Walid Dyab

Theory of Polarization-Selective Coupling and Its Application to Design of Planar Orthomode Transducers

With the rapid and continuous development of new generations of wireless technologies and networks, exploring the underutilized millimeter-wave (mm-wave) band becomes inescapable. Polarization diversity has been an essential factor in the performance and capacity enhancement of various wireless systems including cellular networks. Accordingly, the design and development of dual-polarized antenna feeding structures in the mm-wave band is a must. In this paper, a compact wideband orthomode transducer design in the Ka-band is proposed and explored. The proposed architecture and design are based on a forward mode polarization-selective coupling strategy between two unconventional waveguides. These special waveguides are a combination between two types of guiding structure, namely, nonradiative dielectric waveguide and substrate-integrated waveguide. Polarization-selective coupling can be achieved in these structures due to different mechanisms by which orthogonally oriented modes are guided. Theoretical coupling levels of 0 dB are possible in the designed structure. Analytical analysis and design steps are given in detail. This analysis facilitates a complete control on the single-mode operation for each polarization. This control, besides the structure being planar, represents the main advantages of the proposed structure. Finally, a prototype is implemented and measured where an excellent agreement is achieved with the simulation results.

Characterization of substrate integrated non radiative dielectric slab waveguide for cross-polarized mm-wave components

Hybrid Substrate Integrated Non Radiative Dielectric Slab Waveguides are proposed as a new guiding structure suitable for mm-wave components. The proposed structure is a combination of two well-known guiding structures, each of which has its wide variety of applications but in different regimes of operation. The combination of the two guiding mechanisms in one physical structure gives unique characteristics to the resulting hybrid waveguide. A systematic analytical way is presented in this paper to characterize the new waveguide in terms of its dispersion relation, modes of operation, field solution, bandwidth of single mode operation, and power handling capability. Some possible applications and design recipes are discussed.