NIST examining how radio waves interact with buildings

NIST examining how radio waves interact with buildings

Engineers from the National Institute of Standards and Technology are studying ways to help improve radio communications for first responders inside buildings.

A research team from the NIST laboratories in Boulder, Colo., spent a week in the Washington area last month, radio mapping large buildings and planting transmitters in the old Washington Convention Center before its implosion.

The two-year program, funded by the Justice and Homeland Security departments, has found that radio waves behave in unpredictable ways inside buildings, both intact and demolished.

'It appears that designers are underestimating the amount of attenuation they are getting in these buildings,' said Chris Holloway, a researcher from the Boulder labs. 'Typically, the lower frequencies propagate into the large buildings better, and firefighters are moving to higher frequency systems.'

The study could help in developing new building standards to give firefighters and other responders more reliable radio communications during emergencies.

The program originally was intended to map signal propagation within standing buildings and in rubble from demolition sites, Holloway said. 'Then I woke up one night and thought, 'They implode buildings all the time. Why not put transmitters in a building when it implodes and get a more real-world situation?' '

He found that only a handful of companies do building implosions in this country. The same companies also are often called upon in response to disasters such as earthquakes and bombings, so they were open to the NIST research.

'They were very willing to work with us,' Holloway said.

The Washington Convention Center was the third implosion NIST has wired for sound. A 13-story housing complex in New Orleans was the first, one year ago, and Veterans Memorial Stadium in Philadelphia was next in March. The team plants about 25 battery-powered transmitters in the building, tuned to frequencies near the emergency responder and cellular phone bands.

Mixing radio transmitters and explosives apparently is not a dangerous practice.

'There used to be some issues with radio waves, but with new technology there is not a problem now,' Holloway said.

The team also has mapped standing buildings in Phoenix; Boulder and Colorado Springs, Colo.; and Silver Spring, Md. It found that similar looking buildings often behave differently in terms of radio reception. Radio waves also take unexpected paths through the rubble of demolished buildings, making it difficult to locate persons trapped inside even if radio or cell phone signals can be picked up.

The team expects to release the first of its reports next month and continue research in both standing buildings and demolitions through the year.

'There is a lot more work that needs to be done,' Holloway said.

About the Author

William Jackson is a Maryland-based freelance writer.

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