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The first technique developed was the far-field range, where the antenna under test (AUT) is placed in the far-field of a range antenna. Due to the size required to create a far-field range for large antennas, near-field techniques were developed, which allow the measurement of the field on a distance close to the antenna (typically 3 to 10 ...
4nec2 - A free NEC2/NEC4 implementation for Microsoft Windows. It is a tool for designing 2D and 3D antennas and modeling their near-field/far-field radiation patterns. Numerical Electromagnetics Code NEC2 unofficial home page - NEC2 documentation and code examples; MMANA-GAL basic - A free antenna modeling program based on MININEC. Opens .MAA ...
The near field refers to places nearby the antenna conductors, or inside any polarizable media surrounding it, where the generation and emission of electromagnetic waves can be interfered with while the field lines remain electrically attached to the antenna, hence absorption of radiation in the near field by adjacent conducting objects detectably affects the loading on the signal generator ...
Windows Linux 3D GUI Convergence detector Mesher Algorithm Area of application NEC: open source Yes Yes Yes In some distributions Yes manual MoM: Antenna modeling, especially in Amateur Radio. Widely used as the basis for many GUI-based programs on many platforms. Version 2 is open source, but Versions 3 and 4 are commercially licensed ...
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, allowing for 22.5 degrees of phase deviation over the face of the radiator.
In antenna engineering, sidelobes are the lobes (local maxima) of the far field radiation pattern of an antenna or other radiation source, that are not the main lobe.. The radiation pattern of most antennas shows a pattern of "lobes" at various angles, directions where the radiated signal strength reaches a maximum, separated by "nulls", angles at which the radiated signal strength falls to zero.
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The far-field pattern of an antenna may be determined experimentally at an antenna range, or alternatively, the near-field pattern may be found using a near-field scanner, and the radiation pattern deduced from it by computation. [1] The far-field radiation pattern can also be calculated from the antenna shape by computer programs such as NEC.