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Construction of Bolometers Patent
New design promises higher accuracy at frequencies up to 70 GHZ, while at the same time making the sensors easier to build
TEGAM, Inc., a leading supplier of innovative RF power measurements, was recently awarded Patent No. 8,610,069, “Coaxial to Dual Co-Planar Waveguide Launcher for Microwave Bolometry,” This patent describes a new way to construct bolometers—a type of microwave power sensor that uses thermistors—that makes them more accurate and easier to assembly.
Specifically, the patent describes a sensor with a dual-coplanar sensor architecture that launches a microwave signal from coaxial airline to a unique arrangement of coplanar waveguides, arranged symmetrically on both sides of a thin dielectric substrate. The characteristic impedance of the top and bottom coplanar waveguides is approximately twice the characteristic impedance of the coaxial airline, so the parallel combination of the two coplanar waveguides is the characteristic impedance of the coaxial airline. Further, steps in both the ground planes and center conductor at the point of transition from coaxial to coplanar are used to tune the launch and minimize reflection.
According to Andy Brush, TEGAM CEO, “This development gives TEGAM the tools to move the proven two-thermistor coaxial sensor into today’s manufacturing technology and higher frequencies. Without this technology, the TEGAM 2510A would not be possible.”