  Imaging below the diffraction limit is always a public interest because of
the restricted resolution of conventional imaging systems. To beat the limit,
evanescent harmonics decaying in space must participate in the imaging process.
Here, we introduce the method of spatial spectrum sampling, a novel far-field
superresolution imaging method for microwave and terahertz regime. Strong
dispersion and momentum conservation allow the spoof surface plasmon polaritons
(SSP) structure to become a sensitive probe for spatial harmonics. This enables
that the spatial information of the targets including both propagating and
evanescent components, can be extracted by tuning and recording SSP in the far
field. Then, the subwavelength resolution is constructed by the inversed
Fourier transform of the sampled spatial spectrum. Using the modified
subwavelength metallic grating as the spoof plasmonic structure, a far-field
resolution of 0.17 wavelength is numerically and experimentally verified, and
two-dimensional imaging ability is also fully discussed. The imaging ability
and flexibility can be further optimizing the SSP structures. We are confident
that our working mechanism will have great potentials in the superresolution
imaging applications in the microwave and terahertz frequency range
