Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
2002-06-12
2004-11-30
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C333S202000, C333S219000
Reexamination Certificate
active
06825741
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to planar filters having periodic electromagnetic bandgap (EBG) substrates.
BACKGROUND OF THE INVENTION
An EBG substrate, which is coated with metal on both sides creating a parallel plate, is either periodically loaded with metal or dielectric rods. For metallic inclusions, the substrate is loaded with metallic rods, effectively creating a high pass, two-dimensional filter that blocks energy from propagating in the substrate from DC to an upper cutoff. This form of arrangement is termed a metallo-dielectric EBG (also termed Photonic Bandgap or PBG). For dielectric inclusions, a two-dimensional band stop effect is created within the periodic material. This form of periodic substrate is termed a two-dimensional dielectric EBG.
An EBG defect resonator is made by intentionally interrupting the otherwise periodic lattice. The defect localizes energy within the lattice, and a resonance is created. A single defect resonator has been shown to provide high Qs, which make this resonator a good candidate for a sharp bandwidth, low insertion loss filter.
Using the concept of a constant coupling coefficient filter, a defect resonator is used to develop multipole filters. These filters exhibit excellent insertion loss and isolation due to the high Q exhibited by the Electromagnetic Bandgap (EBG) defect resonators. The fabrication of these filters requires nothing more than simple via apertures on a single substrate plane. In addition, the planar nature of these filters makes the filters amenable to 3-D circuit applications. Finally, since the EBG substrate prohibits substrate modes, the isolation between the input and output ports of the filter can be much greater than that of other planar architectures. Two, three, and six pole 2.7% filters were measured and simulated, with measured results showing insertion losses of −1.23, −1.55, and −3.28 dB, respectively. The out-of-band isolation was measured to be −32, −46, and −82 dB at 650 MHZ away from the center frequency (6% off center) for the three filters.
Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.
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Lee et al., “Diople and tripole metallodielectric photonic bandgap (MPBG) structures for microwave filter and antenna applications”, IEE Proc.-Optoelectron., vol. 147, NO. 6, Dec. 2000, pp. 395-400.*
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Michael J. Hill, Richard W. Ziolkowski, and John Papapolymerou,;Simulated and Measured Results from a Duroid-Based Planar MBG Caity Resonator Filter; IEEE Microwave and Guided Wave Letters, vol. 10 NO. 12, Dec. 2000.
William J. Chappell, Matthew P. Little, and P.B. Katehi, Radiation Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, MI 48109-2122; High Q Two Dimensional Defect Resonators—Measured and Simulated.
Chappell William Johnson
Katehi Linda P. B.
Little Matthew Patrick
Glenn Kimberly E
Lee Benny
The Regents of the University Michigan
Young & Basile P.C.
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