Abstract: Since the term "jet" was first used to describe a feature observed in the galaxy M87 in 1954, technological advances have revealed the existence of jets in a number of astrophysical systems where material is accreted onto central objects. Nevertheless, a unified explanation for their formation and collimation remains elusive. In this regard, protostellar jets are particularly advantageous due to their proximity, allowing us to probe close to their launching platforms, deeply embedded in the parent cloud. Despite decades of research, fundamental aspects of their characterisation, such as the collimation distance, the material velocity, and the magnetic fields, remain poorly understood. In this talk, I will focus on the characterisation of protostellar jets at radio frequencies, addressing these topics from an observational perspective using cutting-edge interferometers such as the JVLA and eMERLIN.