Page 235 - Antennas for Base Stations in Wireless Communications

208 Chapter Six

G L Patch G W
Foam spacer
W
S
L-shaped probe
t
Z 1
Z 1 L Finite ground plane
Vertical feeding via Z 0
(simulations only)
z
Feed line
y
Microwave substrate (e r = 2.33)
x
3D view

Patch
L-shaped probe d L
T
b
Finite ground plane H t z
a
y
Feed line Microwave substrate (e = 2.33)
r
Side view

Parameters L H W T a b v d S t G L G W
Value/mm 22 6 44 0.3 4.5 12 2 0 28.6 1.5748 100 100
(0.367l) (0.1l) (0.733l) (0.005l) (0.0075l) (0.2l) (0.033l) (0l) (0.477l) (0.026l) (1.667l) (1.667l)
29
Figure 6.1 Geometry of twin L-probe coupled patch antenna: 3D view and side view
(© 2005 IEEE)

ground plane has a side length of 100 mm (1.667l). The two L-shaped
probes have the same size vertical arm, a = 4.5 mm (0.075l), and horizon-
tal arm, b = 12 mm (0.2l). The characteristic impedance of the feed line
is Z 0 = 50 Ω and Z 1 = 100 Ω, with a line width of 4.877 mm and 1.41 mm,
respectively. A SMA launcher is connected to the end of the feed line.
In order to demonstrate the effectiveness of the twin-feed design, two
prototypes are fabricated for comparison: the single L-probe fed and the
twin L-probe fed patch antennas. With zero inserted distance (d = 0) again,
the arm lengths of this single L-probe are slightly adjusted (a = 3.5 mm and