The hollow waveguide narrow wall slot array antennas are popular for standing wave excitation. To reduce the frequency dependence of gain and return loss with a simple structure, the hollow waveguide narrow wall slot array is designed in the traveling-wave excitation. A center fed planar antenna was designed using cross junction power dividers and Z-shaped edge shunt slot arrays. As a result of simulation, the directivity of the 10 Z-shaped edge shunt slot linear array was 16.6dBi at the design frequency 75GHz.