Ultra-compact 90° twist based on a pair of two closely placed flat chiral irises

Abstract

A new ultra-compact device for rotating the polarization plane of planar electromagnetic wave in a square waveguide by 90° whose dimension is almost ten times less than wavelength is suggested. It is based on strong interaction of near-fields in two closely placed flat chiral irises. It is shown that this approach due to strong multi-mode and near-field interaction allows rotating the polarization plane by 90° in the several percent bandwidth with the loss level not worse than 0.1 dB.