Wireless functions such as Internet of Things (IoT) devices continue to increase and fill the environment with electromagnetic (EM) waves. Antennas are needed in support of those growing wireless functions, and it can be helpful to know about the characteristics of different antennas, for example, how to find the phase center of an antenna. When performing a far-field approximation of an antenna far from the antenna itself, assuming that the phase center of the antenna occurs at the physical center may be adequate at a far enough distance from the antenna. But closer to the antenna, actual knowledge of the phase center and how to find it can be helpful for some applications.

The phase calculation method involves careful linear measurements to find the phase center of each antenna. Linear measurements were made across several axes of each antenna, with good agreement found between the measurements and simulations conducted to predict where the phase center of the antenna should be in each case. Although there were some concerns for using the measurement approach to find the phase center of highly directive antennas, the calculations are relatively simple and can be applied in situ to estimation the physical phase center of many different mechanical antenna types.

When the model for calculating the phase centers of the antennas was applied to a number of different types of antennas, the results were consistent with measured results and consistent is estimating the different antenna characteristics. The positions of the phase centers for each structure went through little variation in the overall results with consistency that implies the accuracy of the measurement and estimation method. The method is designed to be simple and straightforward and to be applied in real time while working on a particular antenna design.

See “Calculating the Phase Center of an Antenna,” *IEEE Antennas & Propagation Magazine*, Vol. 59, No. 5, October 2017, p. 130.