Abstract: The disclosure provides an apparatus and system with an antenna array. The antenna array includes a plurality of microstrip antenna elements. Each microstrip antenna element includes a dielectric substrate, a radiation patch, a metal bottom plate, a feeding probe, and a short-circuit pillar. The radiation patch is located on an upper surface of the dielectric substrate, the metal bottom plate is located on a lower surface of the dielectric substrate, the feeding probe penetrates the dielectric substrate and connects one end of the radiation patch to the metal bottom plate, and the short-circuit pillar penetrates the dielectric substrate and connects the other end of the radiation patch to the metal bottom plate. The short-circuit pillar is disposed on the radiation patch, and a first-order mode and a second-order mode are simultaneously excited.

Abstract: The HIP creation technique described herein pertains to a technique for creating a human interactive proof (HIP) by applying tearing and/or a conformal transformation to a string of characters while maintaining readability of text. In one embodiment, the technique tears a character string into two or more pieces and applies conformal transformation to warp the pieces in order to create a HIP. The transformation changes the shape and orientation of the characters but preserves angles of the characters which makes it easy for humans to recognize the characters after the transformation. Other embodiments of the technique create HIPs by applying tearing only to a string of characters, or by applying conformal transformation only to the character string.

Abstract: The HIP creation technique described herein pertains to a technique for creating a human interactive proof (HIP) by applying tearing and/or a conformal transformation to a string of characters while maintaining readability of text. In one embodiment, the technique tears a character string into two or more pieces and applies conformal transformation to warp the pieces in order to create a HIP. The transformation changes the shape and orientation of the characters but preserves angles of the characters which makes it easy for humans to recognize the characters after the transformation. Other embodiments of the technique create HIPs by applying tearing only to a string of characters, or by applying conformal transformation only to the character string.