Double MOS Loaded Circular Microstrip Antenna ... - Semantic Scholar
Wireless Pers Commun DOI 10.1007/s11277-012-0856-3
Double MOS Loaded Circular Microstrip Antenna with Airgap for Mobile Communication Surendra Kumar Gupta · Binod Kumar Kanaujia · Ganga Prasad Pandey
© Springer Science+Business Media New York 2012
Abstract A novel model of a wide frequency range double MOS loaded circular microstrip patch antenna with airgap between ground plane and substrate is proposed. In this structure two metal oxide semiconductor (MOS) devices are loaded on the patch to enhance the operating frequency range of antenna. To investigate the antenna, different parameters such as resonance frequency, input impedance, frequency agility, VSWR, radiation pattern etc. are calculated and simulated. The resonant frequency of proposed 10 mm radius patch is upward shifted from 5.2 to 6.8 GHz using 1 mm airgap and by loading MOS, antenna can be tuned down to 1.27 GHz operating frequency, which leads to compactness and tunability of antenna. Proposed antenna can be tuned between 1.27 and 6.8 GHz frequency of operation which makes the antenna highly suitable for wide frequency range of mobile communication. The proposed double MOS loaded antenna possessed 82.94 % frequency agility. The antenna is worth for GPS, WLAN, UMTS, and WiMAX operations. Keywords Circular patch microstrip antenna · Airgap · MOS · Agility · Mobile communication
S. K. Gupta Department of Electronics Engineering, Ambedkar Polytechnic, Government of Delhi, Shakarpur, Delhi, India e-mail: [email protected] B. K. Kanaujia (B) Department of Electronics & Communication Engineering, Ambedkar Institue of Advanced Communication Technologies & Research, Geeta Colony, Delhi, India e-mail: [email protected] G. P. Pandey Department of Electronics & Communication Engineering, Maharaja Agrasen Institue of Tecnology, Rohini, Delhi, India e-mail: [email protected]
123
S. K. Gupta et al.
1 Introduction In recent years the demand of microstrip antennas have been considerably increased in both research and engineering applications due to their ingredient features like low profile, light weight, inexpensive, reliability, conformal structure and ease in fabrication and integration with other microwave components. Due to this microstrip patch antennas are being used for modern mobile communication system such as Wireless Local Area Network (WLAN), Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) etc. Other side, microstrip antennas suffer from low efficiency and narrow bandwidth which limits their versatility. The input impedance of an antenna tends to be sensitive to changes in frequency and it also depends on geometrical shape, dimensions and the fed type of antenna. Hence, the antenna input impedance is a very important parameter which controls the radiated power and the impedance bandwidth [1]. Many efforts have been made to improve impedance bandwidth and frequency tunability. Shorting posts are used to enhance the frequency agility. Using double posts and by adjusting them finely, the maximum 32.5 % tunability was achieved [2]. Impedance bandwidth can be increased by loading patch with stubs, slits and slots. Apart from loading a patch, impedance bandwidth can be improved by increasing the substrate thickness and variable length transmission lines. Various other techniques have been suggested to improve the impedance bandwidth and frequency tunability such as loading varactor diodes, annular ring, stacking of patches and L-strip proximity coupled slot loaded patch [3–10]. Integration of devices like varactor diode, Gunn diode and impedance tuning network in microstrip antennas could not provide sufficient band of operation. Limitations still exists on the ability of these techniques. A circular microstrip antenna with an airgap between ground plane and substrate was proposed in [11]. An increase of the airgap causes a decrease in the dynamic permittivity, results in an upward shift in the resonant frequency of antenna. Hence to overcome bandwidth limitation various configuration of microstrip antennas such as above are proposed which provide dual band, multiband and wide band operation. Such configurations of antennas are widely acceptable for multiservice applications and become good substitute of wide bandwidth requirement which has motivated the authors to work on a novel proposed structure of antenna for wide frequency range applications. In this paper, circular microstrip antenna with airgap between ground plane and substrate is referred as reference antenna [11]. We have proposed to load MOS devices on the circular microstrip patch with airgap between ground plane and substrate to design an antenna that can operate in wide frequency range. The theoretical analysis is carried out using the equivalent circuit concept. The airgap between ground plane and substrate is included for upward shift of resonance frequency and MOS is loaded to achieve tunability and wide frequency range of antenna. The double MOS loaded circular microstrip antenna with airgap is analyzed and simulated on Zeland’s IE3D. The calculated and simulated results are in good agreement. This paper presents easier design of a circular microstrip antenna with airgap with better tunability over wide frequency range.
2 Theoretical Considerations The bandwidth limitation had been the major constraint in the development of microstrip antennas, in recent research wide frequency range tunable antenna is considered a good substitute to this problem. Figure 1 presents the geometry of a wide frequency range tunable double MOS loaded circular microstrip antenna with an airgap between the ground plane
123
Double MOS Loaded Circular Microstrip Antenna Fig. 1 Geometry of double MOS loaded circular microstrip antenna with airgap
and substrate for mobile communication. The circular microstrip antenna is structured as a cavity with magnetic wall along the edge. The structure of this antenna is a two layer cavity: the lower layer is an airgap of Ha with relative permittivity 1 and the upper layer is the dielectric substrate of thickness H with relative permittivity εr . The effect of the airgap below the substrate was considered for obtaining an equivalent permittivity of the medium below the patch. Using an equivalent single layer structure of total height Ht = H + Ha , equivalent permittivity (εre ) is calculated as in [12] and expressed as follows. εr e =
εr (H + Ha ) (1 + εr Ha )
(1)
where εr is the permittivity of the substrate and equivalent permittivity for CMSA without an air gap (Ha = 0), εre = εr . Following the analytical model an improved form of permittivity of transverse magnetic (TM) modes of the medium below the patch in CMSA with airgap, effective permittivity εr,eff is defined as 4εr e εr,dyn εr,e f f = √ √ εr e + εr,dyn
(2)
The term εr,eff is introduced to take into account the effect of the equivalent permittivity (εre ) of the medium below the patch in combination with the dynamic permittivity (εr,dyn ) to improve the model. The resonant frequency and effective radius of the CMSA with airgap are calculated as resonant frequency fr =
αnmc √ 2πae f f εr,e f f
(3)
123
S. K. Gupta et al.
Fig. 2 MOS capacitor. a Schematic. b Equivalent
where c is velocity of light in free space and αnm is mth zero of first kind Bessel function of order n. Effective radius of patch (4) aeff = a (1 + q) where the term q arises due to the fringing fields at the edge of the patch [12]. 2.1 Metal-Oxide-Semiconductor Figure 2 shows a typical Metal-Insulator-Semiconductor (MIS) or Metal-Oxide-Semiconductor (MOS) and its associated capacitances. It is evident that it contains two capacitances: depletion layer capacitance (Cd ) which varies with bias voltage and insulator capacitance (Ci ) which is fixed. The MOS under consideration is Au–Si3 N4 –Si. Total capacitance of MOS (Cmos ) is calculated as in [13] Cmos =
Ci Cd (Ci + Cd )
(5)
here insulation layer capacitance (Ci ) is given by Ci =
ε0 εr o d
(6)
where, εro is relative permittivity and d is the thickness of insulation layer. The depletion layer capacitance (Cd ) is given by Cd =
ε0 εr si X
(7)
where, εr si is relative permittivity of silicon and X is width of depletion layer, given by ⎧
⎫ ⎬ 2 C 2V εr si ε0 ⎨ g i −1 + 1 + X= (8) Ci ⎩ εr si ε0 Q N a ⎭ where Vg is bias voltage, Na is acceptor concentration of doping material and Q is charge of an electron.
123
Double MOS Loaded Circular Microstrip Antenna
Z in
R0
L C
(a)
Ci Ci Z in Cd
Z in C
R0
R0
L
C total
L Cd
(b) Fig. 3 Equivalent circuit of a circular patch microstrip antenna b double MOS loaded circular patch microstrip antenna
Combining equations (5)–(8), Cmos is defined as Cmos =
1+
Ci 2Vg Ci2 εrsi ε0 Q N a
A
(9)
where, A is the cross sectional area of MOS device. 2.2 Double MOS Loaded Circular Microstrip Antenna with Airgap The proposed antenna is a coaxial fed circular microstrip patch with airgap and loaded with MOS. The antenna is analyzed in TM11 mode. A circular microstrip antenna is characterized by parallel combination of resonance resistance R0 , inductance L and capacitance C as presented in Fig. 3a. These parameters are calculated from the theory of modal expansion and cavity model as in [14]. Resonance resistance R0 =
1 Jn2 (kρ) GT Jn2 (ka)
(10)
where Jn is the first kind of Bessel function of order n, ρ is probe position and G T is total conductance associated with dielectric loss, radiation loss, and conduction loss [15].
123
S. K. Gupta et al.
Capacitance associated with antenna C=
QT 2π fr R0
(11)
L=
R0 2π fr Q T
(12)
and inductance
where Q T is total quality factor, which includes radiation loss, dielectric loss and conductance loss. The equivalent circuit of a double MOS loaded circular microstrip antenna with airgap is presented in Fig. 3b. Total capacitance of patch can be calculated as in [16] Ctotal = C + 2Cmos
(13)
where Cmos is the capacitance of MOS. The total input impedance of a double MOS loaded CMSA with airgap is calculated as Z in =
1 R0
1 + ( jωCtotal ) +
1 jωL
(14)
The reflection coefficient () of circular patch is given by =
Z in − Z 0 Z in + Z 0
(15)
where, Z 0 is impedance (50) of coaxial feed. Voltage standing wave ratio (VSWR) of patch is given as VSWR =
1 + || 1 − ||
(16)
The return loss (RL) of the antenna is given by RL = 20 log (||)
(17)
where is reflection coefficient of circular patch.
3 Design Specifications The design specifications of MOS device and CMSA are given in Tables 1 and 2, respectively. Same specifications are considered for the theoretical analysis and simulation of proposed antenna. These specifications provide good performance of proposed antenna as discussed in result section and theoretical results closely match with the simulated results.
123
Double MOS Loaded Circular Microstrip Antenna Table 1 Specifications of MOS
Table 2 Specifications of CMSA
Parameter
Value
MOS capacitor structure
Au–Si3 N4 –Si (n + 0.0005 cm)
Cross section area of device (A)
1.6 × 10−8 m2
Relative permittivity of oxide layer (εr o )
7.5
Relative permittivity of semiconductor (εr si )
11.9
Acceptor concentration (Na )
1.45 × 1022 m−3
Bias voltage range (Vg )
0–5 V
Thickness of oxide layer (d)
100, 200, 300, 400, 500 A◦
Peak values of Cmos
106.2, 53.1, 35.4, 26.5, 21.2 pf
Parameter
Value
Substrate material
Beeswax
Radius of circular patch (a)
10 mm
Substrate thickness (H )
1.5748 mm
Airgap (Ha )
1.00 mm
Relative dielectric constant of substrate material(εr )
2.35
Loss tangent (tanδ)
0.005
Probe position (ρ)
3.1 mm
4 Radiation Pattern The expression for radiation pattern of circular microstrip antenna in TM11 mode is given as in [17] j V ako e− jko r cos(φ)J1 (ko a sin(θ )) 2 r j V ako e− jko r J1 (ko a sin(θ )) Eφ = cos θ sin φ 2 r ko a sin(θ ) Eθ = −
(18) (19)
where V is edge voltage, ko is wave number and r is observation location that may be taken randomly large compared to antenna size. Radiation pattern of antenna is calculated as R = |Eθ|2 + |Eφ|2 For E-plane pattern φ =
0◦ ,
and for H-plane pattern φ =
(20) 90◦ .
5 Results and Discussion In this work double MOS loaded circular patch microstrip antenna with airgap is investigated to achieve wide frequency range characteristics. The theoretical and simulated results for input impedance, MOS capacitance, frequency agility, VSWR and radiation pattern in
123
S. K. Gupta et al.
Fig. 4 Variation of real part of input impedance with frequency of CMSA with various airgap. a Theoretical. b Simulated
respect of performance of antenna are presented in this section. The theoretical results are plotted using MATLAB and simulation is done on IE3D simulator [18]. The Fig. 4a, b show the variation of real part of input impedance with the frequency of circular microstrip patch antenna for different airgap. It is found that the resonance frequency of the antenna increases with increasing the airgap, due to the fact that the effective value of permittivity decreases. The resonant frequency of antenna with 1 mm airgap is upward shifted to 6.8 GHz as compared to 5.2 GHz for circular microstrip antenna without airgap. This upward shift of frequency due
123
Double MOS Loaded Circular Microstrip Antenna
Fig. 5 Variation of capacitance of a MOS with bias voltage
to airgap between ground plane and substrate has broadened the operating range of antenna. Theoretical results are showing good agreement with simulated results, as seen from Fig. 4a, b the simulated real part of input impedance for all three airgap (Ha = 0.0, 0.5 and 1.0 mm) are in good match with theoretical real part of input impedance. Simulated results well verify the matching of input impedance of antenna over its wide frequency range. Figure 5 shows variation of capacitance with bias voltage for a typical MOS. It is found that there is sharp variation in capacitance near zero bias voltage. Capacitance is almost constant for all values of thicknesses for the bias voltage above 1 V. The peak values of capacitances are 106.2, 53.1, 35.4, 26.5, and 21.2 pf for oxide layers of 100, 200, 300, 400 and 500 A◦ , respectively. The variation of resonant frequency with bias voltage for single and double MOS loaded circular microstrip antenna with airgap is shown in Fig. 6a, b, respectively. The variation of resonance frequency is steep at lower bias voltage comparatively to higher bias voltage. It is also found that variation of resonance frequency is negligible for all oxide layers for higher bias voltage. To observe the behavior of agility of antenna, it is simulated for various thickness of oxide layer of MOS. Table 3 shows percentage agility for the single MOS loaded antenna for different oxide layer thickness. Table 4 shows percentage agility for the double MOS loaded antenna for different thickness of oxide layer. It is observed from response thatmaximum agility for double MOS loaded patch is 82.94 % (for 100 A◦ oxide layer). Also, it is evident from Tables 3 and 4 that frequency agility decreases as oxide thickness increases and double MOS loaded antenna has more frequency agility than single MOS loaded antenna. The antennas with different patch radius for 1 mm airgap are simulated to see the effect on agility. The theoretical and simulated variation of frequency agility with radius of patch are in good agreement as shown in Fig. 7. The simulated results of agility are shown for various patch radius (a = 5.0, 10.0, 15.0, 20.0, 25.0 and 30.0 mm) which are close to the theoretical results for respective patch radius. Also it is verified by the simulated results that agility
123
S. K. Gupta et al.
Fig. 6 Variation of resonant frequency with bias voltage of a single MOS loaded CMSA with airgap b double MOS loaded CMSA with airgap
is inversely proportional to the patch radius of proposed antenna. It is found that frequency agility decreases with a increase in the radius of patch, this may be understood by the fact that contribution of MOS capacitance in the antenna decreases as the radius of patch increases. It is evident that antenna has better frequency agility for low patch radius, frequency agility of antenna with 10 mm radius of patch is 82.94 %.
123
Double MOS Loaded Circular Microstrip Antenna Table 3 Frequency agility of single MOS loaded circular microstrip antenna with airgap for different thickness of oxide layer
Table 4 Frequency agility of double MOS loaded circular microstrip antenna with airgap for different thickness of oxide layer
Sr. No.
Oxide thickness (A◦ )
Minimum achievable frequency (GHz)
Total frequency agility (GHz)
Percentage agility (%)
1
100
1.571
5.032
76.20
2
200
2.161
4.442
67.27
3
300
2.579
4.024
60.94
4
400
2.905
3.698
56.00
5
500
3.172
3.431
51.96
Sr. No.
Oxide thickness (A◦ )
Minimum achievable frequency (GHz)
Total frequency agility (GHz)
Percentage agility (%)
1
100
1.127
5.476
82.94
2
200
1.571
5.032
76.20
3
300
1.897
4.706
71.27
4
400
2.161
4.442
67.27
5
500
2.385
4.218
63.88
Fig. 7 Theoretical and simulated variation of frequency agility with radius of patch of double MOS loaded CMSA with airgap (Ha = 1.0 mm)
Figure 8 shows variation of real part of input impedance with frequency for different bias voltage for proposed antenna. The resonant frequency of antenna shows interesting downward shift for different values of thickness of oxide layer. It is found that for 0 V bias voltage
123
S. K. Gupta et al.
Fig. 8 Theoretical and simulated variation of input impedance with frequency with various bias voltage (Vg ) of double MOS loaded CMSA with airgap (Ha = 1.0 mm)
Fig. 9 Theoretical and simulated variation of VSWR with frequency of CMSA with airgap (Ha = 1.0 mm) with and without MOS
123
Double MOS Loaded Circular Microstrip Antenna
Fig. 10 Theoretical and simulated E plane radiation pattern of double MOS loaded CMSA with airgap
Fig. 11 Theoretical and simulated H plane radiation pattern of double MOS loaded CMSA with airgap
and 100 A◦ oxide layer, the resonant frequency of antenna is downward shifted to 1.27 from 6.80 GHz design frequency which is obvious from the fact that maximum capacitance is added into antenna system due to MOS. Hence, the resonant frequency of proposed antenna can be tuned by varying the bias voltage. It is found that variation of resonance frequency with bias voltage provides good tunability of operating frequency of antenna and widen the frequency range and agility of antenna. These findings are equally verified by the simulated results. The theoretical results are in close agreement with simulated results as shown in Fig. 8 for variation of real parts of input impedance with frequency for 5.0 V bias voltage.
123
S. K. Gupta et al.
Figure 9 presents theoretical and simulated results for VSWR of antenna with and without MOS as a function of frequency at Vg = 1 V. The theoretical and simulated graphs show that the resonance impedance at lower frequency remains same as on 6.8 GHz which is obvious from the fact that only imaginary component is added into its equivalent. It is found that theoretically calculated VSWR gives a close match with simulated result. The E-plane and H-plane radiation patterns for MOS loaded CMSA are shown in Figs. 10 and 11, respectively. The theoretical radiation patterns are plotted for different bias voltage (Vg = 1.0, 2.0, 3.0, 4.0 and 5.0 V) and simulated radiation patterns for Vg = 5.0 V for both plane. The simulated results are close to the respective theoretical results. It is found that beam width of antenna decreases with increase in bias voltage for entire range of operation, this is due to the fact that operational frequency of antenna increases with bias voltage.
6 Conclusion A novel model of wide frequency range double MOS loaded circular microstrip antenna with airgap between the ground plane and substrate for mobile communication is presented. Looking into the bandwidth constraints of microstrip antennas, the propose antenna is providing wide frequency range tunability. The minimum operating frequency achieved for double MOS loaded CMSA with 10 mm radius of patch and 1 mm airgap is 1.27 GHz and it can be tuned to any frequency up to design frequency 6.8 GHz. Percentage agility of 82.94 % is achieved for double MOS loaded CMSA with airgap. Further it is seen that antenna operates at higher frequency and agility for lower values of radius of patch and vice-versa; antenna operates up to 18 GHz frequency and 90 % agility for 3 mm radius of patch. Also, various parameters like resonant frequency, beamwidth, etc can be electronically tuned. The antenna is suitable for GPS, WLAN, UMTS, and WiMAX mobile services. Acknowledgments This research work was supported by Department of Science and Technology (Vigyan Aur Prodhyogiki Vibhag) government of India under SERC Scheme project vide sanction order No SR/S3/EECE/0117/2010(G).
References 1. Kaya, A., & Yuksel, E. Y. (2007). Investigation of a compensated rectangular microstrip antenna with negative capacitor and negative inductor for bandwidth enhancement. IEEE Trans on Antennas and Propagation, 55, 1275–1282. 2. Chakravorty, T., & De, A. (2003). A novel method of extending tunability of circular patch using two shorting pins. IEEE Antennas and Propagation Society International Symposium, 2, 736–739. 3. Kanaujia, B. K., Singh, A. K., & Vishvakarma, B. R. (2008). Frequency agile annular ring microstrip antenna loaded with MOS capacitor. Journal of Electromagnetic Wave and Application, 22, 1361–1370. 4. Gautam, A. K., & Vishvakarma, B. R. (2006). Frequency agile microstrip antenna symmetrically loaded with tunnel diodes. Microwave and Optical Technology Letters, 48(9), 1807–1810. 5. Guha, D., & Siddiqui, J. Y. (2003). Resonant frequency of circular microstrip antenna covered with dielectric superstrate. IEEE Trans on Antennas and Propagation, 51, 1649–1652. 6. Chen, H. T., Chen, H. D., & Cheng, Y. T. (1997). Full wave analysis of the anular ring loaded spherical circular microstrip antenna. IEEE Trans on Antennas and Propagation, 45, 1581–1583. 7. Gautam, A. K., & Vishvakarma, B. R. (2007). Analysis of varactor loaded active microstrip antenna. Microwave and Optical Technology Letters, 49, 416–421. 8. Gupta, V., Sinha, S., Koul, S. K., & Bhat, B. (2003). Wideband dielectric resonator loaded suspended microstrip patch antenna. Microwave and Optical Technology Letters, 37, 300–302.
123
Double MOS Loaded Circular Microstrip Antenna 9. Kanaujia, B. K., & Vishvakarma, B. R. (2004). Analysis of gunn integrated annular ring microstrip antenna. IEEE Transaction on Antenna and Propagation, 52, 88–97. 10. Pandey, G. P., Kanaujia, B. K., Gautam, A. K., & Gupta, S. K. (2012). Ultra—Wideband l-strip proximity coupled slot loaded circular microstrip antenna for modern communication systems. Wireless Personal Communications. Springer (Under Press). 11. Lee, K. F., Ho, K. Y., & Dahele, J. S. (1984). Circular disk microstrip antenna with an airgap. IEEE Trans Antenna Propagation, 32, 880–884. 12. Guha, D. (2001). Resonant frequency of circular microstrip antennas with and without air gaps. IEEE Transaction on Antenna and Propagation, 49, 55–59. 13. Sharma, S. K., & Vishvakarma, B. R. (1999). MOS capacitor loaded frequency agile microstrip antenna. International Journal of Electronics, 86, 979–990. 14. Bahl, I. J., & Bhartia, P. (1980). Microstrip antennas. Dedham, MA: Artech House. 15. Abboud, F., Damiano, J. P., & Papiernik, A. (1990). A new model for calculating the input impedance of coax-fed circular microstrip antennas with and without air gaps. IEEE Transaction on Antenna and Propagation, 38, 1882–1885. 16. Pandey, G. P., Kanaujia, B. K., & Gupta, S. K. (2009). Double MOS loaded circular microstrip antenna for frequency agile. In IEEE applied electromagnetic conference Kolkata. 978-1-4244-4819-7/09. 17. Garg, R., Bhartia, P., Bahl, I., & Ittipiboon, A. (2001). Microstrip antenna design hand book. Boston: Artech House. 18. Zeland Software Co. (2009). IE3D v14.0, California.
Author Biographies Surendra Kumar Gupta was born on December 20, 1967 in Village Khata, District Amroha, Uttar Pradesh, India. He did Bachelor degree in Electronics and Telecommunication Engineering from Institution of Engineers (India), Kolkatta in 1994. He completed M.E. in Digital Systems from Motilal Nehru Regional Engg. College, University of Allahabad, India in 1999. He was associated as Quality Assurance Services (Avionics)—Inspector with Air Force Station, Kanpur, India from July 1995 to January 2000. He has worked as Lecturer—Electronics and Communication Engg at Moradabad Institute of Technology, Moradabad, India from February 2000 to June 2002. Presently, he is faculty with Department of Electronics Engg, Ambedkar Polytechnic, Government of Delhi, India from July 2002. He is under going the Ph.D. programme from Uttarakhand Technical University, Dehradun, India. He has authored / co-authored several research papers in International Journals/Conferences. His research interest includes Computer Aided Design and Micro-strip Antenna. He is life member of Indian Society of Technical Education, India and Associate Member of Institute of Engineers, India.
Binod Kumar Kanaujia joined Ambedkar Institute of Technology(AIT) Govt. of N.C.T. Delhi, Geeta colony Delhi-31 as Assistant Professor in January 2008 in the Department of Electronics and Communication Engineering after getting selected by Union Public Service Commission New Delhi. Before joining AIT, Dr. Kanaujia has served in the M. J. P. Rohilkhand University in the capacity of Reader in Electronics and Communication Engineering Department from 26/02/2005 to 30/01/2008 and lecturer in ECE Deptt. from 25/06/1996 to 25/02/2005. While working with MJP Rohilkhand University Dr. Kanaujia has been a active Member of Academic council and Executive council of the university and played a vital role in the academic reforms. He has also served as Head of Department of E&C Department of the university for the period from 25th July 2006 to 30th Jan 2008. Prior to his career in the academics, Dr. Kanaujia has been working as Executive Engineer in the R&D division of M/s UPTRON India Ltd. Dr. Kanaujia presently working as Associate Professor in
123
S. K. Gupta et al. ECE Deptt. of AIT has served various key portfolios i.e. he has been Head of Department of E&C Department of the Ambedkar Institute of Technology from 21 February 2008 to 05 Aug 2010, As Library Incharge of Central Library of AIT from March 2008 to 05 Aug 2010 and responsible for upgrading the Library with the introduction of Fully Automatic Book issue and receiving, on-line journal, on-line retrieval of catalogue of the Library, Establishment of E-Library. Apart from it, he has been holding the Charge of Head of office of Ambedkar Institute of Technology since 09 August 2008 and responsible for day to day administration of the institute. Dr. Kanaujia has done his B.Sc. from Agra University Agra U.P. in 1989 & B.Tech. in Electronics Engineering from KNIT Sultanpur U.P. in 1994. He did his M.Tech. & Ph.D. from Electronics Engineering Department of Banaras Hindu University Varanasi in 1998 and 2004, respectively. He has been awarded Junior Research fellow by UGC Delhi in 2001–2002 for his outstanding work in his field. His has keen research interest in design and Modeling of Microstrip Antenna, Dielectric Resonator Antenna, Left handed Metamaterial Microstrip Antenna, Shorted Microstrip Antenna Wireless Communication, Wireless Communication and Microwave Engineering etc. Till date he has been credited to publish more than 55 research papers in peer-reviewed journals and International/national conferences. Dr. Kanaujia is a Member of IEEE and Life members of the Institution of Engineers (India), Indian Society for Technical Education and The Institute of Electronics and Telecommunication Engineers of India.
Ganga Prasad Pandey was born in village Karka, Pratapgargh District, UP, India. He did B. Tech. in Electronics Engineering from K.N.I.T. Sultanpur, India in 2000. He completed M.E. from Delhi College of Engineering, Delhi (India) in 2004. Presently, he is Asst. Prof. in Electronics and Communication Engineering Department of Maharaja Agrasen Institute of Technology, Delhi, India. He is working towards the Ph.D. degree from Uttarakhand Technical University, Dehradun, India. He has authored/co-authored several research papers in International Journals/Conferences. His research interest includes microwave/millimeter wave integrated circuits, reconfigurable microstrip antennas and devices.
123
Double MOS Loaded Circular Microstrip Antenna with Airgap for Mobile Communication Surendra Kumar Gupta · Binod Kumar Kanaujia · Ganga Prasad Pandey
© Springer Science+Business Media New York 2012
Abstract A novel model of a wide frequency range double MOS loaded circular microstrip patch antenna with airgap between ground plane and substrate is proposed. In this structure two metal oxide semiconductor (MOS) devices are loaded on the patch to enhance the operating frequency range of antenna. To investigate the antenna, different parameters such as resonance frequency, input impedance, frequency agility, VSWR, radiation pattern etc. are calculated and simulated. The resonant frequency of proposed 10 mm radius patch is upward shifted from 5.2 to 6.8 GHz using 1 mm airgap and by loading MOS, antenna can be tuned down to 1.27 GHz operating frequency, which leads to compactness and tunability of antenna. Proposed antenna can be tuned between 1.27 and 6.8 GHz frequency of operation which makes the antenna highly suitable for wide frequency range of mobile communication. The proposed double MOS loaded antenna possessed 82.94 % frequency agility. The antenna is worth for GPS, WLAN, UMTS, and WiMAX operations. Keywords Circular patch microstrip antenna · Airgap · MOS · Agility · Mobile communication
S. K. Gupta Department of Electronics Engineering, Ambedkar Polytechnic, Government of Delhi, Shakarpur, Delhi, India e-mail: [email protected] B. K. Kanaujia (B) Department of Electronics & Communication Engineering, Ambedkar Institue of Advanced Communication Technologies & Research, Geeta Colony, Delhi, India e-mail: [email protected] G. P. Pandey Department of Electronics & Communication Engineering, Maharaja Agrasen Institue of Tecnology, Rohini, Delhi, India e-mail: [email protected]
123
S. K. Gupta et al.
1 Introduction In recent years the demand of microstrip antennas have been considerably increased in both research and engineering applications due to their ingredient features like low profile, light weight, inexpensive, reliability, conformal structure and ease in fabrication and integration with other microwave components. Due to this microstrip patch antennas are being used for modern mobile communication system such as Wireless Local Area Network (WLAN), Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) etc. Other side, microstrip antennas suffer from low efficiency and narrow bandwidth which limits their versatility. The input impedance of an antenna tends to be sensitive to changes in frequency and it also depends on geometrical shape, dimensions and the fed type of antenna. Hence, the antenna input impedance is a very important parameter which controls the radiated power and the impedance bandwidth [1]. Many efforts have been made to improve impedance bandwidth and frequency tunability. Shorting posts are used to enhance the frequency agility. Using double posts and by adjusting them finely, the maximum 32.5 % tunability was achieved [2]. Impedance bandwidth can be increased by loading patch with stubs, slits and slots. Apart from loading a patch, impedance bandwidth can be improved by increasing the substrate thickness and variable length transmission lines. Various other techniques have been suggested to improve the impedance bandwidth and frequency tunability such as loading varactor diodes, annular ring, stacking of patches and L-strip proximity coupled slot loaded patch [3–10]. Integration of devices like varactor diode, Gunn diode and impedance tuning network in microstrip antennas could not provide sufficient band of operation. Limitations still exists on the ability of these techniques. A circular microstrip antenna with an airgap between ground plane and substrate was proposed in [11]. An increase of the airgap causes a decrease in the dynamic permittivity, results in an upward shift in the resonant frequency of antenna. Hence to overcome bandwidth limitation various configuration of microstrip antennas such as above are proposed which provide dual band, multiband and wide band operation. Such configurations of antennas are widely acceptable for multiservice applications and become good substitute of wide bandwidth requirement which has motivated the authors to work on a novel proposed structure of antenna for wide frequency range applications. In this paper, circular microstrip antenna with airgap between ground plane and substrate is referred as reference antenna [11]. We have proposed to load MOS devices on the circular microstrip patch with airgap between ground plane and substrate to design an antenna that can operate in wide frequency range. The theoretical analysis is carried out using the equivalent circuit concept. The airgap between ground plane and substrate is included for upward shift of resonance frequency and MOS is loaded to achieve tunability and wide frequency range of antenna. The double MOS loaded circular microstrip antenna with airgap is analyzed and simulated on Zeland’s IE3D. The calculated and simulated results are in good agreement. This paper presents easier design of a circular microstrip antenna with airgap with better tunability over wide frequency range.
2 Theoretical Considerations The bandwidth limitation had been the major constraint in the development of microstrip antennas, in recent research wide frequency range tunable antenna is considered a good substitute to this problem. Figure 1 presents the geometry of a wide frequency range tunable double MOS loaded circular microstrip antenna with an airgap between the ground plane
123
Double MOS Loaded Circular Microstrip Antenna Fig. 1 Geometry of double MOS loaded circular microstrip antenna with airgap
and substrate for mobile communication. The circular microstrip antenna is structured as a cavity with magnetic wall along the edge. The structure of this antenna is a two layer cavity: the lower layer is an airgap of Ha with relative permittivity 1 and the upper layer is the dielectric substrate of thickness H with relative permittivity εr . The effect of the airgap below the substrate was considered for obtaining an equivalent permittivity of the medium below the patch. Using an equivalent single layer structure of total height Ht = H + Ha , equivalent permittivity (εre ) is calculated as in [12] and expressed as follows. εr e =
εr (H + Ha ) (1 + εr Ha )
(1)
where εr is the permittivity of the substrate and equivalent permittivity for CMSA without an air gap (Ha = 0), εre = εr . Following the analytical model an improved form of permittivity of transverse magnetic (TM) modes of the medium below the patch in CMSA with airgap, effective permittivity εr,eff is defined as 4εr e εr,dyn εr,e f f = √ √ εr e + εr,dyn
(2)
The term εr,eff is introduced to take into account the effect of the equivalent permittivity (εre ) of the medium below the patch in combination with the dynamic permittivity (εr,dyn ) to improve the model. The resonant frequency and effective radius of the CMSA with airgap are calculated as resonant frequency fr =
αnmc √ 2πae f f εr,e f f
(3)
123
S. K. Gupta et al.
Fig. 2 MOS capacitor. a Schematic. b Equivalent
where c is velocity of light in free space and αnm is mth zero of first kind Bessel function of order n. Effective radius of patch (4) aeff = a (1 + q) where the term q arises due to the fringing fields at the edge of the patch [12]. 2.1 Metal-Oxide-Semiconductor Figure 2 shows a typical Metal-Insulator-Semiconductor (MIS) or Metal-Oxide-Semiconductor (MOS) and its associated capacitances. It is evident that it contains two capacitances: depletion layer capacitance (Cd ) which varies with bias voltage and insulator capacitance (Ci ) which is fixed. The MOS under consideration is Au–Si3 N4 –Si. Total capacitance of MOS (Cmos ) is calculated as in [13] Cmos =
Ci Cd (Ci + Cd )
(5)
here insulation layer capacitance (Ci ) is given by Ci =
ε0 εr o d
(6)
where, εro is relative permittivity and d is the thickness of insulation layer. The depletion layer capacitance (Cd ) is given by Cd =
ε0 εr si X
(7)
where, εr si is relative permittivity of silicon and X is width of depletion layer, given by ⎧
⎫ ⎬ 2 C 2V εr si ε0 ⎨ g i −1 + 1 + X= (8) Ci ⎩ εr si ε0 Q N a ⎭ where Vg is bias voltage, Na is acceptor concentration of doping material and Q is charge of an electron.
123
Double MOS Loaded Circular Microstrip Antenna
Z in
R0
L C
(a)
Ci Ci Z in Cd
Z in C
R0
R0
L
C total
L Cd
(b) Fig. 3 Equivalent circuit of a circular patch microstrip antenna b double MOS loaded circular patch microstrip antenna
Combining equations (5)–(8), Cmos is defined as Cmos =
1+
Ci 2Vg Ci2 εrsi ε0 Q N a
A
(9)
where, A is the cross sectional area of MOS device. 2.2 Double MOS Loaded Circular Microstrip Antenna with Airgap The proposed antenna is a coaxial fed circular microstrip patch with airgap and loaded with MOS. The antenna is analyzed in TM11 mode. A circular microstrip antenna is characterized by parallel combination of resonance resistance R0 , inductance L and capacitance C as presented in Fig. 3a. These parameters are calculated from the theory of modal expansion and cavity model as in [14]. Resonance resistance R0 =
1 Jn2 (kρ) GT Jn2 (ka)
(10)
where Jn is the first kind of Bessel function of order n, ρ is probe position and G T is total conductance associated with dielectric loss, radiation loss, and conduction loss [15].
123
S. K. Gupta et al.
Capacitance associated with antenna C=
QT 2π fr R0
(11)
L=
R0 2π fr Q T
(12)
and inductance
where Q T is total quality factor, which includes radiation loss, dielectric loss and conductance loss. The equivalent circuit of a double MOS loaded circular microstrip antenna with airgap is presented in Fig. 3b. Total capacitance of patch can be calculated as in [16] Ctotal = C + 2Cmos
(13)
where Cmos is the capacitance of MOS. The total input impedance of a double MOS loaded CMSA with airgap is calculated as Z in =
1 R0
1 + ( jωCtotal ) +
1 jωL
(14)
The reflection coefficient () of circular patch is given by =
Z in − Z 0 Z in + Z 0
(15)
where, Z 0 is impedance (50) of coaxial feed. Voltage standing wave ratio (VSWR) of patch is given as VSWR =
1 + || 1 − ||
(16)
The return loss (RL) of the antenna is given by RL = 20 log (||)
(17)
where is reflection coefficient of circular patch.
3 Design Specifications The design specifications of MOS device and CMSA are given in Tables 1 and 2, respectively. Same specifications are considered for the theoretical analysis and simulation of proposed antenna. These specifications provide good performance of proposed antenna as discussed in result section and theoretical results closely match with the simulated results.
123
Double MOS Loaded Circular Microstrip Antenna Table 1 Specifications of MOS
Table 2 Specifications of CMSA
Parameter
Value
MOS capacitor structure
Au–Si3 N4 –Si (n + 0.0005 cm)
Cross section area of device (A)
1.6 × 10−8 m2
Relative permittivity of oxide layer (εr o )
7.5
Relative permittivity of semiconductor (εr si )
11.9
Acceptor concentration (Na )
1.45 × 1022 m−3
Bias voltage range (Vg )
0–5 V
Thickness of oxide layer (d)
100, 200, 300, 400, 500 A◦
Peak values of Cmos
106.2, 53.1, 35.4, 26.5, 21.2 pf
Parameter
Value
Substrate material
Beeswax
Radius of circular patch (a)
10 mm
Substrate thickness (H )
1.5748 mm
Airgap (Ha )
1.00 mm
Relative dielectric constant of substrate material(εr )
2.35
Loss tangent (tanδ)
0.005
Probe position (ρ)
3.1 mm
4 Radiation Pattern The expression for radiation pattern of circular microstrip antenna in TM11 mode is given as in [17] j V ako e− jko r cos(φ)J1 (ko a sin(θ )) 2 r j V ako e− jko r J1 (ko a sin(θ )) Eφ = cos θ sin φ 2 r ko a sin(θ ) Eθ = −
(18) (19)
where V is edge voltage, ko is wave number and r is observation location that may be taken randomly large compared to antenna size. Radiation pattern of antenna is calculated as R = |Eθ|2 + |Eφ|2 For E-plane pattern φ =
0◦ ,
and for H-plane pattern φ =
(20) 90◦ .
5 Results and Discussion In this work double MOS loaded circular patch microstrip antenna with airgap is investigated to achieve wide frequency range characteristics. The theoretical and simulated results for input impedance, MOS capacitance, frequency agility, VSWR and radiation pattern in
123
S. K. Gupta et al.
Fig. 4 Variation of real part of input impedance with frequency of CMSA with various airgap. a Theoretical. b Simulated
respect of performance of antenna are presented in this section. The theoretical results are plotted using MATLAB and simulation is done on IE3D simulator [18]. The Fig. 4a, b show the variation of real part of input impedance with the frequency of circular microstrip patch antenna for different airgap. It is found that the resonance frequency of the antenna increases with increasing the airgap, due to the fact that the effective value of permittivity decreases. The resonant frequency of antenna with 1 mm airgap is upward shifted to 6.8 GHz as compared to 5.2 GHz for circular microstrip antenna without airgap. This upward shift of frequency due
123
Double MOS Loaded Circular Microstrip Antenna
Fig. 5 Variation of capacitance of a MOS with bias voltage
to airgap between ground plane and substrate has broadened the operating range of antenna. Theoretical results are showing good agreement with simulated results, as seen from Fig. 4a, b the simulated real part of input impedance for all three airgap (Ha = 0.0, 0.5 and 1.0 mm) are in good match with theoretical real part of input impedance. Simulated results well verify the matching of input impedance of antenna over its wide frequency range. Figure 5 shows variation of capacitance with bias voltage for a typical MOS. It is found that there is sharp variation in capacitance near zero bias voltage. Capacitance is almost constant for all values of thicknesses for the bias voltage above 1 V. The peak values of capacitances are 106.2, 53.1, 35.4, 26.5, and 21.2 pf for oxide layers of 100, 200, 300, 400 and 500 A◦ , respectively. The variation of resonant frequency with bias voltage for single and double MOS loaded circular microstrip antenna with airgap is shown in Fig. 6a, b, respectively. The variation of resonance frequency is steep at lower bias voltage comparatively to higher bias voltage. It is also found that variation of resonance frequency is negligible for all oxide layers for higher bias voltage. To observe the behavior of agility of antenna, it is simulated for various thickness of oxide layer of MOS. Table 3 shows percentage agility for the single MOS loaded antenna for different oxide layer thickness. Table 4 shows percentage agility for the double MOS loaded antenna for different thickness of oxide layer. It is observed from response thatmaximum agility for double MOS loaded patch is 82.94 % (for 100 A◦ oxide layer). Also, it is evident from Tables 3 and 4 that frequency agility decreases as oxide thickness increases and double MOS loaded antenna has more frequency agility than single MOS loaded antenna. The antennas with different patch radius for 1 mm airgap are simulated to see the effect on agility. The theoretical and simulated variation of frequency agility with radius of patch are in good agreement as shown in Fig. 7. The simulated results of agility are shown for various patch radius (a = 5.0, 10.0, 15.0, 20.0, 25.0 and 30.0 mm) which are close to the theoretical results for respective patch radius. Also it is verified by the simulated results that agility
123
S. K. Gupta et al.
Fig. 6 Variation of resonant frequency with bias voltage of a single MOS loaded CMSA with airgap b double MOS loaded CMSA with airgap
is inversely proportional to the patch radius of proposed antenna. It is found that frequency agility decreases with a increase in the radius of patch, this may be understood by the fact that contribution of MOS capacitance in the antenna decreases as the radius of patch increases. It is evident that antenna has better frequency agility for low patch radius, frequency agility of antenna with 10 mm radius of patch is 82.94 %.
123
Double MOS Loaded Circular Microstrip Antenna Table 3 Frequency agility of single MOS loaded circular microstrip antenna with airgap for different thickness of oxide layer
Table 4 Frequency agility of double MOS loaded circular microstrip antenna with airgap for different thickness of oxide layer
Sr. No.
Oxide thickness (A◦ )
Minimum achievable frequency (GHz)
Total frequency agility (GHz)
Percentage agility (%)
1
100
1.571
5.032
76.20
2
200
2.161
4.442
67.27
3
300
2.579
4.024
60.94
4
400
2.905
3.698
56.00
5
500
3.172
3.431
51.96
Sr. No.
Oxide thickness (A◦ )
Minimum achievable frequency (GHz)
Total frequency agility (GHz)
Percentage agility (%)
1
100
1.127
5.476
82.94
2
200
1.571
5.032
76.20
3
300
1.897
4.706
71.27
4
400
2.161
4.442
67.27
5
500
2.385
4.218
63.88
Fig. 7 Theoretical and simulated variation of frequency agility with radius of patch of double MOS loaded CMSA with airgap (Ha = 1.0 mm)
Figure 8 shows variation of real part of input impedance with frequency for different bias voltage for proposed antenna. The resonant frequency of antenna shows interesting downward shift for different values of thickness of oxide layer. It is found that for 0 V bias voltage
123
S. K. Gupta et al.
Fig. 8 Theoretical and simulated variation of input impedance with frequency with various bias voltage (Vg ) of double MOS loaded CMSA with airgap (Ha = 1.0 mm)
Fig. 9 Theoretical and simulated variation of VSWR with frequency of CMSA with airgap (Ha = 1.0 mm) with and without MOS
123
Double MOS Loaded Circular Microstrip Antenna
Fig. 10 Theoretical and simulated E plane radiation pattern of double MOS loaded CMSA with airgap
Fig. 11 Theoretical and simulated H plane radiation pattern of double MOS loaded CMSA with airgap
and 100 A◦ oxide layer, the resonant frequency of antenna is downward shifted to 1.27 from 6.80 GHz design frequency which is obvious from the fact that maximum capacitance is added into antenna system due to MOS. Hence, the resonant frequency of proposed antenna can be tuned by varying the bias voltage. It is found that variation of resonance frequency with bias voltage provides good tunability of operating frequency of antenna and widen the frequency range and agility of antenna. These findings are equally verified by the simulated results. The theoretical results are in close agreement with simulated results as shown in Fig. 8 for variation of real parts of input impedance with frequency for 5.0 V bias voltage.
123
S. K. Gupta et al.
Figure 9 presents theoretical and simulated results for VSWR of antenna with and without MOS as a function of frequency at Vg = 1 V. The theoretical and simulated graphs show that the resonance impedance at lower frequency remains same as on 6.8 GHz which is obvious from the fact that only imaginary component is added into its equivalent. It is found that theoretically calculated VSWR gives a close match with simulated result. The E-plane and H-plane radiation patterns for MOS loaded CMSA are shown in Figs. 10 and 11, respectively. The theoretical radiation patterns are plotted for different bias voltage (Vg = 1.0, 2.0, 3.0, 4.0 and 5.0 V) and simulated radiation patterns for Vg = 5.0 V for both plane. The simulated results are close to the respective theoretical results. It is found that beam width of antenna decreases with increase in bias voltage for entire range of operation, this is due to the fact that operational frequency of antenna increases with bias voltage.
6 Conclusion A novel model of wide frequency range double MOS loaded circular microstrip antenna with airgap between the ground plane and substrate for mobile communication is presented. Looking into the bandwidth constraints of microstrip antennas, the propose antenna is providing wide frequency range tunability. The minimum operating frequency achieved for double MOS loaded CMSA with 10 mm radius of patch and 1 mm airgap is 1.27 GHz and it can be tuned to any frequency up to design frequency 6.8 GHz. Percentage agility of 82.94 % is achieved for double MOS loaded CMSA with airgap. Further it is seen that antenna operates at higher frequency and agility for lower values of radius of patch and vice-versa; antenna operates up to 18 GHz frequency and 90 % agility for 3 mm radius of patch. Also, various parameters like resonant frequency, beamwidth, etc can be electronically tuned. The antenna is suitable for GPS, WLAN, UMTS, and WiMAX mobile services. Acknowledgments This research work was supported by Department of Science and Technology (Vigyan Aur Prodhyogiki Vibhag) government of India under SERC Scheme project vide sanction order No SR/S3/EECE/0117/2010(G).
References 1. Kaya, A., & Yuksel, E. Y. (2007). Investigation of a compensated rectangular microstrip antenna with negative capacitor and negative inductor for bandwidth enhancement. IEEE Trans on Antennas and Propagation, 55, 1275–1282. 2. Chakravorty, T., & De, A. (2003). A novel method of extending tunability of circular patch using two shorting pins. IEEE Antennas and Propagation Society International Symposium, 2, 736–739. 3. Kanaujia, B. K., Singh, A. K., & Vishvakarma, B. R. (2008). Frequency agile annular ring microstrip antenna loaded with MOS capacitor. Journal of Electromagnetic Wave and Application, 22, 1361–1370. 4. Gautam, A. K., & Vishvakarma, B. R. (2006). Frequency agile microstrip antenna symmetrically loaded with tunnel diodes. Microwave and Optical Technology Letters, 48(9), 1807–1810. 5. Guha, D., & Siddiqui, J. Y. (2003). Resonant frequency of circular microstrip antenna covered with dielectric superstrate. IEEE Trans on Antennas and Propagation, 51, 1649–1652. 6. Chen, H. T., Chen, H. D., & Cheng, Y. T. (1997). Full wave analysis of the anular ring loaded spherical circular microstrip antenna. IEEE Trans on Antennas and Propagation, 45, 1581–1583. 7. Gautam, A. K., & Vishvakarma, B. R. (2007). Analysis of varactor loaded active microstrip antenna. Microwave and Optical Technology Letters, 49, 416–421. 8. Gupta, V., Sinha, S., Koul, S. K., & Bhat, B. (2003). Wideband dielectric resonator loaded suspended microstrip patch antenna. Microwave and Optical Technology Letters, 37, 300–302.
123
Double MOS Loaded Circular Microstrip Antenna 9. Kanaujia, B. K., & Vishvakarma, B. R. (2004). Analysis of gunn integrated annular ring microstrip antenna. IEEE Transaction on Antenna and Propagation, 52, 88–97. 10. Pandey, G. P., Kanaujia, B. K., Gautam, A. K., & Gupta, S. K. (2012). Ultra—Wideband l-strip proximity coupled slot loaded circular microstrip antenna for modern communication systems. Wireless Personal Communications. Springer (Under Press). 11. Lee, K. F., Ho, K. Y., & Dahele, J. S. (1984). Circular disk microstrip antenna with an airgap. IEEE Trans Antenna Propagation, 32, 880–884. 12. Guha, D. (2001). Resonant frequency of circular microstrip antennas with and without air gaps. IEEE Transaction on Antenna and Propagation, 49, 55–59. 13. Sharma, S. K., & Vishvakarma, B. R. (1999). MOS capacitor loaded frequency agile microstrip antenna. International Journal of Electronics, 86, 979–990. 14. Bahl, I. J., & Bhartia, P. (1980). Microstrip antennas. Dedham, MA: Artech House. 15. Abboud, F., Damiano, J. P., & Papiernik, A. (1990). A new model for calculating the input impedance of coax-fed circular microstrip antennas with and without air gaps. IEEE Transaction on Antenna and Propagation, 38, 1882–1885. 16. Pandey, G. P., Kanaujia, B. K., & Gupta, S. K. (2009). Double MOS loaded circular microstrip antenna for frequency agile. In IEEE applied electromagnetic conference Kolkata. 978-1-4244-4819-7/09. 17. Garg, R., Bhartia, P., Bahl, I., & Ittipiboon, A. (2001). Microstrip antenna design hand book. Boston: Artech House. 18. Zeland Software Co. (2009). IE3D v14.0, California.
Author Biographies Surendra Kumar Gupta was born on December 20, 1967 in Village Khata, District Amroha, Uttar Pradesh, India. He did Bachelor degree in Electronics and Telecommunication Engineering from Institution of Engineers (India), Kolkatta in 1994. He completed M.E. in Digital Systems from Motilal Nehru Regional Engg. College, University of Allahabad, India in 1999. He was associated as Quality Assurance Services (Avionics)—Inspector with Air Force Station, Kanpur, India from July 1995 to January 2000. He has worked as Lecturer—Electronics and Communication Engg at Moradabad Institute of Technology, Moradabad, India from February 2000 to June 2002. Presently, he is faculty with Department of Electronics Engg, Ambedkar Polytechnic, Government of Delhi, India from July 2002. He is under going the Ph.D. programme from Uttarakhand Technical University, Dehradun, India. He has authored / co-authored several research papers in International Journals/Conferences. His research interest includes Computer Aided Design and Micro-strip Antenna. He is life member of Indian Society of Technical Education, India and Associate Member of Institute of Engineers, India.
Binod Kumar Kanaujia joined Ambedkar Institute of Technology(AIT) Govt. of N.C.T. Delhi, Geeta colony Delhi-31 as Assistant Professor in January 2008 in the Department of Electronics and Communication Engineering after getting selected by Union Public Service Commission New Delhi. Before joining AIT, Dr. Kanaujia has served in the M. J. P. Rohilkhand University in the capacity of Reader in Electronics and Communication Engineering Department from 26/02/2005 to 30/01/2008 and lecturer in ECE Deptt. from 25/06/1996 to 25/02/2005. While working with MJP Rohilkhand University Dr. Kanaujia has been a active Member of Academic council and Executive council of the university and played a vital role in the academic reforms. He has also served as Head of Department of E&C Department of the university for the period from 25th July 2006 to 30th Jan 2008. Prior to his career in the academics, Dr. Kanaujia has been working as Executive Engineer in the R&D division of M/s UPTRON India Ltd. Dr. Kanaujia presently working as Associate Professor in
123
S. K. Gupta et al. ECE Deptt. of AIT has served various key portfolios i.e. he has been Head of Department of E&C Department of the Ambedkar Institute of Technology from 21 February 2008 to 05 Aug 2010, As Library Incharge of Central Library of AIT from March 2008 to 05 Aug 2010 and responsible for upgrading the Library with the introduction of Fully Automatic Book issue and receiving, on-line journal, on-line retrieval of catalogue of the Library, Establishment of E-Library. Apart from it, he has been holding the Charge of Head of office of Ambedkar Institute of Technology since 09 August 2008 and responsible for day to day administration of the institute. Dr. Kanaujia has done his B.Sc. from Agra University Agra U.P. in 1989 & B.Tech. in Electronics Engineering from KNIT Sultanpur U.P. in 1994. He did his M.Tech. & Ph.D. from Electronics Engineering Department of Banaras Hindu University Varanasi in 1998 and 2004, respectively. He has been awarded Junior Research fellow by UGC Delhi in 2001–2002 for his outstanding work in his field. His has keen research interest in design and Modeling of Microstrip Antenna, Dielectric Resonator Antenna, Left handed Metamaterial Microstrip Antenna, Shorted Microstrip Antenna Wireless Communication, Wireless Communication and Microwave Engineering etc. Till date he has been credited to publish more than 55 research papers in peer-reviewed journals and International/national conferences. Dr. Kanaujia is a Member of IEEE and Life members of the Institution of Engineers (India), Indian Society for Technical Education and The Institute of Electronics and Telecommunication Engineers of India.
Ganga Prasad Pandey was born in village Karka, Pratapgargh District, UP, India. He did B. Tech. in Electronics Engineering from K.N.I.T. Sultanpur, India in 2000. He completed M.E. from Delhi College of Engineering, Delhi (India) in 2004. Presently, he is Asst. Prof. in Electronics and Communication Engineering Department of Maharaja Agrasen Institute of Technology, Delhi, India. He is working towards the Ph.D. degree from Uttarakhand Technical University, Dehradun, India. He has authored/co-authored several research papers in International Journals/Conferences. His research interest includes microwave/millimeter wave integrated circuits, reconfigurable microstrip antennas and devices.
123
