Page 129 - Antennas for Base Stations in Wireless Communications

102 Chapter Three

Simulation Results After 100 generations, all criteria were achieved in
most frequency points, and thus the program was terminated. A set
of nondominant solutions was found. Two sets of parameters for the
optimum simulation results, which were obtained by the Orchard-
Elliott method with and without the GA optimization, are shown in
the following illustration. Actually, the eight-element antenna array
with parameters obtained by the GA optimization performs better. Its
simulated input return loss against frequency at port 1 to port 8 is
illustrated in Figure 3.4. It is clearly seen that all ports have satisfied
the return loss requirement (<–10 dB) over the desired operating band-
width (1.71–2.17 GHz).

Without GA With GA
optimization optimization
The height of the patches (h ) N/A 0.187l 0
p
The height of the L-probe (h lp ) N/A 0.1l 0
The length of the L-shaped probe (L ) N/A 0.063l 0
p
Element spacing (E ) 0.8l 0 0.83l 0
1
Element spacing (E ) 0.8l 0 0.77l 0
2
Element spacing (E ) 0.8l 0 0.7l 0
3
Element spacing (E ) 0.8l 0 0.85l 0
4
Element spacing (E ) 0.8l 0 0.75l 0
5
Element spacing (E ) 0.8l 0 0.8l 0
6
Element spacing (E ) 0.8l 0 0.85l 0
7
o
Phase (a ) 0 0
1
o
Phase (a ) −15° −14°
2
o
Phase (a ) −13° −13.4°
3
o
Phase (a ) −25° −22.5°
4
o
Phase (a ) −51° −46°
5
o
Phase (a ) 8° 11.2°
6
o
Phase (a ) 15° 16°
7
o
Phase (a ) 3° 6.7°
8
Amplitude (a ) 0.47 0.49
1
Amplitude (a ) −0.62 −0.63
2
Amplitude (a ) 0.7 0.71
3
Amplitude (a ) −1 −1
4
Amplitude (a ) 0.5 0.52
5
Amplitude (a ) −0.38 −0.39
6
Amplitude (a ) 0.38 0.39
7
Amplitude (a ) −0.47 −0.47
8
The radiation patterns in the elevation plane are shown in Figure 3.5.
It can be observed that the beam peak is located at 0° over the operating
frequency band. Referring to the tables shown in Figure 3.5, the sidelobe