  Various techniques are available in order to obtain information on samples of
a different nature in near-field scanning microwave microscopy (NSMM), with
transmission-line resonator (TLR) techniques considered as the most advanced in
terms of sensitivity and resolution. In this paper, we focus on development of
a TLR-based NSMM supplied by a new source of useful signal: coplanar waveguide
ground potentials imbalance. Electromagnetic modeling of the device and
experimental scanning of two planar structures are conducted to examine the
performance of the proposed technique. Both modeling and experimental results
demonstrate the ability to distinguish symmetric inhomogeneity positions with
respect to the central conductor of the coplanar waveguide by the phase of
imbalance signal. The thin-film structure scanning procedure displays the
possibility of proposed approach to resolve low-contrast structures with
accuracy up to 98.7 %.
