Bernard Piette is a practicing engineer. After working in submarine acoustics, HF electronics, phase-locked loops and telecommunications, he has dedicated his efforts to the design of coaxial cavities and other narrow-band resonators for the last 20 years. He has been a technical manager in several companies specializing in this field, and has designed hundreds of prototypes for numerous French private mobile radio networks such as Radiocom 2000, Rubis and Acropol.