2010 IEEE MTT-S International Microwave Symposium Technical Program

Session: WE4B	Novel Transmission Structures and Characterization
Chair:	George Eleftheriades, U. Toronto
Co-Chair:	Michael Zedler, U. Toronto
Abstract:	This session presents a class of novel transmission structures, ranging from ferroelectric-based geometry and micromachining technique to substrate integrated waveguides, and their characterization. In addition, a special characterization due to conductor profile effects is made for microstrip lines. Theoretical and experimental results are presented for validating novel concepts, and interesting phenomena are discussed with respect to various parameters of periodic, artificial, and bandwidth-enhanced structures for microwave circuit integration and applications.

WE4B-1	Compact Artificial Line Phase Shifter on Ferroelectric Thick-Film Ceramics
3:30 PM-3:50 PM	M. Sazegar¹, Y. Zheng¹, H. Maune¹, X. Zhou², C. Damm¹, R. Jakoby¹, ¹TU-Darmstadt, Darmstadt, Germany, ²Karlsruhe Institute of Technology, Karlsruhe, Germany
(1418)	An artificial transmission line based on Barium-Strontium-Titanate (BST) thick-film is used as a phase shifter in this work. The benefits of artificial transmission lines are exploited to realize a very compact phase shifter with a length of 3mm for 342° differential phase shift. The prototyped phase shifter exhibits a figure of merit (FoM) of 52°/dB in the frequency range 8-10 GHz. The proposed circuit is fabricated in only one photolithography process cycle on a low cost screen printed thick-film ceramic.

WE4B-2	Accurate Analysis of Finite Periodic Substrate Integrated Waveguide Structures and Its Applications
3:50 PM-4:10 PM	L. Han, K. Wu, X. Chen, F. He, Poly-Grames Research Center, Center for Radiofrequency Electronics Research of Quebec (CREER), Ecole Polytechnique (University of Montreal), Montreal, Canada
(1560)	In this paper, we present a systematic analysis of periodic structures based on substrate integrated waveguide (SIW) technology. In the periodic structures of interest, the unit cell is a circularly-shaped SIW section, which can be extended to any shape. In the beginning, the propagation constants of both even and odd modes of the SIW periodic structures are accurately extracted with the help of a numerical thru-line (TL) calibration technique, which utilizes two periodic structure sections having different cell numbers as calibration standards. Then, two design examples are showcased to validate the analysis results. The first example is a planar crossover structure using the circularly-shaped SIW coupling section. The other is a bandpass filter that is designed by making use of the stopband characteristics of the proposed SIW periodic structures. Good agreement is observed between simulation and measurement for both examples.

WE4B-3	Conductor Profile Effects on the Propagation Constant of Microstrip Transmission Lines
4:10 PM-4:30 PM	A. F. Horn, III¹, J. W. Reynolds¹, J. C. Rautio², ¹Rogers Corporation, Rogers, United States, ²Sonnet Software, Inc., North Syracuse, United States
(1577)	We experimentally show that the increase in conductor loss due to roughness is larger than the factor of two predicted by the most widely used roughness factor models. This is consistent with a recent numerical study of the effect of random roughness on conductor loss. The data also show that, for thin substrates, increasing the conductor profile substantially slows the effective velocity of propagation and also increases dispersion, independent of the composition of the dielectric material. Measurements are compared with results from a new conductor model as used in a 3-D planar EM analysis that includes an excess inductance related to the conductor profile. It is shown that this accounts quantitatively for both the insertion loss and phase constant effects.

WE4B-4	Bandwidth Enhancement of Substrate Integrated Waveguide Tunnels by Longitudinal Resonances
4:30 PM-4:50 PM	A. Corona-Chavez², T. Itoh¹, ¹University of California at Los Angeles, Los Angeles, United States, ²INAOE, Puebla, Mexico
(1676)	A new method to achieve wide pass-band characteristics on Substrate Integrated Waveguide (SIW) tunnel section is presented. It will be shown that due to the frequency dispersive nature of the effective permittivity in a waveguide, three in-band longitudinal resonant-modes can be excited from the waveguide-feed interaction. Such modes correspond to the Epsilon Near Zero (ENZ) mode, a half-wavelength mode, and one-wavelength mode.

WE4B-5	Micromachined High Aspect Ratio Coplanar Waveguide with High Impedance and Low Loss on Low Resistivity Silicon
4:50 PM-5:10 PM	S. T. Todd¹, J. E. Bowers¹, N. C. MacDonald², ¹University of California, Santa Barbara, Santa Barbara, United States, ²University of California, Santa Barbara, Santa Barbara, United States
(1781)	A micromachining process has been developed to create high impedance and low loss high aspect ratio coplanar waveguide (HARC) on low resistivity silicon. The process uses silicon DRIE to create an array of tall mesas that are spaced with a precise pitch. The silicon mesa array is then merged into a single solid SiO2 mesa using thermal oxidation. The solid SiO2 mesa creates a wide dielectric for use in high impedance HARC. The complete fabrication process includes DRIE, thermal oxidation, electroplating, planarization, and substrate removal to create HARC on low resistivity silicon with a planar surface. A high impedance HARC has been fabricated on silicon using this method. Measurements show that silicon substrate removal increases the line impedance from ~ 20 Ohms to 57 Ohms, reduces effective dielectric constant from ~ 6 to 2, and reduces attenuation constant from ~ 33 dB/cm to 4 dB/cm @ 30 GHz. Measurements are compared to an analytical model derived for HARC.

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