With a view to increasing the gain of the slot antenna, an extended hemisph
erical lens coupled slot antenna is fabricated. The receiving characteristi
cs for millimeter waves at 94 GHz are theoretically and experimentally stud
ied. It is found that the power gain of the extended hemispherical lens cou
pled slot antenna strongly depends on the radius R, extension length L, die
lectric constant epsilon (r) and absorption coefficient alpha of the lens.
The power gain of the extended hemispherical lens coupled double slot anten
na is increased by 27 dB over the double slot antenna on a dielectric subst
rate without a lens due to the focusing effect of the lens so that the gain
at 94 GHz is 31.5 dBi. (C) 2001 Scripta Technica.