RF Exposure

FCC ID: LDK102042

RF Exposure Info

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FCCID_151994

360 Herndon Parkway Suite 1400 Herndon, VA 20170 http://www.rheintech.com APPENDIX A: RF EXPOSURE CALCULATIONS FOR HIGH GAIN ANTENNAS From FCC 1.1310 table 1A, the maximum permissible RF exposure for an uncontrolled environment is 1mW/cm2. The Electric field generated for a 1mW/cm2 exposure (S) is calculated as follows: S = E2/Z where: S = Power density E = Electric field Z = Impedance. E = √S x Z 1mW/cm2= 10 W/m2 The impedance of free space is 337 ohms, where E and H fields are perpendicular. Thus: E = √10 x 377 = 61.4 V/m which is equivalent to 1mW/cm2 Using the relationship between Electric field E, Power in watts P, and distance in meters d, the corresponding Antenna numeric gain G and the transmitter output power and solving for d, d = √ Peak x 30 x G E Example using the Stub Omni-directional antenna 1. The Numeric gain G of antenna with a gain specified in dB is determined by: G = Log –1 (dB gain/10) G = Log –1 0.22 = 1.66 The table below identifies the distances where the 1mW/cm2 exposure limits may be exceeded during continuous transmission using the external antenna Certification Report For: Cisco System Page 71 Document Number: 2001041 Revision 4

360 Herndon Parkway Suite 1400 Herndon, VA 20170 http://www.rheintech.com TABLE 24: CISCO DIPOLE ANTENNA Antenna Gain Gain Peak output Calculated RF Exposure Minimum RF Exposure Type (dBi) Numeric EIRP Power Separation Distance (cm) Separation Distance (mW) (cm) External 2.2 1.66 177.8 4.8 20 TABLE 25: DELL DIPOLE ANTENNA Antenna Gain Gain Peak output Calculated RF Exposure Minimum RF Exposure Type (dBi) Numeric EIRP Power Separation Distance (cm) Separation Distance (mW) (cm) External -5.6 0.27 30.0 1.5 20 TABLE 26: DELL INVERTED F ANTENNA Antenna Gain Gain Peak output Calculated RF Exposure Minimum RF Exposure Type (dBi) Numeric EIRP Power Separation Distance (cm) Separation Distance (mW) (cm) External -5.6. 0.27 30.0 1.5 20 TABLE 27: TOSHIBA CHIP ANTENNA Antenna Gain Gain Peak output Calculated RF Exposure Minimum RF Exposure Type (dBi) Numeric EIRP Power Separation Distance (cm) Separation Distance (mW) (cm) External 2.1 1.6 176.8 3.7 20 TABLE 28: TOSHIBA INVERTED F ANTENNA Antenna Gain Gain Peak output Calculated RF Exposure Minimum RF Exposure Type (dBi) Numeric EIRP Power Separation Distance (cm) Separation Distance (mW) (cm) External 1.0 1.25 137.2 3.6 20 Certification Report For: Cisco System Page 72 Document Number: 2001041 Revision 4


Document Created: 2001-05-23 11:11:26
Document Modified: 2001-05-23 11:11:26
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