Wide-band Dielectric Septum Loaded Circular Polarizers
Date Issued
2006
Date
2006
Author(s)
Yu, Yi-Chun
DOI
zh-TW
Abstract
In this article, a circular polarizer based on dielectric septum loaded waveguide structure is chosen to be implemented because of its simple structure, good accuracy tolerance and easy tuning property.
Both the perturbation theory and the 2-D full wave analysis have been used to find the waveguide propagation constant and the difference between the propagation constants of the two fundamental modes, Db. It is found that the Db curve increases with frequency rapidly after passing its minimum. To broaden the bandwidth of the polarizer, longitudinal slots were introduced in the waveguide. With these slots, the increasing trend of Db at high frequency could be reduced. The Db curve might even decrease with frequency, depended on slot depth.
In addition to the slot effect, two methods are introduced to modify the probable difference of Db within the desired frequency band, which is caused by either the simulation or fabrication error on slot dimensions. One is parallel cascading two different dielectric septa. The other is attaching two dielectric slices on both faces of septum symmetrically. In this thesis, a V-band wideband design and a Ku/Ka-band dual-band design were implemented as examples for the former and latter methods, respectively.
Subjects
極化器
圓極化
波導
polarizer
quarter wave plate
waveguide
Type
thesis
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