Inter national J our nal of Electrical and Computer Engineering (IJECE) V ol. 9, No. 1, February 2019, pp. 452 459 ISSN: 2088-8708, DOI: 10.11591/ijece.v9i1.pp452-459 452 An ultra wideband antenna f or K u band applications Aziz El F atimi 1 , Seddik Bri 2 , and Adil Saadi 3 1,3 Modeling, Information Processing and Control Systems (MIPCS), National Graduate School of Arts and Crafts, Moulay Ismail Uni v ersity , Meknes, Morocco 2 Materials and Instrumentation (MIM), High School of T echnology , Moulay Ismail Uni v ersity , Meknes, Morocco Article Inf o Article history: Recei v ed Mar 21, 2018 Re vised No v 12, 2018 Accepted No v 26, 2018 K eyw ords: K u band W ideband Microstrip patch Finite element method ABSTRA CT This paper presents a candidate ultra wideband antenna for K u-band wireless communi- cations applications, analyzed and optimized by the finite element method (FEM). This three-dimensional modeling w as realized and compared with published antennas for v al- idate the performances of the proposed antenna. Its design is based on the insertion of se v eral symmetrical slots of dif ferent sizes on the ground plane of a mono-layer patch antenna to o v ercome the main limitation of the narro w bandwidth of patch antennas. The proposed antenna, made on an FR-4 epoxy mono-layer substrate with a defected ground plane (dielectric constant " r = 4,4, loss tangent tan = 0,02 and thickness hs = 1.6 mm). The simulated numerical results obtai ned are v ery satisfying; Bandwidth = 10.48 GHz from f 1 = 9.34 GHz to f 2 = 19.82 GHz, S 11 = -34.17 dB, V oltage Stationary W a v e Ratio VSWR = 1.04 , Gain = 6.27 dB. Copyright c 2019 Institute of Advanced Engineering and Science . All rights r eserved. Corresponding A uthor: Aziz Elf atimi, Modeling, Information Processing and Control Systems (MPICS), National Graduate School of Arts and Crafts, Moulay Ismail Uni v ersity , Meknes, Morocco, B.P . 15290 EL Mansour Meknes 50500, Meknes, Morocco. Email: aziz.elf atimi@edu.umi.ac.ma 1. INTR ODUCTION The adv ent of the microstrip patch antenna has brought a technological re v olution in the field of wireless communication because the adv antages the y of fer in terms of manuf acturing cost, fle xibility and mobility [1], [2]. T oday , it is omnipresent in our daily li v es including the GSM phone, satellite TV and other commercial applications [3], [4], [5]. The typical patch antenna consists of a metal plane (called patch) placed on a dielectric substrate in contact with a ground plane [6]. The patch antenna of fers better g ain performance compared to con v entional dipole or monopole antennas used in the past [7], [8]. Ho we v er , it suf fers from se v eral limitations in relation to the lo w ef ficienc y and lo w ability to radiate electromagnetic ener gy in the free space [9], [10]. Dif ferent forms of microstrip patch antennas are possible depending on the performance and the resonances frequencies required [11], [12]. T oday , the increasing demand for frequencies has led to the appearance of se v eral frequenc y bands. Among them, there is the K u band (K urz-unten), it is the most used of all other frequenc y bands for satellite tele vision. It is con v entionally defined in the electromagnetic spectrum defined by the micro w a v e frequenc y band from 12.4 GHz to 18 GHz. This band is the most widespread i n the w orld, because of the small size of the parables needed for its reception. Ho we v er , it require man y demodulators as well as se v eral uni v ersal lo w noise block-con v erter (LNBs) to recei v e K u-band satellites [13], [14], [15]. The shape chosen for the proposed antenna is the rectangular and trapeze shapes since the y are v ery easy to analyze using both the transmission line and the ca vity model, which are the most accurate for thin substrates [16]. J ournal Homepage: http://iaescor e .com/journal/inde x.php/IJECE Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE ISSN: 2088-8708 453 In a general w ay in ph ysics, before proceeding to the realization of such a ph ysical model one passes by the reduced model. In the field of electromagnetism, se v eral numerical simulation methods ha v e been used to design three-dimensional structures of patches. These methods are the finite dif ference time domain (FDTD), the transmission line matrix (TLM), the finite element method (FEM), the finite inte gration technique (FIT) and other numerical methods [17], [18], [19], [20], [21]. In the follo wing of this paper , the first section will be de v oted to the mathematical formulation of the maxwell’ s equations, then the foll o wing section will describe in detail the proposed antenna and ho w to determine its parameters, at the end of this document a comparison between this antenna and other antennas presented in [22], [23], [24] will be done. 2. UL TRA WIDEB AND ANTENN A DESIGN The microstrip patch antennas (MSA) principle consists of v ery thin metallic strip (called patch) placed abo v e a ground plane where the thickness of the metallic strip is restricted by t << 0 and the height hs is restricted by 0 : 003 0 hs 0 : 05 0 [9][25]. In this section, a Defected Ground Structure antenna is presented, studied and optimi zed using the finite element method. The antenna is designed on a lo w cost FR-4 epoxy substrate with dielectric constant " r = 4 : 4 and loss tangent tan = 0.02 with thickness of 1.6 mm. 2.1. Design of initial patch antenna The calculation of the initial parameters of the proposed microstrip antenna is based on the classical equa- tions presented in [9]. a) Microstrip line width: F or W > h : " ef f = " r + 1 2 + [ " r 1 2 q 1 + 12 h W ] (1) And Z 0 = 120 p " ef f [ W h + 1 : 393 + 2 3 l n ( W h + 1 : 444)] (2) T o ha v e an input impedance equal to 50 , the width of the microstrip must be equal to W f = 3.08 mm as sho wn in Figure 1). In this case we will tak e a rounded v alue of W f = 3 mm. R esul t 8 < : W idth=H eig ht = 1 : 875 E f f ectiv e D iel ectr ic C onstant = 3 : 325 I mp edanc e = 50 : 83 Figure 1. Ef fecti v e dielectric constant and impedance vs microstrip line width An ultr a wideband antenna for K u band applications (Aziz Elfatimi) Evaluation Warning : The document was created with Spire.PDF for Python.
454 ISSN: 2088-8708 b) Microstrip line length: The choice of the start length of the microstrip line w as calculated using equation (3). It is based on a condition for the maximum signal coupling [26]. Then, the design process w as based on the optimization of these parameters on a numerical platform based on the finite element method (FEM). L f = L g = 2 (3) T able 1 presents a parametric study of the ef fect of the v ariation of L f on the resonance frequenc y and the return loss. The microstrip line length has been v arie d from 8 mm to 12 mm by a step of 1 mm. The chosen v alues of the starting parameters are W f = 3 mm and L f = 10 mm. T able 1. Ef fect of the v ariation of L f on the resonance frequenc y and the return loss L f [mm] Resonance frequenc y [GHz] Return loss [dB] 8 25.18 -29.68 9 22.8 -21.83 10 21.05 -15.17 11 19.52 -11.45 12 23.6 -11.62 c) Slot antenna: The multiple slot allo w to control the resonance frequenc y , the reflection coef ficient and the bandwidth by adjusting the width and length of the slot ( W sl ot and L sl ot ). The parameter L f allo ws to control the characteristic input impedance of the antenna. The slot is modeled as a w a v e guide inserted into the substrate. Its parameters are calculated from the follo wing classical equations gi v en in [27]. L sl ot = g 2 (4) g = 0 p " ef f (5) " ef f = " r + 1 2 (6) 0 = c f r (7) 2.2. Design of the pr oposed antenna Figure 2 sho ws the final design of the antenna for a wider bandwidth co v ering the K u band is achie v ed by de v eloping se v eral symmetrical slots. This ne w structure uses four slots with nine parameters namely W 1 , W 2 , W 3 , L 1 , L 2 , L 3 , H , D 1 and D 2 to get better performance; L f is al w ays used to match the impedance of the antenna to 50 . In this article, the v alue of these parameters mentioned abo v e w as determined using a numerical platform with a discretization of 0.01 GHz for the calculation of the frequenc y . The total dimension of the proposed antenna is 22 20 1 : 6 mm 3 . Figure 2. T op vie w and bottom vie w of the proposed antenna IJECE V ol. 9, No. 1, February 2019 : 452 459 Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE ISSN: 2088-8708 455 T able 2 illustrates the dif ferent dimensions of the proposed antenna after a series of numerical optimiza- tion. T able 2. The Optimum Dimensions of the Proposed Antenna P arameter Symbol Dimension (mm) Ground width W g 22 Ground length L g 20 Substrate thickness h s 1.6 W idth of the slot 1 W 1 17 Length of the slot 1 L 1 4 W idth of the slot 2 W 2 8.5 Length of the slot 2 L 2 1.5 W idth of the slot 3 W 3 21 Length of the slot 3 L 3 4 T op width of the slot 4 H 4 Base width of the slot 4 D 1 1 Height of the slot 4 D 2 15 3. NUMERICAL RESUL TS 3.1. Analysis of the pr oposed antenna The fundamental criterion for designing an antenna is the v alue of the return loss ( S 11 ). F or this purpose, the v arious parameters of the antenna are v aried, analyzed and optimized on a numerical platform based on the finite element method (FEM). The ef fect on the return loss by v arying W 1 , H , D 1 and W 3 are depicted in the Figures 3, 4, 5 and 6 respecti v ely . Figure 3 sho ws that with increasing the width W 1 , the resonant frequenc y shifts to the left side. While increasing the height H , the resonance frequenc y shifts to the right side as sho wn in Figure 4). In both cases, the bandwidth impro v es considerably by increasing W 1 and H . Similar in v estig ations are observ ed by v arying the tw o parameters D 1 and W 3 . From the analysis of figures 5 and 6, we can conclude that the base width D 1 and the width W 3 of the slots primarily control the v alue of the reflection coef ficient of the antenna. Simulated return loss shifts to the upper with the increase of the v alue of D 1 and it shifts to the lo wer with the increase of W 3 . The v ariation of D 1 and W 3 has no ef fect on the bandwidth size. The result obtained from the final geometry of the proposed antenna is sho wn in Figure 7. The graph sho ws a maximum v alue of S 11 = - 34.17 dB at a resonance frequenc y of 10.82 GHz. The graph also sho ws that belo w a threshold of -10 dB, the antenna has reached a bandwidth of 10.48 GHz from 9.34 GHz to 19.82 GHz. This which represents more than the bandwidth reached in [22], [23], [24]. Figure 8 sho ws the v ariation of antenna g ain relati v e to the frequenc y . The antenna has maximum g ain of 6.27 dB at 11 GHz and a g ain greater than 4.08 dB o v er the entire frequenc y band from 9.34 GHz to 19.82 GHz. The antenna radiation patterns in the E and H planes at 10.98 GHz, 14.3 GHz, 16 GHz and 18.6 GHz are illustrated in Figure 9, 10, 11 and 12. A directional diagram is observ ed in the plane E and the pseudo omni- directional diagram in the plane H. 3.2. Comparison between the pr oposed antenna and antennas cited in [22], [23], [24] The antenna proposed in [22] achie v es a reflection coef fici ent of -26 dB, a bandwidth of 2.8 GHz from 11.20 GHz to 14.0 GHz and a g ain of 4,65 dB. Another antenna structure w as pr esented in [23] achie v es a max- imum reflection coef ficient of -33 dB at a resonance frequenc y of 14.13 GHz. It also achie v es belo w -10 dB, a bandwidth of 2.5 GHz from 12 GHz to 14.5 GHz with an a v erage g ain of 8 dB o v er the entire band range of 12 GHz to 14.5 GHz. According to [24], an impro v ed bandwidth microstrip antenna has been proposed for satellite communications. Bandwidth has been impro v ed by using parasit ic patches. This antenna has a bandwidth of 4.08 GHz, a return loss of -49.07 dB at the center frequenc y , a maximum g ain of 8.25 dB. In summary , T able 3 presents a comparison between the performances of these antennas. W e find that our proposed antenna realized on a lo w cost FR-4 epoxy substrate realizes a competiti v e performance compared to An ultr a wideband antenna for K u band applications (Aziz Elfatimi) Evaluation Warning : The document was created with Spire.PDF for Python.
456 ISSN: 2088-8708 the other antennas presented in [22], [23], [24]. It also of fers a v ery wide bandwidth can be candidate for satellite communication applications or other cogniti v e applications in the frequenc y range from 9.34 GHz to 19.83 GHz. 4. CONCLUSION In this w ork, a structure of a miniaturized ultra wideband patch, ha ving a simplicity of construction at lo w cost and a better performance, has been proposed for wireless communication applications in the K u band. It can also be performed in antenna array to increase g ain and directi vity . Th i s patch has a lo w cost FR-4 epoxy substrate with constant dielectric " r = 4.4 and tan = 0.02. Se v eral symmetrical slots ha v e been inserted on the ground to increase the size of the bandwidth. This antenna of fers a g ain of 6.27 dB, a v ery wide band of 10.48 GHz from 9.34 GHz to 19.82 GHz, a lo w cost of implementation and a simplicity of manuf acture. The comparati v e study conducted in the last section s ho wed a better performance achie v ed especially the bandwidth. So this antenna can be a v ery good candidate for telecommunication applications in K u-band or other cogniti v e applications. Figure 3. Return loss by v arying W 1 Figure 4. Return loss by v arying H Figure 5. Return loss by v arying D 1 Figure 6. Return loss by v arying W 3 IJECE V ol. 9, No. 1, February 2019 : 452 459 Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE ISSN: 2088-8708 457 Figure 7. Return loss vs frequenc y Figure 8. Gain vs frequenc y Figure 9. Directi vity at f = 10.98 GHz Figure 10. Directi vity at f = 14.3 GHz Figure 11. Directi vity at f = 16 GHz Figure 12. Directi vity at f = 18.6 GHz An ultr a wideband antenna for K u band applications (Aziz Elfatimi) Evaluation Warning : The document was created with Spire.PDF for Python.
458 ISSN: 2088-8708 T able 3. Comparison between antennas P arameter Proposed antenna Ref.[22] Ref. [23] Ref. [24] Substrate material FR-4 epoxy FR-4 epoxy T eflon PTFE - Dielectric constant 4.4 4.4 2.55 - Frequenc y range [GHz] [9.34 - 19.82] [11.2-14] [12 - 14.5] - Return loss [dB] -34.17 dB -26 -33 dB -49.07 dB Bandwidth [GHz] 10.48 GHz 2.8 2.5 GHz 4.08 GHz Gain [dB] 6.27 dB 5.65 8.44 dB 8.25 dB REFERENCES [1] I. Singh and V . T ripathi, “Micro strip patch antenna and its applications: a surv e y , Int. J . Comp. T ec h. Appl , v ol. 2, no. 5, pp. 1595–1599, 2011. [2] A. Dalli, L. Zenk ouar , and S. Bri, “Comparison of circular sector and rectangular patch antenna arrays in c-band, J ournal of Electr oma gnetic Analysis and Applications , v ol. 4, no. 11, p. 457, 2012. [3] M. M atin, B. Sharif, and C. Tsimenidis, “Probe fed stack ed patch antenna for wideband applications , IEEE T r ansactions on Antennas and Pr opa gation , v ol. 55, no. 8, pp. 2385–2388, 2007. [4] R. Arora, A. K umar , S. Khan, and S. Arya, “Finite element modeling and design of rectangular patch antenna with dif ferent feeding techniques, Open J ournal of Antennas and Pr opa gation , v ol. 1, no. 02, p. 11, 2013. [5] M. Alibakhshi-K enari, “Modeling and constructing the microstrip notch-loaded rectangular s-shaped patch antennas using l-strip feeding for multi-band frequenc y performances in the recent wireless telecommunica- tion systems, International J ournal of Micr owave and W ir eless T ec hnolo gies , v ol. 8, no. 8, 2016. [6] L. Kai-F ong, “Microstrip patch antennas—basic properties and some recent adv ances, J ournal of Atmo- spheric and T err estrial Physics , v ol. 51, no. 9-10, pp. 811–818, 1989. [7] H. Mosallaei and K. Sarabandi, Antenna miniaturization and bandwidth enhancement using a reacti v e impedance substrate, IEEE T r ansactions on Antennas and Pr opa gation , v ol. 52, no. 9, pp. 2403–2414, 2004. [8] N. Boukhennouf a, L. Djouane, H. Oudira, M. Amir , and T . F ortaki, “Ef fect of the thickness of high tc superconducting rectangular microstrip patch o v er ground plane with rectangular aperture, International J ournal of Electrical and Computer Engineering (IJECE) , v ol. 8, no. 3, 2018. [9] C. A. Balanis, Antenna thero y analysis and design, 2005. [10] D.-G. F ang, Antenna theory and micr ostrip antennas . CRC Press, 2017. [11] R. Dakir , J. Zbitou, A. Mouhsen, A. T ribak, M. Latrach, and A. Sanchez, A ne w compact and miniaturized gcpw-fed slotted rectangular antenna for wideband uhf fird applications, International J ournal of Electrical and Computer Engineering (IJECE) , v ol. 7, no. 2, pp. 767–774, 2017. [12] Z. Chen et al. , “W ideband microstrip antennas with sandwich substrate, IET Micr owaves, Antennas & Pr op- a gation , v ol. 2, no. 6, pp. 538–546, 2008. [13] R. Azim, M. T . Islam, and N. Mis ran, “Dual polarized microstrip patch antenna for ku-band application, Informacije MIDEM , v ol. 41, no. 2, pp. 114–117, 2011. [14] A. A. M. Ali, N. J. F onseca, F . Coccetti, and H. Aubert, “Design and implementation of tw o-layer compact wideband b utler matrices in siw technology for ku-band applications, IEEE T r ansactions on Antennas and Pr opa gation , v ol. 59, no. 2, pp. 503–512, 2011. [15] M. M. Harane and H. Ammor , A compact dual band elliptical microstrip antenna for ku/k band satellite applications, International J ournal of Electrical and Computer Engineering (IJECE) , v ol. 8, no. 3, pp. 1596–1601, 2018. [16] A. B. Constantine et al. , Antenna theory: analysis and design, MICR OSTRIP ANTENN AS, thir d edition, J ohn wile y & sons , 2005. [17] A. T aflo v e and S. C. Hagness, Computational electr odynamics: the finite-dif fer ence time-domain method . Artech house, 2005. [18] D. Al-Mukhtar and J. Sitch, “T ransmission-line matrix method with irre gularly graded space, in IEE Pr o- ceedings H (Micr owaves, Optics and Antennas) , v ol. 128, no. 6. IET , 1981, pp. 299–305. [19] J. L. V olakis, A. Chatterjee, and L. C. K empel, F inite element method electr oma gnetics: antennas, micr owave cir cuits, and scattering applications . John W ile y & Sons, 1998, v ol. 6. [20] R. Marklein, “The finite inte gration technique as a general tool to compute acoustic, electromagnetic, elasto- IJECE V ol. 9, No. 1, February 2019 : 452 459 Evaluation Warning : The document was created with Spire.PDF for Python.
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