Scanning near-field microwave microscope using a rectangular waveguide probe with different resonant modes of cavity

In this paper, a rectangular waveguide probe is designed as a near-field scanning probe in a microwave microscope. With the use of a rectangular cavity and properly tuning the three-screw tuner to change the resonant mode of the cavity, the structural characteristic of the sample under test can be observed through the cavity perturbation phenomenon. The reflection coefficient acquired from the scanning probe is dependent on the physical parameters of the sample under test. Several samples of various structures are measured to illustrate the operation of the scanning near-field microwave microscope.