The URL can be used to link to this page

DIR-2012-34b CITY OF CUPERTINO 10300 Torre Avenue, Cupertino, California 95014 (408) 777-3308 To: Mayor and City Council Members Chairperson and Planning Commissioners From: Aarti Shrivastava, Director of Community Development� Prepared by: George Schroeder, Assistant Planner Date: October 25, 2012 Subject: Director's Minor Modification, DIR-2012-34, to a previously approved Use Permit (U- 1996-11) to allow the installation of a 13" x 13" microwave antenna and associated equipment on the rooftop of an existing building as part of a point-to-point wireless network between three Seagate Technology sites located at 10200 South De Anza Boulevard. Director's Minor Modification, DIR-2012-35, to a previously approved Use Permit (U-1986-04) to allow the installation of a 13" x 13" microwave antenna and associated equipment on the rooftop of an existing building as part of a point-to-point wireless network between three Seagate Technology sites located at 20400 Stevens Creek Boulevard. Director's Minor Modification, DIR-2012-36, to a previously approved Use Permit (U-1982-04) to allow the installation of two 13" x 13" microwave antennas and associated equipment on the rooftop of an existing building as part of a point-to- point wireless network between three Seagate Technology sites located at 10001 North De Anza Boulevard. Chapter 19.132 of the Cupertino Municipal Code allows for administrative approval of minor changes in a project. The Director reports his decision to the City Council and Planning Commission in time to allow an appeal of the decision within fourteen calendar days. DIR-2012-34: 10200 South De Anza Blvd DIR-2012-35: 20400 Stevens Creek Blvd DIR-2012-36: 10001 North De Anza Blvd Page 2 DISCUSSION The applicant, Heinz Werle, representing Seagate '� l000s r,��}� � ,'A �� .'�. � Technology, is requesting approval to allow the �� „ ��Z�B�. , _ � , -� � � �k . �,,.�.,:. � , � ,. �� installation of 13 inch x 13 inch microwave antennas w,a� •��.� . ,�--�� ";�-" � �� u. �_�, �� # �_, t ��ea�. � ;�t��F:,� .:�..,��j,�' .� and associated small-diameter masts on the rooftops �. �r� r��: �� r�=��"�, � � � ./..�f* .�w �� v `r e Y/.F . •�s�'1{,�.�( ♦t I I 7! of three existing office buildings as part of a 5GHz -t ^,�'=� r��M - �.,.,�$w;�� (low ower , non-Federal Communications ±` ��;�'' �� A�� '�'�� . p ) �..,� � -a�, .�.,�.- ., ,� ,� � Commission FCC re ulated oint-to- oint wireless '�'�� • � � ''�t ' a ='��;� •k-��;' ±' � ) g � p p ��f�� x� � ��. �� ,� r �•, �i��'��'�'�r �r: ,�',��:' '' -'� ,�'-..1 -'"�''"�°,_ 1, ' ' network between the three Seagate sites located at �-,�,��u�� , ; � t�l. ,,.�� ,: � , C __ ; 10200 South De Anza Boulevard (DIR-2012-34), � . � ,��=�� ' �,� ;�� ° ., � ; ,.t ,.a�.. .� � � -.-..,�- • 20400 Stevens Creek Boulevard (DIR-2012-35), and � ' :� `. . ,-.H j. � � • v_�� ----•��, � ., _�;�, i ' 10001 North De Anza Boulevard (DIR-2012-36). The �c-�=� � . t � l�iF � zoaooscs �- � ; ,. � M , wireless network proposes one new antenna each at '�` - - ; �. �, � -,� � � «� � Ne4•, � �` ,�, �.: ��. �� -� 10200 South De Anza Boulevard and 20400 Stevens antenna(s} � �' ° ,�,f,�,T' ��` and assoc. ±n � ` '�� _ 2 Creek Boulevard; and two new antennas at 10001 �` equip. �'}';�_+ , �',�� -�1,..,;i�' �'� �f J � r {%` � � North De Anza Boulevard. The rooftop at 10001 U"P�f _, � c� �: a� ,� �� £ si�ht � ..� � 10240 S De �_ �,:, North De Anza Boulevard has the unobstructed line a„Z��,. � • - �.��...;^ � �`.�r ,,..�.. _ _ ... ... _ _ of sight to the two other Seagate locations. See the Aerial photo showing locations of point-to- photo to the right for reference. point wireless network 10200 South De Anza Boulevard At the Seagate headquarters building, one antenna is proposed to be mounted on a mast attached to an outside wall adjacent to the roof of the penthouse. The total height of the installation will be approximately 70 feet above finish grade. The antenna will project above the existing roof screen by two feet and will be minimally visible from public view. The total setback from the adjacent apartment building at 20380 Stevens Creek Boulevard will be greater than the ordinance-required 75 feet. Based on its height and 18 foot setback from the edge of the roof, it is within the height and setback requirements of the City's Wireless Communications Facilities Ordinance. 20400 Stevens Creek Boulevard At Cupertino City Center Tower I, one antenna is proposed to be mounted onto a 5 foot tall, 2- inch diameter mast on the rooftop. The total height of the installation will be approximately 115 feet above finish grade. Surrounding buildings will obstruct public views to the new installation. The total setback from the adjacent condominium at 20488 Stevens Creek Boulevard will be greater than the ordinance-required 75 feet. Based on its height and 50 foot setback from the edge of the roof, it is within the height and setback requirements of the City's Wireless Communications Facilities Ordinance. DIR-2012-34: 10200 South De Anza Blvd DIR-2012-35: 20400 Stevens Creek Blvd DIR-2012-36: 10001 North De Anza Blvd Page 3 10001 North De Anza Boulevard At the "East West Bank Building," two antennas are proposed to be mounted onto an 8 foot tall, 3.5-inch diameter mast on the rooftop. The total height of the installation will be approximately 65 feet above finish grade. The antenna will project above the existing roof screen by one foot and will be minimally visible from public view. Based on its height and 18 foot setback from the edge of the roof, it is within the height and setback requirements of the City's Wireless Communications Facilities Ordinance. The RF study for the project (Attachment 1) demonstrates that the maximum radio frequency exposure level in a worst case situation for a person anywhere at the ground is 0.00012 mW/cm2, which is 0.012% of the applicable federal public exposure limit and well within federal safety standards. The public exposure limit is reached only within 2.5 inches in front of the antennas, so RF exposures to occupants on floors below the antenna and nearest residents are also well within the federal safety standards. ACTION The Director of Community Development deems the modification minor and approves the project with the following conditions of approval: 1. APPROVED EXHIBITS . Approval is based on exhibits titled: "Seagate Technology, Point-to-Point Wireless Network Proposal, 10200 South De Anza Boulevard;" "Seagate Technology, Point-to-Point Wireless Network Proposal, 20400 Stevens Creek Boulevard;" and "Seagate Technology, Point-to-Point Wireless Network Proposal, 10001 North De Anza Boulevard," prepared by Seagate Technology and consisting of 3, 4, and 5 sheets respectively; except as may be amended by the conditions contained in this resolution. 2. CAMOUFLAGING OF EQUIPMENT The aerials and associated equipment shall be painted a flat gray or similar color in order to minimize visibility. All cables shall be enclosed in a conduit painted to match the building wall or roof color. 3. BUILDING PERMITS The applicant shall consult with the City Building Division to obtain the necessary building permits for the installation of the aerials and associated equipment. DIR-2012-34: 10200 South De Anza Blvd DIR-2012-35: 20400 Stevens Creek Blvd DIR-2012-36: 10001 North De Anza Blvd Page 4 4. ABANDONMENT If after installation, the aerials and associated equipment are not used for its permitted purpose for a continuous period of 18 months, said antennae and associated facilities shall be removed. The applicant shall bear the entire cost of demolition and removal. 5. EXPIRATION DATE This Director's Minor Modification shall expire two (2) years after the effective date of the permit. The applicant may apply for a renewal of the minor modification at which time the Director of Community Development may review the state of wireless communication and camouflage technologies to determine if the visual impact of the personal wireless facility can be reduced. 6. NOTICE OF FEES, DEDICATIONS, RESERVATIONS OR OTHER EXACTIONS The Conditions of Project Approval set forth herein may include certain fees, dedication requirements, reservation requirements, and other exactions. Pursuant to Government Code Section 66020(d) (1), these Conditions constitute written notice of a statement of the amount of such fees, and a description of the dedications, reservations, and other exactions. You are hereby further notified that the 90-day approval period in which you may protest these fees, dedications, reservations, and other exactions, pursuant to Government Code Section 66020(a), has begun. If you fail to file a protest within this 90-day period complying with all of the requirements of Section 66020, you will be legally barred from later challenging such exactions. This approval of the modification is effective October 25, 2012. The fourteen calendar day appeal period will expire on November 8, 2012. Enclosures: Plan sets Attachment 1. RF study prepared by Hammett & Edison, Inc. Referenced attachments that may not be included with this mailed report are available in the Planning Department located at City Hall and may also be viewed at the City's website at zvzuzo.ci�pertino.org. Select the link to "Public Records" at the top bar, then "Planning Department"folder, then "DIR Approvals"folder, then "2012"folder. Select file number DIR-2012-34, DIR-2012-35, or DIR-2012-36. G:\Planning\PDREPORT\DIRreports\2012\DIR-2012-34,DIR-2012-35, and DIR-2012-36.doc Seagate Technology Point-to-Point Wireless Network Proposal 10200 South De Anza Boulevard This document describes the proposed wireless network installation at existing and two new Seagate sites, located near the intersection of De Anza Boulevard and Stevens Creek Boulevard. The affected locations are: • 10200 South De Anza Blvd, existing Seagate site, new installation • 20400 Stevens Creek Blvd, new Seagate location, "Tower" building, has existing installation • 10001 North De Anza Blvd, new Seagate location, "Bank" building, has existing installation The existing Cupertino site does not have proper line of sight to the two new locations. The Bank building, however, does have line of sight to both of the other facilities. Seagate intends to install a SGHz, non-FCC regulated wireless system for use as a data connection between the locations. The installation at each location consists of a 13x13-inch flat, white antennas located on masts to provide sufficient elevation for direct line of sight to provide the data link. The system will have two antennas deployed at the Bank location, and one antenna each on the existing and Tower site. Height and setback were considered to minimize visibility of the antennas from the street while maintaining the required line of sight. Existing roof penetrations were another consideration when choosing the locations. 10200 South De Anza Blvd The Cupertino building will have a single antenna located on a mast which will be affixed to an outside wall adjacent to the roof of the penthouse. There is a screen to which the Seagate signage is mounted which will obscure the antenna from the street. The setback, as indicated in the picture below, is approximately 18 feet, and the antenna elevation above the roof will be approximately 2 feet. � Location of antenna � •.; , �C f,,, ��, .'�f ...� �� '�,�1 .. �' , ,F,rK;: �.,.__ :��,, � �;,":�"'"" � ,� �"Y .�.�� 'r � +r.,, '' y`�� ,. '�:��,` " . # .�, � w.» ""r �BS 1M�■�pe �'•`� � :t, ' '��.. .�`� ,.. � ,:r'r��.:'.'a.' '�, 4�� {� �� a�w� •�� n ±y �,� " s� � �'� t�M�X�, iT � ,� .� •a�r� �� . , : �� .�:� ��r.: �l'1�t�� ;� � ��,., � ,;,�r' - - ,�i�"�';s; +"�V#�. .�� "'»+�"��X`� 4�:q �S' ��''�. �m �� . - ----__- - +�'� ��__-��_ • w �, �, ,, �+,� ,� «�. _ _ r;. 10200 South De Anza Blvd -Street view ��r�-�� F' ,=.w y ,,�.:� �� - �;' �,'��:�:;: �!�' _.C".�.�� ._. ��/�►��.��;p�� .._ , . __�_ ....�� ..� .�,,�., � ��-� F : .� �,,��, t � a j , 4„ �"�rs�r t �: "'"!" ' � � �r • ��w �;.#� `� � , i _� � ,;�:' ;.� s � � ��: , M Set back 18',height 2'above . ��- ��, .;�, � . • �;�_ �;, rooflscreen ��.�• �� ,��;�=k am�• ,, �"'- ��--� � � � � ♦;S.Qe Anza Sivci �.�:�+u� � . , �,�. �. j , t �' �/ � r 9 l . ��/�n��ti1 ! +, � , `� `�.�� a i , �+► �.M �! � � t � � ; :+�� Proposed Antenna Location , `�� . ; " ;�M � -.'- _ . „. , •,� .+... ,�:_ F� .�` __ ___ . .� :�,�. � ..� ,.. � ~� � w � w } � �„�: � i � _ ' ` , � . ��,`N�, .. I � �� 1 � v [ / � ! i ' � '�. Y .�� e��. n � , � � f � ,� < ! � 1 �A +� � t M � �r��.:�.._.:.._'__.�...�._....._..�.�H....,,�,,..,.w.. r - - � � -, 9. ; . �� ! �f� '"�� : � . .. _. � .� . a- C�,. t�� 4 ... � � ._ _.... � _...._ _. �.._ � �,��. sa�s � � �� : ► °- "" - Ila� .. • �. ►'' � , r ,s,'� . . 9 . � �M4�i+�! '.w N .y�� 8q�i ,,�r w" �, a . Y�'�.. � ., ^.r y� s. ,.. . �' �• a � "' w,r' �._' ., � , M �� '+� �� ,:�+yi T *f,.,� �*i ✓`sM'd`' , `� 10200 South De Anza Blvd -Aerial view ��G:� - -_ �� - - . �� This illustration shows a single Unistrut with pipe clamp. Two lengths of Unistrut will be mounted to the wall to support the mast using a similar clamp. M1Aast and anlenna Dz�B� Roof � � n � Roof �6 teet The antenna mount will consist of two horizontal, parallel lengths of Unistrut mounted near the top of the wall. A mast will be clamped to the Unistrut to provide the elevation required to achieve the necessary line of site. The roof and screen are approximately the same height, and a single 13x13" antenna will protrude above this height by 2'. With a height of approximately 50',the antenna would not be visible for a distance of approximately 450'. At this distance, due to the small size of the antenna, it would be virtually invisible. C�� r<; ��, � ��; This is a picture of the 13x13" antenna mounted on a mast Seagate Technology • Point-to-Point Wireless System • Cupertino, California 20400 Stevens Creek Blvd. • 10200 South De Anza Blvd. • 10001 North De Anza Blvd. Statement of Hammett& Edison, Inc., Consulting Engineers The firm of Hammett & Edison, Inc., Consulting Engineers, has been retained on behalf of Seagate Technology, a computer hardware manufacturer, to evaluate a proposed point-to-point wireless system to be installed on three office buildings located in Cupertino, California, for compliance with appropriate guidelines limiting human exposure to radio frequency ("RF") electromagnetic fields. Executive Summary Seagate proposes to install microwave panel antennas above the roofs of the three office buildings located at 20400 Stevens Creek, 10200 South De Anza, and 10001 North De Anza Boulevards in Cupertino. The proposed operations 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 ("FCC") evaluate its actions for possible significant impact on the environment. A summary of the FCC's 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 Frequencv Band Occupational Limit Public Limit Microwave (Point-to-Point) 5,000-80,000 MHz 5.00 mW/cm2 1.00 mW/cm2 BRS (Broadband Radio) 2,600 5.00 1.00 AWS (Advanced Wireless) 2,100 5.00 1.00 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] 30-300 1.00 0.20 General Facility Requirements Base stations typically consist of two distinct parts: the electronic transceivers (also called "radios" or "channels") 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. Because of the short wavelength of the frequencies assigned by the FCC for wireless services, the � ��°-`�= HAMMETT&EDISON,INC. �xz�su�n�vc,t:tit;i:v�;x:tt5 D9FC ` s:w rk��cisc o Page 1 of 3 Seagate Technology • Point-to-Point Wireless System • Cupertino, California 20400 Stevens Creek Blvd. • 10200 South De Anza Blvd. • 10001 North De Anza Blvd. 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. 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 formed at locations very close by (the "near-field" effect) and that at greater distances 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 Seagate, it is proposed to install four Exalt Integrated ExtendAir r5000 Series square microwave panel antennas on three buildings in Cupertino. One antenna would be installed on a short pole above the roof of the tall office building located at 20400 Stevens Creek Boulevard, mounted at an effective height of about 85 feet above ground. A second antenna would be installed on a short pole mounted to the northeast side of the mechanical equipment penthouse above the roof of the four-story Seagate office building located at 10200 South De Anza Boulevard, mounted at an effective height of about 50 feet above ground. The other two antennas would be installed on short poles above the roof of the three-story office building located at 10001 De Anza Boulevard, mounted at an effective height of about 34 feet above ground. The maximum effective radiated power by any of the proposed antennas would be 0.25 watts in the 5 GHz band. Presently located above the roofs of the latter two locations are various antennas for use in other radio services. Study Results For a person anywhere at ground, the maximum RF exposure level due to the proposed Seagate operation is calculated to be 0.00012 mW/cm2, which is 0.012% of the applicable public exposure limit. It should be noted that this result includes several "worst-case" assumptions and therefore is expected to overstate actual power density levels from the proposed operation. HAMMETT&EDISON,INC. ��(R__ ��f,? —,>C,� D9FC ; �x��5ut;r��,c t:�c:�tii;.E:�z4 s:��Hauci4c��} . .•,- ' ,�. Page 2 of 3 � '. ___ l.� .��a _._ _ . . �.. . ...'��{� ..... ... 'd Y�� .-. . #. .. 7, Seagate Technology • Point-to-Point Wireless System • Cupertino, California 20400 Stevens Creek Blvd. • 10200 South De Anza Blvd. • 10001 North De Anza Blvd. No Recommended Mitigation Measures The applicable public exposure limit is calculated to be reached only within 2'/2 inches in front of the antennas. Therefore, the Seagate antennas would be considered intrinsically compliant with the FCC guidelines, and so no mitigation measures are reguired. Conclusion Based on the information and analysis above, it is the undersigned's professional opinion that the operation of the proposed point-to-point wireless system to be located on three office buildings 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, 2013. 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. Q �E� -`�C P�'�"� w y �� E-13026 �� ' � �j M-20878 William F. Ham tt, P.E. � E�.6-30-2013 707/996-5200 October 24, 2012 * � P # �',q�FCTR�G �. �'HAN�Gr,�� OF CA��. ' HAMMETT&EDI50N,INC. c�«�S�.�t:rttic t::vci�t��:r�4 D9FC ; s;�ti rR��hci�eo Page 3 of 3 FCC Radio Frequency Protection Guide The U.S. Congress required (1996 Telecom Act) the Federal Communications Commission ("FCC") 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, "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 standard, developed by the Institute of Electrical and Electronics Engineers and approved as American National Standard ANSI/IEEE C95.1-2006, "Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz," 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: Frequenc� Electroma�netic Fields (f is frequencv of emission in MHzL Applicable Electric Magnetic Equivalent Far-Field Range Field Strength Field Strength Power Density (MHz) (V/m) (A/m) (mW/cm2) 0.3— 1.34 614 614 1.63 1.63 100 100 1.34— 3.0 614 823.8/f 1.63 2.19/f 100 I80/J� 3.0— 30 1842/f 823.8/f 4.89/f 2.19/f 900/f 180/� 30— 300 61.4 27.5 0.163 0.0729 1.0 0.2 300— 1,500 3.54�f 1.59�f �f/106 �j'/238 f/300 f/1500 1,500— 100,000 137 61.4 0.364 0.163 5.0 1.0 1000 � Occupational Exposure 100 PC S � •�� 10 �� FM Cell � a°., q � 1 `� � �� " f ♦ � � 0.1 � Public Exposure �.1 1 1� 1�� 1�3 1�4 1�5 Frequency (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. HAMMETT&EDISON,INC. � coNSULTTNC Errci�Exs FCC Guidelines SAN FRANCISCO Figure 1 RFR.CALCTM Calculation Methodology Assessment by Calculation of Compliance with FCC Exposure Guidelines The U.S. Congress required(1996 Telecom Act) the Federal Communications Commission ("FCC") 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. For a panel or whip antenna, power density s = 180 x 0.1 x Pnet � in mw/cm2, eBW �xD xn �.1x16xr�xPnet and for an aperture antenna, maximum power density sm� _ � x h2 , in mw/cm2, where 6gW = half-power beamwidth of the antenna, in degrees, and Pnet = net power input to the antenna, in watts, D = distance from antenna, in meters, h = aperture height of the antenna, in meters, and r� = 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: 2.56x1.64x100xRFFZ xERP power density S = , in mW/cm2, 4x,�xD2 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. HAMMETT&EDISON,INC. � coNSULTTNC�NCirrEERS Methodology SAN FRANCISCO Figure 2