A clamped dual‐ridged waveguide measurement system for the broadband, nondestructive characterization of sheet materials

Abstract

[1] A novel two-port probe which uses dual-ridged waveguides for the nondestructive, broadband characterization of sheet materials is presented. The new probe is shown to possess approximately 2 to 3 times the bandwidth of traditional coaxial and rectangular/circular waveguide probe systems while maintaining the structural robustness characteristic of rectangular/circular waveguide probe systems. The theoretical development of the probe is presented, namely, by applying Love's equivalence theorem and enforcing the continuity of transverse fields at the dual-ridged waveguide apertures, a system of coupled magnetic field integral equations is derived. The system of coupled magnetic field integral equations is solved using the method of moments to yield theoretical expressions for the reflection and transmission coefficients. The complex permittivity and permeability of the unknown material under test are then found by minimizing the root-mean-square difference between the theoretical and measured reflection and transmission coefficients. Experimental results of two magnetic absorbing materials are presented to validate the new probe. The probe's sensitivity to measured scattering parameter, sample thickness, and flange-plate thickness errors is also investigated.Citation: Hyde, M. W., IV, and M. J. Havrilla (2013), A clamped dual-ridged waveguide measurement system for the broadband, nondestructive characterization of sheet materials, Radio Sci., 48,[628][629][630][631][632][633][634][635][636][637]

Broadband, non‐destructive characterisation of PEC‐backed materials using a dual‐ridged‐waveguide probe

“…The analytical forms for these field distributions can be found in [4] and are not provided here for the sake of brevity.…”

Multi-mode analysis of dual ridged waveguide systems for material characterization

“…The dramatic benefit of using dual-ridged waveguides is a three-fold improvement in bandwidth (and hence, three-fold improvement in resolution). This effort will build upon other work related to dual-ridged waveguides, namely, single and clamped probe research performed by [19,20], which considered dominant-mode propagation only.…”

“…In addition to there robustness, rectangular and circular waveguides do not have the coupling problems previously noted for coaxial waveguides. [21] as well as clamped systems [20] showing the ability to accurately characterize simple materials with approximately 3 times the bandwidth of a traditional X-band waveguide.…”

“…Several techniques have been developed to alleviate this problem such as two thickness method [9,10,26,33], two layer method [3,14,26,34], frequency varying method [26,35], free space backed method [3,25,34], and two iris method [13]. However, these techniques have disadvantages such as instability (two layer method), physically difficult to measure (free space backed method), require prior knowledge of the MUT (two thickness and frequency varying methods), or require two waveguides (two iris method) [20]. As mentioned previously, the accommodation of higher-order modes in a dual-ridged single probe waveguide for the purpose of enhancing material property extraction is investigated as part of this research effort, and is discussed in Chapter 3.…”

“…These estimates are compared to experimental measurements taken from a clamped probe system. Experimental measurement data used was the same data obtained and used in [20]. After comparing Γ 1 and T 1 to reflection and transmission coefficients of the experimental system, an update to and µ is calculated and used to recalculate Γ 1 and T 1 .…”