Transactions on Antennas and Propagation

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Transactions on Antennas and Propagation
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not meet the expectation when the intervals of
H
and
V
differ and the effect of polarization angle intervene. Consider the IPD distribution of inhomogeneous radome under 40° and 80° scan angles, shown in Fig. 16 and 17, respectively, where the corresponding polarization angle distribution is also plotted. Table III shows the corresponding IPD interval. In Fig. 16, the resemblance of
M
and polarization angle distribution can be identified. In Fig. 17,
M
is totally different from polarization angle, and in fact, is similar with incident angle, which is not shown. Nevertheless, it should be emphasized that such a similarity is just a coincidence, which, if the polarization angle has a different distribution (e.g., make a 180° turn, cannot be maintained. ab) c) (d) Fig. 16 IPD of inhomogeneous radome and polarization angle distribution under 40° scan angle. (a) Parallel polarization -
H
. (b) Perpendicular polarization-
V
. (c) Co-polarization -
M
. (d) Polarization angle distribution. ab) c) (d) Fig. 17 IPD of inhomogeneous radome and polarization angle distribution under 80° scan angle. (a) Parallel polarization -
H
. (b) Perpendicular polarization-
V
. (c) Co-polarization -
M
. (d) Polarization angle distribution. TABLE III
IPD
VARIATION INTERVAL OF INHOMOGENEOUS RADOME INTERVAL UNIT
:
RAD
)
40° scan angle 80° scan angle scan angle) Interval of
H
[0.192, 0.208]
[0.186, 0.192]
[0.939, Interval of
V
[0.216, 0.267]
[0.186, 0.215]
[0.926, Interval of
M
[0.192, 0.245]
[0.186, 0.215]
[0.938, Interval length of
H
0.016 0.006 0.186 Interval length of
V
0.051 0.029 0.215 Interval length of
M
0.053 0.029 0.187 Overlap ratio
-0.11 0.21 0.87 Range ratio
0.31 0.21 0.87
jg
-0.14 0.25 1.63 Moreover, Fig. 18 plots the IPD distribution under 6° scan angle when curvature coefficient is 0.2, and Table III lists the corresponding IPD interval. The value 0.2 is arbitrarily selected from the range [0, 0.7], which yields much less BSE than 0.99, as shown in Fig. a. It can be seen that all of the IPD distribution are similar with the incident angle distribution shown in Fig. 9 (d. Therefore, the small curvature coefficient 0.2 yields smaller |BSE|
max than 0.99 due to that they do not disturb the incident angle distribution (which tends to yield smaller BSE than polarization angle distribution under this scan angle, and reduce the interval length of
M
from 0.318 rad to 0.187 rad. ab) c) Fig. 18 IPD of inhomogeneous radome with curvature coefficient 0.2 under 6° scan angle. (a) Parallel polarization -

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