How do you calculate far field?
How do you calculate far field?
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).
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.
What are the far field conditions for an antenna?
Abstract: The far field of an antenna is generally considered to be the region where the outgoing wavefront is planar and the antenna radiation pattern has a polar variation and is independent of the distance from the antenna.
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.
What is a field region?
It’s a region immediately surrounding the antenna where the reactive field predominates. The electric and magnetic fields are not necessarily in phase to each other and the angular field distribution is highly dependent upon the distance and direction from the antenna.
Where does the far field start?
It is widely stated in the antenna literature that the far field of an antenna operating in free space, where all the aforementioned properties must hold, starts from a distance of 2D 2 /Λ, where D is the maximum dimension of the antenna and Λ is the operating wavelength.
What are the advantages of far field antenna measurements?
For certain applications, far-field antenna measurements are the preferred technique for determining the amplitude and/or phase characteristics of an AUT. Low gain antennas operating below 1 GHz, and where partial radiation characteristics are required, are candidates for far-field measurements.
What is the Fraunhofer distance?
The Fraunhofer distance, named after Joseph von Fraunhofer, is the value of: where D is the largest dimension of the radiator (in the case of a magnetic loop antenna, the diameter) and. is the wavelength of the radio wave. This distance provides the limit between the near and far field.
How is antenna range calculated?
To calculate the range of an antenna, you multiply the square root of the antenna’s height above water (in feet) by 1.42. The product will equal the antenna’s communication range in miles.
What is a reactive field?
The reactive near field is the region where the fields are reactive i.e the E and H fields are out of phase by 90 degrees to each other. For propagating or radiating fields, the fields must be orthogonal to each other but in phase.