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Microwave sintered Mg-Cd ferrite substrates for microstrip patch antennas in X-band
Accepted Manuscript Regular paper Microwave Sintered Mg-Cd Ferrite Substrates for Microstrip Patch Antennas in X-band Sanjay R. Bhongale, Hanmant R. Ingavale, Tukaram J. Shinde, Pramod N. Vasambekar PII: DOI: Reference:
S1434-8411(18)31898-3 https://doi.org/10.1016/j.aeue.2018.09.040 AEUE 52519
To appear in:
International Journal of Electronics and Communications
Received Date: Revised Date: Accepted Date:
15 July 2018 20 September 2018 25 September 2018
Please cite this article as: S.R. Bhongale, H.R. Ingavale, T.J. Shinde, P.N. Vasambekar, Microwave Sintered MgCd Ferrite Substrates for Microstrip Patch Antennas in X-band, International Journal of Electronics and Communications (2018), doi: https://doi.org/10.1016/j.aeue.2018.09.040
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Microwave Sintered Mg-Cd Ferrite Substrates for Microstrip Patch Antennas in X-band Sanjay R. Bhongale1, Hanmant R.Ingavale2, Tukaram J. Shinde3, Pramod N. Vasambekar4 1
Department of Physics, Yashavantrao Chavan Institute of Science, Satara, Maharashtra, India.
2
Department of physics, B.V.M.B.S.K.Kanya Mahvidyalaya, Kadegaon, Sangli, Maharashtra,
India. 3
Department of physics, K.R.P. Kanya Mahvidyalaya, Islampur, Dist- Sangli, Maharashtra ,India.
4
Department of Electronics, Shivaji University, Kolhapur, Maharashtra, India.
Corresponding author: S.R. Bhongale ([email protected]) (+919850609352) Abstract The
ferrites
with
chemical
formulae
MgFe2O4,
Mg0.6Cd0.4Fe2O4
and
Mg0.2Cd0.8Fe2O4 specified with Ferrite S1, S2 and S3 were prepared by the oxalate coprecipitation method using AR grade sulphates under microwave sintering technique. The single phase cubic spinel structure formation of all the ferrites was confirmed by XRD and FTIR techniques. The dielectric parameters such as permittivity (εr), dielectric loss tangent (tanδe), permeability (µr) and magnetic loss tangent (tanδm) were determined from parameters S11 and S21 by using material measurement software with VNA.
The
synthesized ferrites S1, S2 and S3 with determined dielectric parameters were used as substrate to design rectangular microstrip patch antenna by simulation using Ansoft Designer SV 2.2. The designed antennas were fabricated by using screen printing technique. The return loss (RL), 10dB % bandwidth and VSWR of these fabricated antennas were measured on vector network analyzer. The simulated and measured values of resonating frequency, return loss (RL), 10dB % bandwidth and VSWR were nearly
matched with each other. Mg0.2Cd0.8Fe2O4 (Ferrite S3) can be used as substrate of antenna for better results. Keywords: Mg- Cd Ferrites, Dielectric Properties, Microstrip Patch Antenna, Return loss. 1. Introduction The modern communication systems in civil sector, satellite communication, radar applications etc. require size reduction of antennas. Such communication system requires antennas with low weight, low cost, low profile, easy integration into microwave ICs without affecting their antenna parameters [1]. Therefore size reduction or miniaturization has become a very important matter now days in the development of patch antennas. The necessary and sufficient characteristics of antennas are small physical size, wide bandwidth and high radiation efficiency. However, size reduction of antenna is difficult due the properties of electromagnetic radiation. The general ways of miniaturization are using slots, use of high permittivity materials, shorting pins and planes [2, 3, 4]. However, use of high dielectric material results in field confinement about the high permittivity area. This reduces antenna efficiency and bandwidth. Therefore researchers shifted towards the use of magneto-dielectric materials for antenna miniaturizations in place of high permittivity materials [5-7]. Also use of materials with moderate permittivity and permeability yields antenna miniaturizations [8]. The ferrite material is one type of magneto-dielectric material which has both permittivity and permeability properties which can miniaturize antenna. Saxena et al. [9-10] has been established the single patch microstrip on substrate of Li-Ti-Zn and Li-Ti-Mg ferrites and found that the change in overall radiation performance of antenna system as well as reduction in patch size as compare to antenna printed on dielectric substrate. Hua su et.al [11] suggested that Ni-Cu-Zn ferrites with matched permeability and permittivity were shows potential candidates for use as substrate to miniaturize the low-frequency antennas. Borah and Bhattacharyya [12] used 5% VF Nickel ferrite/LDPE for enhancement of bandwidth with reduction in size of antenna in Xband applications. Mattei et al. [13] reported that remarkable reduction in magnetic losses of Ni0.6Zn0.2Co0.2Fe1.98O4-δ spinel ferrite may be used as substrate of antennas for
miniaturization. V. Naidu et al. [14] reported that Dy-Sm doped Mg-ferrite has been used as substrate for designing E-shaped microstrip patch antenna. In present investigations we report the design, fabrication and analysis of rectangular microstrip patch antennas on magneto-dielectric material cadmium substituted Mg-ferrite substrate prepared by oxalate co-precipitation method with microwave sintering technique. 2.
Experimental The ferrites with chemical formula Mg1-xCdx Fe2 O4 (x = 0, 0.4, and 0.8) specified
with MgFe2O4 (Ferrite S1) Mg0.6Cd0.4Fe2O4 (Ferrite S2), Mg0.2Cd0.8Fe2O4 (Ferrite S3) were prepared by the oxalate co-precipitation method with microwave sintering technique. The starting chemicals such as the high purity AR grade MgSO 4.7H2O (purity 99.5%, Thomas Baker), 3CdSO4.8H2O (purity 98%, Thomas Baker) and FeSO4.7H2O (purity 99.5%, Thomas Baker) were used. The detailed procedure of preparation of MgCd ferrite was explained elsewhere [15]. This new material was developed under microwave sintering technique. Such technique requires low energy for short duration which plays important role in the consumption of both energy as well as time [15]. Because the energy consummation is an important issue, where as the low time of heating is helps in maintaining the temperature of surrounding at lower level which is intern helps to control the overall temperature of environment. The optimized microwave oven (ONIDA 20XL 800 watts) power of 70% at 10 min was used for final sintering [16]. The structural properties of the synthesized samples were investigated by XRD, SEM, and FTIR techniques. The X-ray diffraction patterns of these samples were created on X-ray powder diffractometer modal D2-Phaser with Cu-Kα (λ= 1.5406 A°) radiation. The surface morphology of ferrites was studied by using Mira-3, Tescan, Brno-Czech
Republic, Field emission scanning electron microscope (FE-SEM). FTIR spectra of the ferrites were drawn in the range of 350 - 800 cm-1 using Perkin-Elmer FTIR spectrum one spectrometer. The synthesized ferrites powder under investigation was milled in agate mortar with acetone base. The powder was pressed into the shape of rectangular pellets with dimensions suitable for WR-90 waveguide under pressure of 5 tons cm-2 by adding polyvinyl acetate as binder. The pellets were finally cured for 1h at 150° C. These pallets were used for measuring scattering parameters such as reflection coefficient (S 11) and transmission coefficient (S21) at Microwave frequencies in the range of 8.2 to 12.4 GHz using vector network analyzer (Agilent N5225A PNA series). The permittivity (εr), dielectric loss tangent (tanδe), permeability (μr) and magnetic loss tangent (tanδm) are determine from measured parameters S11 and S21 by using material measurement software, Agilent module 85071E [17, 18, 19]. The microstrip patch antenna is design on synthesized cadmium substituted Mgferrites S1, S2 and S3 substrates by using software Ansoft Designer SV 2.2 [20]. Alameddine et al.[21] used Ansoft Designer software for design of wideband patch antennas for mobile communication. The parameters of substrate such as permittivity (εr), dielectric loss tangent (tanδe), permeability (μr) and magnetic loss tangent (tanδm) required for designing of an antennas are obtained from the variations of these parameters with frequency at 10.5 GHz which has been discussed in results and discussion section (Fig. 5, 7, 8 and 9) and presented in Table 1. The ferrites S1, S2 and S3 are new materials and not available in the software library. Therefore they are added in the software library with respective evaluated values of real permittivity and permeability. The length of proposed antennas on ferrites S1, S2 and S3 substrates are determined by using eq. [22] L
c 2f r ε r μ r
Table1. Input parameters for design of microstrip patch antenna. Cd Content (x) 0 0.4 0.8
F (GHz)
ε'
μ'
tanδe
tanδm
10.5 10.5 10.5
4.67 4.55 5.91
0.98 1.02 0.76
0.0878 0.293 0.0724
0.0035 0.0037 0.0856
Length L (mm) 6.9 6.9 6.9
Width W (mm) 8 7.3 7.1
Using this length (L), width (W) is selected by optimization in the simulation to suppress higher modes of excitation. The length (L) and width (W) of proposed microstrip antennas at operating frequency 10.5GHz are presented in Table1. M. M. Islam et al. [23] studied the rectangular microstrip patch antenna on conventional FR4 substrate of 40mm length (L) and width (W) with rectangular and circular slots at resonance frequency 10.25GHz. D. Mittal et al. [24] studied the rectangular microstrip patch antenna on conventional FR4 substrate of patch dimensions length Lp = 7.73mm and width Wp = 34.55mm at resonance frequency 7.94GHz. This clearly shows that use of ferrites substrate in present research work reduces the size of patch about 34 to 38% as compared to conventional FR4 substrate. The location on of coaxial feed point is optimized by trial and error method [25]. The designed antennas are simulated in the frequency range 7 to 13 GHz to study the return loss (RL), voltage standing wave ratio (VSWR) and Smith chart. For fabrication of substrates of ferrites S1, S2 and S3 of proposed antennas, the ferrite powder under investigation is milled in an agate mortal with acetone as base. Thereafter the milled powder is pressed in die of 2.25cm at a pressure of 10 ton through hydraulic press for 9 minute. The height of substrate is kept 2mm by polishing it after pressing. The designed patch with proper dimensions and ground plane of silver are printed on substrates by using screen printing technique. The SMA connector is soldered at exact designed feed point by carefully drilling a hole of 1.2 mm diameter in the substrate. The fabricated microstrip patch antennas are used for the measurement of the return loss
(RL), voltage standing wave ratio (VSWR) and Smith chart on vector network analyzer (Model: ROHDE & SCHWARZ ZVL) in the frequency range 7 to 13GHz as shown in the Fig.1. 3. Results and discussion 3.1. Structural Analysis The representative X-ray diffraction pattern, FESEM microphotograph and FT-IR spectrum of ferrite S3 are presented in Fig. 2, 3 and 4 respectively. The presence of peaks in the diffraction pattern (Fig. 2) corresponding to planes (220), (311), (400), (422), (511), (440) confirms the well formation of phase pure single cubic structure of synthesized ferrites. The average crystallite size of S1, S2 and S3 ferrites was found to be 40.59nm, 39.58 and 38.43nm respectively [15]. The surface morphology of ferrites S1, S2 and S3 (Fig.3) shows grain formation of order of 2, 2.7 and 3.8 µm. From Fig. 4, it is observed that the appearance of main absorption bands near 600cm-1 and 400 cm-1 in the FT-IR spectrum confirms well formation ferrites. 3.2. Dielectric Properties The variation of permittivity (εr) with frequency for the S1, S2 and S3 ferrites in Xband is presented in the Fig. 5. From the Fig.5, it is clearly seen that the values of ε r varies from approximately 6.1 to 4.2 on increasing frequency from 8.2GHz to 12.4GHz. With increase in frequency, εr of the all ferrites have been decrease and it is typical behavior of ferrites, due to separation of conducting grains by poorly conducting grain boundaries [28]. The dielectric loss tangent (tanδe) as function of frequency for all the ferrites is presented in Fig. 6. From Fig.6, it is inferred that the variation in tanδe with frequency is maximum for substituted magnesium ferrites as compared to pure magnesium ferrite. The value of tanδe is lower for the S1 and S3 ferrites i.e. close to zero as compared to S2 ferrite
which helps in increase in gain of microstrip patch antennas. For S2 ferrite the hopping of charges between Fe2+ and Fe3+ increases which leads to the hopping conduction results increase in dielectric loss. The variation of permeability (μr) with frequency is displayed in the Fig. 7 for the ferrites S1, S2 and S3. It is inferred that the permeability (μr) shows increase in the value from 0.65 to 1.12 as increase in the frequency. These low values of μr attributed to weak applied field. Similar low value of μr was reported by Arora et al. [27] in the frequency range of 18 GHz to 26.5 GHz for La-Na doped Co-Zr barium hexaferrites.
The
permeability (μr) of S1 and S2 ferrite is comparably higher than that for S3 ferrite. This may be due to increase in reported porosity of the ferrites of S1 (5.5), S2 (3.8) and S3 (2.6) [15]. This causes a high disturbance to magnetic domain motion by inducing small demagnetizing fields, resulting reduction in μr. The magnetic loss tangent (tanδm) as function of frequency for all the ferrites is presented in Fig. 8. Form Fig. 8, it is clear that tanδm value is almost constant and close to zero for magnesium ferrite S1, random variation with frequency for substituted ferrite S2 and decreases with increase in frequency for substituted ferrite S3. Overall value of tanδm is close to zero indicating low losses and plays potential roll in use of these ferrites as substrate for microstrip patch antennas. The dependence of εr, tanδe, μr and tanδm with Cd content at frequency 10.5GHz is shown in the Fig.9. This Fig.9 clearly shows the magnesium ferrite has got relatively lower values of εr as compared to substituted magnesium ferrite in this frequency range. The polarization induced in the material due to alternating voltage is proportional to permittivity. The increase in εr values suggests that interfacial and dipole polarization have enhanced as result of substitution of cadmium with magnesium. This increase in ε r may be attributed to the increase in conductivity of the ferrites with substitution, since ε r is
dependent on conductivity [28]. The remarkable trend has been not observed in the variation of tanδe, μr and tanδm with Cd content at frequency 10.5GHz. Fig.10 represents the variation of miniaturization factor with frequency. From Fig.10, it is observed that miniaturization factor for substrate S2 is nearly constant for frequency range 8.2 to 12.GHz, whereas maximum variation for substrate S3. 3.3. Microstrip patch antenna parameters The simulated geometry of proposed antennas with proper location of points on ferrite substrates S1, S2 and S3 are presented in the Fig.11. The variations of simulated and measured return loss (RL) of all antennas are shown in the Fig.12. The simulated and measured values of return loss at corresponding operating frequency and 10dB % bandwidth are presented in the Table 2. From Fig.11 and Fig.12, it is clearly seen that designed dimensions of patch antenna in simulation are accurate and resonate at operating frequency 10.5 GHz. However, in measurement little change in operating frequencies is observed. This is due to the fabrication error in preparation of antennas in the laboratory. The measured return loss is higher than the simulated return loss due to slit change in the feed point location during fabrication. The antenna on S3 ferrite substrate has lowest simulated and measured return loss signifying good impedance matching as compared with others and also for antenna on FR4 substrate (RL= -17.54dB) [23]. The %10dB bandwidth of antenna on S3 ferrite substrate is larger as compared to antennas on S1, S2 ferrite substrates and FR4 substrate (%10 dB BW=15.51) [23]. Table2. Simulated and Measured output parameters of microstrip patch antenna Cd Frequency Content F (GHz) Simulated Measured (x) 0 10.5 10.64 0.4 10.5 10.38 0.8 10.5 10.35
Return loss RL(dB)
VSWR
% 10dB Bandwidth
Simulated Measured Simulated Measured Simulated Measured
-21.97 -35.01 -40.69
-16.66 -13.38 -20.30
1.17 1.04 1.01
1.44 1.57 1.39
16.44 27.4
34.6 15.9 35.8
The variations of simulated and measured VSWR with frequency of all antennas are depicted in the Fig.12. From this figure, the values of simulated and measured VSWR at resonating frequency are listed in Table 2. The VSWR values are close to one shows good impedance matching at feed locations of antennas. The measured VSWR is quite higher than the simulated VSWR. Simulated and measured VSWR values of antenna on S3 ferrite substrate are lowest as compared to antennas on other substrate. The overall observations about the return loss, 10dB % bandwidth and VSWR, it is inferred that the S3 ferrite has potential to be used as substrate for microstrip patch antenna. Conclusion Nanocrystalline Cadmium substituted Magnesium ferrites were successfully synthesized under microwave heating and its single cubic spinel structure formation was confirmed by XRD and FT-IR analysis. The variation of permittivity (εr) with frequency shows usual typical behavior of ferrites. The value of tanδ e is lower for the S1 and S3 ferrites i.e. close to zero helps in increase in gain of antennas. The permeability (μr) has higher value for ferrites having higher porosity. The value of tanδm of ferrites under investigation is close to zero indicating low losses and these ferrites can be used as substrate for microstrip patch antennas. The study of simulated and measured antenna parameters such as the return loss, 10dB% bandwidth and VSWR was inferred that the S3 ferrite is potential candidate to be used as substrate for microstrip patch antenna. Acknowledgement The authors would like to thank the Department of Electronics, Shivaji University, Kolhaper, Rayat ShikshanSanstha and Yashvantarao Chavan Institute of Science, Satara, References [1] Renato Ci, Emanuela M., Orlandino T., Wideband and UWB Antennas for Wireless Applications: A Comprehensive Review, Hindawi, International Journal of Antennas and Propagation Volume 2017, Article ID 2390808.
[2] Shikha Sukhija, Rakesh K., Sarin A., A U-Shaped Meandered Slot Antenna for Biomedical Applications, Progress In Electromagnetics Research M 2017;62: 65-77. [3] Motevasselian A. Whittow W.G., Patch size reduction of rectangular microstrip antennas by means of a cuboid ridge, IET Microw. Antennas Propag., 2015; 9 (15): 1727-1732. [4] Wakrim L.; Ibnyaich, S.; Hassani M. M., The study of the ground plane effect on a Multiband PIFA Antenna by using Genetic Algorithm and Particle Swarm Optimization. J. Microw. Optoelectron. Electromagn. Appl., São Caetano do Sul, 2016; 15(4): 293-308. [5] Borah K., Bhattacharyya N. S. Magneto-dielectric composite with ferrite inclusions as substrates for microstrip patch antennas at microwave frequencies. Composites: Part B 2012;43: 1309-14. [6] Hua S, Xiaoli T., Huaiwu Z., Yulan J., Feiming B., Low-Loss Magneto-Dielectric Materials: Approaches and Developments, Journal of Elec Materi 2014; 43(2): 299307. [7] Huitema L., Reveyrand T., Mattei J. L., Arnaud E., Decroze C., Monediere T., Frequency Tunable Antenna Using a Magneto-Dielectric Material for DVB-H Application, IEEE Trans. Antennas and Propag., 2013; 61(9):4456-4466. [8] Zhijuan Su et al., Low loss factor Co2Z ferrite composites with equivalent permittivity and permeability for ultra-high frequency applications, Applied Physics Letters, 2014; 105 : 062402-1-; doi: 10.1063/1.4892889. [9] N. K. Saxena, N. Kumar, P. K. S. Pourush, Radiation characteristics of microstrip rectangular patch antenna fabricated on LiTiMg ferrite substrate, AEU - International Journal of Electronics and Communications 2015, 69(12):1741-1744. [10] N. K. Saxena, B. Singh, N, Kumar, P. K. S. Pourush, Microstrip triangular patch antenna fabricated on LiTiZn ferrite substrate and tested in the X band range, AEU International Journal of Electronics and Communications 2012, 66(2):140-142. [11] Hua Su, Xiaoli Tang, Huaiwu Zhang, Yulan Jing, Feiming Bai et al., Low-loss NiCuZn ferrite with matching permeability and permittivity by two step sintering process, J. Appl. Phys., 2013;113:17B301-1-3; doi: 10.1063/1.4793508.
[12] Borah K. and Bhattacharyya N. S., Design of Light Weight Microstrip Patch Antenna on Dielectric and Magnetodielectric Substrate for Broadband Applications in X-Band, Progress In Electromagnetic Research B, 2014;60: 157-168. [13] J.L. Mattei, E. L. Guen, A. Chevalier, A. C. Tarot, Experimental determination of magnetocrystalline anisotropy constants and saturation magnetostriction constants of NiZn and NiZnCo ferrites intended to be used for antennas miniaturization, J. Magn. Magn. Mater. 2015; 374:762–768. [14] V. Naidu et al., Synthesis and Characterization of Novel Nanoceramic Magnesium Ferrite Material Doped with Samarium and Dysprosium for Designing - Microstrip Patch Antenna, Defect and Diffusion Forum, 2012; 332: 35-50. [15] Bhongale S. R., Ingavale H. R., Shinde T. J., Vasambekar P. N. Effect of Microwave Sintering on Synthesis and Structural Properties of Nanocrystalline Mg-Cd Ferrites, J. Matar Sci: Matar Elect. 2017; 28(15):11070-77. [16] S.R. Bhongale, H. R. Ingavale, T. J. Shinde, P. N. Vasambekar, Effect of Nd3+ Substitution on Structural and Magnetic Properties of Mg-Cd Ferrites Synthesized by Microwave Sintering Technique , J. of Rare Earths 2018;36(4):390 – 397. [17] Saini, A., Thakur, A., Thakur, P. Matching permeability and permittivity of Ni0.5Zn0.3Co0.2In0.1Fe1.9O4 ferrite for substrate of large bandwidth miniaturized antenna. J. Matar Sci: Matar Elect. J Mater Sci: Mater Electron. 2016; 27:2816-23. [18] Narang S.B., Pubby K. Single-layer & double-layer microwave absorbers based on Co–Ti substituted barium hexaferrites for application in X and Ku-band, J. Mater. Res. 2017; 31(23): 3682- 93. [19] Hewlett-Packerd Microwave Network Analyzer catalogue 8510 and product note 8510-3 (1987). [20] Ansoft Designer, www.ansoft.com.
[21] K. Alameddine, S. Abou Chahine, M. Rammal, Z. Osman, Wideband patch antennas for mobile communication, International Journal of Electronic Communication (AEU) 2006;60:596-598. [22] R. Garg. P. Bhartia, I. Bahl, and A. Ittipiboon, Microstrip Antennas Design Handbook (London: Artech House 2001) 253. [23] M. M. Islam, M. T. Islam, M. R. I. Faruque and W. Hueyshin, Design of an X-band microstrip patch antenna with enhanced bandwidth, 2013 2nd International Conference on Advances in Electrical Engineering (ICAEE), Dhaka, 2013, pp. 313317. doi: 10.1109/ICAEE.2013.6750355. [24] D. Mittal, A. Nag, A. Kaur and E. Sidhu, High directivity FR4 substrate slotted defected ground microstrip patch antenna for X-band applications, 2016 International Conference on Global Trends in Signal Processing, Information Computing and Communication (ICGTSPICC), Jalgaon, 2016, pp.344-347. doi: 10.1109/ICGTSPICC.2016.7955325. [25] A. Mandal, A. Ghosal, A. Majumdar, A. Ghosh, A. Das and S. K. Das, Analysis of feeding techniques of rectangular microstrip antenna,
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Fig.1. Fabricated antenna on S2 connected to VNA
Fig. 2. XRD patterns of ferrite S3
Fig.3. Microphotograph of ferrite S3
Fig.4. FT-IR spectrum of ferrite S3
Fig.5. Variation of εr with frequency for ferrites S1, S2 and S3
Fig.6. Variation of tanδe with frequency for ferrites S1, S2 and S3.
Fig.7. Variation of μr with frequency for ferrites S1, S2 and S3.
Fig.8. Variation of tanδm with frequency for ferrites S1, S2 and S3.
Fig.9. Variation of εr, μr, tanδe and tanδm with Cd content at 10.5 GHz.
Fig.10. Variation of n with frequency for ferrites S1, S2 and S3.
Fig.11. Simulated geometry of microstrip patch antenna ferrites S1, S2 and S3.
Fig.12. Variation of RL with frequency for ferrites S1, S2 and S3.
Fig.13. Variation of VSWR with frequency for ferrites S1, S2 and S3. Figure captions Fig. 1: Fabricated antenna on S2 connected to VNA.
Fig. 2: XRD patterns of ferrite S3. Fig. 3: Microphotograph of ferrite S3. Fig. 4: FT-IR spectrum of ferrite S3. Fig. 5: Variation of εr with frequency for ferrites S1, S2 and S3. Fig.6: Variation of tanδe with frequency for ferrites S1, S2 and S3. Fig.7: Variation of μr with frequency for ferrites S1, S2 and S3. Fig.8: Variation of tanδm with frequency for ferrites S1, S2 and S3. Fig. 9: Variation of εr, μr, tanδe and tanδm with Cd content at 10.5 GHz. Fig. 10: Variation of n with frequency for ferrites S1, S2 and S3. Fig. 11: Simulated geometry of microstrip patch antenna ferrites S1, S2 and S3. Fig. 12: Variation of RL with frequency for ferrites S1, S2 and S3. Fig.13. Variation of VSWR with frequency for ferrites S1, S2 and S3.
S1434-8411(18)31898-3 https://doi.org/10.1016/j.aeue.2018.09.040 AEUE 52519
To appear in:
International Journal of Electronics and Communications
Received Date: Revised Date: Accepted Date:
15 July 2018 20 September 2018 25 September 2018
Please cite this article as: S.R. Bhongale, H.R. Ingavale, T.J. Shinde, P.N. Vasambekar, Microwave Sintered MgCd Ferrite Substrates for Microstrip Patch Antennas in X-band, International Journal of Electronics and Communications (2018), doi: https://doi.org/10.1016/j.aeue.2018.09.040
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Microwave Sintered Mg-Cd Ferrite Substrates for Microstrip Patch Antennas in X-band Sanjay R. Bhongale1, Hanmant R.Ingavale2, Tukaram J. Shinde3, Pramod N. Vasambekar4 1
Department of Physics, Yashavantrao Chavan Institute of Science, Satara, Maharashtra, India.
2
Department of physics, B.V.M.B.S.K.Kanya Mahvidyalaya, Kadegaon, Sangli, Maharashtra,
India. 3
Department of physics, K.R.P. Kanya Mahvidyalaya, Islampur, Dist- Sangli, Maharashtra ,India.
4
Department of Electronics, Shivaji University, Kolhapur, Maharashtra, India.
Corresponding author: S.R. Bhongale ([email protected]) (+919850609352) Abstract The
ferrites
with
chemical
formulae
MgFe2O4,
Mg0.6Cd0.4Fe2O4
and
Mg0.2Cd0.8Fe2O4 specified with Ferrite S1, S2 and S3 were prepared by the oxalate coprecipitation method using AR grade sulphates under microwave sintering technique. The single phase cubic spinel structure formation of all the ferrites was confirmed by XRD and FTIR techniques. The dielectric parameters such as permittivity (εr), dielectric loss tangent (tanδe), permeability (µr) and magnetic loss tangent (tanδm) were determined from parameters S11 and S21 by using material measurement software with VNA.
The
synthesized ferrites S1, S2 and S3 with determined dielectric parameters were used as substrate to design rectangular microstrip patch antenna by simulation using Ansoft Designer SV 2.2. The designed antennas were fabricated by using screen printing technique. The return loss (RL), 10dB % bandwidth and VSWR of these fabricated antennas were measured on vector network analyzer. The simulated and measured values of resonating frequency, return loss (RL), 10dB % bandwidth and VSWR were nearly
matched with each other. Mg0.2Cd0.8Fe2O4 (Ferrite S3) can be used as substrate of antenna for better results. Keywords: Mg- Cd Ferrites, Dielectric Properties, Microstrip Patch Antenna, Return loss. 1. Introduction The modern communication systems in civil sector, satellite communication, radar applications etc. require size reduction of antennas. Such communication system requires antennas with low weight, low cost, low profile, easy integration into microwave ICs without affecting their antenna parameters [1]. Therefore size reduction or miniaturization has become a very important matter now days in the development of patch antennas. The necessary and sufficient characteristics of antennas are small physical size, wide bandwidth and high radiation efficiency. However, size reduction of antenna is difficult due the properties of electromagnetic radiation. The general ways of miniaturization are using slots, use of high permittivity materials, shorting pins and planes [2, 3, 4]. However, use of high dielectric material results in field confinement about the high permittivity area. This reduces antenna efficiency and bandwidth. Therefore researchers shifted towards the use of magneto-dielectric materials for antenna miniaturizations in place of high permittivity materials [5-7]. Also use of materials with moderate permittivity and permeability yields antenna miniaturizations [8]. The ferrite material is one type of magneto-dielectric material which has both permittivity and permeability properties which can miniaturize antenna. Saxena et al. [9-10] has been established the single patch microstrip on substrate of Li-Ti-Zn and Li-Ti-Mg ferrites and found that the change in overall radiation performance of antenna system as well as reduction in patch size as compare to antenna printed on dielectric substrate. Hua su et.al [11] suggested that Ni-Cu-Zn ferrites with matched permeability and permittivity were shows potential candidates for use as substrate to miniaturize the low-frequency antennas. Borah and Bhattacharyya [12] used 5% VF Nickel ferrite/LDPE for enhancement of bandwidth with reduction in size of antenna in Xband applications. Mattei et al. [13] reported that remarkable reduction in magnetic losses of Ni0.6Zn0.2Co0.2Fe1.98O4-δ spinel ferrite may be used as substrate of antennas for
miniaturization. V. Naidu et al. [14] reported that Dy-Sm doped Mg-ferrite has been used as substrate for designing E-shaped microstrip patch antenna. In present investigations we report the design, fabrication and analysis of rectangular microstrip patch antennas on magneto-dielectric material cadmium substituted Mg-ferrite substrate prepared by oxalate co-precipitation method with microwave sintering technique. 2.
Experimental The ferrites with chemical formula Mg1-xCdx Fe2 O4 (x = 0, 0.4, and 0.8) specified
with MgFe2O4 (Ferrite S1) Mg0.6Cd0.4Fe2O4 (Ferrite S2), Mg0.2Cd0.8Fe2O4 (Ferrite S3) were prepared by the oxalate co-precipitation method with microwave sintering technique. The starting chemicals such as the high purity AR grade MgSO 4.7H2O (purity 99.5%, Thomas Baker), 3CdSO4.8H2O (purity 98%, Thomas Baker) and FeSO4.7H2O (purity 99.5%, Thomas Baker) were used. The detailed procedure of preparation of MgCd ferrite was explained elsewhere [15]. This new material was developed under microwave sintering technique. Such technique requires low energy for short duration which plays important role in the consumption of both energy as well as time [15]. Because the energy consummation is an important issue, where as the low time of heating is helps in maintaining the temperature of surrounding at lower level which is intern helps to control the overall temperature of environment. The optimized microwave oven (ONIDA 20XL 800 watts) power of 70% at 10 min was used for final sintering [16]. The structural properties of the synthesized samples were investigated by XRD, SEM, and FTIR techniques. The X-ray diffraction patterns of these samples were created on X-ray powder diffractometer modal D2-Phaser with Cu-Kα (λ= 1.5406 A°) radiation. The surface morphology of ferrites was studied by using Mira-3, Tescan, Brno-Czech
Republic, Field emission scanning electron microscope (FE-SEM). FTIR spectra of the ferrites were drawn in the range of 350 - 800 cm-1 using Perkin-Elmer FTIR spectrum one spectrometer. The synthesized ferrites powder under investigation was milled in agate mortar with acetone base. The powder was pressed into the shape of rectangular pellets with dimensions suitable for WR-90 waveguide under pressure of 5 tons cm-2 by adding polyvinyl acetate as binder. The pellets were finally cured for 1h at 150° C. These pallets were used for measuring scattering parameters such as reflection coefficient (S 11) and transmission coefficient (S21) at Microwave frequencies in the range of 8.2 to 12.4 GHz using vector network analyzer (Agilent N5225A PNA series). The permittivity (εr), dielectric loss tangent (tanδe), permeability (μr) and magnetic loss tangent (tanδm) are determine from measured parameters S11 and S21 by using material measurement software, Agilent module 85071E [17, 18, 19]. The microstrip patch antenna is design on synthesized cadmium substituted Mgferrites S1, S2 and S3 substrates by using software Ansoft Designer SV 2.2 [20]. Alameddine et al.[21] used Ansoft Designer software for design of wideband patch antennas for mobile communication. The parameters of substrate such as permittivity (εr), dielectric loss tangent (tanδe), permeability (μr) and magnetic loss tangent (tanδm) required for designing of an antennas are obtained from the variations of these parameters with frequency at 10.5 GHz which has been discussed in results and discussion section (Fig. 5, 7, 8 and 9) and presented in Table 1. The ferrites S1, S2 and S3 are new materials and not available in the software library. Therefore they are added in the software library with respective evaluated values of real permittivity and permeability. The length of proposed antennas on ferrites S1, S2 and S3 substrates are determined by using eq. [22] L
c 2f r ε r μ r
Table1. Input parameters for design of microstrip patch antenna. Cd Content (x) 0 0.4 0.8
F (GHz)
ε'
μ'
tanδe
tanδm
10.5 10.5 10.5
4.67 4.55 5.91
0.98 1.02 0.76
0.0878 0.293 0.0724
0.0035 0.0037 0.0856
Length L (mm) 6.9 6.9 6.9
Width W (mm) 8 7.3 7.1
Using this length (L), width (W) is selected by optimization in the simulation to suppress higher modes of excitation. The length (L) and width (W) of proposed microstrip antennas at operating frequency 10.5GHz are presented in Table1. M. M. Islam et al. [23] studied the rectangular microstrip patch antenna on conventional FR4 substrate of 40mm length (L) and width (W) with rectangular and circular slots at resonance frequency 10.25GHz. D. Mittal et al. [24] studied the rectangular microstrip patch antenna on conventional FR4 substrate of patch dimensions length Lp = 7.73mm and width Wp = 34.55mm at resonance frequency 7.94GHz. This clearly shows that use of ferrites substrate in present research work reduces the size of patch about 34 to 38% as compared to conventional FR4 substrate. The location on of coaxial feed point is optimized by trial and error method [25]. The designed antennas are simulated in the frequency range 7 to 13 GHz to study the return loss (RL), voltage standing wave ratio (VSWR) and Smith chart. For fabrication of substrates of ferrites S1, S2 and S3 of proposed antennas, the ferrite powder under investigation is milled in an agate mortal with acetone as base. Thereafter the milled powder is pressed in die of 2.25cm at a pressure of 10 ton through hydraulic press for 9 minute. The height of substrate is kept 2mm by polishing it after pressing. The designed patch with proper dimensions and ground plane of silver are printed on substrates by using screen printing technique. The SMA connector is soldered at exact designed feed point by carefully drilling a hole of 1.2 mm diameter in the substrate. The fabricated microstrip patch antennas are used for the measurement of the return loss
(RL), voltage standing wave ratio (VSWR) and Smith chart on vector network analyzer (Model: ROHDE & SCHWARZ ZVL) in the frequency range 7 to 13GHz as shown in the Fig.1. 3. Results and discussion 3.1. Structural Analysis The representative X-ray diffraction pattern, FESEM microphotograph and FT-IR spectrum of ferrite S3 are presented in Fig. 2, 3 and 4 respectively. The presence of peaks in the diffraction pattern (Fig. 2) corresponding to planes (220), (311), (400), (422), (511), (440) confirms the well formation of phase pure single cubic structure of synthesized ferrites. The average crystallite size of S1, S2 and S3 ferrites was found to be 40.59nm, 39.58 and 38.43nm respectively [15]. The surface morphology of ferrites S1, S2 and S3 (Fig.3) shows grain formation of order of 2, 2.7 and 3.8 µm. From Fig. 4, it is observed that the appearance of main absorption bands near 600cm-1 and 400 cm-1 in the FT-IR spectrum confirms well formation ferrites. 3.2. Dielectric Properties The variation of permittivity (εr) with frequency for the S1, S2 and S3 ferrites in Xband is presented in the Fig. 5. From the Fig.5, it is clearly seen that the values of ε r varies from approximately 6.1 to 4.2 on increasing frequency from 8.2GHz to 12.4GHz. With increase in frequency, εr of the all ferrites have been decrease and it is typical behavior of ferrites, due to separation of conducting grains by poorly conducting grain boundaries [28]. The dielectric loss tangent (tanδe) as function of frequency for all the ferrites is presented in Fig. 6. From Fig.6, it is inferred that the variation in tanδe with frequency is maximum for substituted magnesium ferrites as compared to pure magnesium ferrite. The value of tanδe is lower for the S1 and S3 ferrites i.e. close to zero as compared to S2 ferrite
which helps in increase in gain of microstrip patch antennas. For S2 ferrite the hopping of charges between Fe2+ and Fe3+ increases which leads to the hopping conduction results increase in dielectric loss. The variation of permeability (μr) with frequency is displayed in the Fig. 7 for the ferrites S1, S2 and S3. It is inferred that the permeability (μr) shows increase in the value from 0.65 to 1.12 as increase in the frequency. These low values of μr attributed to weak applied field. Similar low value of μr was reported by Arora et al. [27] in the frequency range of 18 GHz to 26.5 GHz for La-Na doped Co-Zr barium hexaferrites.
The
permeability (μr) of S1 and S2 ferrite is comparably higher than that for S3 ferrite. This may be due to increase in reported porosity of the ferrites of S1 (5.5), S2 (3.8) and S3 (2.6) [15]. This causes a high disturbance to magnetic domain motion by inducing small demagnetizing fields, resulting reduction in μr. The magnetic loss tangent (tanδm) as function of frequency for all the ferrites is presented in Fig. 8. Form Fig. 8, it is clear that tanδm value is almost constant and close to zero for magnesium ferrite S1, random variation with frequency for substituted ferrite S2 and decreases with increase in frequency for substituted ferrite S3. Overall value of tanδm is close to zero indicating low losses and plays potential roll in use of these ferrites as substrate for microstrip patch antennas. The dependence of εr, tanδe, μr and tanδm with Cd content at frequency 10.5GHz is shown in the Fig.9. This Fig.9 clearly shows the magnesium ferrite has got relatively lower values of εr as compared to substituted magnesium ferrite in this frequency range. The polarization induced in the material due to alternating voltage is proportional to permittivity. The increase in εr values suggests that interfacial and dipole polarization have enhanced as result of substitution of cadmium with magnesium. This increase in ε r may be attributed to the increase in conductivity of the ferrites with substitution, since ε r is
dependent on conductivity [28]. The remarkable trend has been not observed in the variation of tanδe, μr and tanδm with Cd content at frequency 10.5GHz. Fig.10 represents the variation of miniaturization factor with frequency. From Fig.10, it is observed that miniaturization factor for substrate S2 is nearly constant for frequency range 8.2 to 12.GHz, whereas maximum variation for substrate S3. 3.3. Microstrip patch antenna parameters The simulated geometry of proposed antennas with proper location of points on ferrite substrates S1, S2 and S3 are presented in the Fig.11. The variations of simulated and measured return loss (RL) of all antennas are shown in the Fig.12. The simulated and measured values of return loss at corresponding operating frequency and 10dB % bandwidth are presented in the Table 2. From Fig.11 and Fig.12, it is clearly seen that designed dimensions of patch antenna in simulation are accurate and resonate at operating frequency 10.5 GHz. However, in measurement little change in operating frequencies is observed. This is due to the fabrication error in preparation of antennas in the laboratory. The measured return loss is higher than the simulated return loss due to slit change in the feed point location during fabrication. The antenna on S3 ferrite substrate has lowest simulated and measured return loss signifying good impedance matching as compared with others and also for antenna on FR4 substrate (RL= -17.54dB) [23]. The %10dB bandwidth of antenna on S3 ferrite substrate is larger as compared to antennas on S1, S2 ferrite substrates and FR4 substrate (%10 dB BW=15.51) [23]. Table2. Simulated and Measured output parameters of microstrip patch antenna Cd Frequency Content F (GHz) Simulated Measured (x) 0 10.5 10.64 0.4 10.5 10.38 0.8 10.5 10.35
Return loss RL(dB)
VSWR
% 10dB Bandwidth
Simulated Measured Simulated Measured Simulated Measured
-21.97 -35.01 -40.69
-16.66 -13.38 -20.30
1.17 1.04 1.01
1.44 1.57 1.39
16.44 27.4
34.6 15.9 35.8
The variations of simulated and measured VSWR with frequency of all antennas are depicted in the Fig.12. From this figure, the values of simulated and measured VSWR at resonating frequency are listed in Table 2. The VSWR values are close to one shows good impedance matching at feed locations of antennas. The measured VSWR is quite higher than the simulated VSWR. Simulated and measured VSWR values of antenna on S3 ferrite substrate are lowest as compared to antennas on other substrate. The overall observations about the return loss, 10dB % bandwidth and VSWR, it is inferred that the S3 ferrite has potential to be used as substrate for microstrip patch antenna. Conclusion Nanocrystalline Cadmium substituted Magnesium ferrites were successfully synthesized under microwave heating and its single cubic spinel structure formation was confirmed by XRD and FT-IR analysis. The variation of permittivity (εr) with frequency shows usual typical behavior of ferrites. The value of tanδ e is lower for the S1 and S3 ferrites i.e. close to zero helps in increase in gain of antennas. The permeability (μr) has higher value for ferrites having higher porosity. The value of tanδm of ferrites under investigation is close to zero indicating low losses and these ferrites can be used as substrate for microstrip patch antennas. The study of simulated and measured antenna parameters such as the return loss, 10dB% bandwidth and VSWR was inferred that the S3 ferrite is potential candidate to be used as substrate for microstrip patch antenna. Acknowledgement The authors would like to thank the Department of Electronics, Shivaji University, Kolhaper, Rayat ShikshanSanstha and Yashvantarao Chavan Institute of Science, Satara, References [1] Renato Ci, Emanuela M., Orlandino T., Wideband and UWB Antennas for Wireless Applications: A Comprehensive Review, Hindawi, International Journal of Antennas and Propagation Volume 2017, Article ID 2390808.
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Fig.1. Fabricated antenna on S2 connected to VNA
Fig. 2. XRD patterns of ferrite S3
Fig.3. Microphotograph of ferrite S3
Fig.4. FT-IR spectrum of ferrite S3
Fig.5. Variation of εr with frequency for ferrites S1, S2 and S3
Fig.6. Variation of tanδe with frequency for ferrites S1, S2 and S3.
Fig.7. Variation of μr with frequency for ferrites S1, S2 and S3.
Fig.8. Variation of tanδm with frequency for ferrites S1, S2 and S3.
Fig.9. Variation of εr, μr, tanδe and tanδm with Cd content at 10.5 GHz.
Fig.10. Variation of n with frequency for ferrites S1, S2 and S3.
Fig.11. Simulated geometry of microstrip patch antenna ferrites S1, S2 and S3.
Fig.12. Variation of RL with frequency for ferrites S1, S2 and S3.
Fig.13. Variation of VSWR with frequency for ferrites S1, S2 and S3. Figure captions Fig. 1: Fabricated antenna on S2 connected to VNA.
Fig. 2: XRD patterns of ferrite S3. Fig. 3: Microphotograph of ferrite S3. Fig. 4: FT-IR spectrum of ferrite S3. Fig. 5: Variation of εr with frequency for ferrites S1, S2 and S3. Fig.6: Variation of tanδe with frequency for ferrites S1, S2 and S3. Fig.7: Variation of μr with frequency for ferrites S1, S2 and S3. Fig.8: Variation of tanδm with frequency for ferrites S1, S2 and S3. Fig. 9: Variation of εr, μr, tanδe and tanδm with Cd content at 10.5 GHz. Fig. 10: Variation of n with frequency for ferrites S1, S2 and S3. Fig. 11: Simulated geometry of microstrip patch antenna ferrites S1, S2 and S3. Fig. 12: Variation of RL with frequency for ferrites S1, S2 and S3. Fig.13. Variation of VSWR with frequency for ferrites S1, S2 and S3.