ANALYSIS OF DIELECTRIC INTEGRATED GUIDE BASED STRUCTURES FOR MILLIMETER WAVE AND OPTICAL FREQUENCY

Abstract

This report investigates properties of transmission lines, which are applicable at millimeter wave and optical frequencies. In general, such wave guiding structures consist of a dielectric layer that is sandwiched between metallic plates. Two of the prominent examples include the non-radiative dielectric (NRD) guide and the slot waveguide. An NRD guide presents various attractive features, like, ease of fabrication, low transmission loss, and suppression of radiation at bends and discontinuities. Hence, it is imperative to implement integrated transition from NRD guide to standard rectangular waveguide, like, WR28. This is because such transitions will be instrumental in successful development of novel front-end components for millimeter-wave applications that are based on NRD guide technology. Additionally, in optical frequency regime, a metal-dielectric interface supports small propagation lengths and localized effect waves (surface plasmons or surface plasmon polaritons, SPP). Plasmonics is a field of photonics, wherein, the flow of light can be molded using metallic nanostructures. The concepts of plasmonics have widespread potential use in several important technological applications, like, optical microscopy, solar cells, efficient solid state light sources, etc. The current work demonstrates design of an NRD guide-to-WR28 transition, whose characteristics are studied using 'finite element method (FEM) based solver. The achieved results exhibit 1- to 2-dB insertion loss in the desired band. Moreover, design of stepped impedance resonator (SIR) based band pass filter (BPF) and band stop filter (BSF) operating at 28 GHz are undertaken. The BPF exhibits an insertion loss of around 2.5-dB, while, the BSF presents an approximate pass band return loss of 1-dB. Furthermore, a slot geometry is examined, modelling its conducting material as drude metal, so as to analyze its effect on propagation characteristics and electromagnetic (EM) fields of the slot structure. 3D EM solvers have been used to obtain field patterns of different propagating modes, their respective propagation constants and guided wavelengths. Besides it, the dispersion diagram and the field plots of the slot waveguide structure are reproduced• using finite integration technique (FIT) based solver. The achieved response closely match the results reported in open literatures.