This part of publication 617 gives symbols on telecommunication circuits (lines and circuit usage; amplified circuits), antennas and radio stations (qualifying symbols; general symbol and examples of use; specific types of antennas and part of antennas; radio stations), microwave technology (transmission paths; one- and two-port devices; multi-port devices; couplers and probes; masers and lasers), miscellaneous block symbols (qualifying symbols for the types of pulse-modulation; signal generators; changers; amplifiers; networks with several pairs of terminals; treshold devices; terminating sets and hybrid transformers; modulators, demodulators, discriminators; concentrators, multiplexers), frequency spectrum diagramss (symbol elements; examples of frequency spectrum diagrams), fibre optics (transmission line; transmission devices).