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In-Depth Information
c
2
f
o
√
reff
L
eff
=
(4)
James and Hall modeled the resonant frequency of the rectangular microstrip
patch antenna for
TM
MN
mode [2] as
m
L
2
1
/
2
2
+
n
W
c
2
√
reff
f
o
=
(5)
where m and n are modes along the length and width of the patch antenna
respectively.
The width of the patch antenna is given by Bahl and Bhartia for effective
radiation [10] as
c
2
f
o
r
+1
2
W
=
(6)
3 Design Procedure
In this section, the design of a microstrip patch antenna is discussed. The objec-
tive is to design an antenna for ISM frequency band (2.45 GHz). The Rogers RT/
Duroid substrate 4350 (Dielectric constant=3.48 and substrate height =0.762
mm) is chosen because of its availability, low cost and low loss. A transmission
line model as discussed in previous sectionisusedtocalculatethephysicaldi-
mensions/parameters of microstrip patch antenna. These physical parameters
are:
-
Calculation of width (W):
The width of the antenna is obtained from (6) by
setting
c
=3
10
8
m/s and
f
0
=2.45GHz.HenceW=27.3mm
∗
-
Calculation of effective dielectric constant (
reff
):
Theeffectivedielectric
constant is obtained from (1) by setting
r
=3.48 , h=0.762 mm and W=27.3
mm. Hence
reff
=3.3
-
Calculation of effective length (
L
eff
):
The effective length of the antenna is
obtained from (4). Hence
L
eff
=33.6 mm
-
Calculation of length extension (L):
The length extension is obtained from
(2). Hence L =0.35 mm
-
Calculation of actual length of patch (L):
The actual length of patch is ob-
tained from (3). Hence L =32.9 mm