K
L
U
X U
L
K
K
U
X U
L
K
T(f, q)
0
2.1
1.9
frequency f (c/a)
frequency f (c/a)
2.1
L
1.7
1.5
1.3
1.1
2
1.9
4
1.7
6
1.5
8
10
1.3
12
1.1
14
0.9
0.9
16
0.7
0.7
18 dB
0
30
60
90
120
angle q (degree)
150
180
(a)
0
30
60
90
120
angle q (degree)
150
180
(b)