  Tensor impedance transmitarrays consist of layers of tensor impedance
surfaces, separated by dielectric spacers. Because the surface impedance of
each layer is a tensor, an arbitrarily polarized incident field is scattered
into its constituent TE and TM components. This gives rise to transmitarrays
capable of altering the polarization state of an incident field. Various tensor
impedance transmitarray have been proposed in the literature to alter the
polarization, however no comprehensive methodology has been proposed to design
these structures. In this work we propose a procedure for designing tensor
impedance transmitarrays using multi-conductor transmissionline (MTL) theory.
We treat the transmitarray by modelling free-space and the dielectric spacers
as an MTL supporting TE and TM modes with each tensor impedance surface as a
shunt load along the MTL. By using simple MTL concepts we can design a
transmitarray to be reflectionless while controlling the transmission through
the layers and thus the transmitted polarization state. We demonstrate this
procedure for two classes of tensor impedance transmitarrays while also
validating the design using full-wave simulation. The first class are symmetric
transmitarrays which can alter a given incident polarization state into a
desired polarization state. The second class are asymmetric transmitarrays
which can also implement chiral polarization effects such as a linear
polarization rotation and a circular polarization selectivity.
