A Surface Waveguide Supporting Transverse Magnetic Mode and Suppressing Transverse Electric Mode and Its Application in Rotman Lens

This paper addresses the problem of surface wave confinement and the suppression of undesired transverse electric (TE) mode propagation inside the grounded dielectric slab when excited by the transverse magnetic (TM) slot launcher. As a solution, we propose a surface waveguide (SWG) design based on self‐complementary Bowtie metasurfaces. Leveraging the concepts of TE soft and TM hard bandwidth operations, the SWG effectively confines TM surface waves while suppressing unwanted TE modes. We present an analytical model capable of calculating the Bowtie metasurface's reflection coefficient for oblique‐incidence excitation. Additionally, a simple yet efficient electromotive force (EMF) algorithm is introduced for analysing the reflection phase for oblique‐incidence excitation across a range of wavenumbers and frequencies. We use the proposed EMF model to calculate the TE soft and TM hard bandwidth operations of the Bowtie metasurface. We present a uniplanar, compact and wideband slot launcher to excite directed and well‐trapped TM mode inside the SWG. We fabricated a novel Rotman lens based on the Bowtie SWG and slot launcher to further support our methodology. The SWG lens exhibits a 56° scanning range, similar to that of its microstrip lens counterpart while offering the potential for reconfigurability and suitability in millimetre‐wave applications.