Page 228 - Antennas for Base Stations in Wireless Communications

Antenna Issues and Technologies for Enhancing System Capacity 201

0
Equiphase
−5 Operative method
Normalized directivity [dB] −15
−10

−20

−25
−30

−35
−40
−90 −60 −30 0 30 60 90
Sky Angle [degree] Ground
(a) q t of 5°

0
Equiphase
−5 Operative method
Normalized directivity [dB] −15
−10

−20

−25
−30
−35

−40
−90 −60 −30 0 30 60 90
Sky Angle [degree] Ground
of 8° (Electrical phase control is 3°)
(b) q t
Figure 5.28 Vertical radiation patterns

to change the main beam direction. The phase difference between the
elements varies. Therefore, the radiation pattern has grating lobes, in
particular, for large remote tilting angles. However, using the operative
method for the shaped radiation pattern still keeps a cosecant beam, as
shown in Figure 5.28b.