  In this paper, the authors propose a two-dimensional, wide dynamic range,
linear displacement sensor using microwave methods. The microwave sensor
circuit employs a cylindrical dielectric resonator proximity coupled to a pair
of orthogonal microstrip lines formed on a microwave substrate. The DR rests on
the substrate and is free to be displaced between the strips on the 2D plane of
the substrate. The strips excite the particular resonant mode of the DR, the
intensity of which varies with the DRs proximity to the strips. The DRs
position can thus be read out in terms of the 2 port S parameters of the
circuit, at a fixed frequency determined by the resonant mode of DR. Such fixed
frequency sensors are robust in operation and cost effective in realization, an
important aspect of this sensor. Initial one-dimensional positioning
simulations of the sensor through three fixed representative paths on the
substrate reveal that the S parameters vary monotonically with the
displacement. Prototype measurements reveal a dynamic range of 23 mm for
horizontal or vertical displacement, and 30 mm for diagonal displacement at the
resonant frequency of 3.67 GHz. Next, 2D positioning test is conducted and a
technique for one to one mapping from the S parameters to the 2D position is
demonstrated. To conclude, the proposed sensors performance is compared with
that of existing 2D sensors.
