P21

RF Exposure Safety

Radio waves can be dangerous

Electromagnetic Radiation (EMR) is all around us. We use it to cook our food in a microwave oven, to communicate on our mobile phone, open our garage doors, and for entertainment. High levels of EMR can be dangerous. With careful management we can control the risks associated with EMR. The Foundation Qualification power limit of ten Watts is considered to be safe and with some simple controls, manageable.

The transmitting antenna is the source of EMR. The higher the power, and the higher the frequency, the greater the hazard.

Antennas that direct their power into a narrow beam of energy (eg. a Yagi Antenna), even at low power, can be dangerous in close proximity. This beam of EMR is measured in Watts of Effective Radiated Power (W ERP) and can be several times more that the power being fed to the antenna. If you plan to use such an antenna you should seek advice from those who are suitably qualified or experienced. Things to know and consider with EMR

Do not touch a transmitting antenna. Above 5 watts, antennas can cause what is known as “RF Burns” which are caused by EMR current penetration and can be severe.

EMR Risk falls rapidly with distance. This is why transmitting antennas are mounted high and out of reach and range of humans and animals.

Exposure time is another factor. If you spend a lot of time using a hand held transceiver, you may consider using an external microphone

The Foundation Level Study Guide

All Blue Tiles form part of the syllabus for the Foundation Level Recognition Certificate (operator licence).  A primary source of information for many of the blue tile topics can be found within the Foundation Level Study Guide.  This is a free download available at:

https://vkradioamateurs.org/flsg/  This is a digital book and contains many links to other resources and explanatory videos.

Information on RF exposure Safety can be found from Page 80 in this book

ACMA Syllabus Extract

According to the ACMA Foundation Syllabus, the required knowledge on this topic is:

9:16 Radio waves can be dangerous

Recall that electromagnetic radiation (EMR) can be dangerous and higher frequencies and power levels and proximity to the source increase the danger.

9.17 Safe Distances

Recall that a safe distance from an antenna depends on the ERP, operating frequency, antenna type and orientation.