Folded Transmitarray Antenna for Satcom Receivers at K-Band

This paper presents the design of a folded, reconfigurable transmitarray antenna operating at K -band. The chosen unit-cell is a 2-bit structure composed of linearly polarized patches and four p-i-n diodes. The antenna achieves switchable circular polarization by employing a random sequential rotation scheme of vertically and horizontally polarized patches in transmission. To reduce the focal distance by a factor of approximately 3 compared to standard illumination, a broadband reflecting polarization converter is integrated into the system. A <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$24 \times 24$</tex> element transmitarray was designed and analyzed using an inhouse simulation tool. The antenna achieves a peak gain of 24.5 dBiC, with scan losses of less than 5 dB across a scan range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 60$</tex> degrees. Finally, the accuracy of the design methodology was validated through comparisons with full-wave simulations, based on a simplified fixed-beam folded transmitarray design.