IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL.

7, 2008 89

Multiband and UWB V-Shaped Antenna

Configuration for Wireless Communications
Applications
Hala Elsadek, Member, IEEE, and Dalia M. Nashaat

Abstract—A new configuration of multiband/ultra-wide-band between the feeding point and the shorting wall, multiband op-
(UWB) antenna is investigated. The antenna is a V-shaped patch eration can be achieved with six resonating modes. Eight modes
with unequal arms coupled electromagnetically to single feed of operation can be achieved by inserting V-shaped slot on the
isosceles triangular PIFA thorough two unequal slots. The six
multiband operations are achieved due to the different lengths radiating surface of the triangular PIFA. Moving the feeding
and widths of the V-shaped patch as well as the two coupling slots. point far from the shorting wall, hence increasing , the res-
Two more modes can be added by loading the triangular planar onating modes become staggered close to each other; hence
inverted F-antenna (PIFA) with V-shaped slot. Wide bandwidth wide bandwidth operation at 2.95 and 4.65 GHz with respec-
of 27% is achieved by simply adjusting the feeding point position,
thus generating staggered resonating modes. UWB operation with
tive bandwidths of 3.5% and 27% is achieved. Folding the PIFA
53% bandwidth can be achieved by folding the shorting wall of shorting wall with appropriate dimensions increases the band-
the triangular PIFA. width to 53% [9].
Index Terms—Multiband, triangular planar inverted F-antenna
(PIFA), ultra-wide-band (UWB), V-shaped patch.
II. ANTENNAS CONFIGURATIONS

I. INTRODUCTION The geometry of the proposed antennas is as shown in

Fig. 1. The dimensions of the V-shaped patch with V-
unequal arms are mm mm ,
A S mobile communication grows rapidly, the demands of
multiple frequency bands are raised. It is desirable for a
single handset to access several different services such as voice,
mm
with dimensions
mm . The isosceles triangular antenna is
mm mm . The
data, and video, at the same time in any place [1], [2]. shorting wall width is equal to for maximum size re-
Due to the attractive merits of wide frequency bandwidth, duction [8]. The ground plane is with rectangular shape
ultra-wide-band (UWB) communication systems have recently of dimensions mm mm . The two
received great attention in the wireless world. A UWB system parts of the structure, V-shaped patch and triangular PIFA,
is defined as any radio system that has a 10 dB bandwidth larger are coupled through V-shaped slot with unequal arms
than 25% percent of the center frequency [3]. Microstrip patch with dimensions mm mm and
antenna as well as planar inverted F-antenna (PIFA) is a suc- mm mm . To add two more resonating
cessful candidate for most wireless communication applications modes, an equal arms V-shaped slot is loaded on the triangular
due to their low profile, light weight, and ease of fabrication and patch radiation surface. The substrate is foam with dielectric
integration with other system components [4]. constant and substrate height mm. It is
Although microstrip PIFA with multiband operation offers worth it to mention that as the ground plane size is reduced,
a number of attractive advantages, it has the disadvantage of the antenna behavior is changed. The operating frequencies are
narrow bandwidth around 4%. Some methods to enhance the changed. For example, at ground plane size reduced to be 45
bandwidth were investigated in the literature using probe feed 55 mm , the antenna behavior changes to be a wide-bandwidth
with L-shape [5] or adding parasitic elements [6]. Wide band- antenna rather than a multiband antenna.
width and multiband characteristics in this letter are achieved by The resonating frequencies can be approximately determined
electromagnetically couple the V-shaped patch with the trian- from the following equation [1], [4]:
gular PIFA. Controlling the coupling mechanisms by adjusting
the feeding point position, one can choose between the multi-
band and wide-band operations [7], [8]. At certain distance (1)

Manuscript received December 15, 2006; revised May 14, 2007. where
The authors are with the Microstrip Department, Electronics Research Insti-
tute, Cairo 12622, Egypt (e-mail: helsadek@mcit.gov.eg).
Color versions of one or more of the figures in this letter are available online
is the resonant frequency at band ;
at http://ieeexplore.ieee.org.
C is the velocity of light m/s;
Digital Object Identifier 10.1109/LAWP.2007.900953

1536-1225/$25.00 © 2008 IEEE

90 IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 7, 2008

Fig. 1. Configuration of the proposed antenna of V-shaped patch with unequal arms coupled to isosceles triangular PIFA through V-shaped slot of unequal arms.

Fig. 3. Comparison between simulated and measured results of the multiband

Fig. 2. Photograph of the fabricated proposed antenna for six multiband oper- proposed antenna configuration.
ations.

is the half-length of the radiating surface or length Adjusting the position of the coaxial feed point at
of the slot at the corresponding operating band . The mm, multiband operation is achieved with resonating
triangular PIFA part is excited by coaxial probe feed. frequencies at 2.88, 3.64, 3.95, 4.38, 4.81, and 5.6 GHz, with
The probe is positioned in the centerline of the shorted reflection coefficients 21.5, 20.7, 26.5, 24.5, 19,
patch at distance from shorting wall. The photograph and 22.5 dB, respectively, and with impedance bandwidths
of the fabricated proposed antenna for multiband of 3.5%, 4%, 4.25%, 6%, 4%, and 7.7%, respectively (the
operation is shown in Fig. 2. The value controls the bandwidth is at reflection coefficient dB). Fig. 3
antenna characteristics. For multiband operation, the illustrates a comparison between the simulated and measured
distance is 16.75 mm while for broadband operation, results for this multiband structure. The radiation pattern of
the distance increased to be 18.5 mm. the antenna is approximately omnidirectional in both E-plane
and H-plane with back-to-front ratio of less than 15 dB and
3 dB beamwidth of about 60 . The deformation in the radiation
III. RESULTS AND DISCUSSION pattern at higher frequencies is acceptable as shown in Fig. 4.
The two arms of the V-shaped patch excite TM mode. The Inserting a V-shaped slot on the triangular PIFA radiating plate
length of the two arms of the V-shaped patch is different in adds two more resonating frequencies.
order to excite two different staggered resonant modes. The Moving coaxial feeding towards open end of triangular PIFA
unequal spacing widths between the coaxially fed triangular antenna at mm, the resonant frequencies of the an-
shorted patch and the V-shaped patch are for different values tenna become staggered close to each other, so achieving wide-
of coupling and thus excite two more different modes. band operation. The bandwidth is 3% at the fundamental mode
The antenna structures are fabricated with thin-film pho- 2.95 GHz, hence the fundamental resonating frequency will ap-
tolithographic technique. The main characteristics are measured proximately not be affected by changing the feed position. The
with 8719 EB vector network analyzer. There are small dif- higher resonance bandwidth is 27% at 4.721 GHz. The reflec-
ferences between measured and simulated results due to some tion coefficients are 21 and 20.7 dB for the two resonating
tolerated fabrication errors as using Duroid RT/5880 with bands, respectively. Fig. 5 presents the comparison between the
thickness 0.508 mm instead of copper clad for covering the simulated and measured results of the wide-band antenna struc-
foam substrate. ture. Folding the shorting wall of the triangular PIFA increases
ELSADEK AND NASHAAT: MULTIBAND AND UWB V-SHAPED ANTENNA CONFIGURATION 91

Fig. 4. The simulated radiation pattern at (a) E-plane and (b) H-plane for multiband proposed antenna configuration with six bands of operation at the lowest and
highest resonating frequencies.

near each other, creating a 27% bandwidth. More bandwidth en-

hancement can be added by folding the shorting wall. UWB be-
havior is achieved with 53% at same resonating frequency. The
antenna gain and radiation pattern are acceptable at almost all
bands of operation. Simulations and measurements comparison
shows good agreement.

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