Copper Conductivity at Millimeter-Wave Frequencies

The conductivity of copper at 40 and 110 GHz has recently been reported as part of the Bell Laboratories WT-4 waveguide field evaluation trial (FET).1 In this experiment, 14 kilometers of 60-mm waveguide was installed and measured. The interior of the steel waveguide was copper-plated and then lined with a thin polyethylene liner. The dielectric liner was used to modify the mode patterns in the waveguide.2 The results of the FET indicated a copper conductivity at 42 GHz that was much higher than that usually experienced at millimeter-wave frequencies. This high conductivity was achieved for waveguide fabricated in a manufacturing environment. A laboratory experiment was devised to isolate the process steps and the mechanism responsible for the high conductivity copper achieved. The results of this experiment are reported here. 43 Table I --Results summary Experimenter Thorpe Tischer Hatano and Nihei Anderson et al Hinderks and Maione Frequency (GHz) 38 35 40 42 43 Percent IACS Remarks High purity copper Etched in acid Etched and annealed Single crystal high purity annealed and etched 5 1 - m m w a v e g u i d e TENI, TE02, TEM, TE().I 60-mm waveguide TE 0 I ; Bell Labs F E T