
= aperture efficiency (unitless, typically 0.5-0.8).
The factor of 0.1 in the numerators converts to the desired units of power density.
Far Field
OET-65 gives this formula for calculating power density in the far field of an individual RF source:
mW
S
2
power density = in /cm,
,
where ERP= total ERP (all polarizations), in kilowatts,
RFF= relative field factor at the direction to the actual point of calculation, and
D= distance from the center of radiation to the point of calculation, in meters.
The factor of 2.56 accounts for the increase in power density due to ground reflection, assuming a
reflection coefficient of 1.6 (1.6 x 1.6 = 2.56). The factor of 1.64 is the gain of a half-wave dipole
relative to an isotropic radiator. The factor of 100 in the numerator converts to the desired units of
power density. This formula has been built into a proprietary program that calculates, at each location
on an arbitrary rectangular grid, the total expected power density from any number of individual
radiation sources. The program also allows for the description of uneven terrain in the vicinity, to
obtain more accurate projections.
Methodology
Figure 2