This presentation addresses the problem of indoor localization of objects or persons using a ultrawideband (UWB) radio-based system. These systems use two types of antennas: at least three sensor antennas with known locations and a target antenna whose location is unknown and needs to be determined. In this work emphasis is given to the target antennas and the influence that an object or a human body has on the antenna. The challenges posed by general dielectric objects are different than challenges posed by human body as will be explained. This motivates the study of different antennas depending on the object they will be attached to in order to achieve good precision in ranging and localization.