Study, development and realisations of the Italian radiotelemeters (radars) in the 1930s and their lack of employment by the Italian armed forces during the Second World War. Analysis of Professor Tiberio and engineer Castellani's work together with other excellente experts and the complicated industrial context. The controversial role of Regia Marina. Appendix with photographs of the main protagonists and of the Italian radiotelemetric means invented in the period.