Emmanouil M. Tentzeris
Georgia Institute of Technology
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Featured researches published by Emmanouil M. Tentzeris.
international microwave symposium | 2005
Anand Raghavan; Edward Gebara; Emmanouil M. Tentzeris; Joy Laskar
An active interference cancellation scheme is presented to mitigate interference between Bluetooth and wireless local area network (IEEE 802.11 b) radios operating in close proximity. This method is extensible to other mutually interfering radio devices. A reference signal correlated to the original interferer is used to generate a cancellation signal by means of amplitude and phase alignment, and filtration. The filter employed emulates the coupling channel responsible for interference. An implementation of this procedure in 0.18-/spl mu/m Si-complementary metal-oxide-semiconductor (CMOS) integrated-circuit (IC) technology is also presented. The circuits fabricated are tunable and are controlled by a closed-loop adaptive process including an error minimization method. The cancellation system designed achieves 15-30 dB of interference suppression for different cases. A total power of 14 mW is dissipated by the CMOS ICs designed.
IEEE Transactions on Microwave Theory and Techniques | 1999
Emmanouil M. Tentzeris; Robert L. Robertson; James Harvey; Linda P. B. Katehi
The stability and dispersion performance of the recently developed Battle-Lemarie multiresolution time-domain schemes is investigated for different stencil sizes. The contribution of wavelets is enhanced and analytical expressions for the maximum allowable time step are derived. It is observed that larger stencils decrease the numerical phase error, making it significantly lower than finite-difference time domain for low and medium discretizations. The addition of wavelets further improves the dispersion performance for discretizations close to the Nyquist limit, though it decreases the value of the maximum time step, guaranteeing the stability of the scheme.
IEEE Transactions on Microwave Theory and Techniques | 2002
Emmanouil M. Tentzeris; Andreas C. Cangellaris; Linda P. B. Katehi; J. Harvey
A space- and time-adaptive two-dimensional multiresolution time-domain (MRTD) algorithm based on arbitrary resolutions of Battle-Lemarie wavelets is proposed. Analytic expressions for the finite-summation coefficients are derived and details concerning the modeling of hard boundaries, excitation, and field reconstruction are extensively discussed. Through the use of a combination of absolute and relative thresholding, a dynamically changing grid is developed with minimal computational requirements in comparison to the finite-difference time-domain technique. After the validation process, MRTD is used for the first time for the numerical optimization of complex RF structures such as evanescent-mode filters.
ieee antennas and propagation society international symposium | 2002
Emmanouil M. Tentzeris; RongLin Li; Kyutae Lim; M. Maeng; E. Tsai; Gerald DeJean; Joy Laskar
Stacked-patch antennas on LTCC (low temperature cofired ceramics) multilayer structures can be easily designed for optimal bandwidth performance by an adjustment of the number of LTCC layers. This paper presents a methodology suitable for the design of compact broadband antennas. It is demonstrated that a stacked-patch antenna on an LTCC substrate with a thickness of less than 0.03/spl lambda//sub 0/ can achieve a bandwidth of up to 7%, which may find applications in a number of wireless communication systems.
IEEE Antennas and Wireless Propagation Letters | 2009
Xiaoxiang He; Sheng Hong; Huagang Xiong; Qishan Zhang; Emmanouil M. Tentzeris
A novel high-gain, dual-band antenna covering IEEE 802.11a/b/g bands is presented in this letter for wireless local area network (WLAN) applications. The antenna is composed of a fork-like monopole, a rectangular ring, and a miniaturized rectangular patch. The backside radiation of the antenna is effectively reflected back by a rectangular metal, so maximum gain with the values of 6.2 and 10.4 dBi are achieved in the lower and higher frequency band, respectively. The return loss, radiation pattern, and the critical design parameters are also investigated in detail. Simulated and measured results verify that the presented antenna is a good solution for dual-band WLAN long-distance communication applications.
IEEE Transactions on Antennas and Propagation | 1999
Emmanouil M. Tentzeris; Robert L. Robertson; James Harvey; Linda P. B. Katehi
The multiresolution time domain technique (MRTD) is applied to the modeling of open microwave circuit problems. Open boundaries are simulated by the use of a novel formulation of the perfect matching layer (PML) absorber. The PML is modeled both in split and nonsplit forms and can be brought right on the surface of the planar components. The applicability of the MRTD technique to complex geometries with high efficiency and accuracy in computing the fields at discontinuities is demonstrated through extensive comparisons to conventional finite difference time domain (FDTD). In addition, the numerical reflectivity of the PML absorber is investigated for a variety of cell sizes, some of which are very close to the Nyquist limit (/spl lambda//2).
ieee antennas and propagation society international symposium | 2002
RongLin Li; Gerald DeJean; E. Tsai; Emmanouil M. Tentzeris; Joy Laskar
The size of a conventional shorted-patch antenna can be reduced by almost a half via folding the shorted patch together with the ground plane. The resonant frequency of the folded shorted-patch antenna may be further lowered by reducing the width of the shorting walls or by moving the folded patch upward. It is shown that the antenna length of a folded shorted-patch can be reduced to less than 1/8 the length of a conventional patch antenna. A practical folded shorted-patch antenna for the Bluetooth ISM band is designed and measured to demonstrate its application potential. This size-reduced antenna can achieve an impedance bandwidth of 4% and has a nearly omnidirectional radiation pattern, which may be suitable for some mobile communications systems.
IEEE Microwave and Wireless Components Letters | 2002
RongLin Li; Emmanouil M. Tentzeris; Joy Laskar; Vincent Fusco; Robert Cahill
A rectangular loop antenna is proposed for DCS-1800 and IMT-2000 mobile phone handsets. By introducing a small gap in the wire loop, an impedance bandwidth of 24% can be achieved. The antenna mounted on a metal box is simulated using the FDTD method. It is found that the introduction of a small gap also results in a radiation pattern with desirable polarization independence and a reduced gain in the direction of the users head. The simulated and measured results are presented.
international conference on wireless communications and applied computational electromagnetics | 2005
Joy Laskar; Stephane Pinel; Chang-Ho Lee; Saikat Sarkar; Bevin G. Perumana; John Papapolymerou; Emmanouil M. Tentzeris
The recent advances of CMOS and SiGe process technologies have now made the design of low-cost highly integrated millimeter-wave radios possible in silicon. In combination with an optimum packaging approach, this represents a unique opportunity to develop Gb/s radio that could address the increasing demand in term of data rate throughput of the emerging broadband wireless communication systems. In this paper, we discuss the circuit and module challenges that enables a successful deployment of 60 GHz gigabits wireless systems.
international microwave symposium | 2001
George E. Ponchak; Emmanouil M. Tentzeris; John Papapolymerou
Three-dimensional circuits built upon multiple layers of polyimide are required for constructing Si-SiGe monolithic microwave/millimeter-wave integrated circuits on CMOS (low resistivity) Si wafers. However, the closely spaced transmission lines are susceptible to high levels of coupling, which degrades circuit performance. In this paper, Finite Difference Time Domain (FDTD) analysis and measured characteristics of novel shielding structures that significantly reduce coupling between embedded microstrip lines are presented.