Determination of phase centers of ultra-wideband antennas

The importance of ultra-wideband (UWB) localization and sensing is growing from day to day, due to continuing improvements in sensitivity and resolution. In the past, the most important system parameters to be optimized concerned predominantly the electronic components. Nowadays, the antenna characteristics tend to limit further improvements. This aspect is worth a thorough inspection of antenna parameters both in the frequency and time domains, e.g., in terms of phase centers. This paper summarizes some fundamental aspects and suitable algorithms as well as measured characteristics of ultra-wideband double-ridged horn antennas, which are intended for use in biomedical radar applications. The limitations of this approach and the relevance of an accurate determination of phase centers are discussed.