1. International Journal of ElectronicsJOURNAL OF ELECTRONICS AND
INTERNATIONAL and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)
ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 5, Issue 1, January (2014), pp. 43-51
© IAEME: www.iaeme.com/ijecet.asp
Journal Impact Factor (2013): 5.8896 (Calculated by GISI)
www.jifactor.com
IJECET
©IAEME
A COMPACT PROXIMITY–FED QUAD BAND–NOTCHED ULTRA–
WIDEBAND PATCH ANTENNA
Ayad Shohdy W. Ghattas1 and Elsayed Esam M. Khaled2
1
2
Electrical Engineering Department, Sohag University, Sohag, Egypt
Electrical Engineering Department, Assiut University, Assiut, Egypt
ABSTRACT
A compact proximity feed printed ultra-wide band (UWB) patch antenna with four notched
bands characteristics is proposed and investigated in this article. The proposed antenna introduces
UWB performance in the frequency range of 3.1 GHz to 11.7 GHz with almost omnidirectional
radiation pattern. Narrow rectangular slits and T–shaped slots are etching in the ground plane to
provide four notched bands at frequencies of 3.5, 3.9, 5.25 and 5.9 GHz to avoid the interference
with the existing wireless networks which occupy bands at these frequencies. The antenna is
designed, simulated and fabricated. The measured data of the fabricated antenna demonstrate good
agreement with the simulated results.
Keywords: Four Notched Bands, Microstrip Patch Antenna, Proximity Feed, UWB Antenna.
1. INTRODUCTION
The ultra–wide band (UWB) antennas have gained high interest in the recent years since
2002 when the unlicensed use of the commercial UWB communications devices is permitted [1–3].
However communications with these antennas need to avoid interference with the existing standard
wireless networks such as WiMAX (3.3–3.6 GHz), C band satellite communication (3.7–4.2 GHz),
lower WLAN (5.15–5.35 GHz), higher WLAN (5.725–5.825 GHz) and LMI C band (5.725–
6.025GHz). To avoid such interference, frequency band-notches are preferably applied directly to the
UWB antennas instead of implementation of additional band stop filters. Most of researches in the
literature are focused to design UWB antennas with a single [4–5], dual [6–7] or triple [8–10]
frequency band–notches. In this paper, a compact planar patch antenna with UWB frequency range
of 3.1 to 11.7 GHz with four rejected band–notches corresponding to the previously mentioned
applications is presented. The proposed antenna in this work is adopted with a proximity-fed line
technique. The desired four notched bands are achieved by etching different shaped slots in the
ground plane of the antenna.
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2. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
The analysis and design of the proposed antenna are carried out using the commercial
software CST microwave studio (MWS) simulator. Also the antenna is fabricated and its
performance parameters are measured using HP8719 vector network analyzer. The simulated results
and the measured data are presented.
2. ANTENNA DESIGN (PARAMETRIC STUDIES)
The antenna is etched on FR4 substrate of a relative permittivity εr = 4.5, loss tangent tan δ =
0.01, a thickness h = 1.5 mm. The total dimension of the substrate and the ground plane is lg × wg =
20 × 20 mm2. The Geometry of the proposed UWB antenna is shown in Fig. 1. The antenna is fed by
a proximity 50 microstrip line of dimensions lf × wf = 12 × 2 mm2 printed on one surface of the
substrate. To achieve UWB range a modified shape looks like a cedar tree is etched in the ground
plane on the other side of the substrate as shown in the figure.
To provide a band–notch in the antenna performance a slot or slots can be etched in the
ground plane with total length corresponding to a half guided wavelength at the notched frequency.
The length of a slot can be considered approximately by [11–12]:
co
l slot ≈
4 f notch
εr +1
(1)
2
where lslot is the length of the slot, fnotch is the centre frequency of the notched band, εr is the
relative permittivity of the antenna substrate, and co is the velocity of light. Firstly to achieve the
proposed band notch at frequency (5.15–5.35 GHz) a two symmetric T–shaped slots of dimensions lt
= 6 mm, wt = 2.5 mm, t = 0.7 mm, g = 0.9 mm and ts = 0.8 mm with total length equal to 2 × lslot
where lslot as it is shown in fig. 1, lslot = t / 2 + lt + ts + wt / 2 = 8.4 mm which approximately
corresponds to notched frequency 5.25 GHz according to equation (1) are etched in the lower part of
the ground plane. Secondly to provide a notched band at 5.725–6.025 GHz, two other symmetric
narrow rectangular slits of dimensions ls1 × ws1 = 7.4 × 0.25 mm2 with total length equal to 2 × lslot
where lslot = 7.65 mm which approximately corresponds to a notched frequency at 5.9 GHz are
etched in the ground plane at both sides of the modified cedar tree–shaped slot. Also to achieve
another band notch at frequency band of 3.7–4.2 GHz, two other symmetric narrow rectangular slits
of dimensions ls2 × ws2 = 11.4 × 0.25 mm2 with total length equal to 2 × lslot where lslot = 11.65 mm
which approximately corresponds to a notched frequency at 3.9 GHz are etched in the ground plane
and at distance d = 0.5 mm from the 5.9 GHz slots. Lastly to provide the fourth–proposed notched
band of 3.3–3.6 GHz, two narrow rectangular symmetric slits of dimensions ls3 × ws3 = 13 × 0.25
mm2 with total length equal to 2 × lslot where lslot = 13.25 mm which approximately corresponds to
the notched frequency of 3.5 GHz are etched in the ground plane at a distance c = 0.25 mm from the
3.9 GHz slots. Dimensions of each part of the antenna are illustrated in detail in Table 1. The antenna
is fabricated and photographs of the top and bottom views of the antenna are shown in Fig. 2.
44

3. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
(a)
(b)
Figure 1: The Geometry of the proposed UWB antenna, (a) bottom–view of the antenna, (b) top–
view of the antenna
Table 1: Dimensions of the elements of the proposed UWB antenna
Dim.
lg
wg
lf
wf
Value (mm)
Dim.
Value (mm)
20
ts
0.8
20
g
0.9
12
t
0.7
2
a
1
ls1
ls2
7.4 11.4
b
c
1.75 0.25
(a)
ls3
ws1
ws2
ws3
lt
wt
13
d
0.5
0.25 0.25 0.25 6 2.5
e
Substrate’s height (h)
3.5
1.5
(b)
Figure 2: Photographs of the fabricated proposed antenna, (a) top–view, (b) bottom–view.
3. IMPLEMENTATION AND RESULTS
The proposed antenna is designed and simulated using the CST MWS simulator software.
Also the antenna is fabricated and tested using the vector network analyzer HP8719. Fig. 3 illustrates
the simulated results and measured data of the S11 parameter as a function of frequency for the
proposed quad band–notched UWB antenna. The simulation results show a bandwidth from 3.1 GHz
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4. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
to 11.7 GHz (8.6 GHz Bandwidth) whereas the measured bandwidth of the antenna is from 2.7 GHz
to 10.3 GHz (7.6 GHz Bandwidth).
Ultimately, the prototype antenna without any slots and with only the modified cedar tree–
shaped slot covers the entire UWB band of 4 – 13 GHz. Fig. 4(a) – (d) shows the gradual processes
for etching the cedar tree–shaped slot in the ground plane which are carried out with the help of the
CST MWS simulator to get the UWB range for the proposed antenna. Fig. 4(e) present the S11 as a
function of frequency for the designs shown in fig. 4(a) – (d) passes through these processes. From
the figure it is observed that, fig. 4(d) shows acceptable UWB range.
0
S11 (dB)
-10
-20
-30
-40
Simulated CST MWS
Measured
-50
1
3
5
7
9
11
13
Frequency (GHz)
Figure 3: Simulated and measured S11 parameter versus frequency of the proposed quad bandnotched UWB antenna
-5
(a)
(b)
S 1 1 (dB )
-15
-25
Fig. 4(a)
Fig. 4(b)
Fig. 4(c)
Fig. 4(d)
-35
-45
-55
1
3
5
7
9
11
13
Frequency (GHz)
(c)
(d)
(e)
Figure 4: (a) – (d) Gradual processes for the modified cedar tree to get UWB range, (e) Simulated
S11 versus frequency of the designs in figures 4(a) – (d)
46

5. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
To achieve a notched band at frequency 5.25 GHz two T–shaped slots are etched in the
ground plane and each is at a distance e from the substrate’s edge. Fig. 5 shows the effect of etching
the T–shaped slots with different values of e on the S11 parameter. The figure illustrates that the
optimum value is e = 3.5 mm to provide a band notch at frequency 5.25 GHz. To achieve another
band notch at frequency 5.9 GHz two narrow rectangular slits of dimensions ls1 × ws1 = 7.4 × 0.25
mm2 are etched in the ground plane at a distance b = 1.75 mm from the right and left edge of the
substrate. Fig. 6 illustrates the effect of etching these slits on the S11 of the proposed antenna with
different values of the distance b. The two slits with a distance b = 1.75 mm provide a band notch at
frequency 5.9 GHz.
Third–notched–band at frequency 3.9 GHz is obtained by etching another two narrow
rectangular slits of dimensions ls2 × ws2 = 11.4 × 0.25 mm2 and separated with a distance d from the
previous slits in the ground plane as shown in fig. 1. Fig. 7 shows the effect of changing the distance
d on the S11 of the proposed antenna. It is clear that the best value is d = 0.5 mm. Furthermore by
etching two other narrow rectangular slits of dimensions ls3 × ws3 = 13 × 0.25 mm2 and at a distance
c from the previous slits a fourth–band notched at frequency 3.5 GHz can be achieved. Fig. 8 shows
the effect of varying the distance c of the two rectangular slits on the center frequency and the band
of the fourth–band notched. The figure demonstrates that the optimum value is c = 0.25 mm.
0
e =3.0 mm
e =3.5 mm
e =4.0 mm
S 11 (dB)
-10
-20
-30
-40
1
3
5
7
9
Frequency (GHz)
11
13
Figure 5: Simulated S11 versus frequency for different values of e of T–shaped slots
0
b = 1.50 mm
b =1.75 mm
b = 2.00 mm
S11 (dB)
-10
-20
-30
-40
1
3
5
7
9
Frequency (GHz)
11
13
Figure 6: Simulated S11 versus frequency for different values of b of narrow slits of dimensions ls1 ×
ws1 = 7.4 × 0.25 mm2
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6. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
0
d = 0.35 mm
d =0.50 mm
d = 0.65 mm
S11 (dB)
-10
-20
-30
-40
1
3
5
7
9
11
13
Frequency (GHz)
Figure 7: Simulated S11 versus frequency for different values of d of narrow slits of dimensions ls2
× ws2 = 11.4 × 0.25 mm2
0
c = 0.10 mm
c = 0.25 mm
c = 0.40 mm
S11 (dB)
-10
-20
-30
-40
-50
1
3
5
7
9
11
13
Frequency (GHz)
Figure 8: Simulated S11 versus frequency for different values of c of narrow slits of dimensions ls3 ×
ws3 = 13 × 0.25 mm2
For more clarification to the antenna design, the simulated surface current distributions of the
proposed quad band–notched UWB antenna at frequencies of 3.5, 3.9, 5.25, and 5.9 GHz are shown
in Fig. 9. It can be seen that the currents mainly concentrate over the corresponding T– and
rectangular–shaped slots at frequencies 3.5, 3.9, 5.25 and 5.9 GHz which means that a large portion
of electromagnetic energy has been stored around the etched slots. This response causes the antenna
to be nonresponsive at the corresponding notch frequencies.
Fig. 10 shows the normalized far-field radiation patterns of Eφ and Eθ in the yz– (E–plane)
and xz– (H–plane) planes of the proposed antenna at frequencies 4.5 GHz, 7 GHz and 9.5 GHz. The
results demonstrate that the radiation patterns exhibit a nearly omnidirectional radiations in the xz–
plane at these frequencies, whereas, in yz–plane the radiation patterns is bi-directional and look like
the radiation from a dipole antenna. Fig. 11 illustrates the gain and the radiation efficiency of the
proposed antenna versus frequency. The figure shows that the proposed antenna has high gain and
48

7. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
good radiation efficiency over the entire frequency band except at the four proposed frequency band–
notches.
(a)
(b)
(c)
(d)
Figure 9: Surface current distributions of the proposed antenna at notched frequencies (a) 3.5 GHz,
(b) 3.9 GHz, (c) 5.25 GHz, (d) 5.9 GHz
0
0
30
30
30
60
60
90
90
120
150
60
60
90
120
30
90
120
120
xz-plane 150
yz-plane
150
(a)
180
0
30
0
30
60
30
60
90
120
30
60
90
60
90
120
150
150
180
90
120
150
120
150
180
150
180
xz-plane
yz-plane
(b)
49

8. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
0
0
90
90
90
90
120
120
120
150
60
60
60
60
120
30
30
30
30
150
150
150
180
180
xz-plane
yz-plane
(c)
Figure 10: Simulated radiation patterns of Eφ (solid line) and Eθ (dashed line) in the xz– and yz–
planes of the proposed antenna at frequencies (a) 4.5 GHz, (b) 7 GHz, (c) 9.5 GHz
100
Antenna Radiation Efficiency%
8
A
ntenna P
eak G (dB
ain
)
6
4
2
0
-2
-4
-6
-8
-10
80
60
40
20
0
-12
1
3
5
7
9
11
1
13
Frequency (GHz)
(a)
3
5
7
9
Frequency (GHz)
11
13
(b)
Figure 11: (a) Simulated antenna peak gain, (b) simulated radiation efficiency of the proposed
antenna
4. CONCLUSION
In this work an UWB antenna with four notched bands is designed. Matching between the
UWB antenna and the 50 ohm microstrip line is done through a proximity feed technique. To obtain
the required four band notches, slots etching in the ground plane are implemented. The effects of
adding these slots on the performance of the antenna are demonstrated. The proposed antenna
provides wideband performance in a frequency band from 3 to 11.7 GHz with notched bands at 3.5,
3.9, 5.25 and 5.9 GHz which correspond to WiMAX, C band satellite communication, lower WLAN,
higher WLAN and LMI C band respectively. The proposed antenna shows omnidirectional radiation
with good radiation efficiency over the frequency band except at the four notched bands. The
proposed antenna is fabricated and the measured data of the S11 showed a very good agreement with
the simulated results. The performances of the antenna illustrate that it is good candidate for UWB
applications.
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9. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 1, January (2014), © IAEME
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