Antenna Far Field Distances

Antenna specifications can seem confusing or, worse yet, can be misinterpreted. Of all the salient antenna specifications, antenna gain appears to present the biggest problem. Some understand the antenna gain provided in datasheets to be valid in the so-called far field region. However, EMC radiated immunity tests do not force using antenna far field operation in many instances. What is the far field region, what does the term far field imply, where is the far field boundary, why is there a debate over the definition of the far field boundary, and how can one apply this far field information to their situation, are all topics that remain unclear to some.