Coaxial cylinder antenna composed with square bracket shaped slots

We earlier developed a slot array antenna on an oversized coaxial cylinder. This antenna is a low loss antenna. When the axis of the antenna is set vertically, its radiation pattern is omnidirectional in the horizontal plane and can be controlled in the vertical plane. Because the traveling wave in the waveguide is the TEM mode, however, a vertical slot on the surface cannot be excited and horizontal polarization cannot be achieved, even though vertical polarization can be achieved easily. Using lean slots to excite vertical components, we earlier developed circularly polarized antennas and horizontally polarized antennas. In this paper, we propose a method of exciting the vertical slot by joining horizontal slots at the ends of the vertical slot.