Extended low-profile planar lens antenna with multilayer metallic-hole array

This paper presents a low-profile antenna based on the use of a multilevel metallic hole array (MHA). The antenna is fed by an open rectangular waveguide placed at a short distance from the MHA. The array operates as a frequency selective surface (FSS) to enhance the directivity of the rectangular aperture within the frequency band of operation of the FSS. The small distance between layers gives the MHA a low-profile shape. In addition, the fabrication of the MHA is straightforward, what facilitates the implementation at any frequency band. A symmetric design with two circles of holes surrounding a central element is presented. The frequency band of operation of the proposed antenna is 19.7-21.2 GHz. Results show an increment of 8 dBi in the maximum directivity with respect to the isolated rectangular aperture.