A 1-bit, Electronically Reconfigurable Transmitarray Element With 3:1 Bandwidth and High-Power-Handling Capability

A 1-bit, electronically reconfigurable transmitarray element is designed, fabricated, and experimentally characterized for ultrawideband, high-power phased-array applications. The proposed device comprises a polarization-rotating structure with a pair of diamond-shaped dipoles sandwiched between two orthogonal custom double-ridge waveguides (DRWGs). Isolated by a thin and highly thermally conductive aluminum nitride (AlN) substrate, two p-i-n-diode-switched cross dipoles are used to provide electronic 0
$^\circ$
/180
$^\circ$
phase shift. To achieve a high average power handling capability, heat dissipation from the p-i-n diode junction is facilitated using proper thermal design and by employing forced-air cooling. Simulations show that the array element offers an insertion loss below 1 dB across the 4.1–12-GHz range, with a phase difference of
$177^\circ \pm 3^\circ$
between two states. The fabricated prototype was tested both at low-and high-power levels, demonstrating that the continuous-wave (CW) power handling capability of the device exceeds 35.5 W over the 6–12-GHz frequency range, and its peak power handling capacity exceeds 1000 W per unit cell (corresponding to a peak power level of 2.85 MW/m
$^2$
) at the
$X$
-band for a pulse duration of 1
$\mu$
s and a pulse repetition frequency of 1000 Hz.