Combined use of genetic algorithms and gradient descent optmization methods for accurate inverse permittivity measurement

Abstract

A novel inverse transmission-line method for the complex permittivity determination of arbitrary shaped materials is presented. Complex permittivity is inferred by using an inverse calculation procedure, which is based on a combined optimization strategy of both genetic algorithms and the gradient descent method. The optimization procedure matches the measured and simulated complex scattering parameters' frequency behavior of materials within a WR340 waveguide. High accuracy and practical suitability are validated through experimental tests. The dielectric properties of PTFE and epoxy resin mixed with iron-oxide-doped fiberglass have been measured for different shapes and positions. Dielectric multilayer structures have been used to demonstrate that this technique is able to measure the individual permittivity of each element of the structure. Both twoand three-dimensional approaches have been carried out and their advantages and drawbacks discussed.

Penentuan Distribusi Permittivitas Struktur Dua Dimensi dengan Gelombang Elektromagnetika

“…Untuk struktur yang tidak homogen, yaitu yang memiliki nilai konstanta yang berubah digunakan pendekatan lain, yaitu dengan dilibatkannya metoda optimasi seperti algoritma genetik, metoda gradient descent atau pendekatan jaringan syaraf [7], [8]. Pendekatan lainnya untuk problem rekonstruksi ini adalah menggunakan persamaan integral dengan kombinasi dekomposisi nilai singular (singular value decomposition/SVD) dan teknik inverse sumber [9], [10].…”

A new sensor-based self-configurable bandstop filter for reducing the energy leakage in industrial microwave ovens

“…GA are a powerful optimization tool whose applicability to complex non-linear electromagnetic problems has been proved in previous works [30][31][32]. In particular, the optimization process when using GA is shown in figure 7.…”

Coaxial to waveguide transitions and device under test characterization by means of inverse techniques

“…An inverse technique [11] provides the estimation of an unknown parameter by comparing the experimental response of the analysed structure to the calculated simulation of the experimental scenario. In this study the two-port scattering matrices (S) of two slightly different coaxial to waveguide transitions and a device under test are simultaneously obtained using an inverse procedure.…”