We report an imaging technique for various samples using a near‐field scanning millimeter‐wave microscope (NSMM) by using a standard tunable rectangular waveguide at operation frequencyf= 60GHz. By monitoring the change ofQ‐factor in the near field zone as the probe scanned over the object, we obtain quantitative images of the sample. By proper tuning process and using proper probe‐tips, we could improve sensitivity and a spatial resolution to better than 500 nm for the patterned YBa2Cu3Oythin films on MgO substrates. © 2003 American Institute of Physics