Abstract: A low noise coaxial microwave window of particular utility in hermetic and high power applications, having a metallic center conductor, a metallic outer support, and a ceramic support brazed between the two conductors. The brazed joints are specially prepared to have a series of layers and sublayers extending from the ceramic to the metal, as follows: ceramic, cermet, cermet-nickel alloy, copper-nickel alloy, copper, braze metal, and metallic piece. The nickel content of the cermet-nickel and copper-nickel alloys is limited so that the alloys are non-magnetic. The nickel-containing alloys assist in bonding the copper layer to the cermet in a reliable, reproducible fashion, but control of the nickel content avoids microwave intermodulation effects. Where the window separates a vacuum from another medium, the surface of the support contacting the vacuum is formed from at least two noncoplanar segments to eliminate the possibility of multipacting. The same techniques are used in waveguide microwave windows.