Experimental Characterization of a Circularly Polarized 1 Bit Unit Cell for Beam Steerable Transmitarrays at Ka-Band

We propose here an experimental characterization procedure applied to a 1 bit reconfigurable transmitarray unit cell working in circular polarization (CP) at Ka-band. The transmission phase of the unit cell is controlled on the receiving side by switching two p-i-n diodes integrated on the radiating element. The CP is generated on the transmitting side with a truncated corner patch antenna. A specific waveguide characterization setup and related procedure have been developed to extract the unit cell S-matrix. The proposed setup includes nonstandard waveguide sections, ad hoc transitions, and an orthomode transducer. The experimental results demonstrate a good agreement with full-wave simulations with a discrepancy of less than 0.1 dB on the measured minimum insertion loss of 1.65 dB at 29 GHz. A 3 dB bandwidth larger than 12% has been measured.