Electronics 2018, 7, 383 5 of 23
in Figure 2b are assumed to be available. Associated quantities are marked with superscript “o”.
E
o
(
x, y
)
is the field on the aperture
Σ
of the reference array (RA) and
F
o
(
r, θ, ∅
)
represents the far-field
radiation. For the differential antenna (DA) shown in Figure 2c, the tangential distribution
E
(
x, y
)
on
the aperture Σ is equal to the difference between the field distributions of the reference array and the
antenna under test, and the corresponding far-field
F
(
r, θ, φ
)
is expressed as the difference between the
fields of reference array (RA) and AUT as
E
(
x, y
)
= E
u
(
x, y
)
−E
o
(
x, y
)
, (2)
F
(
r, θ, φ
)
= F
u
(
r, θ, φ
)
−F
o
(
r, θ, φ
)
. (3)
Electronics 2018, 7, x FOR PEER REVIEW 5 of 24
on the aperture Σ of the reference array (RA) and
(,,∅) represents the far-field radiation. For
the differential antenna (DA) shown in Figure 2c, the tangential distribution (,) on the aperture
Σ is equal to the difference between the field distributions of the reference array and the antenna
under test, and the corresponding far-field (,,) is expressed as the difference between the
fields of reference array (RA) and AUT as
Figure 2. Antenna array: (a) reference antenna without failures; (b) antenna under test (AUT); (c)
differential antenna (DA). The number of failures is 2 within the total element number N = 21.
Figure 2.
Antenna array: (
a
) reference antenna without failures; (
b
) antenna under test (AUT);
(c) differential antenna (DA). The number of failures is 2 within the total element number N = 21.