UNE-EN 60153-4:2017 Hollow metallic waveguides - Part 4: Relevant specifications for circular waveguides (Endorsed by Asociación Española de Normalización in January of 2018.)
2018UNE-EN 60153-4:2017 Hollow metallic waveguides - Part 4: Relevant specifications for circular waveguides (Endorsed by Asociación Española de Normalización in January of 2018.)