### 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. In this paper, the starting distance for the far field is defined for antennas operating in free space and over an imperfect ground plane. First, this paper intends to illustrate that 2D^{2} / λ formula, where D is the maximum dimension of the antenna and λ is the operating wavelength, is not universally valid, it is only valid for antennas where D >> λ. Second, this paper intends to compute a more specific constraint so instead of D >> λ we compute a threshold for D after which the 2D^{2} / λ formula applies. Third, this paper intends to properly interpret D in the formula 2D^{2} / λ when the antenna is operating over an imperfect ground plane. In this paper, we do not use 2D^{2} / λ for antennas operating over an imperfect ground instead we use a formula which depends on the transmitting and receiving antenna's heights over the air-Earth interface.

Original language | English (US) |
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Title of host publication | 2016 IEEE Conference on Antenna Measurements and Applications, CAMA 2016 |

Publisher | Institute of Electrical and Electronics Engineers Inc. |

ISBN (Electronic) | 9781467389327 |

DOIs | |

State | Published - Jan 12 2017 |

Event | 2016 IEEE Conference on Antenna Measurements and Applications, CAMA 2016 - Syracuse, United States Duration: Oct 23 2016 → Oct 27 2016 |

### Publication series

Name | 2016 IEEE Conference on Antenna Measurements and Applications, CAMA 2016 |
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### Other

Other | 2016 IEEE Conference on Antenna Measurements and Applications, CAMA 2016 |
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Country | United States |

City | Syracuse |

Period | 10/23/16 → 10/27/16 |

### Keywords

- Far Field
- Near Field
- Radial
- Transverse

### ASJC Scopus subject areas

- Instrumentation
- Radiation

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## Cite this

*2016 IEEE Conference on Antenna Measurements and Applications, CAMA 2016*[7815743] (2016 IEEE Conference on Antenna Measurements and Applications, CAMA 2016). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/CAMA.2016.7815743