Journal ArticleDOI
Tailoring Antenna Focal Plane Characteristics for a Compact Free-Space Microwave Complex Dielectric Permittivity Measurement Setup
Jayaram Kizhekke Pakkathillam,Balamurugan T. Sivaprakasam,Jayaprakash Poojali,C. V. Krishnamurthy,Kavitha Arunachalam +4 more
TLDR
This article presents a compact precision free-space microwave measurement setup with a choice of three dielectric lenses to tailor the antenna focal plane characteristics for extracting complex dielectrics permittivity of small samples.Abstract:
This article presents a compact precision free-space microwave measurement setup with a choice of three dielectric lenses to tailor the antenna focal plane characteristics for extracting complex dielectric permittivity of small samples. Custom designed spot-focusing horn antenna pairs were used to achieve a compact setup with antenna separation distance, ${2}{f}_{l}$ : $4{\lambda }_{c}$ – $8{\lambda }_{c}$ and focal spot size, ${f}_{s}$ : $1{\lambda }_{c}$ – $1.5{\lambda }_{c}$ , where ${\lambda }_{c}$ is the wavelength at center frequency. Using the compact free-space setup, relative complex permittivity ( ${\varepsilon '-j\varepsilon ''}$ ) was extracted over 8–12 GHz for low- and high-loss dielectrics with lateral dimensions, $3.3{\lambda }_{c}\times 3.3{\lambda }_{c}$ and $10{\lambda }_{c}\times 10{\lambda }_{c}$ . For large materials under test (MUTs), i.e., $10{\lambda }_{c}\times 10{\lambda }_{c}$ , measurement accuracy in dielectric constant, ${\Delta \varepsilon '}$ % was $3.3{\lambda }_{c}\times 3.3{\lambda }_{c}$ ), ${\Delta \varepsilon '}$ % was ${\Delta }\text {tan}{\delta }$ ) varied over 0.002–0.016 and 0.015–0.056 for large ( $10{\lambda }_{c}\times 10{\lambda }_{c}$ ) and small MUTs ( $3.3{\lambda }_{c}\times 3.3{\lambda }_{c}$ ), respectively. For large MUTs, biconvex lens pair with the smallest ${f}_{s}$ ( $1{\lambda }_{c}$ ) and ${f}_{l}$ ( $4{\lambda }_{c}$ ) among the three lenses yielded the best accuracy in dielectric constant ( ${\varepsilon '}$ ) due to tight field focusing at the focal plane. The plano-convex lens pair yielded the best accuracy in loss tangent ( $\text {tan}{\delta =\varepsilon ''/\varepsilon '}$ ) for large MUTs due to slow variation in the phase of the local plane wave. By tailoring antenna focal plane characteristics, a compact free-space setup that is $6\times $ – $10\times $ smaller than the classical setup for handling MUTs that are 1/5th of the size used in classical setup is demonstrated without compromising the measurement accuracy.read more
Citations
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Journal ArticleDOI
Rectangular Waveguide Characterization of Biaxial Material Using TM11 Mode
TL;DR: In this paper , a novel measurement technique is presented to determine the electromagnetic parameters of a biaxial material loaded in the rectangular waveguide (RWG) for the first time, in which the TM11 waveguide mode is used as an incident file for characterization.
In Situ Measurement of Absorbing Properties of Materials Based on Near-Field Reflection Method
TL;DR: In this article , a miniaturized ultrawideband antenna, a decoupling structure, and a shielding cover are designed, and an in situ measurement probe is constructed.
Journal ArticleDOI
In Situ Measurement of Absorbing Properties of Materials Based on Near-Field Reflection Method
TL;DR: In this article , a miniaturized ultrawideband antenna, a decoupling structure, and a shielding cover are designed, and an in situ measurement probe is constructed.
Journal ArticleDOI
Rectangular Waveguide Characterization of Biaxial Material Using TM<sub>11</sub> Mode
TL;DR: In this article , a novel measurement technique is presented to determine the electromagnetic parameters of a biaxial material loaded in the rectangular waveguide, minimizing the difference between the measured and the theoretically calculated scattering parameters.
Journal ArticleDOI
Permittivity Estimation Based on Transmission Coefficient for Gaussian Beam in Free-Space Method
TL;DR: In this article , a free space method using a pair of horn antennas with dielectric lenses was proposed to estimate the permittivity of a sample with good accuracy by equalizing a measured transmission coefficient of the sample to a transmission coefficient for a Gaussian beam, which is approximately equal to the transmission coefficient multiplied by a term that changes the phase.
References
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Journal ArticleDOI
Free-space measurement of complex permittivity and complex permeability of magnetic materials at microwave frequencies
TL;DR: In this article, a free-space measurement system operating in the 8.2-40 GHz frequency range is used to measure the reflection and transmission coefficients, S/sub 11/ and S/ sub 21/, of planar samples.
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A method for solving algebraic equations using an automatic computer
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TL;DR: In this paper, a review covers approximately 15 years of development in the techniques used to measure dielectric properties of materials over the frequency range 1 MHz to 1500 GHz, including time and frequency-domain methods; reflection, transmission, and resonant methods, guided and free-space methods; discrete-frequency and broad-band methods, especially Fourier transform spectroscopy.
Journal ArticleDOI
Noniterative stable transmission/reflection method for low-loss material complex permittivity determination
TL;DR: In this article, a non-iterative transmission/reflection method for permittivity measurements using arbitrary sample lengths in wide-band frequencies was proposed, based on a simplified version of the well-known Nicolson-Ross-Weir (NRW) method.