Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A spatially shifted beam approach to subwavelength focusing   Although negative-refractive-index metamaterials have successfully achieved
subwavelength focusing, image resolution is limited by the presence of losses.
In this Letter, a metal transmission screen with subwavelength spaced slots is
proposed that focuses the near-field beyond the diffraction limit and
furthermore, is easily scaled from microwave frequencies to the optical regime.
An analytical model based on the superposition of shifted beam patterns is
developed that agrees very well with full-wave simulations and is corroborated
by experimental results at microwave frequencies.

4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex