Aspheric dielectric lens antenna for millimeter-wave imaging system

The imaging systems require low aberration and large depth of focus (DOF) to get an acceptable sharpness of the image. The lens antenna consists of a dielectric lens and an antenna array on the focus plane of the lens which has a great effect on the imaging quality of the system. In this paper, an aspheric biconvex lens with an aperture diameter of 430 mm is designed in W-band which could obtain a beam spot with a diameter of less than 30 mm. The dielectric lens with an object distance of 3.50 m is made of High Density Polyethylene which has a dielectric constant of 2.3 at 89 GHz. The designed antenna array is one-dimensional array with horn antennas. The test results indicate that the lens antenna proposed in this paper has a spatial resolution of almost 27.5 mm at the object plane and the depth of focus is 1.6 m.