Near-field scanning microwave microscope using a dielectric resonator

Abstract

We describe a near-field scanning microwave microscope which uses a high-quality dielectric resonator with a tunable screw. The operating frequency isf= 4.5 GHz. The probe tip is mounted in a cylindrical resonant cavity coupled to a dielectric resonator. By tuning the tunable screw coming through the top cover, we could improve sensitivity, signal-to-noise ratio, and spatial resolution to better than 1.5 Jim. To demonstrate the ability of local microwave characterization, the surface resistance of metallic thin films has been mapped.

Nondestructive characterization of various thin films using a near-field scanning millimeter-wave microscope

“…It follows from this relation [13,18] that the resonant frequency change Do depends on the interaction between the tip and the sample. As the sample-tip distance decreased, the coupled dipole interaction between the sample and the tip increases and generates a large fractional change in the resonance frequency.…”

“…As the distance between probe tip and sample decreased, the reflection coefficient S 11 shifted from 21.918 dB at d ¼ 30 mm to 18 dB at d ¼ 1 mm and the resonance frequency changed from f ¼ 39:312 GHz to f ¼ 39:317 GHz: The sensitivity of NSMM images depended on the sample-tip distance and the structure of the probe tip. In the simple coupled dipole model [13,18], the sample and the probe tips are modeled as combinations of spheres with polarizabilities a s and a t in a driving electric field E. The modulation of polarizability due to dipole-dipole interaction is described by…”

“…The spatial resolution is determined by the probe tip size and sensitivity of the NSMM, which depends on the Qfactor of the resonator. Thus, in order to improve the spatial resolution, both the quality factor of the resonator and the sensitivity of the probe should be maximized [2][3][4][5][6]13]. In this millimeterwave microscope, a sharpened probe tip rather than a waveguide slit is used as a point-like evanescent field emitter because the spatial resolution can be determined by the size of the probe tip and the slit-type resonator probe has a lower quality factor than that of the standard waveguide resonator [10,11].…”

“…Recently, many groups have demonstrated a high spatial resolution and sensitive imaging technique using a near-field scanning microscope for the micro-and millimeter-wave range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. For the millimeter-wave range, many groups have demonstrated an imaging technique using a nearfield millimeter-wave scanning microscope (NSMM) using a slit probe which showed a spatial resolution of about 30-100 mm [1][2][3][4][5][6][7][8][9][10][11][12].…”

Traceable measurement and imaging of the complex permittivity of a multiphase mineral specimen at micron scales using a microwave microscope

“…A jewel hole can be used to make the attachment more secure. , strip-line [22] and dielectric resonators [23]. The instrument described ( Fig.…”