This paper discusses a new approach to the joining of Ku-band waveguides made of high-strength crack-sensitive aluminum alloys, Al6061 and Al6063. Using a pulsed Nd:YAG laser system in combination with a pulsed wire feed drive, rectangular waveguide segments are welded. The results clearly show the potential to employ welding as a substitute to conventional brazing and soldering processes: the electrical and mechanical performances are close to the ones of a milled waveguide. Furthermore, the presented welding process is completely automated.