Near and Far Field

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The near and far field regions are generally used terms in antenna measurements. The near field and far field of an antenna or other isolated source of electromagnetic radiation are regions around the source where different parts of the field are relatively more or less important. The boundary between the two regions is only vaguely defined, and depends on the dominant wavelength ( ) emitted by the source. Roughly speaking, the near field is the region within a radius r ll lambda, while the far field is the region for which r gg lambda. The two regions are defined simply for mathematical convenience, enabling certain simplifying approximations. These regions are sometimes also called the near zone and far zone. The latter is also frequently referred to as the radiation zone, or free space.

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High Quality Content by WIKIPEDIA articles! The near and far field regions are generally used terms in antenna measurements. The near field and far field of an antenna or other isolated source of electromagnetic radiation are regions around the source where different parts of the field are relatively more or less important. The boundary between the two regions is only vaguely defined, and depends on the dominant wavelength ( ) emitted by the source. Roughly speaking, the near field is the region within a radius r ll lambda, while the far field is the region for which r gg lambda. The two regions are defined simply for mathematical convenience, enabling certain simplifying approximations. These regions are sometimes also called the near zone and far zone. The latter is also frequently referred to as the radiation zone, or free space.