Compact, High-Efficiency Circularly Polarized Reconfigurable Transmitarray Antenna Based on Electromagnetic Modulator

An extremely compact circularly polarized folded reconfigurable transmitarray antenna (CPFRTA) without any traditional phase shifter is proposed, based on polarization-regulating and phase-regulating metasurface (MS) technologies. The CPFRTA consists of a feed antenna, a reconfigurable transmitarray (RTA), and a polarized rotating reflector (PRR). Through triple reflection, linear polarization (LP) wave receiving, the y - polarized waves emitted by the feed get converted into CP waves. By integrating two PIN diodes, the RTA become a programmable phase shifter with 1-bit resolution. Finally, the original LP spherical wave is changed into a high - gain CP beam, which can deflect autonomously. This strategy innovatively reduces the antenna profile to 0.15D (where D is the diameter of CPFRTA). Moreover, by optimizing the phase distribution of the RTA, a breakthrough peak efficiency of 25.3% is achieved. To confirm the design methodology, a prototype was manufactured and measured. Measured results closely align with simulations, demonstrating that the CPFRTA achieves a peak gain of 18.1 dBi at 12 GHz with a maximum beam scanning angle of ±60°.