This paper presents the fabrication, modeling, and testing of a metamaterial based passive wireless temperature sensor consisting of an array of closed ring resonators (CRRs) embedded in a dielectric material matrix. A mixture of 70 vol% Boron Nitride (BN) and 30 vol% Barium Titanate (BTO) is used as the dielectric matrix and copper washers are used as CRRs. Conventional powder compression is used for the sensor fabrication. The feasibility of wireless temperature sensing is demonstrated up to 200 C. The resonance frequency of the sensor decreases from 11.93 GHz at room temperature to 11.85 GHz at 200 C, providing a sensitivity of 0.462 MHz C. The repeatability of temperature sensing tests is carried out to quantify the repeatability. The highest standard deviation observed is 0.012 GHz at 200 C.
Abstract-Digital manufacturing, or 3D printing, is a rapidly emerging technology which enables novel designs that incorporate complex geometries and even multiple materials. In electromagnetics and circuits, 3D printing allows the dielectrics to take on new and profound functionality. This paper introduces negative uniaxial metamaterials (NUMs) which are birefringent structures that can be used to manipulate electromagnetic fields at a very small scale. The NUMs presented here are composed of alternating layers of two different dielectric materials. The physics of the NUMs are explained and simple analytical equations for the effective dielectric tensor are derived. Using these equations, the NUMs are optimized for strength of anisotropy and for space stretching derived from transformation optics. The analytical equations are validated through rigorous simulations and by laboratory measurements. Three NUMs where manufactured using 3D printing where each exhibited anisotropy in a different orientation for measurement purposes. All of the data from the analytical equations, simulations, and experiments are in excellent agreement confirming that the physics of the NUMs is well understood and that NUMs can be designed quickly and easily using just the analytical equations.
Abstract-In this work we report an ultra-thin all-dielectric antenna that was designed, built, tested, and compared with simulated data. The objective of this research was to develop an antenna that is easily manufactured by common 3D printers available today. 3D printing is quickly revolutionizing manufacturing and the need to incorporate electrical elements like antennas is rising. Multi-material 3D printing that can build parts with conductors and dielectrics is the future, but at present it is very immature and largely inaccessible. The antenna presented here represents our first steps in developing all-dielectric antennas that can be manufactured today with commonly available 3D printers and materials. A monolithic antenna would have additional mechanical benefits when subjected to bending or thermal cycling. With this goal in mind, an ultra-thin all-dielectric antenna was developed. The antenna operates by taking advantage of total internal reflection and exciting a leaky whispering gallery mode. The antenna reported here operates at 2.4 GHz and was able to be as thin as 1.5 mm.
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