Flip-flop low profile wideband reflectarray antenna for ka-band

A novel broadband flip-flop low profile Reflectarray (RA) is designed for Ka-Band based on the principle of dual side printed substrate. First, the reflected wave phase curve is obtained by varying the patch size on top layer while energy is coupled through a bottom slot of equal size to the patch. Such a cell provides 360° degress reflected phase with almost linear behavior. Second, the element is flipped and analysis for reflected phase when square slot is varied on top layer while the complementary patch, is varied in the bottom layer. Both methods provide full 360 degrees phase range. In both methods, a small air gap is introduced below substrate to add GND plane on bottom. The proposed methods provide broadband using the thinnest available substrate. Both designs achieve good performance in term of Half Power Beam width (HPBW), Side Love Level (SLL), cross polarization and gain bandwidth (at 30 GHz). The first 15*15 RA design provides, HPBW of 6.6 degrees, SLL -20 dB, cross polarization -25 dB down than copolar component, 1dB gain bandwidth of 14.5 % and 3-dB bandwidth of 23.2 % centered. Similarly, the second flipped 15*15 RA design provides, SLL of -17 dB, cross polarization of -25 dB down than copolar component, 1-dB gain bandwidth of 11.5 % and 3-dB bandwidth of 21 %.