Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Microwave measurements of the photonic bandgap in a two-dimensional
  photonic crystal slab   We have measured the photonic bandgap in the transmission of microwaves
through a two-dimensional photonic crystal slab. The structure was constructed
by cementing acrylic rods in a hexagonal closed-packed array to form
rectangular stacks. We find a bandgap centered at approximately 11 GHz, whose
depth, width and center frequency vary with the number of layers in the slab,
angle of incidence and microwave polarization.

23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org