HIRF is an acronym for High Intensity Radiated Fields and refers to radio frequency

Radio frequency

Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...

 energy of a strength sufficient to cause adversely effect either the performance of a device subjected to it, or to a living organism. A microwave oven

Microwave oven

A microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...

 is an example of this principle put to controlled, safe use.

The U.S. Food and Drug Administration (FDA), and U.S. Federal Communications Commission

Federal Communications Commission

The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...

 (FCC) set limits for the amounts of Radio Frequency Energy exposure permitted in a standard work-day.

Radio-Frequency Energy is non-ionizing electromagnetic radiation

Radiation

In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...

, its effects on tissue are through heating.
Electronic components are Affected via rectification

Rectification

Rectification has the following technical meanings:* Rectification, in astrology* Rectification , a concept found in biology and industrial chemistry* Chinese history: see Cheng Feng...

 of the RF and a corresponding shift in the bias points of the components in the field.

History

The U.S. Federal Aviation Authority (FAA) and industry EMC leaders have periodically met to define the adequacy of protection requirements for civil avionics from outside interference since 1980. In 1986 The FAA Technical Center contracted for a definition of the electromagnetic environment for civil aviation. This study was performed by the Electromagnetic Compatibility Analysis Center (ECAC). The study has shown levels of exposure to this threat as high as 4 orders of magnitude(10000 times) higher than the then current civil aircraft EMC susceptibility test certification standards of 1 volt/meter (DO-160). This environment was also 2 orders of magnitude higher (100 times) than the then prevailing military avionics systems test standards (Mil-Std-461/462).

Units of measurement

An RF electromagnetic wave has both an electric and a magnetic component (electric field and magnetic field), and it is often convenient to express the intensity of the RF environment at a given location in terms of units specific to each component. For example, the unit "volts per meter" (V/m) is used to express the strength of the electric field (electric "field strength"), and the unit "amperes per meter" (A/m) is used to express the strength of the magnetic field (magnetic "field strength"). Another commonly used unit for characterizing the total electromagnetic field is "power density." Power density is most appropriately used when the point of measurement is far enough away from an antenna

Antenna (radio)

An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

to be located in the "far-field" zone of the antenna.