  We present the design and experimental results of a near-field scanning
microwave microscope (NSMM) working at a frequency of 1GHz. Our microscope is
unique in that the sensing probe is separated from the excitation electrode to
significantly suppress the common-mode signal. Coplanar waveguides were
patterned onto a silicon nitride cantilever interchangeable with atomic force
microscope (AFM) tips, which are robust for high speed scanning. In the contact
mode that we are currently using, the numerical analysis shows that contrast
comes from both the variation in local dielectric properties and the sample
topography. Our microscope demonstrates the ability to achieve high resolution
microwave images on buried structures, as well as nano-particles, nano-wires,
and biological samples.
