NON RADIATIVE DIELECTRIC (NRD) GUIDE BASED TRANSITIONS

Abstract

This thesis deals with the design and development of a Non Radiative Dielectric (NRD) Guide based transitions which can be useful to develop an integral part of the components for the millimeter wave integrated circuits. NRD is a typical H-waveguide in which the distance or spacing between the two metallic plates is less than the half of the wavelength in vacuum. This was first introduced by the Yoneyama in the year of 1981. This guide offers advantages like low transmission losses, ease of fabrication, suppression of radiation at bends & discontinuities etc. In this thesis work, a NRD guide alongwith its transitions for various other transmission lines like rectangular waveguide, horns and microstrip lines has been proposed in which dielectric strip of Poly Lactic Acid (PLA) has been sandwiched between two parallel metal plates separated by a distance smaller than half a wavelength in vacuum. This dielectric guide is particularly applicable in millimeter (mm) wave integrated circuits, since it is not only small in size, but also gives various advantages as given above. Initially, a waveguide transition for the proposed NRD guide was simulated and analysed, however, it was found that normal or standard waveguide for the NRD guide will not work. Also, it was found to be very costly to fabricate custom or tailor made rectangular waveguide. Thus, other methods like rectangular waveguide with horns and microstrip lines have been used to realize a good transition with low losses. For all the various transitions of NRD guide, ANSYS HFSS software has been used for undertaking the simulation and analysis of the structures. NRD guide has been realized using Polylactic acid (PLA) material as dielectric for a band of 24 GHz frequency with centre frequency at 24.5 GHz. This NRD guide has been prepared by sandwiching PLA strip between Foam strips to provide support to the NRD guide as it is quite small in dimensions. Various results, simulated & measured, have been obtained and same has been presented in this dissertation.