Ultra-Wideband Antenna’s Design Techniques

Abstract

The main objective of this paper is to understand the different methodologies which have been adopted in the recent
years in design of Ultra-Wideband Antenna. Methods/Statistical analysis: The patch of the UWB antenna is etched with
circular rings to obtain wider bandwidth. Rabbet structured patch can also be utilized for enhancing bandwidth. Ground
plane of UWB antenna’s in some cases is parabolic and some have T or L-shape slots to enhance antenna characteristics
like increasing bandwidth, band notching at certain frequencies etc. dielectric substrate FR4 is preferred in most of the
UWB antenna designs due to less return loss and better bandwidth utilization. Findings: With help of circular patch,
more than 160% of Bandwidth is attainable. Use of triangular slots in ground plane can help increase the bandwidth
by 45%. A further alteration in ground plane such as grooved ground plane can help minimize the surface waves.
Application/Improvements: Since T-shaped slots increases directivity so they are preferred in air-bore applications.
L-shaped slots in ground plane helps in RADAR applications.

Full text

Indian Journal of Science and Technology, Vol 9(47), DOI: 10.17485/ijst/2016/v9i47/106431, December 2016
ISSN (Print) : 0974-6846
ISSN (Online) : 0974-5645
* Author for correspondence
1. Introduction
Antenna is a device which converts guided electromagnetic
energy in transmission line to radiated electromagnetic
energy in free space. It not only helps in transferring
energy but also acts as a probing device. Ultra-wideband
(UWB) antennas concept was rst given by Oliver
Lodge in 1898. But UWB antennas gained importance
in 2002 when US Federal Communication Commission
(FCC) provided authorization to UWB systems to be
commercially used. FCC allocated the bandwidth of 3.1
to 10.6 GHz which is one of the largest band allocated by
FCC for unlicensed use1. Owing to this large bandwidth
and certain important characteristics, UWB antennas
are prominent in various wireless applications like EM
testing, monitoring, medical imaging, tracking etc. UWB
systems employ short pulses of radio energy to transmit a
signal. Usage of short pulses provides certain advantages
like high data rates2. Due to large bandwidth occupied
by short pulses, data rates up to hundred of Megabytes
per second is obtained which in turn leads to high data
security as it is very dicult to track data at such a speed.
Moreover multipath fading is avoided as there is no
overlapping between reected signals and original signals
due to short pulse transmission.
Although wide services are provided by third
generation communication technologies which include
fast internet access, video telephony etc but UWB
provides much larger bandwidth for high data rate
communication. e power required is very small which
is 0.5 mW according to FCC. e major requirement of
UWB antenna is that it must posses’ Omni-directional
radiation pattern for wireless communication with low
directivity and uniform gain. Further there exists variety
of narrowband systems in range of UWB systems, like
IEEE 802.16 WiMAX (3.3-3.6 GHz), C-band systems
(3.7-4.2 GHz), IEEE 802.11a WLAN (5.15-5.825 GHz),
which interfere with UWB pattern and which must be
avoided. Numerous technologies are proposed to provide
band notching in order to avoid interference from the
above mentioned bands. e simplest technique to this
is incorporate into radiator various shapes and sizes
of slots. Moreover matching circuits are introduced as
these improve the performance of antenna. Not only this,
due to low power requirement, UWB antenna should
have high radiation eciency3. Moving further, size of
Abstract
The main objective of this paper is to understand the different methodologies which have been adopted in the recent
years in design of Ultra-Wideband Antenna. Methods/Statistical analysis: The patch of the UWB antenna is etched with
circular rings to obtain wider bandwidth. Rabbet structured patch can also be utilized for enhancing bandwidth. Ground
plane of UWB antenna’s in some cases is parabolic and some have T or L-shape slots to enhance antenna characteristics
like increasing bandwidth, band notching at certain frequencies etc. dielectric substrate FR4 is preferred in most of the
UWB antenna designs due to less return loss and better bandwidth utilization. Findings: With help of circular patch,
more than 160% of Bandwidth is attainable. Use of triangular slots in ground plane can help increase the bandwidth
by 45%. A further alteration in ground plane such as grooved ground plane can help minimize the surface waves.
Application/Improvements: Since T-shaped slots increases directivity so they are preferred in air-bore applications.
L-shaped slots in ground plane helps in RADAR applications.
Keywords: Archimedean Spiral, Band Notching, Planar and Non Planar Antennas
Ultra-Wideband Antenna’s Design Techniques
Jaspreet Kaur and Gurpreet Kumar*
Department of School of Electronics and Communication Engineering, Lovely Professional University,
Jalandhar - Delhi G.T. Road, Phagwara – 144411, Punjab, India;
jaspreetkaursandhu589@gail.com, gurpreet.14632@lpu.co.in

Vol 9 (47) | December 2016 | www.indjst.org Indian Journal of Science and Technology
2
Ultra-Wideband Antenna’s Design Techniques
UWB antenna plays a major role. It should be as small
as possible as it is used for many indoor applications and
portable devices.
is paper proposes the various technologies and
design considerations which are being proposed till date
which have dierent VSWR, gain, eciency based on the
dierent technique used in UWB antenna design.
2. Planar and Non Planar UWB
Antenna
UWB is a form of micro strip antenna with a radiating
patch over a ground plane which can have planar or non
planar structures. Several antennas have been proposed
in recent years but planar antennas have gained high
importance due to low fabrication cost, low prole, wide
bandwidth and high radiation eciency. Various shapes
of planar antennas have been reported4–6. Comparisons
were carried out between monopole planar antennas of
varying length and width and with dierent shapes like
rectangular, square, circular and elliptical. Circular was
found to provide wide bandwidth4. Wider bandwidth
was obtained by etching multiple circular rings in the
radiating patch of planar conformable antenna with
resonating frequency given by the equation7:
(1)
Where
fr=resonant frequency
c=velocity of light
r=radius of patch
Next moving to rectangular patch antenna with
microstrip feed line will have resonant frequency in5
given by equation as follows:
(2)
Where l=length of planar element
r=radius of equivalent cylindrical wire
e eective dielectric constant can be given by the
equation as:
(3)
Besides the simple planar structures modied
structures were proposed lie the rabbet structured
metallic patch for enhancing bandwidth6. Apart from
the planar structures several conformable non planar
antennas have been designed for providing exibility to
be used for various scenarios7. Variation of directivity of
antenna with dierent conforming shapes is shown in
Table 1.
Table 1. Variations of directivity with various shapes
S.no Radius of
curvature mm
Frequency GHz Directivity dBi
1 27.765 3.5 2.325
6 2.007
9 4.086
2 18.243 3.5 2.632
6 2.366
9 4.742
3 8.685 3.5 2.534
6 3.514
9 6.029
4Square shaped 3.5 2.430
6 4.158
9 5.393
5 Modied
square shaped
3.5 2.593
6 4.239
9 4.633
3. Impact of Dielectric Constant
It has been found that dielectric constant of substrate
material have the most sensitive impact on antennas
performance. A small change in dielectric substrate
constant can cause change in operating frequency as
found in11 given as:
(4)
Among the various substrates available FR4 is
considered as the best substrate due to its better utilization
of bandwidth, resonating frequency, return loss8. Substrate
thickness inuences the radiation characteristics of
UWB antenna. ick substrates provide better eciency

Jaspreet Kaur and Gurpreet Kumar
Vol 9 (47) | December 2016 | www.indjst.org Indian Journal of Science and Technology 3
but large element size reported by Balanis12. Substrate
with low dielectric constant leads to increase in Omni-
directional radiation bandwidth13. Bandwidths, resonant
frequency, return loss of dierent dielectric substrates
are given in Table 2. e eect of dielectric substrate was
analyzed on frequency independent Archimedean spiral
UWB antenna by shire14.
Table 2. Antenna characteristics for dierent substrate
material
Material Dielectric
constant
Band-
width
(GHz)
Resonating
frequency
(GHz)
Return
loss(dB)
FR4 4.1 9.745
(2.9980-
12.7350)
4.3356 -24.3854
7.4765 -42.2670
9.9732 -28.4086
12.1477 -13.4235
Teon 2.1 9.4893
(2.9000-
12.3893)
5.3020 -27.7461
8.4430 -20.5721
11.1812 -16.6554
Quartz 3.78 8.28
(2.9700-
12.1200)
4.4161 -27.2814
7.6376 -26.6020
10.2148 -21.5166
Polysty-
rene
2.6 9 (2.9350-
13.8230)
4.8993 -28.0574
8.2013 -20.8018
10.8591 -17.1622
Neltech 3 8.91
(2.9400-
12.8000)
4.5772 -28.2154
7.9597 -24.1389
10.6174 -21.4509
4. Technologies for Improved
Antenna Characteristics
For design of a UWB antenna, dierent applications
require dierent antenna characteristics. Bandwidth ratio
is dened as:
(5)
Various monopole planar antennas are shown in
Figure 1 with dierent shapes with bandwidth ratio
ranging from 2:1 to 12:1. A bandwidth of more than
160 % was acquired with radiating patch of circular
shape and a corner shaped ground plane with multiband
characteristics by sachin Sharma15. Comparison of
bandwidth of dierent geometries of planar monopoles
was done where circular and elliptical planar monopole
antennas have wider bandwidth which is shown in Table
3. Besides bandwidth, gain of antenna is important
parameter and uniform gain is desirable. Gain of antenna
can be improved by various technologies proposed like
usage of Frequency Selective Surface (FSS) with multiple
layers, FSS with single layer16,17. In case of UWB antennas,
Friis’s law determine the link behavior of antenna in free
space where gain and power will be function of frequency,
so Friis’s law in form of power spectral density can be
given by equation:
(6)
Figure 1. Monopole planar antennas with varying
bandwidth.
Antenna characteristics can be improved by modifying
the shape of ground plane. Triangular slots can be inserted
inside the ground plane which increases the bandwidth by
45% as compared to normal ground plane18. A swastika
antenna was proposed with inverted L shaped slot and
concentric rings which provided maximum bandwidth
and least return loss19. Since the above UWB antennas
were solely used to improve bandwidth by varying ground
plane, grooved ground plane antennas were developed20
which led to suppressing of surface waves and helped in
improving impedance as well as radiation performance.
Modied ground plane with parabolic ground

Vol 9 (47) | December 2016 | www.indjst.org Indian Journal of Science and Technology
4
Ultra-Wideband Antenna’s Design Techniques
plane etched with T-shaped slots are used for air borne
applications due to increased directivity. Apart from this
UWB antennas with either L-shaped or parabolic ground
plane has found its applications in radar applications and
microwave imaging.
5. Band Notched Characteristics
Since various frequency bands exist in UWB’s existence
as shown in Table 4 which must be suppressed to stop
interference of existing bands. A single, dual or triple band
notched characteristics antennas were proposed in recent
year which employ dierent technologies to attain band
notching. But they all have similar working in which gain
decreases and VSWR increases at that particular band
notched frequency. Current distribution for frequency
notching is shown in Figure 2.
Table 4. Comparison of various bands
Unlicensed bands Frequency of op-
eration (GHz)
Bandwidth
(MHz)
ISM at 2.4 GHz 2.4000-2.4835 83.5
U-N at 5 GHz 5.15-5.35 5.75-5.85 300
UWB 3.1-10.6 7,500
Various dual band notched antennas were proposed
with dierent radiating patches and slotted ground plane
in20,21. e length of slot in band notched antennas is
calculated by equation reported in22 which is given as:
(7)
Triple band notched characteristics can be obtained
by inserting various slots in metallic patch and the ground
plane with a single slot for each rejected frequency as
designed by maiti23. So by inserting dierent slots or using
parasitic elements as lters to certain frequency band
notching in antennas is obtained.
(a)
(b)
Figure 2. Current distribution (a) normal frequency (b)
band notched frequency.
5. Conclusion
is paper provides a review of various technologies
being used for design of UWB antenna. Various planar
monopole antennas can be designed with varying shapes
Table 3. Bandwidth and VSWR of circular and elliptical monopoles
Conguration a (cm) b (cm) Frequency range
for VSWR<2
eoretical Lower
freq. VSWR<2
Band width
ratio
CDM 2.5 2.5 1.17 to12.00 1.28 10.2:1
EDM1A
EDM1B
2.6 2.4 1.21 to 13
1.20 to 12.50
1.31
1.24
10.7:1
10.4:1
EDM2A
EDM2B
2.7 2.3 1.38 to 11.49
1.13 to 12.00
1.37
1.20
8.3:1
10.6:1
EDM3A
EDM3B
2.8 2.2 1.37 to 11.30
1.08 to 11.43
1.41
1.17
8.2:1
10.6:1
EDM4A
EDM4B
2.9 2.1 1.58 to 10.45
1.09 to10.45
1.46
1.13
6.6:1
9.6:1

Jaspreet Kaur and Gurpreet Kumar
Vol 9 (47) | December 2016 | www.indjst.org Indian Journal of Science and Technology 5
but circular is preferred due to ease of fabrication.
Non planar antennas were also proposed with varying
shapes with increasing directivity with smaller radius of
curvature. Dielectric substrate has great eect on fringing
eect, resonant frequency of UWB antenna which must
be chosen appropriately for its design. ere are various
substrates present with dierent electrical properties and
varying bandwidth and return loss. e eciency of the
UWB antennas can be improved by decreasing dielectric
constant of a substrate or by increasing the size of patch.
Insertion of slots or parasitic elements helps in achieving
band notched antenna with reduces interference from
other unlicensed bands within the range of UWB antenna.
From all the past researches, there is need for
improvement of impedance characteristics by varying
pattern on the ground plane. Secondly, group delays
in UWB antennas must be minimized by making
arrangements for less dispersion of pulses. irdly,
mutual coupling must be reduced between multiple
elements which leads to impedance mismatch which
must be improved using matching circuits.
7. References
1. Federal Communications Commission, Washington, DC.
FCC report and order on UWB technology; 2002 Apr 22.
2. Oppermann I, Hämäläinen M, Iinatti J. UWB: eory and
its applications. Wiley; 2004 Sep. p. 248.
3. Nikookar H, Prasad R. Introduction to ultra wideband for
wireless communications. Springer; 2009. p. 1–183.
4. Agrawall NP, Kumar G, Ray KP. Wide band planar mono-
pole antennas. IEEE Transactions on Antennas and Propa-
gation.1998 Feb; 46(2):294–5.
5. Arivazhagan S, Priyadharshin RA, Vidhya S. Design and
simulation of planar rectangular antenna. International
Conference on Computer, Communication and Electrical
Technology – ICCCET; 2011.
6. Lim EG, Wang Z, Juans G, Man K, Zhang N. Design and
optimization of a planar UWB antenna. IEE; 2013.
7. Geethananda M, Alex ZC, Shamb K. Design of planar
multi-ring monopole antenna for UWB applications. IEEE
Sponsored 2nd International Conference on Electronics and
Communication Systems, ICECS; 2015.
8. Hsu CH, Haochang C, Hsieh WY. Design of multilateral
monopole planar antenna with rabbet structure for UWB
applications. In the Asia-Pacic Microwave Conference
(APMC), IEEE Xplore Digital Library. 2015 Dec 6–9; 2:1–3.
9. Ahmed M, Das DK, Rahman A. Study of a conformal UWB
antenna designed on various non-planar surfaces. Lough-
borough Antennas and Propagation Conference; 2012 Nov.
10. Carver KR, Mink JW. Microstrip antenna technology. IEEE
Transactions on Antennas and Propagation. 1981 Jan; AP-
29(1):2–24.
11. Ujwala D, Ramkiran DS, Brahmani N. Study of eect of
substrate material on performance of UWB antenna. Inter-
national Journal of Computational Engineering Research.
2013 Apr; 3(4):252–7.
12. Balanis CA. Antenna theory and design. second edition,
Wiley India(P.) Ltd; 2007.
13. Mishra SK, Gupta RK, Mukherjee J. Eect of substrate
material on radiation characteristics of an UWB antenna.
Loughborough Antennas and Propagation Conference;
2010 Nov.
14. Shire AM, Seman FC. Eects of dielectric substrate on per-
formance of UWB archimedean spiral antenna. IEEE Con-
ference on Space Science and Communication; 2013 Jul.
15. Sachin Sharma, Manish kumar savita. Multi Band Circu-
lar Antenna for Ultra Wideband Wireless Systems. In the
Proceedings of Nirma University International Conference
on Engineering (NUiCONE); 2012 Dec 6–8; IEEE Xplore
Digital Library; 2013 Apr 4.
16. Ranga JY, Matekovits L, Weily AR, Esselle KP. A constant
gain ultra-wide band antenna with a multi-layer frequency
selective surface. Progress in Electromagnetics Research
Letters. 2013; 38:119–25.
17. Yahya R, Itami M. Design of constant gain UWB planar
antenna using single layer FSS. IEEE International Sympo-
sium on Antennas and Propagation and USNC/URSI Na-
tional Radio Science Meeting. IEEE; 2015 Jul 19–24.
18. Azim R, Islam MT, Misran N. Ground modied double
sided printed compact UWB antenna. Electronics Letters.
2011 Jan 6; 47(1):9–11.
19. Raju SD, Haranath B, Panwar L. Novel UWB swastika slot
antenna with concentric circular slots and modied ground
plane with inverted L-shaped slots. International Confer-
ence on Advances in Computing, Communications and
Informatics (ICACCI), IEEE Xplore Digital Library; 2015
Aug 10–13. p. 76–81.
20. Bai X, Liang X, Jeng J. Improved coupled UWB dual-po-
larized antenna array with corrugated ground. Electronic
Letters. 2014; 50(22):1564–6.
21. Hao L, Ziqiang X, Bo W. Design of compact UWB planar
antenna with dual band-notched for WLAN and WiMAX.
International Workshop on Microwave and Millimeter
wave Circuits and System Technology. IEEE Xplore Digital
Library; 2013 Oct 24–25. p. 44–6.
22. Jiang HS, Ming WG, Long Z. Design of a compact Dou-
ble - sided printed Band-notched planar Antenna for UWB
Applications. International Conference on Microwave and
Millimeter Wave Technology (ICMMT). IEEE Xplore Dig-
ital Library; 2012.
23. Satyabratamaiti, NaikatmanaPani, Amrit Mukherjee. Anal-
ysis and Design a Planar Elliptical shaped UWB Antenna
with Triple Band Notch Characteristics. International Con-
ference on Signal Propagation and Computer Technology

Vol 9 (47) | December 2016 | www.indjst.org Indian Journal of Science and Technology
6
Ultra-Wideband Antenna’s Design Techniques
(ICSPCT); 2014 Jul 12–13; IEEE Xplore Digital Library;
2014 Aug 28.
24. Melo DR, Kawakatsu MN, Nascimento DC and Dmitriev
V. Planar monopole ultra wideband antennas with rounded
patch and ground plane possessing improved impedance
matching. Microwave and Optical Technology Letters.
2012; 54(2):335–8.
25. Sung Y. Bandwidth enhancement of a microstrip line-fed
printed wide-slot antenna with a parasitic center patch.
IEEE Transactions on Antennas and Propagation. 2012
Apr; 60(4):1712–6.
26. Fan ST, Yin YZ, Lee B, Hu W, Yang X. Bandwidth enhance-
ment of a printed slot antenna with a pair of parasitic patch-
es. In IEEE Antennas and Wireless Propagation Letters.
2012; 11:1230–3.
27. Hed A, Hayouni M. Band-notched UWB antennas: recent
trends and development. 14th Mediterranean Microwave
Symposium (MMS); 2014 Dec 12–14. p. 1–4.
28. Gupta S, Dhillon SS, Khera P, Marwaha A. Dual band
U-slotted
29. Patch Antenna for C Band and X Band Radar Applications.
5th International Conference on Computational Intelli-
gence and Communication Networks (CICN); 2013 Sep
27–29. p. 41–5.
30. Sze JY, Wong KL. Bandwidth enhancement of a microstrip
line-fed printed wide-slot antenna. IEEE Transactions on
Antennas and Propagation. 2001; 49(7):1020–4.
31. Pozar DM, Schaubert DH Ed., Micrsotrip Antenna, New
York, IEEE press.