  A design method of programmable transmitarray with independent controls of
transmission amplitude and phase is proposed in C-band. The unit cell with
cascaded structures mainly consists of four parts, including the receiving
antenna, reconfigurable attenuator with PIN diodes, reconfigurable phase
shifter with varactors and transmitting antenna. Correspondingly, various
manipulations of spatial electromagnetic (EM) fields are achieved by varying
the bias voltages of PIN diodes and varactors in the transmitarray. The
fabricated unit cell is measured in a standard waveguide, and the whole array
with 8*8 unit cells is measured with two horns for calibration of the
programmable EM features. The experimental results show that the transmission
magnitude can range from -16 dB to -3.6 dB and the transmission phase achieves
270-degree coverage independently under the 16-bit programmable control. To
further exhibit the capability and functionality of the proposed transmitarray,
the waveform engineering of adaptive beamforming and power-allocation
beamforming are separately realized in the experiment. The measured results
have good agreements with our theoretical calculations, verifying the validity
of our design method.

Applied Physics