Linear taper slot antenna directivity improvement via substrate perforation: a FDTD evaluation

This paper examines the concept of using an array of holes in the substrate for improving the directivity of linear taper slot antennas (LTSAs) previously observed experimentally. The finite-difference time-domain (FDTD) numerical technique is used to demonstrate the utility of this concept and the results clearly show that substantial radiation performance improvement of LTSAs can be achieved. It was found that if the holes´ electrical size and spacing is a fraction of the material wavelength, the effect of the perforation is to lower the effective dielectric constant of a substrate to the volumetric average of the dielectric material and free-space. But if the holes´ electrical size and spacing become comparable to or larger than a wavelength the volumetric average model does not strictly hold.