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This communication presents an experimental validation of a backscattering-protected bifilar edge line (BEL) constructed entirely by metallic materials. This waveguide relies on the principle of parity (P) time-reversal (T) duality (D) symmetry. In the ideal case, parity time-reversal duality (PTD)-symmetric structures have been theoretically demonstrated to be robust against backscattering for a certain class of discontinuities, namely, those still respecting the PTD symmetry. The waveguide analyzed here is constituted by a parallel plate waveguide (PPW) in which each of the two walls comprises two parts: a perfect electric conductor (PEC) and a perfect magnetic conductor (PMC) joint by an edge. On the two opposite walls, the faced boundary conditions (BCs) exhibit a dual nature. The PMC is emulated by metallic short pillars (square cross-sectional pins). Two distinct pillar geometries are investigated for implementing the PMC. In the first case, the pillars of the top and bottom walls are aligned with each other along the propagation direction, whereas, in the second case, the pillars on the top-right wall are strategically shifted to control the dispersion of the mode supported by the structure. Numerical and experimental results are shown, demonstrating the ability to confine the electromagnetic (EM) field in the proximity of the BEL over a large bandwidth, while maintaining the backscattering protection in the 22–26.5-GHz band.

Anisotropic self-complementary metasurfaces (SCMs) are structures constituted by a “self-dual” (according to Babinet’s duality principle) alternance of inductive and capacitive complementary strips. They support orthogonally polarized surface-wave modes with the same phase velocity in the principal direction of propagation. The isofrequency dispersion curves of these modes are hyperbolas, and therefore, these metasurfaces (MTSs) fall in the category of hyperbolic MTSs. It is shown here that the hyperbolas may degenerate in some cases into almost straight lines, which implies that the velocity of energy transport is constantly directed along the complementary strips at any frequency and for any possible phasing orthogonal to the strips. In this circumstance, the SCM can be conveniently used to design dual-polarized leaky-wave antennas by modulating the impedances of the complementary strips. Each strip behaves as a channel, which can be independently fed with the desired phase and amplitude. We demonstrate here that these antennas exhibit a strong decoupling between both co-polar and cross-polar channels, even when the distance between strips is electrically small. This increases the performance of the antenna, especially in azimuthal beam scanning. A prototype at 2.6 GHz has been constructed and successfully measured confirming the theoretical conjectures.