Gain Improvement of Planar Antenna Arrays Employing a Tubular Metallic Framing

This study focuses on planar antenna arrays in which each radiating element is surrounded by a metallic tubular structure. Circular polarization is achieved through the use of open-ended square waveguides functioning as radiating elements. The proposed metallic framing technique results in enhanced gain and significant suppression of backlobe radiation. Two design options for the metallic framing are considered: in the first case, the tubes are not interconnected, while in the second, they are connected at the angle of 45°. Arrays comprising $3 \times 3,4 \times 4$, and $5 \times 5$ elements are analyzed. The relationship between the gain and the tube diameter is explored, and optimal tube dimensions that maximize gain are identified.