Browse Definitions:
Definition

volt per meter (V/m)

The standard unit of electric field (E-field) strength is the volt per meter (V/m). An E field of 1 V/m is represented by a potential difference of 1 V existing between two points that are 1 m apart. Reduced to base SI units, 1 V/m is the equivalent of one meter kilogram per second cubed per ampere (m ? kg ? s -3 ? A -1 ).

The volt per meter, or some fractional unit based on it, is used as a means of specifying the intensity of the electromagnetic field (EM field) produced by a radio transmitter. Although an EM field contains a magnetic (M) component as well as an electric (E) component, the relative field strength of radio signals is easier to measure in free space by sampling only the E component. The magnitude of the E component from a distant radio transmitter is often much less than 1 V/m, and in such cases, fractional units are preferred. One millivolt per meter (mV/m) is equal to 10 -3 V/m; one microvolt per meter (? V/m) is equal to 10 -6 V/m; one nanovolt per meter (nV/m) is equal to 10 -9 V/m; one picovolt per meter (pV/m) is equal to 10 -12 V/m.

The magnitude of the E component of a radio wave varies inversely with the distance from the transmitter in a free-space, line-of-sight link. If the distance is doubled, the E-field intensity is cut in half; if the distance increases by a factor of 10, the E-field intensity becomes 1/10 (0.1 times) as great. The E component of an EM field is measured in a single dimension, so the intensity-versus-distance relation is a straight inverse rule, not the inverse-square law.

When expressing the intensity of EM fields at infrared ( IR ), visible, ultraviolet (UV), X-ray, and gamma-ray wavelength s, the watt per meter squared, or one of the fractional units based on it, is more commonly used.

Also see electromagnetic field .

This was last updated in March 2011

Join the conversation

1 comment

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

I hate to say this but i am old school. I remember when things were simpler. When any RF transmitter that emitted RF it was rated in watts. If you had an amateur radio station you knew how many watts you were transmitting.

So if you had a portable RF watt meter with an antenna then the closer you got to the transmitter the more watts the meter would read. And vice versa.

So if a cell tower was transmitting 40 watts of RF and you were at a distance of about 100 meters it would read a very low wattage. Simple not complex math.
You could still get a ratio of the RF output to the RF watts as you went further away. And we know that Rf at high frequency should be at a safe level of about 5 milliwats (that is what it used to be). Simple you get an RF watt meter and test the equivalent watts at a distance and determine what is a safe distance. All this other science and math is great for the actual engineers who have to build this stuff.
Cancel

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

  • audit program (audit plan)

    An audit program, also called an audit plan, is an action plan that documents what procedures an auditor will follow to validate ...

SearchSecurity

  • computer worm

    A computer worm is a type of malicious software program whose primary function is to infect other computers while remaining ...

  • black hat

    Black hat refers to a hacker who breaks into a computer system or network with malicious intent.

  • copyright

    Copyright is a legal term describing ownership of control of the rights to the use and distribution of certain works of creative ...

SearchHealthIT

SearchDisasterRecovery

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

SearchStorage

SearchSolidStateStorage

  • RRAM or ReRAM (resistive RAM)

    RRAM or ReRAM (resistive random access memory) is a form of nonvolatile storage that operates by changing the resistance of a ...

  • JEDEC

    JEDEC is a global industry group that develops open standards for microelectronics.

  • M.2 SSD

    An M.2 SSD is a solid-state drive (SSD) that conforms to a computer industry specification written for internally mounted storage...

SearchCloudStorage

  • Google Cloud Storage

    Google Cloud Storage is an enterprise public cloud storage platform that can house large unstructured data sets.

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

Close