Radiation hazard exclusion zones iso-surfaces
The attached script assists the user to render radiation hazard images that demonstrate the boundaries for general public (yellow) and occupation (red) exclusion zones around single or multiple simultaneously transmitting radiators. It offers step-by-step instructions and basic data validity inspection as part of a fully automated process. ICNIRP and ARPANSA radiation hazard standards / guidelines are catered for.
Menus and Options
The script has 3 possible decision areas:
1. The main menu area and possible data loading subsection.
This is the first view of the script and allows the user to select the following options:
- ICNIRP or ARPANSA as standard for rendering of radiation hazard exclusion zones. Only E-field levels are currently considered.
- Output choices, i.e. individual transmitter images, aggregate multiple simultaneous transmitter images or both.
- Data sources, i.e. already loaded data sets or selecting data via an iterative process. If the iterative loading process is selected a second menu will open up to assist the user in selecting data files to add to the current session. Data blocks have to contain near-field data blocks computed by FEKO and cannot include data sets that were previously stored in the POSTFEKO session.
2. Individual radiator exclusion zone rendering specification.
The menu system presents a list of drop-down menus, which indicate all possible sources of near-field data in the current POSTFEKO session. Each drop-down menu can be used to select the appropriate block of data to use as basis for plotting exclusion zones for that particular transmitter.
3. Multiple radiators aggregate exclusion zone rendering specification.
The menu system presents a list of drop-down menus, which indicate all possible sources of near-field data in the current POSTFEKO session. Each drop-down menu can be used to select the appropriate blocks of data to include while compiling the aggregated effective exclusion zones for those simultaneous transmitters.
FEKO computes E-field values in V/m peak magnitude, while both ICNIRP and ARPANSA provide reference level tables in V/m RMS. In order to render exclusion zones with iso-surfaces at the magnitude level as specified by the respective reference level tables, the E-fields computed by FEKO are all scaled by a factor of 0.7071 before being used for plotting or aggregation events.
When field contributions for different radiators are added together to form equivalent exclusion zones for simultaneous transmitters, the following aggregation process is followed:
- Each contribution (block of field data) is simplified to its magnitude for all points in the computed block, i.e. discarding phase information. This represents a "worst case" field level at any particular point.
- The magnitude of field contributions are then scaled by the inverse of the appropriate reference level to convert the data block to represent the fraction of the reference level that is contributed by each point.
- All data blocks (stated as fractions of contribution) are then added together to form a new data block representing the fraction of contribution for all transmitters radiating simultaneously.
- Blocks such as those mentioned here are maintained separately for public and occupational exclusion zone representations. When rendering these blocks a level of "1" is thus the exclusion zone boundary for maximum exposure.
Reference levels are obtainable from documents published by ICNIRP and ARPANSA respectively. The following tables were implemented in the current version of the wizard.
Reference levels for time averaged exposure to RMS electric and magnetic fields (perturbed fields)
Download Archive Contents
The download archive contain three files:
- radhaz_isosurfaces_wizard.lua - The primary script of the wizard. Run this script from the script editor or install it as an application macro in POSTFEKO for regular use.
- radhaz_tools.lua - A helper script that contains several sub-functions that are regularly used by the primary script.
- radhaz_tower_ICNIRP_lobes.png - An image that is displayed in the primary display window to demonstrate possible output results.