The art and engineering of modern antenna near-field measurements

This paper reviews the development of the antenna near-field measurement techniques and highlights some of the key features of these methods. The introduction of the near-field technique has opened a venue for accurate, stable and highly controllable indoor antenna measurements. Many interesting variations are developed in taking the near-field data on different surfaces which has further fostered the implementation of the near-field techniques. The planar, cylindrical and spherical chambers are nowadays very well-known and widely used for different applications. The researchers have also used many novel schemes in sampling the near-field data over the desired surfaces. For instance, plane-polar, bi-polar and spiral techniques have each provided unique characteristics or benefits to the art of near-field measurements. The notable fact regarding all of these techniques is that; they need a reasonably accurate measurement of both amplitude and phase of the near-field. Recently a very appealing alternative approach is introduced. These methods rely only on the amplitude measurement of near-field and are called phaseless techniques. They are capable of extracting the near-field phase merely based on amplitude-only measurements. The difficulties of measuring phase at higher frequencies have made them a unique solution for the needs of modern near-field facilities. This paper will also cover a typical application of this method in extracting the far-field of directive antennas in UCLA bi-polar facility and performs diagnostic processing using the phaseless techniques.