Development of Odd Orientation Array Antenna by using Leucaena Leucocephala Substrate A.A. Azlan 1, M.T.Ali 1, M.Z. Awang 1, M.F Jamlos 2 1
Antenna Research Centre (ARC), Microwave Technology Centre (MTC), Faculty of Electrical Eng. (FKE), UiTM, Shah Alam. Email:
[email protected],
[email protected],
[email protected], 2 Advanced Communication Engineering Centre, School of Computer and Communication Engineering, Universiti Malaysia Perlis. E-mail:
[email protected]
Abstract— The research paper covered the 3 by 3 odd orientation array antenna (OOAA) design and fabrication by using Leucaena leucochephala bio-composite substrate material. The objective of the paper was to utilize and design off centered orientation feed array antenna with circular BalUn and dual matching stub to control the impedance mismatch issue onto the bio-composite substrate with the mixture of 70% stem wood Leucaena leucochephala at 40 mesh and 30% of polypropylene polymer act as laminator and noted as PB7030 substrate. The PB7030 reported constant on all dielectric constant (εr = 3.02) and loss Tangent (Tan δ = 0.0082) value for the WLAN 2.4GHz applications. The overall result show some good agreement between simulation and fabricated result (Gain =7.15dBi, VSWR=1.01, S11=-34.34dB and Bandwidth = 0.201GHz). All comparison result between simulation and fabricated antenna analyzed and displayed in the form of data and graph. Index Terms—. Leucaena leucochephala, bio-composite, odd orientation array antenna
I.
INTRODUCTION
The fabrication of low cost, low dielectric constant value and environmentally friendly substrate was desirable and offered higher demand lately. The implementation of Biocomposite material not only implies the green technology campaign but also it help some of the nation to the drive new economic growth by contributing to fiscal consolidation, enhancing the productivity through greater efficiency in use of natural and reusable resources [1]-[2] .In order to support the green technology campaign, the usage of bio-composite substrate material with the technique of wood plastic composite (WPC) seem very significant for the usage in high frequency applications. The elaborated fabrication process, dielectric constant (εr) and loss Tangent (Tan δ) value for PB7030 substrate were briefly discussed in [3]. Beside substrate, antenna structure also plays the important role for the success of wireless system. Normally, the array technique were chosen to enhance the gain of the antenna system, and most of the time the design of arrayed structure were feed at the center of the antenna structure [4]-[5].Lately, there is not much highlight by the antenna designer to fabricate the odd array structure system since the design will create high impedance at the center of the feed due to off-centered structure design. In this research paper, the implementation of stub matching system and circular Balance to Unbalance
(BalUn) were introduced to fix the high impedance issue at the center of the design .The basic parameter of the design were given in table 1. TABLE 1: BASIC ANTENNA DESIGN PARAMETER
II.
ANTENNA DESIGN
The basic design of the proposed 3 by 3 OOAA antenna was inspired by the design of the combination between single and 2 by 2 patch array antenna [6]. The gain of the 3 by 3 OOAA antenna raise significantly from 2.91 dBi for single patch, 5.2 dBi for 2 by 2 array and 8.2 dBi for proposed 3 by 3 OOAA antenna with overall length 151 mm x 147 mm. The overall dimension for proposed 3 by 3 OOAA antennas were show in figure 1.
Figure 1: Overall OOAA antenna dimension
Since the design applied the unbalanced feeding technique, the coaxial probe was situated about λ/3 to the left and 2λ/3 to the right of the proposed design. A. Rectangular patch and array design The design of the proposed antenna consists of arraying of nine rectangular patches like figure 1. The structure of single patch antenna [7]-[8] was show in figure 2 while the array structure was shown in figure 3.
The antenna length is given by equation 2 (2) The antenna extension length ΔL, given by equation 3
(3) The effective dielectric constant (εreff), given by equation 4
(4) The patch feed line formula is given from equation 5 while equation 6 show the feed line array formula.
Figure 2: Single patch structure
(5)
As shown in figure 2, there is a hole with diameter of 6mm, the hole drilled directly from antenna structure right up to the back of the ground of the antenna. The purposes are to hold the copper structure to the substrate by using nylon screw, since the design used thick copper 0.35mm. Most of the array structures were shown in figure 3.
(6)
B. Stub and BalUn design The function of circular BalUn [9] and short type matching stub, was to control the operating frequency and maintaining the low impedance to the nearest 50 ohm, due to off centered feed contributed high impedance. The key of the design rely on this two matching system. The formula of circular BalUn was given by equation 7, while equation 8 to 9 distributed for the stub design. The overall dimension of the Balun and matching stub design is given by figure 4.
Figure 3: Array structure The design of rectangular patches and array dimension were distributed by equation 1 to equation 6. The width of antenna is given by equation 1.
(1)
Figure 4: stub and BalUn dimension
(7)
setup shown in figure 6, whereby the horn antenna 7dBi model XA-WDB, 1 to 18GHz used as Tx antenna. The most of the setup parameter were given in Table 2 and to define the parameter measurement equation (13) to (14) was introduced.
Where
(13) Where (8)
For short circuit stub is defined as: (9)
L PL = 10 log
PT PR
(14)
TABLE 2: GAIN PARAMETER
If the overall calculation were turn up to be negative the distance has to be increase by λ/2. C. Truncated bend design A truncated lines is a process of bending the end of the array to minimize the reflection effect of the antenna. Truncated process sliced off some capacitance, restoring the line back to its original characteristic impedance. The figure 5 below shows the important parameters of a truncated bend. While equation (10)–(12) show the important equation to design the truncated line.
Note: PT: Power Transmit PR: Power Receive d: Distance F: Frequency GT: Gain transmit (HORN at 2.4GHz)
Figure 5: Truncated design parameter (10)
⎛ ⎛ 52 65 ⎛⎜ − 1 . 35 W + X = ⎜ D⎜ e⎝ H ⎜ ⎜ 10 10 ⎝ ⎝ A=
⎛D⎞ X −⎜ ⎟ ⎝ 2 ⎠
⎞ ⎟ ⎠
⎞⎞ ⎟⎟ ⎟⎟ ⎠⎠
(11)
(12)
D. Antenna gain and radiation Pattern measurement The practical gain measurement was distributed by equation (13)-(14) (two ray propagation model). All gain and radiation pattern measurement were conducted inside anechoic chamber. The distance between transmitting (TX) and receiving (Rx) antenna was fixed to 1m and most of the
Figure 6: Radiation pattern and gain measurement inside anechoic chamber The final design of the proposed OOAA antenna integrated with the PB7030 substrate was show in figure 7. The attachment between copper structures with the substrate was done by using nylon screw (to hold the antenna structure). The thickness of 0.35mm copper structure were cut by using board router LPKF ProtoMart S103 where the thickness of copper can be define, so that the board router machine can cut according to thickness of the copper.
Note: CASE 1: Circular BalUn and stub installed CASE 2: Circular BalUn and stub Discard (both eliminated) CASE 3: Circular BalUn Eliminated but Stub Remain CASE 4: Circular BalUn Remain but Stub Eliminated
Y X
Figure 7: Final fabrication of proposed OOAA antenna (Front view) while at the back was covered fully by copper III.
RESULT AND DISCUSSION
The novelty of the proposed structure were focused at the installation of the circular BalUn and matching stub to control the mismatch, due to off centered structure. The study was split into 4 case categories. Table 3 shows all simulated result by using CST software at 2.42 GHz. Figure 8 show the CST simulated, real part of the impedance observed at the feeding line.
In most cases on table 3, the imaginary part was reported to be capacitive, since the result show negative value. Among the four cases, Case 1 shows the most stable impedance value at 52.1 –j1.6 Ω resonant at 2.42 GHz. At this case, the value of capacitive show at the lowest value and the reported real part impedance almost reach perfect impedance match at 50 Ω. For cases 2, the impedance reported highly mismatch at 73.3 –j24.1 Ω and resonant at 2.37 GHz. The differences of 21.2 Ω when compare between case 1 and case 2. The result for case 3 show some increment of impedance at 90.6 –j30.2Ω which resonant at 2.41 GHz, while case 4 show 46.6 –j19.1Ω but resonant at 2.39GHz. So the nearest case that suite almost 50Ωimpedance with resonant to the desired 2.42GHz frequency was distributed by case 1 (fabricated cases).The additional of circular BalUn and matching stub to fix the mismatch issue was very significant to the proposed OOAA antenna since the installation of stub and circular BalUn was not only to solve the issue of matching the impedance but also control the resonant frequency. A. S11 and Radiation pattern The comparison between simulation (CST software) and fabrication of proposed OOAA antenna have been done, where the S11 result show in figure 9 and radiation pattern for both simulation fabricated antenna were shown in figure 10.
Figure 8: Real part of impedance plot with observe frequency at 2.42GHz TABLE 3: IMPEDANCE FOR 4 CASES CATEGORY
Figure 9: S11 result for proposed OOAA antenna
stub to fix and control the frequency seem very much help to maintain the feed line impedance closers to impedance of 50 ohm. The measurement of the gain between simulation and practical antenna seem show some agreement with the differences only occurs about 1.05dBi. The overall design increase significantly about 3dBi from 2 by 2 array antenna with overall dimension about 151mm x 147mm. 2350. The fabrication antenna show some narrower back lobe result with -8dB at 1800, -5 dB at 1600 and -5.1db at 2150. V.
ACKNOWLEDGEMENT
The authors would like to acknowledge Malaysian Timber Industry Board (MTIB), Fidec (Banting, Malaysia) especially En. Zulkepli bin Abd Rani, Director of Fiber and Bio-composite center (FIDEC), for allowing the author to use the facility in FIDEC lab that possible of accomplishment of this article. Figure 10: Radiation pattern between simulation and fabricated proposed OOAA antenna (Phi=0) The simulation of proposed OOAA antenna was reported at frequency of 2.42GHz with S11 value at -32.19dB. The bandwidth of the antenna covered for bandwidth of 0.046GHz. The fabrication proposed OOAA antenna show wider on bandwidth with 0.201GHz, but the operating frequency for the fabricated antenna shifted to the right with the value of S11 at 34.34dB at 2.45GHz. Figure 9 show the simulation result in figure 9, show some low back lobe generation about -10db at 1800, -11 dB at 1400 and -11.2dB at radiation pattern plot for both simulation and fabrication antenna. Both plots were observe at Phi =00, with the gain reported 8.2 dBi for simulation and 7.15dBi for fabricated antenna. Table 4 below, show the overall parameter result for proposed OOAA antenna between simulations and fabricated back to back. Table 4: OVERALL RESULT FOR BOTH SIMULATIONS AND MEASUREMENT OF OOAA ANTENNA
REFERENCES [1]
E. Hansen, “Market And Innovation Considerations In Development Of Natural Wood Fiber Composites,” 2008.
[2]
K. Joseph, B. James, S. Thomas, and L. H. De Carvalho, “A Review On Sisal Fiber Reinforced Polymer,” Rev. Bras. Eng. Agrícola e Ambient., vol. 3, no. 083, pp. 367–379, 1999.
[3]
A. A. Azlan, M. K. A. Badrun, M. T. Ali, Z. Awang, Z. M. Saad, and A. H. Awang, “A Comparative Study of Material Leucaena Leucocephala Stem Wood Plastic Composite ( WPC ) Substrate with FR4 Substrate throughout Single Patch Antenna Design,” Prog. Electromagn. Res. B, vol. 59, no. April, pp. 151–166, 2014.
[4]
F. Qingyuan, S. Lizhong, J. Ming, H. Yong, and Q. Xiaolin, “Wideband Dual-linear Polarized Stacked Patch Antenna with Asymmery Feeding,” TELKOMNIKA Indones. J. Electr. Eng., vol. 12, no. 1, pp. 106–112, 2014.
[5]
M. A. S. Natera, A. García-aguilar, J. Mora-cuevas, J. F. González, P. Padilla, D. Torre, J. G. Trujillo, R. M. Rodríguez-osorio, M. S. Pérez, L. D. H. Ariet, and M. S. Castañer, “New Antenna Array Architectures for Satellite Communications,” Universidad Politécnica de Madrid, Spain, 2010.
[6]
M. Ghiyasvand, A. Bakhtiari, and R. A. Sadeghzadeh, “Novel microstrip patch antenna to use in 2 × 2 sub arrays for DBS reception,” Indian J. Sci. Technol., vol. 5, no. 7, pp. 2967–2971, 2012.
[7]
X.-A. W. F. Xu, L. Tang and X. Chen, “ACTIVE UWB "Printed Antenna With Tunable And Switchable Band-Notched Functions,” Prog. Electromagn. Res. Lett., vol. 30, no. February, pp. 21–28, 2012.
[8]
M. Hajian and B. Kuijpers, “Active scan-beam reflectarray antenna loaded with tunable capacitor,” Antennas …, pp. 1158–1161, 2009.
[9]
S. R. Besf, “Shunt-Stub-Line lmpe ance Martching : A Wave R flection Analysis Tutorial,” Ieee Antenna and propagation Magazine, vol. 44, no. 1, p. 44, 2002.
IV. CONCLUSION A new 3 by 3 OOAA antenna with operating frequency 2.42GHz (for WLAN IEEE 802.11, application) have been simulate, design ,fabricated and measured by using Leucaena leucochephala PB7030 substrate. The antenna was feed with off centered feed orientation with coaxial feed, contributed mismatch to the design and provide low impedance at the feed point. The introduction of circular BalUn and matching
