Radiofrequency (RF maxima) Propagation and Calculated Exposure Probability within Enclosures using GEV Theory | Chapter 12 | Novel Perspectives of Engineering Research Vol. 6

 The behaviour of radiofrequency waves propagating in open space differs from those propagating in enclosed spaces. If propagating rf waves have wavelengths that are half wavelength multiples of the openings of these orifices, confined or enclosed areas such as buildings where people live and work can operate as waveguides. Waves having a frequency higher than the cut-off frequency can propagate and create hot spots within under these conditions.

The measurement of maxima electric field intensities at 54 grid locations within an empty rectangular metallic cuboid of particular dimensions provided empirical support for the theory of rf wave guide propagation inside massive structures. These rf maxima intensities were recorded at varied angles of approach, AOA, of the incoming rf waves to the entrance of the confined space for varying frequencies representing modes TE10 to TE33. The Generalized Extreme Value (GEV) model was found to best represent these measured rf electric field intensities, with the statistics of extremes providing the best fit for the distribution.

The number of hot spots (maximum of maxima intensities) was identified, and a Poisson distribution model was used to quantify the likelihood of a human within the region being exposed to one or more of these hot spots.

Author(S) Details

Ricardo J. Rodriguez
University of the Southern Caribbean, Trinidad, West Indies.

Winston G. Lewis
University of the West Indies, Trinidad, West Indies.

View Book:- https://stm.bookpi.org/NPER-V6/article/view/5506

A Theoretical Model for RF Propagation within Rectangular Enclosures Using Waveguide Concepts | Chapter 5 | New Approaches in Engineering Research Vol. 16

 In order to completely appreciate the nature of the danger, properly identifying and managing hazards at work can be a lengthy effort that extends into the domain of uncertainty, probability, and prediction models. As a result, corporations cannot be held liable for knowledge gaps in the training of individuals they hire to guarantee a safe and healthy working environment, particularly where hidden hazards exist.

Authorities tasked with establishing RF (radiofrequency) and microwave exposure standards are particularly concerned with electromagnetic wave propagation at frequencies in the SAR (specific absorption rate) area. Despite the lack of solid proof that non-ionizing electromagnetic radiation causes adverse health consequences other than thermal impacts, every effort should be made to ensure that workers and the general public are sufficiently safeguarded against unwanted radiation exposure. Standards, on the other hand, define exposure limits for free space, plane wave propagation, but they fall short of accumulating data on wave intensities following reflection and diffraction off wall surfaces.

This review looks at a theoretical model for possible energy build-up owing to RF propagation in restricted areas with bigger dimensions and a waveguide design. Silos, tanks, pipes, air-conditioning ducts, tunnels, and operator cabins on board boats are examples of confined spaces. Rf waves reflect off the walls in these confined spaces and mix constructively or destructively with incident waves, resulting in reinforcement or cancellation, respectively. When there is reinforcement, the wave's intensity for a given distance may exceed the exposure limit for that distance from the source, exposing the worker to higher intensities than the recognised limit and posing a health and safety risk. Waveguide theory and physics concepts have been offered as the building blocks for the model construction in this approach.

Author(S) Details

Ricardo Rodriguez
Department of Mechanical and Manufacturing Engineering, The University of the West Indies, St. Augustine Campus, Trinidad and Tobago

Winston G. Lewis
Department of Mechanical and Manufacturing Engineering, The University of the West Indies, St. Augustine Campus, Trinidad and Tobago

View Book:- https://stm.bookpi.org/NAER-V16/article/view/4058