Person:
Tentzeris,
Emmanouil M.
Tentzeris,
Emmanouil M.
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ItemEffect of Permittivity and Permeability of a Flexible Magnetic Composite Material on the Performance and Miniaturization Capability of Planar Antennas for RFID and Wearable Wireless Applications(Georgia Institute of Technology, 2009-12) Martin, Lara J. ; Ooi, Sooliam ; Staiculescu, Daniela ; Hill, Michael D. ; Wong, C. P. ; Tentzeris, Emmanouil M.This paper is an investigation of the feasibility of applying a mechanically flexible magnetic composite material to radio frequency identification (RFID) planar antennas operating in the lower ultrahigh-frequency (UHF) spectrum (∼300– 500 MHz). A key challenge is that the magnetic loss introduced by the magnetic composite must be sufficiently low for successful application at the targeted operating frequency. A flexible magnetic composite comprised of particles of Z-phase Co hexaferrite, also known as Co₂Z, in a silicone matrix was developed. To the authors’ knowledge, this is the first flexible magnetic composite demonstrated to work at these frequencies. The benchmarking structure was a quarter-wavelength microstrip patch antenna. Antennas on the developed magnetic composite and pure silicone substrates were electromagnetically modeled in Ansoft High- Frequency Sounder System full wave electromagnetic software. A prototype of the antenna on the magnetic composite was fabricated, and good agreement between the simulated and measured results was found. Comparison of the antennas on the magnetic composite versus the pure silicone substrate showed miniaturization capability of 2.4× and performance differences of increased bandwidth and reduced gain, both of which were attributed in part to the increase in the dielectric and magnetic losses. A key finding of this paper is that a small amount of permeability (μr∼2.5) can provide a substantial capability for miniaturization, while sufficiently low-magnetic loss can be introduced for successful application at the targeted operating frequency. This magnetic composite shows the capability to fulfill this balance and to be a feasible option for RFID, flexible wearable, and conformal applications in the lower UHF spectrum.
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ItemConformal Magnetic Composite RFID for Wearable RF and Bio-Monitoring Applications(Georgia Institute of Technology, 2008-12-12) Yang, Li ; Martin, Lara J. ; Staiculescu, Daniela ; Wong, C. P. ; Tentzeris, Emmanouil M.This paper introduces for the first time a novel flexible magnetic composite material for RF identification (RFID) and wearable RF antennas. First, one conformal RFID tag working at 480 MHz is designed and fabricated as a benchmarking prototype and the miniaturization concept is verified. Then, the impact of the material is thoroughly investigated using a hybrid method involving electromagnetic and statistical tools. Two separate statistical experiments are performed, one for the analysis of the impact of the relative permittivity and permeability of the proposed material and the other for the evaluation of the impact of the dielectric and magnetic loss on the antenna performance. Finally, the effect of the bending of the antenna is investigated, both on the S-parameters and on the radiation pattern. The successful implementation of the flexible magnetic composite material enables the significant miniaturization of RF passives and antennas in UHF frequency bands, especially when conformal modules that can be easily fine-tuned are required in critical biomedical and pharmaceutical applications.
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ItemLightweight, deployable, dual-frequency/polarization microstrip antenna array for remote sensing of precipitation(Georgia Institute of Technology, 2006-03-15) Papapolymerou, Ioannis John ; Tentzeris, Emmanouil M.