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DESIGN OF A MICROSTRIP-FED MONOPOLE
ANTENNA WITH A WIDE SLOT GROUND PLANE
FOR UWB APPLICATIONS
L.T. Akhil B igh 1and M s. A. Kayal izhi2
Anand Ins i u e o Highe Technology
ABSTRACT
In his pape , he design o a mic os ip- ed monopole an enna wi h a wide slo g ound plane o uwb
applica ions is p esen ed. A wide slo g ound plane is inse ed in he g ound plane and e ched. The
subs a e used is 4 epoxy wi h a hickness o 1.6mm. The size o he an enna is 30*30mm, hence i ’s a
compac one. The apezoidal pa ch placed on he uppe su ace o he subs a e. The adia ing s ip
connec ed o mic os ip line eed ape ed a one end. The simula ion esul s shows ha a e u n loss o less
han -10dB and a VSWR alue less han 1.58 h ough he bandwid h 3 o 12.5 dB is ob ained. The
simula ion so wa e used is high equency s uc u al simula o (HFSS).
Index Te ms—Plana Monopole, T apezoidal Pa ch, Ul a wide bandwid h, high equency
s uc u al simula o .
1.INTRODUCTION
The apid de elopmen in Ul awideband (UWB) wi eless communica ion echnology, he UWB
an ennas ha e been a ac ed he esea che s in pe sonal and gene al applica ions. The FCC
( ede al communica ion commission) alloca ed he use o equency ange om 3.1 o 10.6 GHz
o UWB applica ions. The mic os ip pa ch an ennas a e conside ed o UWB applica ions. The
cha ac e is ics o hese pa ch an ennas a e low p o ile, compac i.e., small size, in expensi e,
con o mable o plana and non-plana su aces and omnidi ec ional adia ion pa e n. The use o
monopole an enna is a easible one, as i can be implemen ed in a smalle a ea. Using he wide
slo p o ides wide band adia ion pe o mance and i can also be easily ab ica ed.
The e a e a ious echniques ha e been handled by many esea che s o design pa ch an enna o
UWB applica ions. A squa e/ ec angula monopole moun ed abo e he ci cula g ound plane in
[1]. A ec angula pa ch wi h slo ed ends used in [2]. Di e en echniques ha e been adap ed o
a ain he band no ch unc ion o cu o undesi ed equency band om 5 o 6 GHz in [3], [4],
[6]. A ape ed slo wi h a ec angula pa ch is used in [5]. A semi-ci cula pa ch wi h a ec angula
pa ch wi h wo s eps abo e he pa ch and a small ci cula hole in he pa ch wi h semi-ci cula
s ip o a ain he band no ch unc ion in [7].
In his le e a mic os ip- ed monopole an enna wi h a hexagonal shaped wide slo used in he
Elec ical Enginee ing: An In e na ional Jou nal (EEIJ), Vol. 1, No. 1, June 2014
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g ound plane o i he desi ed UWB applica ion. By using he wide slo a smoo hly ape ed
ansi ion is employed o e ec i ely ob ain impedance ma ching o e he UWB bandwid h. The
ben junc ions ound he pa ch a e connec ed o a mic os ip eed ape ed a one end o enhance
he bandwid h. This design a ains he success ul inc emen o -10dB and VSWR o less han 1.58
h ough he bandwid h 3 o 12.5 dB; i co e s he en i e UWB equency ange. This design
suppo s he lowe and highe equency ange, inspi e o i s small size.
2. ANTENNA STRUCTURE AND PARAMETERS
The simula ed An enna design is shown in Fig.1. The o e all size o he an enna is 30 *30mm;
i ’s a compac one. The me al s ip moun ed on he o he side o he subs a e, is o 4 epoxy wi h
a hickness o 1.6mm and ela i e pe mi i i y o 4.4. Ino de o ob ain be e pe o mance he
an enna should a ain he loss angen o 0.02. The hexagonal shaped slo is e ched on he o he
side o he subs a e. The me al s ip consis s o mic os ip eed line which i sel ac as a adia ing
elemen . This s uc u e is connec ed o a ma ching ne wo k o 50- impedance. To educe
e lec ion caused by sudden changes in he wid h pa ch, he eed line is ape ed a one end. The
poin in which he me al s ip is connec ed o he eed line is he mos c i ical sec ion o he
design. By op imizing any changes can inc ease he uppe equency and hence dec eases he
e lec ion in he highe equency.
Ino de o adia e he ene gy pe pendicula o he plane o he an enna, he slo is e ched on he
g ound plane. Also, he g ound plane which supp esses he back adia ions and helps o
enhances he gain. The eed line used is mic os ip line eed i educes he spu ious adia ion, as
he subs a e used is 4, he hickness is no so high. The bandwid h p o ided by he eed line is
na ow, he adia o pa ch which o e comes his d awback and p o ides wide band wid h. The
simula ion is done using HFSS so wa e e sion 12. I wo ks in FDTD ( ini e di e ence ime
domain) o FEM ( ini e elemen me hod).
Fig. 1. Simula ed design o he p oposed an enna.
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3.ANTENNA DESIGN AND PARAMETRIC STUDY
The an enna design consis s o se e al pa ame e s. The g ound plane wi h a size o 30*30mm is
designed. To inse he slo in he g ound plane, he dimensions a e, he lowe end wid h=19.7,
leng h=11.2 om he lowe end, uppe end wid h=17.8, leng h =25 om he lowe end
connec ed o he cen e posi ion o wid h=26.8, leng h=17.8 om he lowe end. The FR4
subs a e wi h hickness 1.6 e ched on he uppe su ace o he g ound plane. The ound ace o
he adia o pa ch o wid h=7.5mm connec ed o he o he ace wi h a wid h=6.5mm, esembles
like a apezoidal one wi h ben junc ions.
The pa ch o ms ound end connec ed o he eed line wi h ape ed a one end. The an enna is
ma ched wi h lumped po .
4.RETURN LOSS AND VSWR
The e u n loss om he equency 3 o 12.5GHz is ob ained. The simula ion esul s wi h a
maximum esonance o -42dB is ob ained is shown in Fig. 2.
The VSWR alue o 1.58 is ob ained as shown in
Fig. 3. VSWR
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5. RADIATION PATTERN
Fig. 4. Simula ed E-plane adia ion pa e n (in dB) o (a)4.5, (b)8.8, (c) 10 and (d) 12.5 GHz
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Fig. 5. Simula ed H-plane adia ion (in dB) o (a) 4.5, (b)8.8, (c)10, (d)12.5 GHz
The 3-D a - ield compu ed adia ion pa e n in bo h E-plane and H-plane is shown abo e. The
adia ion pa e n ob ained is omnidi ec ional. This an enna beha es like a con en ional monopole.
When he equency is inc eased, he adia ion pa e n ge s dis u bed, bu s ill he pa e n ob ained
is omnidi ec ional.
6.GAIN AND DIRECTIVITY
The maximum gain alue ob ained is 5.1857 and he calcula ed di ec i i y is 5.5897. The e o e
he simula ed e iciency o he designed an enna is 92.287. The 3-D pola ep esen a ion o gain
and di ec i i y, shown in Fig. 6 and Fig. 7. The gain alue esembles wi h he adia ion pa e n
wi h de ia ions. The di ec i i y alue ob ained is cons an h oughou he en i e equency band.
Elec ical Enginee ing: An In e na ional Jou nal (EEIJ), Vol. 1, No. 1, June 2014
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Fig. 7. Di ec i i y
7.CONCLUSION
The p oposed an enna shows ha he equency band o 3 o 12.5 GHz o VSWR less han o
equal o 1.58 is ob ained. This design suppo s bo h he lowe and highe ange. This design is a
good candida e o mobile and pe sonal UWB applica ions due o i s compac ness.
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