Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Development of high-power and ultra-high-vacuum waveguide coupler
  working at C/X band   Waveguide directional couplers working at 5.712/11.9924 GHz are developed.
Even holes symmetrical to the structure are drilled along the central line of
the narrow-wall of waveguide, which are used to couple the electromagnetic
power from the main-waveguide to the sub-waveguide. The final prototypes have
got satisfactory performances of high-power, ultra-high-vacuum and
high-directivity. The microwave measurement results are also qualified.

2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg