RF Safety Training--compressed

RF Safety Training

Intro Slide

RF Awareness and Safety Training

 

Objectives

 

This course is an introduction

to the safety issues associated with antennas

that you may encounter in your work place.

Steve Baier-Anderson, P.E.

[email protected]

 

Waterford Consultants, LLC

201 Loudoun Street, Suite 300

Leesburg, VA 20175

www.waterfordconsultants.com

 

Course Outline

 

  • RF Physical Characteristics
  • Biological Effects
  • Standards and Guidelines
  • Evaluating Compliance
  • RF Safety
  • Wireless Site Characteristics

 

RF Physical Characteristics

From Ampere’s Law:

An electric current gives rise to a magnetic field

From Faraday’s Law:

A changing magnetic field within a loop gives rise to an electric field which produces a current

B

B

I

I

James Maxwell (1860’s) recognized the reciprocity in these phenomena to develop the unified theory of electomagnetism: a changing electric field produces a changing magnetic field and vice-versa.

 

RF Physical Characteristics

Electromagnetic (EM) Wave

  • A wave of energy consisting of oscillating, orthogonal electric and magnetic fields propagating at the speed of light. This is a “plane wave”.
  • Constant ratio between the amplitudes of the E and H fields
  • An antenna converts an alternating current into an EM wave

E-Field

H-Field

= wavelength

 

Energy in a Photon

 

 

 

 

 

hotspot question-What's wrong with this picture?

RF Physical Characteristics

Electromagnetic Wave Field Strength

In terms of electric field: volts per meter

In terms of magnetic field: amps per meter

 

 

 

 

 

Power Density

Transmitted energy spreads (area) with distance

Power is energy flow per unit of time

 

 

 

 

 

 

 

 

 

Impedance of

Free Space (377 )

 

RF Physical Characteristics

 

Power Transfer

A receiving antenna has a physical aperture (area) through which power can be transferred from the available power density (flux over an area)

 

 

 

 

 

 

 

 

 

 

Energy Transfer

A receiving antenna transfers energy from the available power density over time (Watts Time)

 

 

 

 

 

 

 

 

A

 

RF Physical Characteristics

 

 

Solar Panel Analogy

A solar panel has a physical aperture (area=A) through which power can be transferred from the available power density