Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A novel variable-distance antenna test range and high spatial resolution
  corroboration of the inverse square law for 433.5 MHz radiation   A novel, low-budget, open-air, slant-geometry antenna test range for UHF
radiation is presented. It was designed primarily to facilitate variation of
the distance between emitter and receiver antennas, but has also the potential
for adaptation to simultaneous variation of distance and receiver antenna
orientation. In support of the validity of the range the inverse square law for
433.5 MHz radiation between two naked half-wave dipole antennas was tested with
high spatial resolution from close to the far field limit outward to 46
wavelengths. The ratio of sine-amplitude input voltages to the receiver antenna
at two distances between the antennas diminished in proportion to the
corresponding inverse distance ratio to the power 0.9970 +/- 0.0051 (R^2 =
0.992). This value is indistinguishable from the theoretical value of 1 and
confirms the proportionality of the electric field strength to the inverse
distance from the radiation source. Given the known proportionality of
irradiance to the square of the electric field strength, the result
corroborates the inverse square law for irradiance at the lowest frequency for
which thus far data have been published.

30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin