# RF Wireless World

## Home of RF and Wireless Vendors and Resources

One Stop For Your RF and Wireless Need

## RF Exposure calculator

This page of converters and calculators section covers RF Exposure calculator. Specific Absorption Rate and incident power density calculations can be done by RF exposure calculator. SAR (Specific Absorption Rate) is used as unit of measure to determine RF exposure limit. It has unit of W/Kg , rate of energy absorption for unit mass of substance.

RMS electric field in V/m (input1) :

Biological substance conductivity in S/m (input2) :

mass density in Kg/m3 (input3) :

Specific Absorption Rate(SAR)(Output1):

Incident Power Density (Output2):

RF exposure calculator example:
Electric field(rms)= 5, conductivity= 1, mass density = 1.3E03 (1.3 x 103)
RF Exposure limit or SAR = 0.0192 W/kg, Power density = 0.066

Conductivities of scalp, CSF, skull and brain are specified as 0.3300, 1.0000, 0.0042 and 0.3300 S/m commonly.

### RF exposure calculator equation

Electromagnetic radiation exposure above certain limit can cause harmful effects to human being. This RF exposures can cause health risks in the form of health deficiency, brain deseases and cancers of various forms.

RF exposures are of two types viz. ionising and nonionising. ICNIRP have come up with RF exposure limits for general public and occupational applications.

For the assessment of the RF exposure level, it is required to measure following:
•  Electric field intensity
•  Magnetic field intensity (H)
•  Specific absorption rate (SAR)
The selection of measurement depends on the location of the observer (i.e. near field or far field region) and field impedance. Following equation or formula is used for RF exposure limit calculation. Hence this RF exposure calculator is very useful for various reasons. ### Calculating E from Transmitter power and Gain to be used in RF exposure calculator

Sometimes it is required to calculate electric field(E) to be used in the above RF exposure calculator for SAR calculation. Following calculator calculates Electric Field(E) in V/m from transmitter power(Pt) and antenna gain(Gt) at a distance r from the antenna position.

E = ( (30*Pt*Gt)0.5 / r ) V/m

Antenna Transmitter power in dBm (input1) :

Antenna Gain in dB(input2) :

Measurement Distance from Antenna (input3) :

RMS Electric field (V/m) (Output) :

EXAMPLE:
INPUTS: Antenna power = 23dBm, Antenna Gain = 12 dBi, Distance = 800 meters
OUTPUT: RMS electric field =0.012 V/m

### Useful converters and calculators

Following is the list of useful converters and calculators.

dBm to Watt converter
Stripline Impedance calculator
Microstrip line impedance
Antenna G/T
Noise temp. to NF