Design of a Compact, High Gain, Efficient and Low ... - onlinepresent.org

Advanced Science and Technology Letters Vol.147 (SMART DSC-2017), pp.17-25 http://dx.doi.org/10.14257/astl.2017.147.03

Design of a Compact, High Gain, Efficient and Low Cross Polarization Meander Line Cornered Microstrip Patch Antenna with EBG Structure for VSAT Applications Karteek Viswanadha1 and Dr. N.S Raghava2 Ph.D Scholar1, Delhi Technological University1, [email protected] Professor2 Delhi Technological University2 [email protected]

Abstract. Microstrip patch antennas are used in a wide variety of applications due to their compactness and planar nature. Usually microstrip patch antennas have moderate gain, directivity and efficiency. Many types of patches like slotted patches with different shapes are proposed in order to achieve high gain and directivity. Most of these antennas suffer from surface waves which will degrade their performance. In order to reduce the surface waves, ground plane is modified in such a way that the frequency selectivity can be increased. Defective Ground Structures (DGS) and Electromagnetic Bandgap Structures (EBG) are two types of ground planes frequently used to reduce the unwanted radiation. This paper presents the design of a meander edged microstrip patch antenna with square shape EBG structure in Advance Design System2016(ADS-2016) having maximum efficiency. The proposed antenna is designed to have gain, directivity of 9.7dBi and cross polarization of -50dB at 17.92GHz which indeed makes it suitable for VSAT applications. Keywords: We would like to encourage you to list your keywords in this section.

1 Introduction Design of wireless communication systems needs to be compatible and efficient. Along with many compatible radio amplifiers and mixers, planar antennas are also proposed which can be easily integrated with the transceiver. Many planar antennas like microstrip patch, Planar Inverted F-Antenna (PIFA) are used to achieve compactness and ease of integration. Microstrip patch antennas are widely used in many applications due to their ease of fabrication, compactness and planar nature [1]. Microstrip patch arrays are used in satellite transceivers due to the beam forming ability. Wide variety of patch antennas like circular patch, bow-tie patch, triangular patch are proposed to meet specifications such as wide bandwidth, high gain, polarization diversity and circular polarization. These antennas are highly directional

ISSN: 2287-1233 ASTL Copyright © 2017 SERSC

Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)

and their gain varies from 4dBi to 7dBi depending on the shape of the patch. Gain and bandwidth are inversely proportional and there should be trade-off between gain and bandwidth. These usually suffer from low bandwidth and high losses. Gain increases if the proper phase of excitation is provided to the patch array. Apart from patch arrays, slotted patches can be used in order to increase the gain at the cost of bandwidth [2]. Gain and directivity depends on the shape of the slot and the position of the slot. In [3], multi slotted antenna is proposed to achieve high of 9.4dBi with bandwidth of 0.58GHz. 3-dB bandwidth in azimuth and elevation planes is 60.88𝑜 and 39𝑜 respectively. The bandwidth and gain of a slotted patch antenna can also be increased by shorting the patch and the ground. This special feature is utilised in Planar Inverted F-Antenna (PIFA) [4]. The gain and bandwidth can be varied by varying the position of the shorted plate. This not only increases the above specifications but also compatibility. Electrical length of these antennas is reduced making them compatible at the expense of efficiency. These antennas have the capability to produce wide bandwidth in multiple bands. In [5], the slot is made in the PIFA which makes the antenna to achieve bandwidth of 1GHz at 0.89GHz and 1.93GHz respectively. Gain and bandwidth are varied by changing the length and width of shorting plate. Grooved slot antenna is proposed [6] to achieve bandwidth of 1.5GHz with gain of 6dBi and reasonable Specific Absorption Rate (SAR). In [10], multiple shorted pins PIFA is proposed where the side walls are covered with Perfect Electric Conductor (PEC). Substrate inside the antenna box is tempered so as to improve the bandwidth and gain. In [11], the antenna is tuned and bandwidth is enhanced using shorting straps. The antenna proposed in [12] consists of dual elements with dual shorting pins surmounted on a folded ground plane which acts as a perfect PEC case. Circular shaped fractal PIFA antenna is proposed in [7] where it provides high efficiency and gain. Reducing the area of the ground plane increases the efficiency and gain and variation of position of shorting plate has no impact on gain and efficiency [8]. Varying the substrate features also affect the specifications of an antenna [9]. Planar antennas are often prone to surface waves which severely affect the gain of these antennas. In order to prevent the surface waves, ground of planar antenna is drilled exactly below the antenna. This type of ground is named as Defective Ground Structure (DGS). DGS patch antennas reduce surface waves with the reduction in efficiency and increase in the side lobes [13]. Different shapes of DGS planar antennas are proposed in order to reduce the unwanted radiations. The variation in the size and positions of slots on the ground plane will shift the frequency of operation with the degradation in the performance of an antenna. Another method to reduce the surface waves is to place slots periodically on the ground plane except on the area below the planar antenna which is kept unetched. This type of structure is called electronic band gap structure [EBG] [14-17]. Planar antennas with EBG structures often provide high gain. Simple EBG Planar antennas can only possess high efficiency at L, S and C bands respectively [18-19]. At the upper band of extremely high frequencies, EBG planar antennas provide high directivity with low efficiency and therefore the gain of these antennas decreases at the Ku, K, Ka bands etc.

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Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)

2 Design of Proposed Antenna Figure.1 shows the layout in Advanced Design System-2016 of the proposed antenna with length equal to 7.7mm and width equal to 11.1mm calculated from the below design equations. Antenna is mounted on the EBG of length (L) equal to 19.25mm and width (W) equal to 27.75mm. EBG slots of square type with side (a) of 1mm. Spacing (s) between two EBG slots is chosen to be 0.2mm. Meander lines are placed at the corners of the patch. Width (𝑤1 ) and length (𝑎𝑜 ) of the meander lines are 0.762mm and 1.24mm respectively. RT-Rogers duroid 5880 (𝜀𝑟 = 2.2) is used as a substrate which is sandwiched between EBG structure and the proposed patch antenna with the height of 2.54mm respectively. Moreover, a notch is made on the nonradiating side of the patch with the width and length (t) of 0.762mm and 1.52mm respectively. Inset feed is used to excite the antenna with the feed line having length (𝑙𝑜 ) and width (𝑤𝑜 ) of 2.24 mm and 1.2 mm respectively. Inset into feed is inserted to chosen to have depth and length of 0.12mm and 0.23mm respectively. The design equations of inset fed microstrip patch antenna are: ∆𝐿 ℎ

= 0.412

h≈ 0.06

𝜆𝑎𝑖𝑟

𝑐

2

𝑟

𝑟 +1

𝜀𝑒𝑓𝑓 = 𝑐 2𝑓𝑟

𝜀𝑟 +1 2

+

(1) (2)

√𝜀𝑟

𝑊𝑝 = √ 𝑓 𝜀

𝐿𝑝 =

𝑊𝑝 +0.264) ℎ 𝑊𝑝 (𝜀𝑒𝑓𝑓 −0.258)( +0.8) ℎ

(𝜀𝑒𝑓𝑓 +0.3)(

(3) 𝜀𝑟 −1

1

2

√1+12ℎ/𝑊

-2∆𝐿

(4) (5)

‘h’ is the height of the substrate ‘𝑊𝑝 ’ is the width of the patch ‘𝜀𝑒𝑓𝑓 ’ is effective dielectric constant ‘𝐿𝑝 ’ is the length of the patch ‘∆𝐿’ is the normalized extension length ‘𝑓𝑟 ’ is the resonant frequency ‘c’ is the velocity of light

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Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)

Fig. 1. Layout of the proposed antenna

Figure.2 (a) & 2(b) shows the 3-D model and top view of the proposed patch antenna. The whole structure is designed on an infinite ground assumed to be a perfect electric conductor.

Fig. 2(a). 3-D model of the proposed patch antenna

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Fig. 2(b). Top view of the proposed patch antenna

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Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)

2.1 Design Equations of EBG

Fig. 3(a). EBG structure used with proposed antenna

Fig. 3 (b). Lumped element equivalent circuit of the proposed EBG structure

EBG structure in figure.3 consists of three portions: a metallic ground, a substrate on which the periodic metallic patches are surmounted. The parameters of the proposed EBG structure are labeled in Figure.3 as slot with side ‘a’, spacing between the slots ‘s’, substrate height ‘h’ and dielectric constant ′εr ′. When the periodicity (a + s) is small compared to the operating wavelength, the operation mechanism of this EBG structure can be explained using an effective medium model with equivalent lumped LC elements, as shown in Fig.3(b). The capacitor results from the gap between the patches and the inductor results from the current along adjacent patches. Capacitor results due to the air gap of the slot and inductor results due to the current flow along the adjacent slots. Impedance and resonant frequency of the parallel LC circuit are calculated given by: Z=

jωL

𝜔𝑜 = C=

1

(7)

√LC

aεo (1+εr ) [πcosh−1 [

L = µo h

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(6)

(1−ω2 LC)

s+a ]] a

(8) (9)

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Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)

3 Results and Discussions Figure.4 shows the magnitude plot of reflection co-efficient of the proposed antenna. A reflection co-efficient of -10.166dB is obtained at 17.92GHz. Polar plots of electric, magnetic fields, radiation patterns are observed at 17.92GHz. Unwanted frequencies / surface waves are highly reduced with the use of EBG structures.

Fig. 4. Magnitude and phase plot of reflection co-efficient

Figure 5 shows the 3-D plot of the radiation pattern of the proposed antenna and the values of parameters related to the radiation pattern. Figure.6 shows the consolidated 2-D plot of gain, directivity, co-polarization, cross polarization etc. The side lobes are totally suppressed and the directivity is enhanced. Figure 7 shows the detailed values of different parameters of 3-D pattern.

Fig. 5. 3-D plot of radiation pattern

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Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)

Fig. 6. Consolidated 2-D plot of all the parameters of antenna

Moreover, magnetic field is minimum in the direction of electric field and the electric field is minimum in the direction of magnetic field.

Fig.7. Simulated values of 3-D radiation pattern

Table 1 shows the various parameters of the proposed antenna is presented at the resonant frequency of 17.92 GHz.

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Advanced Science and Technology Letters Vol.147 (SMART DSC-2017)

Table 1. Performance parameters of the proposed antenna structure.

Gain (dB) (Fig.6 &7) 9.7

Directi vity (dB) (Fig.6& 7) 9.7

Reflection Coeffici ent (dB) (Fig.4) -10.166

Cross Polarizat ion (dB) (Fig.6) -50

Efficie ncy (%) (Fig.6 &7) 100

Bandwi dth (MHz) (Fig.4) 100

4 Conclusion The same gain can be achieved using 2-element microstrip patch array at the expense of compactness. The meander edged patch antenna provides high gain and efficiency with compactness. The above results of the proposed antenna make it suitable for the high data communications and especially for the Very Small Aperture Terminal (VSAT) applications. The proposed patch antenna is under the process of fabrication.

References 1. 2. 3. 4. 5. 6. 7. 8. 9.

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Gary Breed et.al "The fundamentals of patch antenna design and performance ", High frequency electronics, 2009 pp. 49-51. Liu, Yong et al. “Some Recent Developments of microstrip patch antenna”, Internal Journal of Antennas and Propagation 2012, pp. 1-10. Gupta, Sushila, and Esha Johari. "Dual Band Slotted Microstrip Patch Antenna For Wireless Applications". SAMRIDDHI: A Journal of Physical Sciences, Engineering and Technology, 2015 Kumar, Naveen, Thakur,Abhishek and Sharma Jitender "Study of Planar Inverted-F Antenna (PIFA) for Mobile Devices", International Journal of Electronics & Communication Technology, 2013, Vol-4,issue-3, pp. 83-85. Firoozy, Nariman, and Mahmoud Shirazi. "Planar Inverted-F Antenna (PIFA) Design Dissection For Cellular Communication Application", Journal of Electromagnetic Analysis and Applications, 2011, pp. 406-411. Saini, Sahil, Satbir Singh, and Naveen Kumar. "A Review Of Various Planar Inverted Fantenna (PIFA) Structures For Wireless Applications". International Journal of Electrical & Electronics Engg, 2015, pp. 63-65. Wei He, Jian, and Kah Seng Chung. "Design Considerations Of Planar Inverted-F Antenna (PIFA) On A Finite Ground Plane", International Symposium on Multi-Dimensional Mobile communications, 2004. Son, Tae-Ho, and Jae-Ho Lee. "Inverted Π Feeding PIFA For Gain Improvement For The Mobile Phone". The Journal of Korean Institute of Electromagnetic Engineering and Science, 2007, pp. 1337-1344. Kristensson, G., P. Waller, and A. Derneryd. "Radiation Efficiency And Surface Waves For Patch Antennas On Inhomogeneous Substrates", IEEE Proceedings - Microwaves, Antennas and Propagation, 2003, pp. 474- 477.

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10. Ahmad, Muhammad Sajjad, and Che Young Kim. "Dual-Element PIFA Design With Dual Shorting Pins For Multiband Communication Devices", International Journal of Antennas and Propagation ,2015, pp. 1-8. 11. Chattha, H.T., Yi Huang, and Yang Lu. "PIFA Bandwidth Enhancement By Changing The Widths Of Feed And Shorting Plates", IEEE Antennas and Wireless Propagation Letters 8 ,2009, pp. 637-640. 12. Ahmad, Muhammad Sajjad, and Che Young Kim. "Dual-Element PIFA Design With Dual Shorting Pins For Multiband Communication Devices". International Journal of Antennas and Propagation, 2015, pp.1-8. 13. Monika Sontakke et al. "Microstrip Patch Antenna With DGS For Bluetooth Application". International Journal of Engineering Research, Vol.6. 14. N. S. Raghava and Asok De, “A broadband compact microstrip antenna with EBG structure”, Kalpana Chawla Space Technology Cell, IIT, Kharagpur, India, 2008. 15. Shivam Guatam, Komalbir and N. S. Raghava, “Design and Analysis of Uniplanar Compact Electromagnetic Bandgap Structures,”, Progress in Electromagnetics Research Symposium, Prague, Czech Republic, 2015, pp. 2092 – 2094 16. N.S Raghava, Asok De, “Dual frequency Square Slot Rectangular Microstrip antenna with electronic band gap ground,” 8th International Conference on Microwaves, Antenna Propagation and Remote Sensing (ICMARS-2012), Jodhpur, India, 2012. 17. Dilraj Singh, N. S. Raghava, Animesh Biswas and Asok De, “Dual frequency rectangular notch square microstrip antenna with EBG,” presented at International Symposium on Microwaves, Banglore, India, 2008. 18. Amol Choudhary, N. S. Raghava, Animesh Biswas and Asok De, “A Highly Efficient Rectangular Microstrip Antenna with Hexagonal Holes as an Electromagnetic Bandgap Structure in the Ground Plane”, Recent Advances in Microwave Theory and Applications, India, 2008, pp.152-153 19. Amol Choudhary, N. S. Raghava and Asok De, “A High Gain Rectangular Patch Radiator with Square Holes in the Ground Plane,” European Electromagnetic Symposium, Switzerland, 2008.

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