Efficient numerical analysis of periodic structures using the theory of characteristic modes

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2022-12

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Yiğit, Haykır

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The characteristic mode analysis has become a popular and versatile tool in antenna design and analysis. This analysis provides useful information about radiation characteristics of scatterers and offers physical insight into the radiation problem. Hence it can also be exploited in the solution of periodic structures. In this work, an integral based simulation program has been developed to perform the modal analysis of periodic structures. This dissertation consists of three interrelated parts. In the first part, the characteristic mode analysis is extended to the periodic unit cell solution. This analysis yields distinct perspective to the analysis of the reflectarray problem. In the second part, the resonance behavior of the mode of interest is modified by applying continuous load distribution over the unit cell element. However since such loading is hard to realize, an approach has been developed to reduce the load distribution on the ring-type unit cell element into two discrete loads. Subsequently, a novel method is introduced that allows to find the reactive load values in advance that shift the reflection band of the ring-type frequency selective surface element to desired frequency. Thus, the need for optimization-based methods that increase the solution cost has been eliminated. In the last part, the finite array solution is evaluated in which characteristic modes are used as macro basis functions. Afterwards, a multilevel matrix reduction method is presented for the array of differently sized elements using characteristic modes. This thesis work leads efficient and original analysis of large periodic structures using the theory of characteristic modes.

Subject Keywords

Characteristic mode analysis, Periodic unit cell, Reactive loading, Macro basis functions

URI

https://hdl.handle.net/11511/101277

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

H. Yiğit, “Efficient numerical analysis of periodic structures using the theory of characteristic modes,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.