Fabrication of a double-layer corporate-feed waveguide slot array by powder metal laser process

The double-layer corporate-feed hollow waveguide slot array antenna with 12×16 elements is fabricated by the powder metal laser process in the 60 GHz band. The symmetrical feed circuit for 12×16 elements is designed by introducing cross junctions and asymmetrical T-junction. We design that the bandwidth for VSWR less than 1.2 is 9.63% and the maximum deviation from 58 GHz to 65 GHz is 1.34 dB in amplitude and 11.6 degrees in phase among all the output ports. The powder metal laser process can fabricate antennas with isolated etching patterns and multilayer structures regularly. The measured directivity of the copper antenna is comparable to the designed one by reflecting good near-field distribution within 5 dB amplitude and 60-degree phase variation. The estimated overall conductor loss is about 2 dB in the copper antenna in the measurement. A rectangular cavity resonator in a waveguide is introduced to evaluate the effective conductivity of aluminum by the powder metal laser process.