Page 244 - Antennas for Base Stations in Wireless Communications

New Unidirectional Antennas for Various Wireless Base Stations 217

70 70
60 60
50 50
Input Resistance (O) 30 30 Input Resistance (O)
40
40

20
20
10

0 10
0
−10 −10
−20 −20
0.5 1 1.5 2 2.5 3 3.5
Frequency (GHz)
50
Figure 6.10 Simulated input impedance of the designed DFPA
(© 2007 IEEE)

10
8
6 4 The antenna gain attains a
Antenna Gain (dBi) 2 0 stable value of 8.5 dBi

Measured Gain
−2
−4 Simulated Gain
−6 -
−8
1 1.5 2 2.5 3 3.5
Frequency (GHz)
Figure 6.11 Simulated and measured antenna gains of the devised
50
DFPA (© 2007 IEEE)

It is well understood that for the vast majority of broadband patch
antennas, radiation performance is inevitably degenerated, especially in
the E-plane, at higher operating frequencies. By making use of the differ-
ential plate feeding scheme, the instability issue is evidently ameliorated.
Simulated and measured radiation patterns of the proposed antenna
in both E-plane (x-z plane, f = 0°) and H-plane (y-z plane, f = 90°) at
1.37 GHz, 2.17 GHz, and 2.97 GHz are illustrated in Figure 6.12, showing