Three Degrees of Freedom Cells and a Perforated Dielectric for Wideband Reflectarray Fabrication

A self-covered, single-layer, inexpensive wideband reflectarray antenna is proposed using a class of Triangular Bowtie (TB) elements printed on interior side of a periodically perforated dielectric. Such an element has three degrees of freedom (air hole, angle, and length). Drilling periodic air holes within thick FR4 dielectric, the loss of unit cell is decreased. By changing the values of length, and angle of TB patch, two different phase diagrams are obtained that the sum of their ranges is more than 700°. With the help of such a unit cell, a center-fed reflectarray is designed and simulated. To validate the simulated results, a $270 \times 270 \times 3.9 \mathrm{~mm}^{3}$ array with focal length 26.1 cm is implemented and exactly tested. The achieved results by measuring reveal a bandwidth of 42.6% $(9.7 \sim 14.9 \mathrm{GHz})$ for $1-\mathrm{dB}$ gain, and peak gain value 29.1 dB with maximum efficiency 58% at central frequency 12 GHz.