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RF Exposure Calculator


This is a main beam power density estimation program, it is intended for use as part of an evaluation of RF field strengths for safety, it does not replace the need for real world measurements.

Average power at antenna in Watts (Ptx - Latt = Pout)  
[?] TX Output less Line Loss equals Power at Antenna...

* For 2Ways, don't forget to include losses in isolators, cavities, combiners, duplexers etc.
* Antenna gain is irrelevant in this calculation

Example...
We have 36m of LDF4-50A, at 90MHz this is 0.741 db loss,
4 Connectors at 0.05db each, and OVP with 0.15db loss
giving us a Total Transmission Line Loss (Latt) of 1.091db.
Our Transmitter has an output (Ptx) of 50w

The formula for Pout is 10^ -Latt10 * Ptx
In our example, that's 10 -1.09110 * 50 which = 38.89

So Ptx 50w - Latt 1.091db gives 38.89w Pout (at Antenna)

Antenna gain in dBi (add 2.15 for dipoles, and antennas rated in dbd)
Distance from the centre of antenna to point of interest in Metres  
[?] The center point is the physical centre of a dipole, dipole array, colinear, the overall total length of multiple combined bays (eg, in FM broadcasting).

The point of interest, is the area where people congregate and are safe from EMR. This is the uncontrolled zone, public areas with no access or time restrictions, eg: footpath, a coffee shop, care facility, next to, or under your transmitter free from effects.

Frequency of operation in MHz
Include the effects of Ground Reflections  
[?] In most cases, the ground reflection factor is needed to provide a truly worst-case estimate of the compliance distance in the main beam of the antenna.

Including ground reflection effects may yield more accurate results, especially with very low mounted antennas, non-directional antennas, and calculations below the main lobe of directional antennas

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