Dimension parameter of the Bi-ellipse Microstripline Array antenna design.
Abstract
The objectives of this research include obtaining and verifying the impedance formula of the designed bi-ellipse microstrip antenna and correlating the results obtained through simulation and experimentation. The research also aims to obtain the structure and dimensions that provide optimal characteristics of the designed bi-ellipse microstrip antenna and produce a prototype at S, C and X-Band frequencies. This research produced the structure and dimensions of a bi-ellipse microstrip antenna that provide optimal characteristics of antenna. The characteristics results of the antenna parameters in this research include a 8x2 array, with a bandwidth value of around 100.0 MHz obtained at a working frequency of 7.09GHz (7.04 GHz - 7.14 GHz), with a reflection coefficient value of 0.02, Voltage Standing Wave Ratio (VSWR) of 1.06, return loss of −30.00 dB and a gain of 7.30 dB. For the 8x4 array, a bandwidth value of approximately 210.0 MHz is obtained at a working frequency range of 2.85GHz, which ranges from 2.74GHz - 2.95GHz, with a reflection coefficient value of 0.04, Voltage Standing Wave Ratio (VSWR) of 1.09, return loss of −27.06 dB and a gain of 8.19 dB. The results presented above fulfill the indicators of good antenna characteristics parameters applicable to radar communication systems.
Keywords
- Microstrip Antenna
- Array
- Bi-Ellipse
- Impedance Formula
- Radar
1. Introduction
Electromagnetic field theory is essential in designing and analyzing the shape and size of the antenna. In general, the electromagnetic fields generated depend on the distance of the source access and terrain. The further course of electromagnetic fields affects the spread process from the transmitter to the receiver, weakening the signals. Therefore, the required antenna design with specific dimensions, such as a high gain value and significant directivity with return loss is minimal. Various studies have been conducted on microstrip antenna. In this research, a new type of antenna is design with an nxn array bi-ellipse microstrip. This is an antenna type microstrip with various characteristics, including a thin cross-section, lightweight mass, simple to make, and can be easily integrated with Microwave Integrated Circuits (MICs) made in multifrequency.
In this research, the nxn array bi-ellipse microstrip antenna is developed in multiband frequency for satellite communication. The optimization of the width feeding stripline is meant to enhance the performance of the antenna. The proposed nxn array bi-ellipse microstrip antenna operates in multiband frequency. It targets the multiband frequency, reflection coefficient less than 1, Voltage Standing Wave Ratio (VSWR) less than 2, and gain more than 5 dB.
Numerous studies have been conducted on a wide variety of designs and shapes of microstrip antenna by providing slots, patches, and adding several arrays. The use of a slot can increase bandwidth. This is because smaller widths increase the bandwidth, number of arrays, and antenna gain [1, 2, 3]. According to previous studies, the antenna’s array is used to direct radiated power toward a desired angular sector. The number, geometrical arrangement, relative amplitudes, and phases of the array element depend on the angular pattern that needs to be achieved.
Other research used a flexible, compact antenna array operating at a frequency of 3.2-13GHz, which covers the standard Ultra-Wide Band (UWB). The design aimed to integrate Multiple Input Multiple Output (MIMO) based flexible electronics for Internet of Things (IoT) applications. The proposed antenna is printed on a single side of a 50.8 μm Kapton Polyimide substrate, which consists of two half-elliptical shaped radiating elements fed by two Coplanar Waveguide (CPW) structures. The simulated and measured results showed that the proposed antenna array achieves a broad impedance bandwidth with reasonable isolation performance of
2. Theories
2.1 Microstrip antenna
Microstrip antennas are electrically thin, lightweight, comfortable, low cost, easily fabricated and can be connected to Microwave Integrated Circuits (MICs) at various frequencies [11]. There are various types of microstrip antenna designs on the taper section. There is a rectangular, circular, triangle shape according to the empirical analysis of antenna design. The design of the antennas varies with the single side and the double side. This study designed bi-ellipse microstripline antenna with 8x2 and 8x4 array, to produce greater gain so that it could be more optimally applied to radar communication systems.
2.2 Array factor
Microstrip antennas arranged in Array are not only useful for widening bandwidth but also have an impact on the radiation pattern produced. The radiation pattern in the Antenna is generally written with the equation:
The relationship with the wave emitted from the antenna array (Y) with the multiplier of complex numbers (wi) in the function (θ, ∅), is obtained:
With k is the wave vector in the incoming wave.
Next can be written:
AF = Array Factor (as an Antenna position function) [11].
2.3 Antenna design and optimization
In principle, the microstrip antenna has a characteristic narrow bandwidth. It has several advantages, including a thin, small, light in weight, and can be applied to the Microwave Integrated Circuit (MICs). The bandwidth can be widened using the array technique or by a panel system [11, 12, 13, 14, 15, 16]. The panel systems (engineering array) involve strengthening (gain) of an antenna. In contrast, the rationing array technique is commonly used microstrip line. Graphically, microstrip antenna design is shown in Figure 1.
2.3.1 Empirical analysis and design
Figure 2 shows the microstrip antenna design dimensions.
The following Table 1 is a dimension parameter of the antenna design:
Parameters | Dimension | Description |
---|---|---|
Wg | 100 | Width |
Lg | 50 | Length |
l1 | 30 mm | Length of feeding stripline |
l2 = l3 | 15 mm | Length of curve stripline |
w1 = w2 | 1 mm | Width of stripline |
w3 | 2 mm | Width of curve stripline |
θ | 30o | Gradient in curve line |
Antenna arrangement with a transmission line. In the transmission line length l equivalent circuit is described as follows (Figure 3):
The first calculation involves finding the total electricity permittivity (εrtot) using the capacitor equation as follows.
where εr1 is εr for air (εr1 = 1), εr2 is εr for substrate (εr FR4 = 4.3),
A capacitor equation is used in this empirical analysis because, in principle, this is a device that stores electrical energy in an electric field. The capacitor made of two parallel conducting plates separated by a dielectric that is a parallel plate capacitor. When a battery is connected across the capacitor, one plate gets attached to the positive end and another to the negative. The potential of the battery is then applied across that capacitor. In this case, plate one is in positive potency with respect to plate two. At steady-state conditions, the current tries to flow from the battery through the capacitor from its positive to the negative plate unsuccessfully. This is because of the two separation of these plates with an insulating material. This is in line with the microstrip work principal in specific dielectric substrates.
To calculate the effective permittivity electricity (
Where εr is the same with εrtot, h is dtot, and w is the width for patch and strip line side [11, 12].
Permittivity is a material property that affects the Coulomb force between two points charges.
The following equation is used to determine the maximum dimension in the patch side (w1):
where c is lightspeed in air, εr is electricity permittivity, and f is frequency [12].
To calculate the effective width strip line side (w2,3), the following formula is used.
Where f is frequency, μo is permeability constant, and Zo is characteristic impedance [12].
Permeability is derived from a magnetic field’s production by an electric current or charge and all other formulas for the magnetic field produced in a vacuum.
The calculation wavelength of the substrate (
From the analysis above formula (1)–(5), the parameters for antenna fabrication can be fixed [11, 12, 13].
2.3.2 Simulation
The simulations were created using Finite different Time Domain (FDTD) method. The selection method of fabrication was essential to optimize the results, which reflect the optimal parameters generated as characteristic of the designed antenna. The numerical analysis of nxn array double bi-ellipse microstrip antenna design involves Preparation, Reader Review, Determination of the substrate and the dimensions of the antenna, and analyzing the empirical formula antenna design numerically, characterizing outcome parameters microstrip antenna through data analysis and calculations. Fabrication is carried out using the FR4 material substrate with a UV photoresist laminate technique.
2.3.3 Fabrication
Bi-Ellipse microstripline array varians antenna prototype was fabricated by UV photoresist laminate. In our work, the antenna prototypes are fabricated on Flame Retardant 4 (FR4) material with 4.3 dielectric constant. The first step in the fabrication process is to generate the photo mask artwork by printing on stabline or rubylith negative film of the desired geometry on butter sheet. Using the precision cutting blade of a manually operated co-ordino graph the opaque layer of the stabiline or rubylith film is cut to the proper geometry and can be removed to produce either a positive or negative film representation of the antenna sketches. The design dimensions and tolerances are verified on a cordax measuring instrument using optical scanning. Enlarged artwork should be photo reduced using a high precession camera to produce high resolution negative, which is later used for exposing the photo resist. The photographic negative must be now held in very close contact with the polyethylene cover sheet of the applied photo resist using a vacuum frame copy board or other technique, to assure the fine line resolution required. With exposure to proper wavelength of light, polymerization of the exposed photo resist occurs making it insoluble in the developer solution. Now, it is then coated with a negative photo resist and exposed to UV-radiation and it is immersed in developer solution up to two minutes through the mask. The exposed photo resist hardens and those in the unexposed areas are washed off using a developer. The unwanted copper portions are now removed using Ferric Chloride (FeCl3) solution. FeCl3 dissolves the copper coating on the laminate except which is underneath the hardened photo resist layer after few minutes. Finally, the laminate is then washed with water and cleaned in acetone solution to remove the hardened negative photo resist. The fabrication process has shown in the following Figure 4.
3. Result and discussion
The data of the antenna design is obtained using a network analyzer in the chamber. To compare the simulation results, the antenna is measured using Network Analyzer. This is meant to determine the antenna design characteristics, including S11 Parameter, Bandwidth, VSWR, coefficient reflection, and return loss. The chamber in the laboratory is used to determine the gain and polarization pattern. An experimental schematic diagram in the laboratory is shown in Figure 5.
The Figures 6 and 7 show the comparison between simulation and measurement results of the antenna S11-parameters and gain for 2x2 and 2x4 array models, respectively.
In the simulation, 8x2 array
In the simulation, an 8x4 array
The following Table 2 summarizes the results of the proposed antenna.
Parameters | fc (GHz) | RL (dB) | VSWR | Γ | Gain (dB) |
---|---|---|---|---|---|
8x2 array bi-ellipse microstrip antenna | |||||
Model 1 | |||||
Simulated | 7.12 | −33.75 | 1.04 | 0.02 | 6.90 |
Measured | 7.04 | −32.43 | 1.05 | 0.02 | 6.61 |
Model 2 | |||||
Simulated | 7.11 | −36.74 | 1.03 | 0.01 | 7.49 |
Measured | 7.14 | −30.00 | 1.06 | 0.03 | 7.30 |
8x4 array bi-ellipse microstrip antenna | |||||
Model 1 | |||||
Simulated | 2.97 | −29.23 | 1.07 | 0.03 | 7.28 |
Measured | 2.95 | −27.01 | 1.09 | 0.04 | 6.75 |
Model 2 | |||||
Simulated | 2.82 | −29.83 | 1.07 | 0.03 | 8.46 |
Measured | 2.74 | −27.06 | 1.09 | 0.04 | 8.19 |
The polarization and radiation pattern in the nxn array double bi-ellipse microstrip antenna design is linear and omnidirectional radiation pattern. The performance-based on polarization is presented in Figure 8.
This research indicates that the
4. Conclusions
This study aims to design a bi-ellipse Microstripline Antenna Array consisting of more optimal characteristics parameters. The empirical formula and numeric analysis were optimally applied to the satellite communication system in relation to the antenna’s characteristics. The analysis result showed that a 8x2 array bi-ellipse microstripline antenna parameter obtained, comprises of 1.06 VSWR, 0.02 Reflection Coefficient, and − 30.00 dB Return Loss. Also, a 8x4 array, consists of 1.09 VSWR, 0.04 Reflection Coefficient, and − 27.06 dB Return Loss. These two simulations and measurement are compared to design a
Acknowledgments
The authors would like to thank the Indonesian Ministry of Research, Technology and Higher Education through LPDP and PKPI (Sandwich-like) scholarships, Center for Environmental Remote Sensing (CEReS), Josaphat Tetuko Sri Sumantyo (JMRSL Chiba University), Promotor Yono Hadi Pramono and Mashuri (Physics Department, ITS Surabaya), and Ganesha University of Education (Undiksha), Singaraja Bali.
Appendices and Nomenclature
R | Barriers [ohm] |
β | Betha [−] |
C | Capacitance [Farad] |
Fc | Center of frequency [Hz] |
Zo | Characteristic impedance [ohm] |
G | Conductance [kg−1m−2s3A2] |
εeff | Effective permittivity [−] |
E | Efficiency [%] |
ω | Frequency [Hz] |
Ω | Impedance [ohm] |
L | Inductance [kgm2s−2A−2] |
Zin | Input impedance [ohm] |
∼ | Infinite [−] |
L | Length [m] |
Zl | Load impedance [ohm] |
μo | Permeability [−] |
Γ | Reflection coefficient [−] |
εr | Relative permittivity [−] |
RL | Return loss [dB] |
S11 | Return loss parameter [dB] |
θ | Tetha, Gradient [°] |
VSWR | Voltage Standing Wave Ratio [−] |
λ | Wavelength [m] |
λo | Wavelength in the air [m] |
λg | Wavelength in the substrate [m] |
W | Wide [m] |
H | Width of the substrate [m] |
T | Width patch [m] |
References
- 1.
Artawan HP. Yono. “Perancangan antena panel mikrostrip horn array 2x2 untuk komunikasi wi-fi pada frekuensi 2,4GHz”, Prosiding ,Seminar Nasional MIPA . Universitas Negeri Malang. April 2010;1 :2-8 - 2.
Artawan, Hadi Pramono, Yono. “Perancangan antenna mikrostrip horn untuk aplikasi antena panel pada frekuensi 2,4GHz”, Prosiding ,Seminar Nasional Teknologi Informasi (SNTI) , Universitas Tarumanegara, Jakarta, ISSN 1829-9156, Vol. 7, pp. 38-44, November 2010 - 3.
Risfaula E. “Antena mikrostrip panel berisi 5 larik dipole dengan feedline koaksial waveguide untuk komunikasi 2,4 GHz”, Tesis Magister. Program Keahlian Optoelektronika Jurusan fisika FMIPA-ITS: Surabaya; Jan. 2011 - 4.
Ibrahim MS. 2×2 circularly polarized MIMO antenna at Ka-band for fifth generation applications. International Journal on Communication Antenna and Propagation. Sept. 2019; 9 (2):2-7 - 5.
Kurniawan Farohaji, Sri Sumantyo, J. T, Gao Steven, Ito Koichi, Edi Santosa C. “Square-shaped feeding truncated circularly polarised slot antenna”. IET Microwaves, Antenna & Propagation Journals . ISSN 1751-8725, Vol. 12, pp. 1279-1286, July 2018 - 6.
Mao-Chun X, Steven G, Yi W, Sri Sumantyo JT. Compact broadband dual-sense circularly polarized microstrip antenna/array with enhanced isolation. IEEE Transactions on Antennas and Propagation. October 2017; 65 (12):7073-7082 - 7.
Qi L, Steven G, Mohammed S, Sri Sumantyo JT, Li J, Gao W, et al. Dual circularly polarised equilateral triangular patch array. IEEE Transactions on Antennas and Propagation. April 2016; 64 (6):2255-2262 - 8.
Mahmood ZS, Nasret AN, Awed AY. Design of new multiband slot antennas for wi-fi devices. International Journal on Communication Antenna and Propagation. Sept. 2019; 9 (5):5-10 - 9.
Alja'afreh S, Khalfalla A, Omar A. Universal antenna with a small non-ground portion for smartphone applications. International Journal on Communication Antenna and Propagation. Sept. 2019; 9 (4):8-14 - 10.
Prasad RK, Srivastava DK, Saini JP. Design and analysis of gain and bandwidth enhanced triangular microstrip patch antenna. International Journal on Communication Antenna and Propagation. March 2018; 8 (1):1-5 - 11.
Balanis CAATA. and Design . Second ed. New York: John Wiley and Sons; 1997 - 12.
Edward, Terry. Foundation For Microstrip Circuit Design . Knaresborough England, 1991 - 13.
Shafai. Microstrip Antena Design Handbook. Profesor University Of Manitoba. Canada: Wimmipeg; 2001 - 14.
Kraus, John, D. Electromagnetics . Third ed. New York: McGraw-Hill; 1984 - 15.
Hund EMC. Component and Circuit . New York: McGraw Hill; 1989 - 16.
Gao S, Luo Q, Zhu F. Circularly Polarized Antenna . Ltd: John Wiley & Sons; 2014