Dodecagon-Shaped Frequency Reconfigurable Antenna Practically Loaded with 3-Delta Structures for ISM Band and Wireless Applications

Abstract

Dodecagon-Shaped Frequency Reconfigurable Antenna Practically Loaded with 3-Delta Structures for ISM Band and Wireless Applications

ABSTRACT
An edge fed, dual band, quarter-wave transformer coupled, monopole, ultra-wideband (UWB),
dodecagon-shaped miniaturized frequency reconfigurable antenna for ISM and wireless applications
is designed, analyzed and investigated. The impedance transformer is utilized in the structure
for impedance matching and hence results in lower reflection coefficient values. The antenna uses
defected ground structure (DGS) in the bottom and radiating patch that is practically loaded with
three numbers of delta structures. The use of DGS reduces the value of gain and provides ultrawideband
bandwidth across the designed frequency. The addition of three delta structures in the
patch improves the value of gain. Miniaturizing in the size of the antenna has been achieved by
reducing the ground along the width that led to a total 30.41% size reduction in the fundamental
circular patch antenna. The antenna exhibits two bands 1.82–3.61 GHz and 5.24–12.43 GHz thus
antenna is suitable for ISM band, PCS, 5G, Wi-Fi/WiMAX/WLAN and other wireless applications. The
fabricated antenna is frequency reconfigured by utilizing the switching property of four numbers
of PIN diodes (BAP64-02V). Frequency reconfigurable antenna is used flexibly and versatile for various
microwave applications based on the switching conditions (more than eight digital combination
cases) of PIN diodes. The prototype measured results provide good agreements with the simulated
reflection coefficients values in some mode of operations. Antenna radiating patch and ground
is etched on FR-4 substrate of dimension 52mm×59mm×1.6mm using printed circuit board
technology.

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Dodecagon-Shaped Frequency Reconfigurable
Antenna Practically Loaded with 3-Delta Structures
for ISM Band and Wireless Applications
Atul Varshney, T. Mary Neebha, Vipul Sharma, J. Grace Jency & A. Diana
Andrushia
To cite this article: Atul Varshney, T. Mary Neebha, Vipul Sharma, J. Grace Jency & A. Diana
Andrushia (2022): Dodecagon-Shaped Frequency Reconfigurable Antenna Practically Loaded
with 3-Delta Structures for ISM Band and Wireless Applications, IETE Journal of Research, DOI:
10.1080/03772063.2022.2034536
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Published online: 17 Feb 2022.
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IETE JOURNAL OF RESEARCH
https://doi.org/10.1080/03772063.2022.2034536
Dodecagon-Shaped Frequency Reconfigurable Antenna Practically Loaded with
3-Delta Structures for ISM Band and Wireless Applications
Atul Varshney 1,T.MaryNeebha 2, Vipul Sharma 1, J. Grace Jency 2and A. Diana Andrushia 2
1ECE Department, FET, Gurukula Kangri University, Haridwar, Uttarakhand 249404, India; 2ECE Department, Karunya Institute of Technology
and Science, Coimbatore, Tamil Nadu 641114, India
ABSTRACT
An edge fed, dual band, quarter-wave transformer coupled, monopole, ultra-wideband (UWB),
dodecagon-shaped miniaturized frequency reconfigurable antenna for ISM and wireless applica-
tions is designed, analysed and investigated. The impedance transformer is utilized in the structure
for impedance matching and hence results in lower reflection coefficient values. The antenna uses
defected ground structure (DGS) in the bottom and radiating patch that is practically loaded with
three numbers of delta structures. The use of DGS reduces the value of gain and provides ultra-
wideband bandwidth across the designed frequency. The addition of three delta structures in the
patch improves the value of gain. Miniaturizing in the size of the antenna has been achieved by
reducing the ground along the width that led to a total 30.41% size reduction in the fundamen-
tal circular patch antenna. The antenna exhibits two bands 1.82–3.61 GHz and 5.24–12.43 GHz thus
antenna is suitable for ISM band, PCS, 5G, Wi-Fi/WiMAX/WLAN and other wireless applications. The
fabricated antenna is frequency reconfigured by utilizing the switching property of four numbers
of PIN diodes (BAP64-02V). Frequency reconfigurable antenna is used flexibly and versatile for vari-
ous microwave applications based on the switching conditions (more than eight digital combination
cases) of PIN diodes. The prototype measured results provide good agreements with the simulated
reflection coefficients values in some mode of operations. Antenna radiating patch and ground
is etched on FR-4 substrate of dimension 52 mm ×59 mm ×1.6 mm using printed circuit board
technology.
KEYWORDS
Defected ground structure;
frequency reconfigurable;
ISM band; PIN diode; UWB
1. INTRODUCTION
The current milieu provides a breakneck in the growth
of wireless communications in applications like GPS and
RFID systems, satellite phones, unmanned aerial vehi-
cles (UAN), optical wireless communications (OWC),
articial intelligence (AI) and so forth. The antenna
plays a vital character in demarcating the performance
of these devices. Hence, a lot of emphasis and analy-
sis are hefted in designing the antennas to ensure good
system-level performance. A high-performance antenna
demands multi band operation, higher data rate, rea-
sonable diversity gains and better link reliability. The
recongurable antenna is one which can change its fre-
quency and its properties of radiation during the runtime
that is it can adapt itself dynamically. The antenna is
able to search for available networks and is able to con-
nect to them leaving the occupied networks by cognitive
means. This is dierent from smart antennas which use
external networking mechanisms to achieve the purpose,
as it uses the mechanism of reconguring its frequency
and radiation properties internally. As the name suggests
the recongurable antenna is used in the ultra-wideband
spectrum in order to achieve spatial and directional
data.
Numerous frequency recongurable antennas based on
switching capabilities of PIN-diodes have been designed,
developed and tested because of their easy assembly
and low economic cost [1,2]. G. Chen et al.presented
a CPW fed frequency recongurable dual mode, dual-
band folded slot antenna for wireless applications without
blockingcapacitoranddicultbiasnetworkrequire-
ments [2] . V. V. R e d d y d e s i g n e d a n d a n a l y z e d t h r e e ( 1 .
Minkowski,2.Half-circledand3.Kochfractalcurves)
asymmetrical fractal antennas those are connected with
RF GHz diodes to generate circularly polarized radi-
ation [3]. R. K. Singh et al.developedandtesteda
switchable polarization recongurable planar antenna
for WLAN/Wi-Fi applications [4]. Fouad Fertas et al.
presented a quad band CPW fed monopole slotted
compact antenna with switchable frequency for LTE
bands, WiMAX, WLAN and X-band satellite communi-
cation applications [5]. Nguyen-Trong N. et al.demon-
strated a method to control and switch the resonance
© 2022 IETE

2 A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA
of the two bands relative tuning ranges of approxi-
mately 11% using four varactors along with two DC bias
voltages [6]. Youcef B. Chaouche et al. demonstrated
a CPW fed dual band frequency-recongurable using
BAR50-02V double U-shaped CPW fed planar antenna
for WLAN/WiMAX application with gain between 2.3
and 3.90dBi and bidirectional radiation pattern [7].
Boukarkar et al. developed a magnetic-dipole frequency-
tuned dual-band antenna using a very simple DC bias
circuit for WLAN and WiMAX applications [8]. Xiao-
Lin Yang et al. presented a frequency tunable compact
monopole smart antenna which easily switched from
narrowband state to dual-band state using GaAS FET
(SKY13298-360LF from Skyworks) switch for WLAN,
WiMAX and PCS applications. FET is directly driven
by a digital signal of value 3.3 V that obsoletes the
need of blocking capacitor and DC bias network [9].
Even though, un-frequency recongured antennas are
very trendy for wireless WLAN operations [10–14]. J.
Kulkarni and C. Sim proposed a very compact, maze
shaped multi-band, miniaturized antenna without the
use of any extra hardware, costly substrate and lumped
elements [14]. MIMO antennas for high speed data
rate and reliability are the backbone of future wire-
less applications. Authors [15,16] demonstrated a high
isolation and wide band, 2-port CPW-fed and Flex-
ible/Transparent Connected-Ground MIMO antennas
those are useful in 5G NR sub-6 GHz, n77/n78/n79,
Wi-Fi-5,V2X/DSRC,Wi-Fi-6 Indian National Satellite
System INSAT-C for future wireless [15,16].
Inthereportedworkanedgefed,quarter-waveimpedance
transformer coupled, miniaturized, monopole, ultra-
wideband (UWB), dodecagon-shaped dual-band fre-
quency recongurable antenna using 4 numbers of RF
switches (BAR64-02V) for ISM, wireless, radar and mili-
tary applications has been developed, fabricated, investi-
gated and tested. The proposed antenna is multi-tuned
ultra-wideband (UWB) in nature with a single notch
band.
2. DESIGN METHODOLOGY
AntennaisdesignedandfabricatedonasubstrateFR-
4 of permittivity 4.4 with a thickness of 1.6 mm at
2.45 GHz. The patch antenna is a reduced volume (minia-
turized) version of a fundamental circular microstrip
patch antenna whose basic size is generally 4a ×4a,
where “a” is the radius of the circular microstrip radiating
patch.
2.1 Design Equations
The proposed antenna is developed by using the funda-
mental circular patch basic design equations
[10,11,13,17].
Figure 1: Dodecagon-shaped antenna (a) with full DGS, (b) with
reduced DGS and (c) excitation port

A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA 3
2.2 Design Development
Initially, the fundamental monopole circular patch
antenna was designed with radius 16.6 mm [17]. The
overall size of this antenna is 66.4mm ×66.4 mm [18].
Further, three isosceles deltas with each arm length equal
to λg/8 have been attached to the dodecagon-shaped
patchtoimprovegainandmaketheperformanceof
the antenna ultra-wideband as depicted in Figure 1(a).
Figure 2: Miniaturized dodecagon-shaped antenna (a) bottom
ground view and (b) top patch view
Further, the width of the ground is decreased to minia-
turize the size of the antenna along width as shown in
Figure 1(b), without aecting its reection coecient and
gain. This results in a total 30.41% reduction in the total
fundamental circular microstrip area. The miniaturized
version of the dodecagon-shaped microstrip antenna is
illustrated in Figure 2. A quarter wavelength impedance
transformer is introduced between 50microstrip exci-
tation feed and 398dodecagon antenna patch to
improve impedance matching as shown in Figure 2(b).
Theoretically, characteristics impedance of quarter wave
transformer is Zc=√(50 ×398)=141 ,itslength,
λg/4 =16.8 mm and its calculated width is 0.236 mm
[13], while it’s simulated length and width are 13.8 and
2.1 mm, respectively,at designed frequency of 2.45 GHz.
The antenna is again further modied as shown in
Figure 3.Rectangularcutsofsize3mm×1.6 mm are
placed in each isosceles triangle and feed. Afterward
these are attached with the dodecagon by a rectangle of
size 1.6 mm ×1.6 mm. This is the nal design for fre-
quency recongurable. Once the simulation has been
tested and optimized for this un-frequency recongured
antenna, BAR64-02V PIN diodes have connected after
fabrication. The equivalent circuits of these have shown
in Figure 5[19,20].TheswitchingofPINdiodesiscarried
out with a 2 V battery and 0.1μF capacitor.
2.3 Effect of Adding Three Delta Structures into
Dodecagon-Shaped Monopole Antenna
Eect of loading monopole dodecagon-shaped antenna
with three isosceles delta structures has been displayed
Figure 3: Modified Dodecagon-shaped un-frequency reconfi-
grable antenna without PIN diodes

4 A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA
Table 1: Three delta structures loading effect on monopole
dodecagon-shaped antenna
Freq. Reson.
bands Freq.
Antenna (GHz) (GHz) Performance parameters
Dodecagon shaped
without delta
1.79–4.46,
5.49–7.19,
7.97–8.90,
10.11–10.8
2.69,
6.80,
8.26,
10.50
Gain: 4.11dBi
Directivity:4.31dBi
Efficiency:95.76%
No. of bands: 04
No. of notch bands:
Three (4.46–5.49 GHz,
7.19–7.97 GHz, and
8.90–10.11 GHz)
-Quad-band broadband
antenna
Dodecagon shaped
with three deltas
1.79–3.73,
5.27–6.10,
6.48–11.47
3.10,
5.60,
8.98,
10.94
Gain:4.12dBi
Directivity:4.35dBi
Efficiency:96.1%
No. of bands: 03
No. of notch bands:
Two (3.73–5.27 GHz and
6.10–6.48 GHz)
-Tri-band multi-tuned
ultra-wideband with
1.54 GHz and 380 MHz
notch band
Dodecagon shaped
with three
slotted base
deltas
1.83–3.64,
5.25–12.04
2.86,
5.62,
7.26,
8.87,
10.9
Gain: 4.14dBi
Directivity: 4.34dBi
Efficiency:95.46%
No. of bands: Quad
No. of notch bands: single
(3.64–5.25 GHz)
-Dual band multi-tuned
ultra-wideband with
1.61 GHz notch band
Figure 4: Three isosceles deltas loading effect on dodecagon
monopole antenna
in Table 1.ItisclearfromTable1and the reec-
tion coecient plot of Figure 4that quad-broadband
nature of monopole dodecagon antenna is converted into
tri-band multi-tuned ultra-wideband (1.79–11.47 GHz)
nature with two small notch bands (3.73–5.27 GHz and
6.10–6.48 GHz) as it is loaded with three isosceles deltas.
Attheendthreeslotsaremadeinthebaseofeach
Table 2: Optimized parameter dimensions
Simulated
Parameter Calculated Optimized
Para-meter Designation/ Parameter Parameter
Name Description values (mm) values (mm)
TThickness of radiating patch 0.035 0.035
wPort width 3.0 3.0
hSubstrate/port height 1.6 1.6
Lsub Substrate length 66.4 59
Wsub Substrate width 66.4 52
Lgnd Defected ground structure
length
16.8 16
Wgnd Defected ground structure
width
66.4 50
aDodecagon circular patch
radius
16.592 16.6
L1Length of edge feed microstrip 16.6 3.0
L2Length of impedance
transformer
16.8 12.2
L3Length of PIN diode connect
portion
–1.6
W1Width of edge feed microstrip 3.06 3.0
W2Width of impedance
transformer
0.236 2.1
W3Width of PIN diode connect
portion
–1.6
SSide arm length of dodecagon
polygon
8.593 8.593
SDSide arm length of isosceles
triangle (in all three deltas)
8.4 10.12
SHHeight of isosceles triangle (in
all three deltas)
7.27 8.8
SBBase arm length of isosceles
triangle (in all three deltas)
8.4 10
Lcut Cut length of delta (in all three
deltas)
–1.6
Wcut Cut width of delta (in all three
deltas)
–3.0
delta that results in the ultra-wideband (1.83–12.04 GHz)
below −10 dB reection coecient and multi-tuned with
a notch band (3.64–5.25 GHz) of 1.61 GHz, this also led
to improve the gain of monopole antenna by a small
amount at designed frequency.
2.4 Insertion of PIN Diodes
Earliest, two diodes are connected in fed and arm1 as
shown in Figure 5(a). Secondly, the two more PIN diodes
are connected in rest two side deltas as depicted in
Figure 5(b). The optimized dimensions have been dis-
played in symbolic form in Figure 5(c) and their respec-
tive measurements with respect to theoretically calcu-
lated parameter values are depicted in Table 2.
A symbol of PIN diode (BAR64-2V) along with its equiv-
alent circuits when PIN is in ON state and in O State
respectively, are represented in Figure 6(a–c) [20]. Val-
ues of resistor, capacitor and inductor are standard and
taken directly from the data sheet of BAR64-02V there is
no provision of parameter variation as every PIN diode
has a xed internal equivalent circuit. According to the
size of PIN diode dimensions (1.6 mm ×1.6 mm), two

A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA 5
Figure 5: Modified dodecagon-shaped frequency reconfigure-
able antenna with (a) two PIN diodesone in feed and arm1, (b)
four PIN diodes one in feed and rest three are in each delta and
(c) optimized dimensions display
Figure 6: (a) PIN diode symbol (b) ON (forward biased) state and
(c) OFF (reverse biased) state [20] (d) Biasing arrangement of PIN
diode
rectangular strips (1.6 mm ×0.8 mm) has been divided
and lumped RLC values are applied in these strips
accordingtoPINdiodeONandOFFconditions[20].
Biasing arrangement of the PIN diode is shown in
Figure 6(d).
2.5 Frequency Reconfigurable Antenna Prototype
Figure 7illustrates the prototype images of the frequency
recongurable antenna along with connections of four
PIN diodes with connecting wires for biasing. The 2 V
dc biasing to four PIN diodes are applied using variable
power supply and a 0.1μF capacitor.
3. RESULTS AND DISCUSSIONS
The various modes of switching combinations of PIN
connected in the microstrip dodecagon structure arms
of patch antenna have been simulated and measured
using Keysight technology VNA (N9917A) as depicted
in Figure 8.

6 A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA
Figure 7: Prototype of frequency reconfigurable microstrip antenna using BAR64-02V and bias connections
Figure 8: Laboratory measurements of prototype of proposed
reconfigurable antenna
3.1 Dodecagon-Shaped Antenna Switching with
Two PIN Diodes (one PIN-Diode in Front Delta
Arm and Other in Feed)
Table 3represents the comparison of the simulated resul-
tant parameters of un-frequency recongured antenna
when not even a single diode is connected in the patch
and frequency recongured antenna when one diode is
connected in the front delta arm of the radiating patch.
The two recongurable switching cases have been dis-
cussed when the PIN is forward biased (ON) state and
reverse biased (in OFF) state. Their reection coe-
cient curves S11 have been indicated in Figure 9.Itis
observed that when PIN is forward biased (ON) the
overall electrical patch length increased and the fre-
quencyshifttowardstheleftandinothercasewhen
PIN is reverse biased (OFF) state the electrical patch
length decreased since the front main delta arm detached
from the patch and results in frequency shift towards
right to the non-recongurable antenna. Abberiviations
of Table 3are f0=Designed frequency (2.45 GHz);
N=number of bands, 1 =PIN diode ON; 0 =
PIN diode OFF; D1=PIN Diode in Delta Arm1; fL–
fH=−10 dB Frequency Span around resonance fre-
quency; fL=lower frequency, fH=higher frequency,
FBW =−10 dB Fractional Bandwidth; fr=Resonance
Frequencies; S11 =Reection Coecient; G =Peak
Gain at f0;D=directivity at f0,η=Radiation Eciency.
3.2 Mode of Operations Without PIN Diode
(Un-Frequency Reconfigured) and with PIN
Diodes Frequency Reconfigurable Antenna
(with one PIN-Diode in Front Delta Arm)
Table 4illustrates the comparison of the simulated
resultant parameters of un-frequency recongured and
frequency recongured antenna when two diodes are
connectedoutofwhichonediodeisconnectedin
the feed and another PIN diode is connected in the
front delta arm of the radiating patch as shown in
Figure 5(a). Abbreviations for Table 4:f0=Designed
frequency (2.45 GHz); N=number of bands, 1 =PIN
diode ON; 0 =PIN diode OFF; X=don’t care either
0or1;D
1=PIN Diode in Delta Arm1; D4=PIN
Diode in microstrip feed line; fL–fH=−10 dB Fre-
quency Span around resonance frequency; fL=lower
frequency, IH=higher frequency, FBW =−10 dB
Fractional Bandwidth; Ir=Resonance Frequencies;
S11 =Reection Coecient; G =Peak Gain at f0;
D=directivity at f0;η=Radiation eciency.
The two recongurable switching modes operations have
been discussed when the PIN diode in the front delta

A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA 7
Table 3: Mode of operations performance table without PIN diodes (un-frequency reconfigured)
and with PIN diodes (frequency reconfigurable)
MODE D1NBand
Span
fL–fH
GHz
FBW
%
frGHz –S11
dB
GdBi D
dBi
η
%
WithoutPIN Diodes X 2 1.82–3.61
5.24–12.43
65.93
81.38
2.92
7.18
21.66
25.09
6.74 @
2.12GHz
4.31 95.40
With PIN Diodes 0 2 1.84–3.70
5.12–12.03
67.15
80.58
3.02,
7.25
9.30
10.95
25.49
25.29
30.13
27.62
4.157 4.34 95.66
1 3 1.67–3.52
4.94–5.81
6.49–6.96
71.29
16.18
6.99
2.73
5.27
6.70
27.04
15.47
28.18
4.15 4.39 94.65
Figure 9: S11 curves without and with frequency reconfigurable microstrip antenna with one pin-diode is connected in main delta arm
Table 4: Frequency switching operation with two PIN diodes
CASE D4D1NBand Span
fLto fH
(GHz)
FBW
(%)
fr
GHz
–S11
dB
G
dBi
D
dBi
η
%
1 1 0 3 1.80–3.77
4.65–5.17
7.49–7.59
70.73
10.59
1.32
3.09
4.87
7.01
19.27
11.27
20.43
3.93 4.29 91.99
2 1 1 2 1.84–3.64
6.54–7.54
65.69
14.20
2.74
7.15
16.67
23.08
3.97 4.34 91.83
3 and 4 0 X No meaningful results (not realistic one)
arm is in ON state and in OFF state. In both the cases
their reection coecient curves S11 have been shown
in Figure 10.ItisobservedthatwhenthePINdiode
is forward biased (in ON state) the overall microstrip
patch antenna electrical length increased and the fre-
quencyshifttowardstheleftandinothercasewhenPIN
is reverse biased (in OFF state) the overall microstrip
patch antenna electrical length decreased since the front
main delta arm detached from the patch and results in
frequency shift towards right to the non-recongurable
antenna.
3.3 Frequency Reconfigurable (Switching)
Antenna with Four-Diodes (One Diode in
Microstrip Feed and Rest Three Diodes are
Delta Arms)
The dodecagon-shaped three delta loaded structure can
be frequency recongured by connecting four pin diodes
according to Figure 5(b). Table 5presents the eight pos-
sible combinations of three PIN diodes connected in the
three delta arms. One PIN is connected in the microstrip
feed line, which is always in ON state and controls the
overall functioning of the other three diodes. When

8 A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA
Figure 10: S11 curves of antenna with two switching operations of PIN
Figure 11: Reflection coefficient curves of 8-digital switching combinations of frequency reconfigurable antenna
the feed PIN is in OFF state no any possible combina-
tions of delta arms PIN diodes are in working mode.
Thesecasesarementionedinthetableascase9–16.
The comparison of the simulated resultant parameters
of un-frequency recongured and when one diode is
connected in the feed line and other three diodes are con-
nected in the three delta arms of the radiating patch as
shown in Figure 5(b). The eight recongurable switch-
ing cases have been discussed when the PIN diodes in
three delta arms are in ON/OFF states. In all the cases

A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA 9
Table 5: Frequency reconfigurable antenna with four diodes
No. of Band Resonance Ref. Peak Gain Peak Max.
bands fL–fHFBW Freq. Coeff., G(dBi) Directivity Radiation
CASE D4D3D2D1(N)(GHz) (%)fr(GHz) –S11 (dB) @f0D(dBi) Efficiency, η(%)
1 1 0 0 0 2 2.01–5.44,
6.95–13.66
92.08,
65.11
3.39
7.34
10.32
12.09
13.12
23.33
18.24
22.14
18.04
16.64
3.86 4.25 91.5
2 1 0 0 1 2 1.87–5.57,
6.68–13.68
99.46,
68.76
2.75
4.96
7.17
10.36
11.72
13.15
18.0
17.95
16.84
22.28
16.72
16.38
3.94 4.33 91.5
3 1 0 1 0 2 1.64–5.76,
6.53–13.63
111.4,
70.78
2.75
4.78
6.97
10.48
11.98
13.04
22.15
27.98
13.85
20.58
18.06
16.99
3.806 4.2 91.4
4 1 0 1 1 2 1.92–5.88,
6.60–13.60
101.5
69.3
2.78
4.80
7.08
10.50
11.96
13.04
17.61
20.53
15.99
20.33
17.64
17.04
3.896 4.29 91.4
5 1 1 0 0 2 1.90–3.57,
4.23–7.34
61.06
53.76
3.03
5.38
6.9
18.19
17.52
16.43
3.83 4.22 91.4
6 1 1 0 1 2 1.87–3.43,
4.27–7.38
58.86,
53.39
2.72
4.64
7.01
15.95
18.62
16.5
3.9 4.29 91.3
7 1 1 1 0 2 1.97–3.61,
4.11–7.19
58.19,
54.51
3.02
5.29
6.79
18.23
18.86
16.7
3.81 4.21 91.2
8 1 1 1 1 2 1.78–3.52,
4.20–7.15
65.66
51.98
2.68
4.67
6.85
16.52
16.25
13.76
3.92 4.33 91
9 and 16 0 X X X Not significant results
their reection coecient curves S11 have been shown in
Figure 11. Abbreviations for Table 5are f0=Designed
frequency (2.45 GHz); N=number of bands; 1 =PIN
diode ON; 0 =PIN diode OFF; X =don’t care either
0or1;D
4=PIN Diode in Feed; D3=PIN Diode
in Delta Arm3; D2=PIN Diode in Delta Arm2;
D1=PIN Diode in Delta Arm1; fLto fH=−10 dB Fre-
quency Span; FBW =−10 dB Fractional Bandwidth;
fr=Resonance Frequencies; S11 =Reection Coef-
cient; G =Peak Gain at f0;D=directivity at f0;
η=Radiation Eciency.
3.4 Radiation Pattern
The gain radiation patterns in E-plane and H-plane direc-
tions for every eight switching modes of D4D3D2D1
(1000 to 1111 cases) of Table 5are represented in
Figure 12.ThepatternisOmni-directionalinE-plane
direction and bi-directional in H-plane direction in all
case. As gain radiation patterns and their radiation direc-
tions (directivity) are constant and unaected by the
switching mode of operations of PIN diode combina-
tions,thisconrmsthatthePINdiodeonlyprovidefre-
quency recongurable modes of operation and pattern
reconguration is not possible with PIN diode. Pattern
reconguration is possible only with varactor diode.
3.5 Performance Comparison with Recently
Published Frequency Reconfigurable
Antennas
It is observed from the competitive Table 6that the pro-
posed antenna is novel in the sense that it has higher
electrical length than monopole circular antenna as three
isosceles triangles increases the overall electrical length
of the antenna that results in ultra-wideband bandwidth
with a notch band of 3.61–5.24GHz and little improve-
mentinthegainanddirectivityofeachmodeofswitch-
ing operations. The antenna is economic as it is fabricated
on low cost FR-4 substrate and utilizing four PIN diodes
with very simple biasing arrangement (Figure 6(d)) for
total 8 switching modes of operations.

10 A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA
Figure 12: Gain radiation patterns at 2.45 GHz with =0° (E-Plane), =90° (H-Plane)

A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA 11
Table 6: Comparison of existing frequency reconfigurable antennas with proposed antenna
Switching Antenna Size
No. of Mode of (mm3)And
Ref. Description switches Bands Operation Substrate Miniaturization
[2] CPW fed slotted
dual mode
operated
antenna
3 (PIN diodes
MA4AGBLP912)
2
[3.2–3.6 GHz] and
[4.9–5.35 GHz]
2 RO4350B
(r=3.48,
h=1.524 mm, tan
δ=0:0037)
30X40X1.524, 30.41%
[3] Fractal boundary
antennas with
Coaxial probe
feed
4 (PIN Diodes
MA4P789)
3
(fr=1.8, 2.48, 3.4 GHz)
8RTDuroid
(r=2.2,
h=3.2 mm,
tan δ=0:0009)
48X48X3.2,
0%
[4] V-shaped
truncated corner
with impedance
transformer
edge feed
3 (PIN diodes
MA4SPS402)
1
(FBW =3.94% and
2.12% for both CP
cases, fr=5.08 GHz,
5.18 Hz)
3 N9000 Neltec (tan
δ=0.002,
r=2.2,
h=0.762 mm)
48X50X0.762,
0%
[5] A Compact
Slot-Antenna
with Tuneable
Frequency with
CPW fed
34
a. [2.37–2.75 GHz],
b. [3.15–4.08 GHz], c.
[4.48–5.92 GHz], and d.
[6.69–8.31 GHz]
8 FR4 (tan
δ=0.017,
h=1.6 mm,
r=4.3)
24X29X1.6,
160.7%
[6]Acoaxfed
dual-pattern
frequency-
reconfigurable
dual-band
antenna
4(Varactor
MACOM
MA46H120)
2
[2.62–2.91 GHz] and [
3.42–3.81 GHz], Tuning
bandwidth =11% in
both the cases
8 Duroid Roger
RO4350B
(r=3.66, tan
δ=0.004)
33X34,
115.8%
[7] Double U-shaped
monopole CPW
fed printed
Microstrip
antenna for
WiMAX/WLAN
applications
1 (PIN diodes
BAR50-02V)
when switch: 1.OFF:
Single band
[2.8–3.5 GHz] and
2.ON: Dual Band
[2.8–4.1 GHz/4.9–5.8 GHz]
2FR4(r=3.66,
h=1.524 mm,
tan δ=0.004)
30X25X1.524,
0%
[18] CPW fed dual-band
frequency-
tunable
antenna
2(Varactor
diodes
Infineon
BB857)
2[3.28–3.51 GHz] and
[5.47–6.03 GHz]
4F4B
(h=0.764 mm)
40X40X0.764,
0%
This Work Dodecagon-
Shaped
Microstrip
Antenna
Practically
Loaded
with 3-Delta
Structures
4 (PIN diodes
BAP64- 02 V)
2 [1.82–3.61 GHz] and
[5.24–12.43 GHz]
8 FR4 (tan δ=0.02,
h=1.6 mm,
r=4.4)
52X59X1.6,
30.41%
4. CONCLUSION
The simulated S11 andmeasuredS
11 results of the pro-
totype antenna are in good agreement. In some opera-
tional modes, measurement results may vary because of
some soldering, DC biasing and improper value selec-
tion of capacitor. The dierence between the simulated
S11 andmeasuredS
11 graphs is because of the solder-
ing contact of PIN diodes, fabrication of prototype and
improper soldering connections. The designed frequency
recongurable antenna shows elastic behavior for numer-
ous wireless applications with digital binary switching
combinations of PIN diodes. In every case, the antenna
shows an Omni-directional radiation pattern at the
designed frequency. This antenna can easily be converted
into a pattern recongurable by changing each PIN diode
with a capacitor. The proposed antenna can also be pat-
tern/beam recongured in near future. The behavior of
this antenna can be systematized by a program either in
MATLAB/Python or using IoT. Thereby, the implemen-
tation of a designed prototype with software controlling
programs will change the nature of the antenna into a
smarter one.
ACKNOWLEDGEMENTS
The authors are grateful to Hon’ble Vice-Chancellor, Gurukul
Kangri University, Haridwar, India for providing software and
hardware support for the development of the project. The
authors are also grateful to Karunya University, Coimbatore for
providing technical support in various measurements.
ORCID
Atul Varshney http://orcid.org/0000-0003-0440-4937
T. Ma r y Ne e b h a http://orcid.org/0000-0002-0981-3089
Vipul Sharma http://orcid.org/0000-0002-5705-4259

12 A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA
J. Grace Jency http://orcid.org/0000-0003-1352-9846
A. Diana Andrushia http://orcid.org/0000-0003-0001-2733
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A. VARSHNEY ET AL.: DODECAGON-SHAPED FREQUENCY RECONFIGURABLE ANTENNA 13
AUTHORS
Atul Varshney is an Assistant Profes-
sor in ECE Department, Gurukul Kan-
gri University, Haridwar, India. He is a
RF microwave and antenna researcher
and published many patents, research arti-
cles and books in this particular area.
He has received his MTech in Microwave
from MITS, India in 2008. He also did a
microstrip to waveguide transition project from ISRO-SAC,
Ahmedabad. His research interests include fabrication and
design of microstrip to waveguide transitions, ring resonators,
microwave lters, planar antennas, metamaterial and fractal
structures, RLC Electrical Equivalent circuits generation of any
microwave 2D/3D components, frequency and pattern recon-
gurable antennas etc.
Corresponding author. Email: 260984atul@gmail.com
T. M a r y Ne e b ha is an Assistant Professor
in ECE department, KITS, Tamil Nadu,
India.HerresearchareaincludesRFand
microwave devices, antenna design, meta-
materials, exible antenna development,
material characterization, design of mil-
limeter and conformal antennas, DRA,
machine learning techniques and opti-
mization techniques. She has published >50 papers. Her
present major contribution is in the DRDO funded project on
“wearable antenna design” worth 40 lakhs. The outcome of the
work has been published in SCIE indexed journals and sub-
mitted for patents. She is an active member of IEEE and a life
member of IETE.
Email: maryneebha@karunya.edu
Vipul Sharma is an Associate Professor
in ECE department, Gurukul Kangri Uni-
versity,Haridwar,India.DrSharmaisan
antenna researcher and he has got many
patents, research articles and books in this
particular area.
Email: vipul.s@redimail.com
J. Grace Jenc y, did her doctorate in MEMS
piezo resistive accelerometer at KITS,
Tamil Nadu, In d i a . She pub l i s hed many
research papers. Her specialization area
includes and exible capacitors and use of
MEMS in biomedical applications. Now
her interest is oriented towards miniatur-
ized exible antennas. She has expertise in
dierent simulation tools like ANSYS, Xilinux and SPICE tools.
She is a reviewer of Micro Electronics Journal.
Email: grace@gemspolytechnic.edu
A. Diana Andrushia, received her PhD in
Information and Communication Engi-
neeringwithemphasisonComputer
Vision and Image Unde rstanding from
Anna University (2018) India. She is
Assist. Professor in ECE Department at
KITS, Coimbatore, Tamil Nadu, India.
Her area of research includes Computer
Vision, applications of AI in Structural Health Monitoring,
Precision Agriculture and Pattern Recognition.
Email: diana@karunya.edu