Fig. 4: FPRFS structure and FPRFS emulated patch antennas.
From: A multifunctional smart field-programmable radio frequency surface

a The planar structure of the pixelated RF surface with a programmed 1 × 2-2-1 patch antenna and the vertical structure of the FPRFS. b A mounted SMA connector on the FPRFS with inverted polarity. c The schematic of an FPRFS-based antenna with inverted coaxial feeder polarity (IP). d Reflection coefficient frequency span of all FPRFS emulated IP rectangular patch antennas. e Reflection coefficients of the FPRFS emulated and conventional 1 × 2-2-1 patch antennas. f–h The electric field cavity mode comparisons between the conventional reference patch and the FPRFS emulated patch antennas at three transverse magnetic (TM) modes.