IACS Institutional Repository

Singh, W Shambhunath

Singh, N Shanta

Soni, Ajay

Singh, S Dorendrajit

Singh, L Robindro

Okram, Gunadhor S

Indian J. Phys. 81 (12), 1267-1274 (2007) 
Characterisation of ZnS nanocrystals prepared by wet 
chemical method 
W Shambhunath Singhd\ N Shanta Singhd, Ajay Soni\ S Dorendrajit Singhb 
L Robindro Singhb and Gunadhor S Okramr 
-Department of Physics, Manipur College, Imphal-795 008. Manipui. India 
department of Physics, Manipur University, Canchipur, Imphal-795 003, Manipur. India 
CUGC-DAE Consortium for Scientific Research, Indore-452 017, Madhya Pradesh, India 
E-mail snath\ui sancharnet in 
Received 1 March 2007, accepted 7 September 2007 
Abstract : ZnS nanocrystals of different sizes have been prepared by wet chemical method X-Ray 
diffraction (XRD) pattern of ZnS powder shows the zinc blende structure of the crystals with a size variation 
from 2.9 to 1.6 nm with the addition of capping agent C2H5OSH The optical absorption of ZnS deposited on quartz 
shows the blue shift with the increase in the bandgap from 3.6 to 4 0 eV The observed low thermal activation 
energy of 0.4 eV determined from resistivity data on the pellets of capped ZnS suggests the formation of charge 
carrier traps in the presence of capping agent Thermolummescence (TL) glow curves of the nanostructured 
ZnS crystals could not be observed 
Keywords : Nanostructures, semiconductors, chemical synthesis, optical properties 
PACSNos. : 81.07.Bc, 78.67.Bf 
1. Introduction 
Group ll-VI semiconductors occupy a prominent place in the semiconductor physics and 
optoelectronic devices as they show a high efficiency of radiative recombination, high 
absorption co-efficient and direct band gaps corresponding to a wide spectrum of 
wavelengths from ultraviolet to infra-red regions. Since the theoretical explanation of the 
quantum confinement effect of zero dimensional nanomaterials or quantum dots by Efros 
and Efros [1] and their novel properties and potential applications [2] these materials have 
drawn the interests of many researchers in recent years. Special attention is paid to 
Corresponding Author 
© 2007 IACS 
1268 W Shambhunath Singh et al 
nanocrystalline semiconductors for their remarkable properties such as nanoelectronics. 
quantum electronics, sensor technology, non-linear optics and solar technology, different 
from their conventional counterparts [3]. 
Among ll-VI semiconductors CdS and ZnS are widely used as window layers of solar 
cells. They exhibit strong size-dependent optical properties. Increase in the band gap and 
hence the blue shift in the optical absorbance with decrease in the particle size is observed 
This effect occurs when the size of the nanocrystals is smaller than the corresponding 
bulk Bohr exciton radius, a consequence of localisation of charge carriers and hence 
quantum confinement [4]. Extensive investigations [5-17] have been carried out on ll-V! 
semiconductor nanomaterials as they are relatively easy to synthesise and can generally 
be prepared as nanoparticles, or in thin film forms. Among a number of methods for the 
preparation of ZnS wet chemical synthesis process offers an inexpensive and simple 
means to synthesize such particles with good control of size and size distribution by 
optimising various parameters and can be deposited over a large area. Many workers 
[18-21] reported the use of using NH4OH as complexing agent of Zn to form [Zn(NH3)4]2+, 
which ensures the slow release of Zn2+ ions from the complex during the reaction. It also 
can vary the pH of the reaction bath. 
In this paper we present the preparation of nanostructured ZnS crystals using wet 
chemical method using inorganic precursors ZnCI2 and Na2S as the sources of Zn and S 
respectively. Mercaptoethanol (C2H5OSH) and liquor ammonia in form of NH4OH have been 
used as capping agent and complexing agent respectively. XRD pattern of the prepared 
ZnS powder shows that with the addition of C2H5OSH the size of ZnS decreases from 2.9 
nm to 1.6 nm. The size of the particles has also been calculated using effective mass 
approximation (EMA). The blue shift has been observed in the absorbance spectra of ZnS 
thin films deposited on quartz by normal dip coating with the addition of C2H5OSH. This 
is due to the quantum confinement effect. The band gap calculated using the absorbance 
spectra increases from 3.6 to 4.0 eV Chen et al [12, 13] reported thermoluminescence 
(TL) glow curve of ZnS nanocrystals and studied the surface states of the nanoparticles. 
They have pointed out that electron or hole traps are produced in the band gaps of the 
nanocrystals even without irradiation since in such particles, ions at the surface increase 
rapidly when the size becomes smaller. Carriers (electrons or holes) trapped in such 
surface states or defect states may be released by thermal stimulation and recombine at 
recombination centers to give out TL. Further, the observed TL of nanocrystalline ZnS 
samples has been attributed to the long wavelength peak in the absorbance spectrum 
and hence to the presence of surface states. However, Kumbhojkar et al [9] could not 
observe any red shifted peak in the absorption spectra of ZnS. Indeed, for deeper 
understanding on ZnS nanocrystals, their electrical properties in the low temperature are 
also desirable. So far, this has been mostly reported for high temperatures [22,23]. In this 
paper low temperature resistivity of ZnS prepared with and without capping agent over a 
range of temperature 150 to 300 K has been measured. ZnS prepared without capping 
agent remains as an insulator over this range of temperature whereas ZnS prepared with 
C2H5OSH shows a transition at around 250 K giving a thermal activation energy of 0.4 eV 
Characterisation of ZnS nanocrystals prepared by wet chemical method 1269 
which is an indication of charge carrier traps. The thermoluminescence (TL) readout of 
ZnS nanocrystals before and after irradiation by
 Y-rays has been recorded. However no TL 
of ZnS nanocrystal could be observed. 
2. Experimental details 
The preparation method reported by Qu et al [17] has been modified with the addition of 
NH4OH. The ZnS samples are prepared using ZnCI2 (GR, Merck) and Na2S (GR, Merck) 
as sources of Zn and S respectively. Liquor ammonia (30% GR, Merck) is added to 100 
ml of freshly prepared ZnCI2 (0.1 M) solution. The solution becomes turbid initially but on 
adding excess ammonia the solution becomes clear as before indicating the formation of 
the complex [Zn(NH3)4]2+. NH4CI is used as buffer solution. Following the standard method 
[18], the chemically and ultrasonically cleaned quartz and glass substrates are mounted 
in the reaction bath before the addition of Na2S. The mixture is then heated upto 70°C 
and 0.1 M Na2S is added at the rate of 1 ml per minute under nitrogen atmosphere with 
constant stirring. The reaction is carried out using different molarities of the capping agent 
C2H5OSH. Thin films of ZnS are thus deposited on quartz and glass substrates by dip 
coating method. Further, the reaction is continued to obtain the precipitate of ZnS. The 
precipitate is centrifuged, washed with distilled water several times to extract any excess 
Na2S, and finally extracted with methanol. The precipitates of ZnS are air-dried at 40°C. 
ZnS nanocrystals thus prepared without capping agent is labeled as Z1, with C2H5OSH 
(0.001 M) as Z2 and C2H5OSH (0.05 M) as Z3. 
The particle size and crystal structure of the samples are determined from XRD data 
obtained using Rigaku 18 kW Rotating X-ray generator equipped with Rigaku D-Max-300, 
0 - 20 Goniometer with CuKa X-radiation. The ionic composition is determined using energy 
dispersive X-rays (EDX) data. The micrographs are recorded using a Digital Instruments 
Nanoscope AFM (E Verson-245). The optical absorbance of ZnS deposited on quartz is 
recorded using UV-Visible Spectrophotometer (Systronics-2202). The TL readout data of 
ZnS nanocrystals before and after y-rays irradiation has been recorded using a TL recorder 
(RCA931A). The resistivity data are collected on the pellets of 8 mm diameter of dried 
ZnS with the help of a Keithley 6517A electrometer and a 240 Lakeshore temperature 
controller in the temperature range 150 K to 300 K. 
3. Results and discussion 
The XRD patterns of nanostructured ZnS powders Z1, Z2 and Z3 indicate that the crystallites 
exist in the zinc blende structure (Figure 1) with prominent peaks at the 20 values of 
28.75°, 48.05° and 57.17° corresponding to (111), (220) and (311) planes respectively 
[JCPDS Card No. 80-0020]. Close observation of the patterns shows gradual broadening 
of the peaks, say (111) peak. These peaks have been utilised to estimate the size of the 
crystallites using Scherrer formula [24], D = ftt /(/Jcos0), where D is the average grain 
size, K is a constant (~1), P is the full width at half maximum and a is the Bragg's 
angle. The crystallite sizes thus estimated for the Z1, Z2 and Z3 samples are in decreasing 
1270 W Shambhunath Singh et a/ 
order (Table 1) Figure 2 shows a representative 2-dimensional AFM picture of the pellet 
of Z2 The nanostructured particles are seen to be agglomerated to from a gram having a 
size of about 30 nm with rather well defined grain boundaries 
800 
600 
(111) 
(220) 
s 400 
200 
t i (311) 
** l \ tt»*v'^>»wm now,, 22 
* * * * * * z3 
20 40 60 
2B (degrees) 
80 100 
Figure 1 XRD patterns of nanostructured crystals of ZnS (Z1) corresponds to ZnS prepared without 
cappant (Z2) and (Z3) those with 0 001 M and 0 05 mercaptoethano! as cappant 
Scan size 
Scan rate 
Number of samples 
^50 0 nm 
20 35 Hz 
256 
Figure 2. Two dimensional AFM image of pellet of dried nanocrystailme ZnS particles prepared with 0 001 
M mercaptoethanol (Z2) 
The optical absorbance of the Z1, Z2 and Z3 samples are shown in Figure 3 It is 
clearly seen from the figure that there is blue shift in the absorption edge of the optical 
spectra of ZnS as the particle size decreases due to the quantum confinement effect 
Characterisation of ZnS nanocrystals prepared by wet chemical method 1271 
Table 1. Grain size of Z1, Z2 and Z3 samples obtained from XRD data 
Sample Grain size Band gap 
from XRD (eV) 
(nm) 
21 2 9 3 6 
22 2 0 3 8 
Z3 1.6 4 0 
The band gap of the sample is calculated from the absorbance spectra shown in Figure 3 
using the relation [25] (at*,fn = A(hv~Eg), where a is the absorption co-efficient, hi> is 
the photon energy, A is a constant and Eg is the band gap of the material. The value of 
n in the exponent is 1/2 for direct, allowed transitions. 
0 7 
0 6,. 
05,-
0 4 . 
I 
<
 03 , . 
0 2 . 
0 1 . 
200 300 400 500 
k(nm) 
Figure 3. Absorbance spectra of thin films of nanocrystalline ZnS deposited on quartz substrate (Z1) 
corresponds to ZnS prepared without cappant, (Z2) and (Z3) those with 0 001 M and 0 05 M cappant 
Figure 4 shows the plots of (ahvf vs. hv- The linear portion of the plot of ( a / v f vs 
hv in the region of strong absorption has been extrapolated to obtain the intercept on 
the hv axis. The intercept gives the value of the band gap Eg, which is also listed in 
Table 1. It is clear that the band gap increases with decrease in particle size. From Table 
1 it is also observed that optical bandgap of the particles Z2 and Z3 are found to exceed 
the bandgap 3.6 eV of bulk ZnS. This can be attributed to the quantum confinement 
effect as the particle size becomes smaller than the Bohr exciton radius (2.5 nm) of ZnS. 
The exciton energy E obtained using effective mass approximation (EMA) for strong 
confinement is given by [4] Es = Eg + (h2n2 )/(2JU/=?2 ) - (l .786e2 )/(4ne0t*R) - 0.248ERV , 
where ix is the reduced effective mass, e is the dielectric constant of ZnS and c0 is 
the permittivity in vacuum, Epy is the effective Rydberg energy. Using this relation the 
and EMA and their band gaps 
Gram size 
from EMA 
(nm) 
2 4 
1 9 
1272 W Shambhunath Singh et al 
grain size of Z2 and Z3 are found to be 2 4 nm and 1 9 nm respectively (Table 1) The 
gram size determined from XRD data and EMA are found to agree 
1 5 
E O 
A 05 . 
4 5 
Figure 4. Variation of (hva) vs h\ of thin films of ZnS the linear portion of the curves has been 
extrapolated to obtain the intercept to give the band gap of ZnS crystals (Z1) corresponds to ZnS 
prepared without cappant (Z2) and (Z3) those with 0 001 M and 0 05 cappant 
Figure 5 shows the variation of log resistivity (In p ) with the reciprocal of temperature 
1000/7" The resistivity p of Z1 shows a fairly large constant value over this temperature 
range, indicative of highly insulating nature However, the resistivity of Z2 shows a transition 
at around 250 K and the linear fit of the curve of Z2 over the region of transition shows 
that it follows the Arrhenius equation p = pQ exp(£a IkT), where Ea is the thermal activation 
energy and kB is the Boltzmann constant The thermal activation energy of the 
26 
Inp 
24 
22 
(Z1> 
yi^iiUmtttttttti:: 
' (22) 
1000/T 
Figure 5. Variation of In p with 1000/7 of pellets of ZnS nanocrystats prepared without cappant (Z1) 
and prepared with 0 001 M mercaptoethanol (22) 
Characterisation ofZnS nanocrystals prepared by wet chemical method 1273 
nanostructured ZnS crystals Z2 prepared using mercaptoethanol is then obtained from the 
slope of the linear portion of the curve of Z2 The value of Ea is found to be 0 4 eV is 
much smaller than the band gap of 3 6 eV of bulk ZnS Ion and Antohe [26] in their 
investigation of temperature dependence of electrical resistance of CdSe thin films placed 
in a He closed cycle cryostat reported the presence of a deep donor level located at 0 37 
eV below the bottom edge of the conduction band The present observed value of E of 
0 4 eV is close to their reported value of CdSe thin films To understand this better, ^ we 
attempt to record the TL glow curves of these ZnS crystals both before and after y-rays 
irradiation However, no TL response is observed It is interesting to note that electron or 
hole traps are produced in the band gaps of the nanocrystals even without irradiation 
since in such particles ions at the surface increase rapidly when the size becomes smaller 
[12,13] Carriers trapped in such surface states may be released by thermal stimulation 
and recombine at recombination centers to give TL Chen et al [12 13] observed TL of 
nanocrystalline ZnS samples, which has been attributed to the long wavelength peak in 
the absorbance spectrum and further to the presence of surface states On the other 
hand, Kumbhojkar et al did not observe any red shifted peak in the absorption spectra of 
ZnS [9] The thermal activation energy of 0 4 eV found from the present resistivity data 
may thus be associated with the charge carrier traps in the presence of the cappant The 
activation energy of 0 4 eV, being in the far infra-red region, is thus corroborated with 
absence of peak in UV-Visible absorption spectra and TL read out 
4. Conclusion 
Nanocrystalline ZnS particles both in powder and thin film have been prepared using wet 
chemical method The sizes of crystallites are found to lie in the range of 1 6-2 9 nm 
The optical and electrical properties have been studied The quantum confinement effect 
is apparent from the observed blue shift of the absorption spectra The band gap increases 
from 3 6 to 4 0 eV as the size decreases from 2 9 to 1 6 nm Resistivity of pallets of 
nanocrystalline ZnS prepared with capping agent gives the thermal activation energy of 
0 4 eV, which is associated with the formation of charge carrier traps in the presence of 
the capping agent 
Acknowledgment 
One of the authors (WSS) wishes to thank the University Grants Commission, New Delhi 
for financial assistance [vide its letter F No 30-5/2004(SR)] We also would like to thank 
V Ganesan and N P Lalla, UGC-DAE CSR, Indore for AFM and XRD measurements 
References 
[1] Al L Efros and A L Efros Phys Semicond Sov 16 772 (1982) 
[2] L E Brus J Phys Chem 90 2555 (1986) 
[3] T Tnndade and P N L Pickett O'Brien Chem Mater 13 3843 (2001) 
[4] A D Yoffe Advances in Phys 42 173 (1993) 
15] S Mahamun., A A Khosrav,, M Kundu. A Kshirsagar A Badekar D B Avasare, P Smgh and S K 
Kulkarni J Appl Phys 73 5237 (1998) 
1274 W Shambhunath Singh et al 
[6] K K Nanda, S N Sarangi, S Mohanty and S N Sahu Thin Solid Films 322 21 (1998) 
[7] S N Bahera, S N Sahu and K K Nanda Indian J Phys 74A 81 (2000) 
[8] L Brus AppI Phys A53 465 (1991) 
[9] N Kumbhojkar, V V Nikesh, A Kshirsagar and S Mahamuni J AppI Phys 88 6260 (2000) 
[10] I K Battisha, H H Afify, G Fattah El Abd and Y Badr Fizika 11 31 (2002) 
[11] T Ogata, H Hosokawa, T Oshiro, Y Wada, T Sakata, H Mori and S Yanagida Chem Lett 21 1665 
(1992) 
[12] W Chen, Z Wang, Z Lin and L Lin J AppI Phys 82 3111 (1997) 
[13] W Chen, Z Wang, Z Lin and L Lin AppI Phys Lett 70 1465 (1997) 
[14] S Banerjee, R Pal, A B Maity, S Chaudhun and A K Pal Nanostructured Materials 3 301 (1997) 
[15] A Osinky, Y Qui, J Mahan, H Temkin, S A Gurevich, S I Nesterov, E M Tanklevskaia, V Tretyakov 
and O A Lavrova AppI Phys Lett 71 509 (1997) 
[16] I O Oladeji and L Chow Thin Solid Films 474 77 (2004) 
[17] S C Qu, W H Zhou, F Q Liu, N F Chen, Z G Wang, H Y Pan and D P Yu AppI Phys Lett 80 3605 
(2002) 
[18] I O Oladeji and L Chow J Electrechem Soc 144 2342 (1997) 
[19] A Antony, K V Murali R Manoj and M K Jayaraj Matt Chem and Phys 90 106 (2005) 
[20] P K Ghosh, M K Mitra and K K Chattopadhyay Nanotechnology 16 107 (2005) 
[21] I O Oladeji and L Chow Thin Solid Films 339 148 (1999) 
[22] A U Ubale and D K Kulkarni Bull Mat Sc 28 43 (2005) 
[23] A Ashour, H H Afifi and S A Mahmoud Thin Solid Films 248 253 (1994) 
[24] Ch Hammond The Basis of Crystallography and Diffraction (Oxford Oxford) p148 (1887) 
[25] J I Pankove Optical Processes in semiconductors (New Jersey, USA Prentice Hall) p34 (1971) 
[26] L ion and S Atohe J AppI Phys 97 013513 (2005) 


Characterisation of ZnS Nanocrystals Prepared by Wet Chemical Method

Bhunia, S

Biswas, S

Sarkar, D

Sarkar, P P

flfepid Communication 
Indian J. Phys. 82 (7) 829-832 (2008) 
# 
Experimental investigation on single layer single-feed 
dual frequency (dual band) reduced sized slotted square 
microstrip patch antenna 
S Bhunia1, S Biswas2, D Sarkar2 and P P Sarkar2* 
1Academy of Technology, Hooghly-712 121, West Bengal, India 
2USIC, University of Kalyani, Kalyani, Nadia-741 235, West Bengal, India 
E-mail : parthabe91@yahoo.co.in 
Received 14 August 2007, accepted 13 May 2008 
Abstract : A novel, compact, single probe-feed square microstrip patch antenna for operation in dual frequency 
can be achieved by cutting a circular slot having an inner square patch at its centre.From the experimental results 
obtained, the antenna size using the proposed design method can be reduced by about 70% compared to what is 
achieved in conventional design method using a simple square patch without the slot. This paper focuses about 
the typical results obtained experimentally. 
Keywords : Dual frequency, dual band microstrip antenna. 
PACSNo. : 84.40.Ba 
1. Introduction 
In the designing of global positioning system and voteless communication, system 
miniaturization of the antenna has a vital role. Due|to the lightness of microstrip 
antennas, they are well suited for systems to be moused on airborne platforms, like 
synthetic-aperture radar (SAR). The broadening of tota^bandwidth can be achieved by 
using dual frequency patch antenna. Dual frequency antennas exhibit a dual resonant 
behavior in a single radiating structure. If any system requires two resonant frequencies, 
too far apart, dual frequency antenna with higher frequency ratio can be used instead 
of two different.antenna arrays to reduce the area and weight. Different techniques 
have been reported to reduce the patch antenna size, such as a square-ring patch fed 
by a microstrip line, the use of cross and bend slots embedded in the radiating patch 
[1-3] and the use of a slot in the ground plane [4}. Another duai frequency antenna 
•Corresponding Author • 2 0 0 8 , A C S 
830 S Bhunia, S Biswas, D Sarkarand P P Sarkar 
with square slot or rectangular slot loading have been reported in Refs. [5,6]. A 
compact dual-frequency microstrip antenna has been proposed in Ref. [7], which uses 
the rectangular microstrip patch loaded with one shorting pin. Characteristics of dual 
frequency compact rectangular microstrip patch antenna with a number of shorting pins 
have also been studied in Ref. [8]. A size reduction of the microstrip patch up to 51%, 
operating in dual-polarization mode by cutting symmetric pattern of cross slots from the 
square probe-fed patch has been reported in Ref. [9]. 
In this paper, we propose a single-feed antenna design by cutting a circular slot 
having an inner square patch at its centre. Results show that the proposed antenna 
is about 70% smaller compared to a traditional square patch antenna operating at the 
same frequency and we get the dual frequency operation in two different bands i.e. 
S and C bands having frequency ratio 
2. Antenna design 
The configuration of the compact-dual frequency antenna is shown in Figure 1. The 
antenna consists of a square microstrip patch of side L = 26 mm with a circular slot 
of diameter D « 20 mm having an inner square patch of side length W = 10 mm 
supported on a grounded dielectric sheet of thickness h = 1.5875 mm and dielectric 
constant er = 2.4. The probe feed (radius rp = 0.5 mm) is placed at the center of the 
square patch. Due to the additional slot perturbation for the horizontal patch surface 
current path as compared to the reference antenna without slot, surface current paths 
of the two resonant modes can be lengthened, which lowers the corresponding 
resonant frequencies. 
Ground plana 
Figure 1. Geometry of square patch antenna with a slot. 
Experimental Investigation on single layer single-feed dual frequency (dual band) etc. 831 
3. Experimental results 
Figure 2 shows the typical results of the measured return loss. The first two resonant 
frequencies are 2009 MHz and 6112.5 MHz. The corresponding return losses are 
-10.7 dB and -15.8 dB. The 10 dB bandwidth of the first resonant frequency is about 
44 MHz, which is 2.19% of the resonant frequency. The 10 dB bandwidth of the 
second resonant frequency is about 150 MHz, which is 2.454% of the resonant 
frequency. The reference square patch antenna without slot resonating at 2009 MHz 
has the dimension L = 47.23 mm. However, the antenna proposed in this work has 
the dimension of L = 26 mm only. Hence, an antenna size reduction of about 69.69% 
can be easily achieved. Chen et al. has reported [5] 17% size reduction by cutting a 
square slot inside the rectangular patch. The 10 dB bandwidth of about 1.8% and of 
2% have been reported for the two resonant frequencies 1932 MHz and 2475 MHz. 
0.00E+00 
-2.00E+00 
-4.00E+00 
-6.00E+00 
-8.00E+00 
-1.00E+01 
-1.20E+01 
-1.40E+01 
-1.60E+01 
-1.80E+01 
Frequency (Ghz) — > 
Figure 2. Return loss against frequency. 
Figure 3 shows the radiation pattern of the proposed microstrip antenna in which 
the normalized amplitude (in dB) and radiation angle are plotted along Y axis and X 
axis, respectively. It is seen that the radiation pattern In H plane is better at higher 
frequency. The half-power beam width is about 100° and 120° for the 1st and 2nd 
resonant frequencies, respectively. 
-3SJ 
For the 1* 
resonant 
frequency 
Figure 3. Radiation pattern. 
832 S Blum, S Biswas, D Sartor and PP Sartor 
4. Conclusion 
In our designed slotted square microstrip patch antenna, we have two resonant 
frequencies. Considering 10 dB bandwidth, we have 2.19% and 2.45% bandwidth of 
the two resonant frequencies that are better than the experimental results reported in 
Refs. [5,9]. At the same time, we have achieved about 70% size reduction. The two 
frequencies in two different bands i.e. S and C bands are well separated having the 
frequency ratio -3.04. The above results are encouraging. The proposed antenna may 
be used in synthetic-aperture radar (SAR) system. 
References 
[1] C Y Huang, J Y Wu and K L Wong IEEE Trans. Antennas Propag. 47 605 (1999) 
(2] H Iwasaki IEEE Trans. Antennas Propag. 441399 (1996) 
[3] W S Chen, C K Wu and K L Wong Electron. Lett. 34 1278 (1998) 
[4] J S Row and C Y Ai Electron Lett 401093 (2004) 
[5] W S Chen Electron Lett. 34 231 (1998) 
[6] S C Gao and J Li Progr. Electromagn. Res. PIER 23 59 (1999) 
[7] K L Wong and W S Chen Electron. Lett. 33 646 (1997) 
[8] S C Gao and L W Li IEEE Transaction on Vehicular Technology 51 8 (2002) 
[9] K Gosalia and G Lazzi IEEE Trans. Antenna Prop. 51 2182 (2003) 


Experimental Investigation on Single Layer Single-Feed Dual Frequency (Dual Band) Reduced Sized Slotted Square Microstrip Patch Antenna

Melagiriyappa, E

Jayanna, H S

Chouqule, B K

Structure and DC Conductivity Studies of Sm<SUP>3+</SUP> Substituted Mg-Zn Ferrities

Front Title

Khan, F Liakath Ali

Sivagurunathan, P

Muhammad, G Shakil

Mehrotra, S S

Indian J. Phys. 81(7) 665-672(2007) 
w 
Dielectric relaxation studies of higher order alcohol 
complexes with alkyl acrylates using time domain 
reflectometry 
F Liakath Ali Khan1*, P Sivagurunathan1, G Shakil Muhammad2 and S C Mehrotra3 
department of Physics, Annamalai University, Annamalai Nagar-608 002, Tamilnadu, India 
^Department of Physics, Islamiah College, Vaniyambadi-635 752, Tamilnadu, India 
•^Department of Computer Science, Dr B A Marathwada University, Aurangabad-431 004, Maharashtra, India 
E-mail shamisardar^yahoo com 
Received 25 October 2006, accepted 21 May 2007 
Abstract : Using picosecond time domain reflectometry (TDR), dielectric relaxation studies have been earned out for alkyl 
acrylates (methyl acrylate, ethyl acrylate and butyl acrylate) with higher order alcohols (1-octanol, 1-nonanol and 1-dodecanol) 
mixtures over the frequency range 10 MHz to 20 GHz at 303 K Static permittivity iQ. dielectric constant *_ at high frequency and 
relaxation time r were found through dielectric measurements for different concentration of each system The Kirkwood 
correlation factor and the excess inverse relaxation time were determined ^ and discussed to yield information on the molecular 
interaction of the systems Deviation from the linearity of various models suggest molecular association through hydrogen 
bonding between the -OH group of alcohols and C=0 group of esters The values of the static dielectric constant and the relaxation 
time increase with an increase in the percentage of alcohol in alkyl acrylate 
Keywords : Dielectric relaxation, time domain reflectometry, higher order alcohol-acrylates mixtures 
PACS Nos. : 77.22 ch, 77.84 Nh 
1. Introduction 
The study of dielectric relaxation of binary polar liquid mixtures consisting of both 
associative/nonassociative or one associative and other nonassociative liquids, has 
attracted the attention of several workers in the recent past [1-3]. The acrylates have 
been an important chemical group with considerable application in industry [4]. The 
acrylic esters are unique molecules with unsaturated structures alongside a carbonyl 
group. The solution chemistry of these compounds can be strongly influenced by the 
aggregation phenomena, which can play a significant role in the physical properties of 
these polar molecules [5]. Syamalamba and Premaswarup [6] have studied the 
dielectric properties of methyl, ethyl and butyl acrylate in the microwave region at 
'Corresponding Author © 2 0 0 7 , A C S 
666 F Liakath Ali Khan, P Sivagurunathan, G Shakil Muhammad and S C Mehrotra 
different temperatures and compared their results with those on butyrates. Dielectric 
relaxation studies of aromatic esters in the microwave region for different temperatures 
are reported by Saxena et al. [7] using the Higasi method. Shirke et al. (8-9] have 
reported the dielectric parameters of methyl acetate and ethyl acetate with primary 
alcohol mixtures at different concentrations and temperatures. Chaudhari et al. [10] 
studied the dielectric properties of butyl acetate-alcohol mixtures using the time domain 
technique. There are many studies of the dielectric behaviour of alcohol mixtures with 
structure breaking and structure making [11]. The studies of Kirkwood correlation factor 
provide valuable information regarding the solute-solvent interaction in binary mixtures 
especially when one of the components has antiparallel orientation of dipoles [12]. 
The present paper reports the dielectric relaxation studies of alkyl acrylates 
(methyl acryiate, ethyl acrylate and butyl acrylate) with higher order alcohol (1-octanol, 
1-nonanol and 1-dodecanol) mixtures at 303 K for different concentrations in the 
microwave region (10 MHz to 20 GHz) using time domain reflectometry (TDR). 
2. Experimental 
2.1. Materials : 
Methyl acrylate (MA), ethyl acrylate (EA), and butyl acrylate (BA) were purchased from 
Aldrich with purity >99% (Spectroscopic grade) and used without further purification. AR 
grade alcohols (1-octanol, 1-nonanol and 1-dodecanol) were purified by standard 
procedures [13]. 
2.2. Apparatus . 
The complex permittivity spectra were studied using time domain reflectometry. The 
Hewlett-Packard HP 54750 sampling oscilloscope with HP 54754 A TDR plug-in module 
was used. A fast rising step voltage pulse of about 39 ps rise time generated by a 
tunnel diode was propagated through a flexible coaxial cable. The sample was placed 
at the end of the coaxial line in the standard military application (SMA) coaxial cell. 
The physical dimensions of the cell are very important. The impedance of the cell 
should be matched with that of the coaxial transmission line to which the cell is 
connected. The impedance of the coaxial line is 50 Q. The SMA cell has a 3.5 mm 
outer diameter and a 1.35 mm effective pin length. All measurements were done under 
open load conditions. The change in the pulse after reflection from the sample placed 
in the cell was monitored by the sampling oscilloscope. In this experiment, a time 
window of 5 ns was used. The reflected pulses without sample /=?7(f) and with sample 
Rx(t) were digitized in 1024 points in the memory of the oscilloscope. 
A temperature controller system with a water bath and thermostat was used to 
maintain a constant temperature within the accuracy limit of ±1°C. The sample cell was 
surrounded by a thermal-insulating container through which temperature-controlled water 
was circulated. The temperature at the cell was monitored using a microprocessor-
controlled thermometer. 
Dielectric relaxation studies of higher order alcohol complexes with alkyl acrylates etc 667 
2 3 Data analysis • 
The time-dependent data were processed to obtain complex reflection coefficient 
spectra P *(<*>) over the frequency range from 10 MHZ to 20 GHz using Fourier 
transformation [14,15] as 
p * (co) = (cl jo) d)[p ((o)/q (to)], (1) 
where p(co) and q(co) are Fourier transforms of (R, (t) - Rx(t)) and (d/dt)(R,(t) + Rx(t))t 
respectively, c is the velocity of light, w is angular frequency, d is the effective pin 
length and j = V^T 
The complex permittivity spectra t*(d) were obtained from reflection coefficient 
spectra p*{aj) by applying a bilinear calibration method [16] The experimental values of 
t* are fitted with the Debye equation [17] 
f*(ftj) = r + f ° ~ f " , (2) 
1 + j(D r ' W 
with f0, t„ and r as fitting parameters A non linear least squares fit method [18] was 
used to determine the values of dielectric parameters 
3. The Kirkwood model 
The structural information about the liquids from the dielectric relaxation parameter may 
be obtained using the Kirkwood correlation parameter g [19] This factor is also a 
parameter for obtaining information regarding orientation of electric dipoles in polar 
liquids For a pure liquid, Kirkwood correlation factor g is given by the expression 
4nN^2 p, (£0-Q(2g0 + O 
9/cT m, £0(*~+2)2 ' ( ' 
where ju is dipole moment, p, is density at temperature 7, ml is molecular weight, k 
is Boltzman constant, N is Avogadro's number, e0 is static dielectric constant and £„ 
is the dielectric constant at high frequency, often represented by the square of 
refractive index. For the mixture of two polar liquids {A) and (B), eq (3) is modified 
by Kumbharkhane et al [20,21] The Kirkwood equation for the mixture is expressed 
as ' 
47tN(llA2pA MB2PB y 1neff - ( * 0 m - O ( 2 * 0 m + O 
) 
9
 " e0m^+V* ' (4) 
where XA and XB are volume fraction of liquids A (alcohol) and B (ester), respectively. 
The calculated values of geU using eq. (4) for all the systems at different concentrations 
are given in Tables 1-3. The effective values of the correlation factor g8ff for esters are 
smaller than its corresponding values in different alcohols. The values of g*" for pure 
liquid esters are less than unity indicating the antiparallel orientation of the electric 
668 F Uakath Ali Khan, P Sivagurunathan, G Shakil Muhammad andSC Mehrotra 
Table 1. Static permittivity e0. dielectric constant at high frequency c, relaxation time rand effective Kirkwood 
correlation factor g,Bfor 1-octanol + alkyl acrylate mixtures. 
Vol. % of 1-octanol 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
Methyl acrylate 
6.72 
5.63 
7.08 
9.47 
10.73 
2.45 
2.38 
2.43 
2.49 
2.56 
5.45 
52.59 
168.87 
357.13 
826.56 
1.01 
1.63 
1.92 
2.19 
2.29 
''o 
£"«. 
r(ps) 
g*ti 
Ethyl acrylate 
4.52 
4.69 
6.13 
8.09 
10.73 
2.23 
2.25 
2.31 
2.38 
2.56 
6.33 
68.21 
173.18 
385.34 
826.56 
0.89 
1.49 
1.67 
2.04 
2.29 
Butyl acrylate 
2.46 
3.37 
4.97 
6.43 
10.73 
2.16 
2.05 
2.23 
2.29 
2.56 
8 47 
76.35 
189.47 
423.22 
826.56 
0.91 
1.36 
1.54 
1.89 
2.29 
dipoles and the geti values for pure alcohols are greater than unity indicating a high 
degree of coordinated chain-like structures. 
3.1. The excess inverse relaxation time : 
The information related to the heterogeneous interaction may also be obtained by the 
value of excess inverse relaxation time [22]. The excess inverse relaxation time ( 1 / T ) E 
is defined as : 
(1/r)E = (1/r)m - [(MT)AXA - ( l / r ) ^ (5) 
where (Mr)E is excess inverse relaxation time. 
The quantitative information regarding the dynamics of solute-solvent interaction obtained 
from excess inverse relaxation is as follows : 
(i) (MT)E = 0 : there is no change in the dynamics of liquid A and B interaction. 
Dielectric relaxation studies of higher order alcohol complexes with alkylacrylates etc. 669 
Table 2. Static permittivity e0, dielectric constant at high frequency £., relaxation time r and effective Kirkwood 
correlation factor gett for 1-nonanol + alkyl acrylate mixtures. 
Vol.% of 1-nonanol 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
Methyl acrylate Ethyl acrylate 
^ 0 
6.72 
4.32 
6.18 
7.59 
9.07 
2.45 
2.34 
2.39 
2.45 
2.50 
4.52 
3.11 
5.07 
6.23 
9.07 
2.23 
2.26 
2.31 
2.38 
2.50 
r(ps) 
5.45 
76.24 
223.51 
417.25 
943.69 
6.33 
89.63 
247.58 
463.14 
943.69 
9°" 
1.01 
1.71 
2.03 
2.26 
2.34 
0.89 
1.59 
1.88 
2.14 
2.34 
Butyl acrylate 
2.46 
2.05 
3.84 
5.19 
9.07 
2.16 
2.18 
2.23 
2.30 
2.50 
8.47 
96.35 
278.15 
507.21 
943.69 
0 91 
1 41 
1.62 
2.03 
2.34 
(ii) {MT)E < 0 : the liquid A and liquid B interaction produces a field such that the 
effective dipoles rotate slowly, 
(iii) (1/r)E > 0 : the liquid A and liquid B interaction produces a field such that the 
effective dipoles rotate fastly i.e. the field will co-operate in rotation of dipoles. 
4. Results and discussion 
The determined values of static dielectric constant e0 and dielectric constant at high 
frequency e^ for solutions of different concentrations of alcohols are presented in Tables 
1-3. The static dielectric constant for the mixtures increases towards the dielectric 
constant of the respective alcohol. Increase of dielectric constant is due to the 
transition of spherical molecular aggregates into elongated aggregates giving rise to 
parallel-orientation of the dipoles. Similar conclusions were drawn by Shirke et ai [8, 
9] for alkyl acetate-alcohols systems. From Tables 1-3, it is also noticed that eQ and 
670 F Uakath Ali Khan, P Sivagurunathan, G Shakil Muhammad and S C Mehrotra 
Table 3. Static permittiv.ty e0 dielectnc constant at high frequency e„ relaxation time rand effective Kirkwood 
correlation factor g* for 1-dodecanol + alkyl acrylate mixtures. 
Vol% of 1-dodecanol 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
0 
25 
50 
75 
100 
Methyl acrylate 
6 72 
3 18 
5 23 
6 89 
7 92 
Ethyl acrylate 
4 52 
2 12 
4.19 
5 32 
7 92 
2 45 2 23 
2 29 
2 35 
2 41 
2 46 
2 18 
2 23 
2 33 
2.46 
r(ps) 
5 45 
91 31 
352 39 
563 18 
1082 45 
9 
1 01 
1 86 
2 18 
2.32 
2.41 
6 33 
103 56 
386 17 
611.28 
1082 45 
•H 
0 89 
1 69 
1 98 
2.12 
2.41 
Butyl acrylate 
2.46 
1.09 
3.37 
4 1 8 
7.92 
2 16 
2 09 
2.16 
2.25 
2 46 
8.47 
128 15 
421 39 
743.52 
1082 45 
0.91 
1 45 
1 72 
1.95 
2.41 
r values of mixtures lie between the individual component values, which indicates the 
solute-solvent interaction between the -OH group of alcohol and C=0 group of ester [8]. 
The dielectric relaxation time shows continuous increase with chain length of 
esters and acidity of proton donors (alcohols) and offers hindrance to the rotation of 
the molecule. The increase in relaxation time with chain length is to be expected in 
view of the fact that hydroxyl group reorientation depends to some extent on the length 
of the alkyl group, and the viscosity of the liquid. At high concentration of alcohol in 
the mixtures, there are a large number of alcohol molecules surrounding the ester 
molecules. 
The associative alcohol molecules act as proton donors enabling hydrogen 
bonding with ester molecules. Thus, dipole-dipole interaction occurs in such a way that 
the effective dipole moment gets increased and linear a-multimers are formed [23]. The 
Dielectric relaxation studies of higher order alcohol complexes with alkylacrylates etc. 671 
dipole-dipole interaction is the interaction of the -OH group of alcohol with C=0 of 
ester. At low concentration of alcohol in the mixtures, there are only a small number 
of alcohol molecules to enable dipole-dipole interaction through hydrogen bonding with 
the non-associative ester molecules. As a result, weak intermolecular interaction 
occurs. The relaxation time increases with increasing alkyl chain length of ester and 
alcohol indicating that the degree of cooperation for reorientation of the molecules 
increases with increasing length and the bulk of cluster increases. 
The values of getf for pure liquids of esters are close to unity indicating no dipole 
correlation and goft values for pure alcohols are greater than unity indicating a high 
degree of coordinated chain-like structures. For the mixtures of alcohols with esters, 
the values of (jfeff show an increasing trend with the increasing concentration of alcohols 
in all the mixture. This trend suggests reorientation of neighborhood molecules of the 
constituent polar liquids forming a tendency towards parallel alignment of dipoles. This 
conclusion is similar to that arrived from the variation of dielectric constant with 
concentration. 
The dielectric relaxation times show continuous increase as the volume fraction 
of alkyl acrylates decreases and it increases with increasing chain length for these 
straight chain alcohol molecules and offer hindrance to the rotation of the molecule. 
The variation of (1/r)E for alkyl acrylates (methyl acrylate, ethyl acrylate and butyl 
acrylate) with alcohols (octanol, 1-nonanol and 1-dodecanol) at different compositions is 
given in Figure 1. (1/r)E values are negative for all the systems studied. This indicates 
0 00 - j 
-0 02 °4 
-0 04 J 
-0 06 H 
-0 08 •] 
•0.10 A 
^ -0 14 4 
*" -0 16 J 
-0.18 J 
-0 20 -j 
-0.22 J 
-0 24 J 
-0.26 -] 
-0.28 J 
Figure 1. Excess inverse relaxation time (Mtf versus volume fraction of higher order alcohols in alkyl 
acrylates. 
the formation of multimers through hydrogen bonding with slower rotation and parallel 
orientation of dipoles. For the systems of alcohols with the esters considered here, the 
existence of the intermolecular heterointeraction is in the following order : 1-octanol < 
1-nonanol < 1-dodecanol and methyl acrylate < ethyl acrylate < butyl acrylate. 
- • -BA+1 
- • - B A + 1 
A - B A + 1 
- V — EA+1 
- • - E A + 1 
—<~EA+1 
- • - M A + 1 
- # — M A + 1 
—•— MAt l 
-OCTANOL 
-NONANOl 
-DODECANOL 
-OCTANOL 
-NONANOL 
-DODECANOL 
-OCTANOL 
-NONANOL 
-DODECANOL 
Volume fraction of alcohols 
672 F Uakath All Khan, P Sivagurunathan, G Shakil Muhammad and S C Mehrotra 
5. Conclusion 
The dielectric constants, the relaxation times, the Kirkwood correlation factor and 
inverse relaxation times for alkyl acrylates with higher order alcohols mixtures of various 
concentrations have been reported The dielectric parameters show significant change 
with concentration and alkyl chain length The negative excess inverse relaxation time 
values obtained for all the systems, indicate that the solute-solvent interaction hinders 
the rotation of the dipoles of the system 
References 
[1] S Mashimo, T Umehara, T Ota, S Kawabara and N Shmyashiki J Mol Uq 36 135 (1987) 
[2] M Tabellout, P Lanceuleur, J R Emery and R Petnck J Chem Soc Faraday Trans IBB 1493 (1990) 
[3] S Mashimo and S Kuwabara J Chem Phys 90 3292 (1989) 
[4] N V Sastry, N J Jam, Alex George and P Bahadur Fluid Phase Equhb 163 275 (1999) 
[5] J S Rowlinson and F L Swinton Liquids and Liquid Mixtures (3rd edn) (London Butterworth) (1982) 
[6] K Syamalamba and D Premaswarup Indian J Pure Appl Phys 3 267 (1965) 
[7] S K Saxena, J P Shukia and M C Saxena Indian J Pure Appl Phys 19 588 (1981) 
[8] R M Shirke, A Chaudhan, N M More and P B Patil J Chem Engg Data 45 917 (2000) 
[9] R M Shirke, A Chaudhan N M More and P B Patil J Mol Uq 94 27 (2001) 
[10] A Chaudhan, R M Shirke, N M More and P B Patil J Sol Chem 31 305 (2002) 
[11] AC Kumbharkhane, S M Puranik and S C Mehrotra Indian J Pure Appl Phys 4 62 (1992) 
[12] M T Hosamani, R H Fattepur, D K Deshpande and S C Mehrotra J Chem Soc Faraday Trans II 91 623 
(1995) 
[13] A I Vogal, Text Book of Practical Organic Chemistry, (3rd edn ) (London Longman) (1957) 
[14] HA Samulon Proc IRE 39175 (1951) 
[15] C E Shannon Proc. IRE 3710 (1949) 
[16] R H Cole IEEE Trans Instrum Meas IM 32 42 (1943) 
[17] P Debye Polar Molecules (New York Chemical Catalog) (1929) 
[18] PR Bevington Data Reduction and Error Analysis for the Physical Sciences (New York McGraw-Hill) 
(1969) 
[19] J G Kirkwood J Chem Phys 7 911 (1939) 
[20] A C Kumbharakhane, S M Puranik and S C Mehrotra J Mol Uq 50 143 (1991) 
[21] AC Kumbharkhane, S M Puranik and S C Mehrotra J Mol Uq 51 261 (1992) 
[22] A Chaudhan and S C Mehrotra Mol Phys 100 3907 (2002) 
[23] T Thenappan and A Prabakar Devaraj J Mol Uq 123 72 (2006) 


English

Dielectric Relaxation Studies of Higher Order Alcohol Complexes with Alkyl Acrylates Using Time Domain Reflectometry

Ozdemir, Leyla

Karacoban, Betul

Urer, Guldem

Electric Dipole Transitions for some Excited States in Neutral Silver

Indian J. Phys. 81 (8), 755-756 (2W71 
DYTP5 
Vol. 81 • No, 8 • August 2007 
ONTENTS 
Front Title 749 
Advisory Board and Editors 751-752 
From Editor's Desk 753 
Front Contents 755-756 
Astrophysics, Atmospheric & Space Physics 
Blue jet models and associated lightning flashes 
R BHATTACHARYA, R DAS, R GUHA, S DE AND A B BHATTACHARYA 757-766 
Behaviour of cosmic ray daily variation and solar activity on 
anomalous days 
RAJESH K MISHRA AND REKHA AGARWAL MISHRA 767-777 
Condensed Matter & Materials Physics 
Excess refractive index studies on CSA-DMSO binary mixture 
showing lyophase 
C J SREELATHA, CH SATYANARAYANA AND P ANURADHA 779-785 
Analysis of ferrite based planar array of rectangular patch 
microstrip antenna in X-band 
MADHURIKA MAHAJAN, TAPAS CHAKRAVARTY AND SUNIL K KHAH 787-792 
[ Cont'd, on next page 
756 Contents 
Nuclear Physics 
Sensitivity of nulcear matter EOS parameters on neutron 
star properties 
C J CHAMMASHERIL AND P C VINODKUMAR 793-801 
Three-body formalism for deuteron stripping reactions on 40Ca 
ANJANA ACHARYA 803-817 
Particle Physics 
Non-singlet structure function at low and high xin the next-to-leading 
order and CCFR neutrino data 
D K CHOUDHURY AND PIJUSH KANTI DHAR 819-830 
Forthcoming Publications 831 
Notes for Contributors 833-836 
Our Special Publications 837-838 


Front Contents

Indian J. Plm. 81 (4) 495-497 (2007) cHote 
Experimental investigation on dual-frequency broad band 
microstrip antenna with swastika slot 
i 
S Bhunia1, S Biswas2, D Sarkar2 andP P Sarkar2* 
Academy of Technology, Hooghly-712 121, West Bengal, India 
2US1C. University of Kalyani, KaIyani-741 235, Nadia. West Bengal, India 
Received 2 November 2006, accepted 23 March 2007 
Abstract : This note presents a novel design of dual-frequency (J* and X-band) microstnp antenna and the 
experimental results of its performance are reported In this design, a 'swastika' slot has been cut out from the 
square microstnp patch antenna The antenna unit can be incorporated into arrays, and offer the possibility of a 
compact, light-weight and cost effective antenna array design for various applications such as television broad 
casting, mobile communications and radar systems In this note dual frequency band has been obtained with 
lower frequency 10 dB bandwidth of 200 MHz and higher frequency bandwidth of about 1 4 GHz which is quite 
broad 
Keywords : Dual frequency, microstnp antenna 
PACSNo. : 84 40Ba 
Microstnp patches are an attractive type of antenna and are widely employed in many 
practical applications because of their low cost, conformability, and ease of manufacture, 
integration with RF devices etc. Dual frequency microstrip antennas with a single feed, 
are required in various radar and communications system such as synthetic aperture 
radar (SAR), dual-band GSM/DCS 1800 mobile communications system, and Global 
positioning system (GPS) [1-3]. Dual frequency microstrip antennas with square slot 
has been reported in Ret. [4]. A compact dual frequency microstrip antenna has been 
proposed in Ref. [5], which has used the rectangular microstrip patch loaded with one 
shorted pin. The characteristics of a dual frequency compact antenna which uses a 
rectangular microstrip patch with different number of shorting pins has been reported in 
Ref. [6]. An aperture-stacked patch microstrip antenna has been studied in Ref. [7] to 
increase the band width. In applications such as broadcasting, personal communications, 
and radar systems, considerable efforts have been devoted to the development of dual-
frequency patch antennas [8,9] and antennas with dual polarizations. In addition, when 
'Corresponding Author ® 2 0 0 7 , A C S 
496 S Bhunta, S Biswas, D Sarkar and P P Sarkar 
multi-frequencies are closer to each other, the antenna may have a broad operating 
band width [10]. This note focuses on the development of a novel microstrip antenna 
to enhance the band width by cutting a 'swastika' slot on a square patch The 
characteristic of the present proposed dual-frequency design method using a single 
coaxial feed is experimentally studied; typical results of the proposed design are 
presented and discussed. 
Figure 1 shows the proposed probe-fed dual frequency microstrip patch antenna 
The antenna has been probe-fed at the corner of the square patch. A swastika slot is 
etched out from the center of the square patch having a side length L = 26 mm and 
is fabricated on a substrate (PTFE) of thickness h = 1 5875 mm and relative 
permittivity er = 2.4 The other dimensions are shown in Figure 1. 
26mm 
3mm T 
^ 4 5mm ^ I 
Swastika 
Slot 
i 
i 
E 
B 
o 
i 
20 mm 
Patch 
1 o 
Feeding 
^ Point 
c,=2.4 
\ Ground Plane 
Figure 1. Geometry of square microstnp patch antenna unit with swastika slot. 
The experimental results are shown in Figures 2(a), 2(b). Figure 2(a) gives the 
antennas return loss. The lower band has a center frequency of 7.006 GHz at which 
the return loss is -16.5 dB. The return loss is lower than -10 dB from 6.906 GHz to 
7.106 GHz, giving a bandwidth of 200 MHz. The higher frequency band has a center 
frequency 10.604 GHz at which the return loss is -26.3 dB. The return loss is lower 
than -10 dB from 10.204 GHz to 11.604 GHz, giving a wide band with of 1.4 GHz 
Figure 2(b) gives the phase plot against frequency which shows that the phase angle 
becomes 0 degree i.e., microstrip patch antenna unit resonate at frequencies 7 906 
GHz, 9.105 GHz, 10.704 Ghz. 
Experimental investigation on dual-frequency broad band microstrip antenna with swastika slot 497 
Return Loss Phase vs Frequency 
Frequency (GHz) 
(a) 
Frequency (GHz) 
(b) 
Figure 2. (a) Return and (b) phase spectrum for microstrip antenna unit 
A dual frequency broadband square microstrip antenna with a swastika slot using 
a single probe feed has been successfully designed. Presently, extensive efforts have 
been provided for size reduction of antennas But in this note our goal is to broaden 
the bandwidth of the antenna. In this work 1.4 GHz antenna bandwidth below 10 dB 
return loss has been successfully achieved 
References 
[1] Hand book of microstrip antennas J R James and P S Hall (eds ) (London, UK Peter Peregrmus) 
(1989) 
[2] S C Gao and S S Zhong Int J RF Microwave CAE 9 42 (1999) 
[3] S C Gao Dual-Polarized Microstrip Antenna Elements and Arrays for Active Integration (Shanghai( 
China Shanghai Univ Press) (1999) 
[4] W S Chen Electron Lett 34 231 (1998) 
[5] K L Wong and W S Chen Electron Lett 33 646 (1997) 
[6] S C Gao, Le-Wei Li and Tat-Soon Yeo IEEE Transactions on Vehichelar Technology 51 28 (2002) 
[7] S D Targonski, R B Waterhouse and D M Pozar Trans Antennas Propagat 46 1245 (1998) 
[8] S Maci and G Gentili IEEE Antennas Propagat 39 13 (1997) 
[9] R Pokuls. J Uher and D M Pozar IEEE Trans Antennas Propagat 46 1289 (1998) 
[10] T A Denidnl and Q Rao IEEE Antennas Wireless Propagat Lett 3 321 (2004) 


Experimental Investigation on Dual-Frequency Broad Band Microstrip Antenna with Swastika Slot

Indian I Phys, 81 (4), 507-508 (2007) 
r Special Publications 
•Commemorative Volumes to mark the celebration of 75th year 
of publication of Indian Journal of Physics: Vdjumes 1-6 
1. Frontiers in Materials Physics 
Guest Editor: D Chakravorty 
Price : Rs. 600.00 (10 articles, 247 pages, illustrated) 
Date of Publication: 2002 
2. Frontiers in Astrophysics 
Guest Editor: Sandip K Chakrabarti 
Price : Rs. 600.00 (12 articles, 303 pages, illustrated) 
DateofPublication:2002 
3. Frontiers in Atomic, Molecular & Optical Physics 
Guest Editors : S S Bhattacharyya and S C Mukherjee 
Price : Rs. 600.00 (15 articles, 429 pages, illustrated) 
Date ofTublication: 2003 
4. Frontiers in High Energy Physics 
Guest Editors : Amitava Raychaudhuri and Partha Mitra 
Price : Rs. 600.00 (11 articles. 281 pages, illustrated) 
Date of Publication: 2004 
5. Frontiers in Condensed Matter Physics 
Guest Editors : J K Bhattacharjee and B K Chakrabarti 
Price: Rs. 600.00 (7 articles, 308 Pages, illustrated) 
Date of Publication : 2005 
6. Frontiers in Biophysics 
Guest Editors: T P Singh and Chanchal Das Gupta 
Price : Rs. 600.00 (12 articles, 188 pages, illustrated) 
Dale of Publication: 2005 
*For Volumes 1-6, please contact Publishers: 
Messrs. Allied Publishers Pvt. Ltd. 
A-104, Mayapuri, Phase-II, New Delhi-! 10 064, India 
J7, Chittaranjan Avenue, Kolkata-700 072, India 
15, J. N. Heredia Marg, Ballard Estate, Mumbai-400 038, India 
751, Anna Salai, Chennai-600 002, India 
508 Our Special Publications 
11, Landmark Papers in Indian Journal of Physics 
[192&-2001] 
Guest Editors : J K Bhattacharjee and 
D S Ray" 
Price : Rs. 500.00; VS $. 50.00 (289 pages, 
illustrated) 
Date of Publication : December, 2002 
III 75th Year of Discovery of Raman Effect : 
A Special Issue of India Journal of Physics 
11928-20031 
Guest Editor : S Chakravorti 
Price : Rs. 500,00; US $. 50.00 (164 pages, 
illustrated) 
Date of Publication : February, 2003 
IV. Production of Radioactive Ion Beams 
[PRORIB-2001] 
Proceedings of the DAE-BRNS sponsored 
International Workshop-A Special Issue of 
Indian Journal of Physics 
Guest Editor: Alok Chakrabarti 
Price : Rs. 200.00; US $. 50.00 (226 pages, 
illustrated) 
Date of Publication : May, 2002 
V Commemoration Volume on Professor K S 
Krishnan: 
Birth Centenary (1898-1998] 
Guest Editors : S Ray and C K Majumdar 
Price : Rs. 100.00; US $. 40.00 (332 pages, 
illustrated) 
Date of Publication : December, 1999 
VI. Physics and Technology of Accelerators : A 
Special Issue of Indian Journal of Physics on 
the occasion of Golden Jubilee of India's 
Independence 
Guest Editor : Debashis Basu 
Price : Rs. 100.00; US $. 40.00 (236 pages, 
illustrated) 
Date of Publication : December, 1999 
VII. Recent Trends in Statistical Physics: A Special 
Issue of 
Indian Journal of Physics 
Guest Editor: J K Bhattacharjee 
Price : Rs. 100.00; US $. 40,00 (140 pages, 
illustrated) 
Date of Publication : August, 1998 
VIII. XI DAE Symposium of High Energy Physics 
: A Special 
. Issue of Indian Journal of Physics 
Guest Editor : Ranabir Dutt and Asim K Ray 
Price : Rs. 300.00; US $. 100.00 (395 pages, 
illustrated) 
Date of Publication : February, 1997 
IX. Lectures of Theoretical Physics Scminai 
Circuit 11990-92| : A Special Issue of Indian 
Journal of Physics 
Guest Editors : C K Majumdar and Part ha 
Ghosh 
Price : Rs. 80.00; US $. 35.00 (100 pages. 
illustrated) 
Date of Publication : November, 1993 
X. Commemoration Volume on Professoi 
Mcghnad Saha: Birth Centenary 11893-19931 
Editors : H Bancrjcc and S P Sen Gupta 
Price : Rs. 140.00; US $. 40.00 (240 pages, 
illustrated) 
Date of Publication : December, 1993 
XI. High Temperature Superconductivit> 
Lectures of 
Theoretical Physics Seminar Circuit f 1989-
90j : A Special Issue of Indian Journal ol 
Physics 
Editors : B K Chaudhun and S P Sen Gupta 
Price : Rs. 80.00; US $. 30.00 (220 pages, 
illustrated) 
Date of Publication : March, 1992 
XII. Commemoration Volume on Professor C V 
Raman: 
Birth Centenary 11888-1988] 
Editor : S P Sen Gupta 
Price : Rs. 50.00; VS $. 25.00 (225 pages, 
illustrated) 
Date of Publication : July, 1989 


Our Special Publications

Indian Association for the Cultivation of Science

Not a member yet

Characterisation of ZnS Nanocrystals Prepared by Wet Chemical Method

Experimental Investigation on Single Layer Single-Feed Dual Frequency (Dual Band) Reduced Sized Slotted Square Microstrip Patch Antenna

Structure and DC Conductivity Studies of Sm<SUP>3+</SUP> Substituted Mg-Zn Ferrities

Front Title

Dielectric Relaxation Studies of Higher Order Alcohol Complexes with Alkyl Acrylates Using Time Domain Reflectometry

Electric Dipole Transitions for some Excited States in Neutral Silver

Front Contents

Experimental Investigation on Dual-Frequency Broad Band Microstrip Antenna with Swastika Slot

Our Special Publications

Front Title

6,371

8,071