Effects of fire/heat/smoke on radio communications 1

[DougBooth]

Further to numerous anecdotal reports of radio communications "failures" at fires, I am keen to uncover any research papers or similar material which deals with this effect. The most probable cause identified to date for this effect is based on the fire's modification of the radio refractive index above the fire - leading either to severe sub-refraction or alternatively to specular reflection and consequent strong multi-path signal cancellation.

If any colleagues have details on the source of material which could shed some light on this issue, I would be most grateful. The issue is of considerable interest to fire agencies around the world, but little research appears to have been done to date.

Thanks

Doug Booth
Fax +61 3 9262 8383

 

[DougBooth]

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[DougBooth]

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[navam]

This is intrigueing. Are you saying that radiocommunications are severely affected near a fire? Does it apply to cellphones as well as radio?

Daniel

 

[jef]

I don't have any studies to share with you, but I may have an idea as to how to proceed. A couple of years ago (summer of 1998?), you may remember that the rain forest in the Yucatan caught on fire with visibility affected as far north as Dallas, TX. We were operating an LMDS trial system at the time in Dallas with no imact to our fade margin in spite of the fact that visibility was down to 1/4th mile at times. It was worse the further south you traveled toward Mexico. It seems that there would have been widespread communications outages reported if the smoke were the culprit. However, I don't remember that being reported and I followed the story very closely. But if there were outages, it seems that there would be reports to that effect. Maybe you can do an internet search on that issue. I suspect that there may be more of an atmospheric diffraction issue due to intense heat and heat gradients in or around the fire. (unscientific speculation). - Good Luck

 

[halcorn]

Usually this is called "Flame attenuation". It has been studied by the miltary very extensively. Look in that area for more information.