Biomedical Engineering Reference
In-Depth Information
Fig. 8
Geometry of three antenna arrays with different locations of the soft-surface structure,
a
Along
x
-axial,
b
Along
y
-axial,
c
Along both
x
-axial and
y
-axial(from [
10
], reprinted with
permission from IEEE)
Fig. 9
Comparison of simulated |
S
11
| and gain with different locations.
a
Simulated |
S
11
|,
b
Simulated gain (from [
10
], reprinted with permission from IEEE)
The simulated |
S
11
| and gain of the soft-surface structure at different locations are
compared in Fig.
9
. The simulated results of the conventional L-probe patch antenna
array without any soft-surface structure are also shown as a reference. If the soft-
surface structure is changed to be along the
y
-axis as in Fig.
8
b, the impedance is
mismatched seriously, and the gain is not improved as significantly as the case with
soft-surface structure along the
x
-axis as in Fig.
8
a. The reason is that the coupling
along
y
-axis between antenna elements are stronger than that along
x
-axis. For the
case with soft-surface structures along both
x
-axis and
y
-axis, as in Fig.
8
c, the
impedance matching becomes worse to result in lower gain than that for the case
with soft-surface structures only along
x
-axis. Both good impedance and radiation
performance of the antenna array can be achieved by placing the soft-surface structure
just along the
x
-axis.
Antenna Arrays With or Without the Soft-surface Structure
Figure
1
shows the 3D view and side view geometry figures of the three different
types of antenna arrays with or without the novel soft-surface structure, respectively.
Design I shown in Fig.
10
a is the L-probe patch antenna array without any soft-
surface structure. Design II shown in Fig.
10
b is the L-probe patch antenna array with
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