New Method for Predicting the Electromagnetic Field at a Finite Distance Using Fresnel Field Transformation

In this letter, we propose a new method to predict the field at the finite distance from a source antenna. The Fresnel fields measured using a far-field measurement system are transformed into the Fresnel or finite-distance far field, after multiplying with a weighting factor. To check the validity of this method, we compared the results with a simulated aperture antenna with uniform current distribution, as well as with an actual horn antenna. The transformed patterns agreed closely with the exact field patterns. The proposed method is very useful for predicting the electromagnetic field located out of chamber range in a far-field measurement system.