What is the meaning of near field?

Definition of near field communication : a technology for digitally transmitting information over short distances (usually between a smartphone and another device) using radio waves.

What is near field vs far field?

The key difference between near field and far field is that near field is a region that is close to an antenna or a scattering object, whereas far-field is the region that occurs at a distance from the antenna or the scattering object.

What is considered far field?

When talking about antennas the far field is the region that is at a large distance from the antenna. In the far field the radiation pattern does not change shape as the distance increases.

What is near field distance?

From Figure 1, the near field extends for approximately 3.5 m. Stores with several entry doors often have a number of RFID antennas spaced across the entry area to give complete coverage because the field intensity falls rapidly with distance from the antenna.

How do you calculate near field?

We can estimate the new point that the near field occurs from the probe face by multiplying the portion of the beam in water by the ratio of the steel to water velocities; 20 X (1500/5900) = 5.1mm. 5.1mm is the equivalent steel distance that the beam has travelled in the water.

What is near field earthquake?

Near-field earthquakes have higher acceleration and more limited frequencies compared with higher frequencies of far-field earthquakes. The seismographs of such earthquakes, especially when they undergo progressive direction effects, contain long-pulse periods of high ranges observed at the onset of earthquake records.

At what distance from the antenna does the far field start?

At what distance from the antenna does the far field start? Explanation: The far field that is approximately 10 wavelengths from the antenna is the radio wave with the composite electric and magnetic fields. For example, at 2.4 GHz, one wavelength is 984/2400 = 0.41 feet.

How far is far field?

The far-field distance is the distance from the transmitting antenna to the beginning of the Fraunhofer region, or far field.

How do you categorize earthquakes?

Seismographic networks measure earthquakes by their magnitude, energy release and intensity. Years ago, all magnitude scales were based on the recorded waveform lengths or the length of a seismic wave from one peak to the next.

How do you calculate far field distance?

Antenna near field distance equation As we know that space around an antenna is subdivided into four regions viz. reactive near field ( up to λ), reactive radiating near field ( up to 3*λ) , radiating (fresnel) near field (up to 2*D2 /λ) and radiating far field ( >=2*D2 /λ).

What are the field conditions for an antenna?

Antennas are usually used to transfer signals at large distances which are considered to be in the far-field region. One condition that must be met when making measurements in the far field region is that the distance from the antenna must be much greater than the size of the antenna and the wavelength.