Loss evaluation of post-wall waveguides and its effect on antenna efficiency in millimeter-wave bands

Loss evaluation has been done on various transmission lines for the purpose of a precise antenna design in millimeter-wave bands. The transmission losses have been estimated per unit length by measuring the losses of microstrip lines and post-wall waveguides on substrates with different thickness in different wavebands. Compared the experimental losses with the simulated results, the frequency dependence of the effective conductivity and the complex permittivity obtained by a whispering gallery mode resonator method are quantitatively confirmed. The effects of the transmission loss on the antenna efficiency as well as other loss factors are discussed by measurements with different sizes of post-wall waveguide-fed parallel plate slot arrays.