1. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME
43
TAPERED CIRCULAR MICROSTRIP ANTENNA WITH MODIFIED
GROUND PLANE FOR UWB COMMUNICATIONS
Mrs. Archana Agarwal1
, Manish Kumar2
, Priyanka Jain3
, Shagun Maheshwari4
1
(Electronics & Communication, Institute of Technology & Management, Bhilwara (Raj.), India)
2
(Electronics & Communication, Institute of Technology & Management, Bhilwara (Raj.), India)
3
(Electronics & Communication, Institute of Technology & Management, Bhilwara (Raj.), India)
4
(Electronics & Communication, Institute of Technology & Management, Bhilwara (Raj.), India)
ABSTRACT
The recent allocation of the 3.1–10.6 GHz frequency spectrums for ultra-wideband
(UWB) wireless communication by the Federal Communications Commission (FCC) has
presented various opportunities and challenges for antenna designers. This paper focuses on
UWB technique of cutting a notch at the ground pattern opposite the microstrip line with
rectangular tapered corners. The proposed UWB antenna is designed on 45 mm×30 mm×1.6
mm substrate (FR-4 lossy) and simulated using CST software. Result shows that a slot in the
ground plane pattern beneath the microstrip line with the tapered corners and patch provides
enhancement in bandwidth. With the optimized dimension of notch and feed line, 119.53%
bandwidth is obtained ranging from 3.15GHz to 12.5GHz which satisfies the system
requirements for S-DMB, WIBRO, WLAN, CMMB and the entire UWB.
Keywords: Bandwidth, Microstrip Patch antenna, Tapering, Ultra wideband (UWB)
I. INTRODUCTION
The regulation for ultrawide band was officially released in 2002 by Federal
Communication Commission (FCC) and spectrum of 3.1-10.6GHz is allocated for this band
[1]. Ultra-wideband (UWB) communication systems have the promise of very high
bandwidth, reduced fading from multipath, Higher data rates over large bandwidth (BW) and
large channel capacity, Less complexity and cost, Low power consumption. These features
are desirable for both indoor and outdoor handheld UWB antenna applications. Radiating
elements patches of printed antennas have a variety of forms, as triangular, rectangular,
square, elliptical, and circular, among others. However, it has been found that circular
INTERNATIONAL JOURNAL OF ELECTRONICS AND
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ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 4, Issue 3, May – June, 2013, pp. 43-47
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2. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME
44
structures have smaller dimensions related with the operation frequency, Moreover, the
circular structure offers another important advantage: the only control variable for the
structure design is the patch radius, that is the reason circular or disk antennas are very
popular and widely used nowadays. In this Letter, we present another promising bandwidth-
enhancement technique by providing the cutting slot in the ground plane pattern beneath the
microstrip line. It is possible to adjust the coupling between the antenna element and the
ground planeappropriately; thereby it is possible to widen the bandwidth. This method is
more effective than that of the use of an asymmetrical feed arrangement [2], a double feed
[5], a bevelling radiating element [3], adjusting the gap between radiating element and
ground plane [4], abevelling ground pattern [6], and so on.
II. ANTENNA DESIGN
This design focuses on the UWB circular shaped patch antenna. Firstly a simple circular
shaped patch antenna is designed having radius of R=10mm with microstrip feedline
technique. It is fabricated on a 45 mm×30 mm×1.6 mm FR-4 (lossy) dielectric substrate
(Dielectric constant εr=4.4, Loss tangent= 0.02)with a feed line and a finite ground plane.
(a) Top View (b) Bottom View
Fig. 1 Geometry of Circular UWB antenna
Later on cut a slot in ground plane beneath the microstrip feed line and tapered the
corners. Fig. 2 and 3show the measured return loss against frequency curve at different depth
and width of slot in the ground pattern respectively. It can be see that the cutting slot depth
has effective impedance matching rather than the slot width as a gap between the radiating
element and the ground plane.

3. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME
45
Fig.2 Measured Return Loss against frequency of circular UWB antenna with different
cutting slot depth in ground plane
t = 0.5mm
t = 1.0mm
t = 1.5mm
Finally the top patch is modified along with the feedline dimension modifications to
obtain the UWB properties. The optimized dimensions of ground plane as shown in figure 5.8
are: W1=30m, L1=14mm, L2=2mm, W2=4mm, W3=5mm, W4=7.5mm, t=1mm. The top
circular shaped patch is cut as shown in figure 5.8. The dimensions of cut are C1=10mm,
C2=9.5mm. The width and length of feedline is designed to be S1=3mm and S2=2.5mm. Fig.
4 and 5 show the VSWR curve and smith chart of proposed circular UWB antenna.
Fig.3 Measured return loss against frequency of circular UWB antenna with different
cutting slot width in ground plane
W3 = 3.0mm
W3 = 4.0mm
W3 = 5.0mm

4. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME
46
Fig.4 Measured VSWR against frequency of circular patch UWB antenna with t = 1mm
and W3 = 5mm
Fig.5 Smith chart of proposed circular UWB antenna
III. CONCLUSION
Ultra wide band is rapidly advancing as a high data rate wireless communication
technology. In this article the circular tapered with modified ground plane antenna is
designed. It is being observed that 119.53% Bandwidth is obtained ranging from 3.15GHz to
12.5 GHz which is comparatively very large then the antennas previously designed by the
researchers.

5. International Journal of Electronics and Communication Engineering & Technology (IJECET),
ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME
47
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