But there is a limited amount of radio frequency spectrum available.

VOA: special.2010.03.19

Other anti-counterfeit efforts include the use of radio frequency identification tags.

VOA: special.2010.03.01

AM radio can be sent over larger distances, but the quality of the sound is not as good as a later kind of radio signal processing, called frequency modulation.

VOA: special.2010.12.08

They will be decreasing in size and frequency, but at this point they're still large enough to be of concern in hampering the rescue efforts."

VOA: standard.2010.01.13

Storm frequency,he says, comes in cycles of 30 years.

VOA: standard.2009.12.21

"If there is any truth to that, can you imagine the impact on hunger, on acute and chronic malnutrition?" Scientists say the warming of the planet will be gradual, but that extreme weather events will increase in frequency and intensity.

VOA: standard.2010.01.02