proceedings

Proceedings Wideband Reconfigurable with Beams † Switching for Systems Applications

Faouzi Rahmani 1,* , Naima Amar Touhami 1, Abdelmounaim Belbachir Kchairi 2 and Nihade Taher 3

1 Faculty of Sciences, Abdelmalek Essaadi University, Tetuan 93030, Morocco; [email protected] 2 Faculty of Sciences and Techniques, Hassan II University of Casablanca, Casablanca 20006, Morocco; [email protected] 3 National School of Applied Sciences, Abdelmalek Essaadi University, Tetuan 93030, Morocco; [email protected] * Correspondence: [email protected]; Tel.: +212-671-307-689 Presented at the 14th International Conference on Interdisciplinarity in Engineering—INTER-ENG 2020, † Târgu Mures, , Romania, 8–9 October 2020.

  Published: 18 December 2020

Abstract: In this paper, a new wideband reconfigurable antenna with beams switching for wireless systems applications is presented and studied. The radiation pattern of the proposed antenna can be changed using the PIN diodes. The designed antenna has a bandwidth of 26.75% from 5.31 to 6.95 GHz and can steer the beam in the azimuth plane. The simulated realized gain of the antenna obtained is 5.9 dB at 5.8 GHz. The proposed antenna can operate for various wireless systems, such as Wi-Fi, WiMAX, Intelligent Transportation System (ITS) and C-band satellite. The simulated results are also presented and investigated.

Keywords: reconfigurable antenna; PIN diode; radiation pattern; wideband; Wi-Fi; WiMAX; ITS

1. Introduction With the rapid development of electronic and wireless communication, performance is important in any antenna system. The reconfigurable antennas have gained more attention due to their flexibility in operating frequency, polarization and radiation pattern reconfiguration [1–4]. This makes them highly suitable for different wireless communication systems. This antenna type can electronically change its parameters in response to different environments, which has been studied extensively. This means it can satisfy the diverse requirements and strict standards of advanced wireless communication systems due to its numerous merits such as reducing size, expanding capacity and wide cover. Optical, mechanical or electronic switching can be used to accomplish reconfiguration. Electronic switching is achieved using lumped components, for example, varactor diodes [5], PIN diodes [6–14], RF MEMS switches [15] or FET transistors. The reality that distinct wireless applications, such as Wi-Fi, WiMAX and ITS, use various operating bands and the exigency of Wideband reconfigurable antennas for wireless terminals is also rising. Multifunction in antennas is an important characteristic that has currently generated more interest in antenna design development. Contrast with accustomed antennas, multifunctional antennas offers the capability to dynamically alter several antenna parameters. In recent years, this antenna type has been proposed and developed more and more. To realize the pattern reconfigurability, there are various main technical and methods in the literature. The antenna in [15] performed six operating states by monitoring the states of MEMS switches. The antenna in [16] achieved two states by controlling the state of two PIN diodes between the and patch elements.

Proceedings 2020, 63, 36; doi:10.3390/proceedings2020063036 www.mdpi.com/journal/proceedings Proceedings 2020, 63, 36 2 of 9

radiation pattern of the antenna in [17] would be reconfigured in two modes in the azimuth plane by Proceedingssteering2020 the, 63state, 36 of two PIN diodes. In Ref. [18], by shifting the states of the four PIN diodes, four2 of 9 pattern reconfigurable states were obtainable. To increase the antenna performance, we propose to use four radiation cells connected to a central circular patch by using PIN diodes. The PIN diodes are very Basedreliable on asince circular there monopole are no moving patch parts and and three are ship-shaped extremely low parasitic cost. Patch patches, antenna the radiationcan be integrated pattern of theeasily antenna with in PIN [17 ]diode would switches be reconfigured to form inreconfigur two modesable inpatch the azimuthantennas plane[18,19]. by In steering addition the to state the of twopattern PIN diodes. reconfigurability, In Ref. [18 the], by objective shifting is theto increa statesse of the the bandwidth four PIN and diodes, miniaturize four pattern the antenna reconfigurable size. states wereIn this obtainable. work, we propose To increase a new the performance, radiation pattern we propose antenna to using use four four radiation fan-shaped cells connectedradiation to cells a central that operate circular either patch as by reflector(s) using PIN or diodes.director(s) The according PIN diodes to the are PIN very diodes reliable states, since and there area nosquare moving planar parts ground. and are The extremely radiation low pattern cost. Patchcan be antenna changed can into be four integrated states using easily four with switches. PIN diode switchesThe antenna to form main reconfigurable beam can be patchswitched antennas to four [ 18directions,19]. In additionin the azimuth to the plane pattern by reconfigurability,controlling the thestates objective (ON isor to OFF) increase of four the bandwidthMicrosemi andMPP420 miniaturize3 PIN diodes the antenna [20]. The size. designed antenna has a bandwidthIn this work, of 5.31–6.95 we propose GHz aand new can reconfigurable operate for various radiation wireless pattern systems, antenna such using as Wi-Fi, four fan-shapedWiMAX radiationand ITS. cells that operate either as reflector(s) or director(s) according to the PIN diodes states, and a squareThis work planar will ground. begin by The descri radiationbing the pattern wideband can bereconfigurable changed into antenna four states design using and four operation switches. Theprinciple antenna to main realize beam the can reconfigurability be switched to of four the directionsradiation patterns. in the azimuth The design plane evolutions by controlling process the statesfor (ONthe or proposed OFF) of fourantenna Microsemi and parametric MPP4203 study PIN will diodes be presented [20]. The in designed Sections antenna 3 and 4, hasrespectively. a bandwidth The of 5.31–6.95simulation GHz results and can of the operate proposed for various antenna wireless at operating systems, states such will asbe Wi-Fi,presented WiMAX in Section and ITS.5. Finally, theThis conclusion work will is given begin in by Section describing 6. the wideband reconfigurable antenna design and operation principle to realize the reconfigurability of the radiation patterns. The design evolutions process 2. Antenna Design for the proposed antenna and parametric study will be presented in Sections3 and4, respectively. The simulationThe proposed results antenna of the consisted proposed of a antenna central circul at operatingar patch and states four will radiation be presented cells graved in Section on h = 5. Finally,0.8 mm the thick conclusion Rogers RT5880 is given substrate in Section with6. a relative dielectric constant of 2.2 and a dissipation factor of 0.0009. A square-shaped is printed on the bottom surface of the substrate as shown in 2.Figure Antenna 1. The Design first (yellow area) part is a circular patch located at the center of the proposed antenna, which is connected to the inner pin of the . The second (red area) parts are four fan-shaped The proposed antenna consisted of a central circular patch and four radiation cells graved on radiation cells, which distribute around the antenna center symmetrically as shown in Figure 1a. h = 0.8The mm sizethick of Rogersthe substrate RT5880 is (W substrate × L × h) with = (60 amm relative × 60 mm dielectric × 0.8 mm). constant The radiation of 2.2 and elements a dissipation are factorconnected of 0.0009. to the A central square-shaped circular pa groundtch using plane four isswitches printed in on the the gap bottom between surface them, ofthe the width substrate of this as showngap is in 0.3 Figure mm.1 The. The four first PIN (yellow diodes area) are mounted part is a circularin the gap patch between located the at circular the center patch of and the the proposed four antenna,parasitic which patches is connected as shown in to Figure the inner 2. This pin ante of thenna coaxial was obtained cable. Theafter second many optimizations (red area) parts using are an four fan-shapedelectromagnetic radiation simulator cells, which (CST distributeMicrowave around Studio). the The antenna optimized center parameter symmetrically values as shownof the in Figureproposed1a. wideband reconfigurable radiation pattern antenna are given in Table 1.

(a) (b) (c)

FigureFigure 1. 1.The The designed designed reconfigurablereconfigurable antenna: ( (aa)) Top Top view; view; (b (b) )side side view; view; (c ()c bottom) bottom view. view.

The size of the substrate is (W L h) = (60 mm 60 mm 0.8 mm). The radiation elements are × × × × connected to the central circular patch using four switches in the gap between them, the width of this gap is 0.3 mm. The four PIN diodes are mounted in the gap between the circular patch and the four parasitic patches as shown in Figure2. This antenna was obtained after many optimizations using an electromagnetic simulator (CST Microwave Studio). The optimized parameter values of the proposed wideband reconfigurable radiation pattern antenna are given in Table1. Proceedings 2020, 63, 36 3 of 9 ProceedingsProceedings 20202020,, 6363,, 3636 33 ofof 99

FigureFigureFigure 2.2. TheThe proposedproposed enlargedenlarged antennaantenna center:center:center: TopTop view. view.view. Table 1. Dimensions of the proposed antenna. TableTable 1.1. DimensionsDimensions ofof thethe proposedproposed antenna.antenna. Parameter W W0 W1 WC WS Wg L L0 ParameterParameter WW W0 W0 W1 W1 W WCC WWSS WWgg LL L0L0 Dimension 30 mm 20.2 mm 3 mm 4.4 mm 34 mm 4.1 mm 30 mm 21 mm DimensionDimension 3030 mmmm 20.2 20.2 mmmm 3 3 mmmm 4.4 4.4 mmmm 34 34 mmmm 4.1 4.1 mmmm 30 30 mmmm 21 21 mmmm L1 L2 LC LS z h β α L1L1 L2L2 L LCC LLSS zz h h ββ αα 4.54.54.5 mmmm 2.8 2.8 mm mmmm 4.95 4.95 4.95 mm mmmm 34 mm34 34 mmmm 5 mm 5 5 mmmm 0.8 0.8 0.8mm mmmm 40◦ 40° 40° 90◦ 90° 90°

3.3. DesignDesign EvolutionEvolution ProcedureProcedure FigureFigure 3 33 shows showsshows thethethe designdesigndesign evolutionevolutionevolution ofofof thethethe proposed prproposedoposed antenna,antenna,antenna, withwithwith correspondingcorrecorrespondingsponding resultsresultsresults ofofof simulatedsimulated reflection reflectionreflection coefficient coecoefficientfficient S S11S1111 (dB) (dB) as as shown shown in in Figure Figure 4 4a,4a,a, and andand simulated simulatedsimulated gain gaingain realized realizedrealized over overover frequencyfrequency of of each each step step as as shown shown in in Figure Figure 4 4b.4b.b. The ThThee simulation simulationsimulation resultsresultsresults are areare obtained obtainedobtained when whenwhen the thethe antenna antennaantenna operatesoperates in in state state 1. 1. ThisThis studystudy gives gives the the same same results results for for the the other other operation operation states. states.

((aa)) ((bb)) ((cc)) ((dd))

FigureFigure 3. 3. DesignDesign evolution evolution ofof thethe proposed proposedproposed antenna: antenna:antenna: ( (a(aa))) initial initialinitial antenna; antenna;antenna; ( b ((bb)) Improved) ImprovedImproved antenna antennaantenna design designdesign 1; 1;(1;c ) ((c Improvedc)) ImprovedImproved antenna antennaantenna design designdesign 2; (2;2;d )((dd Final)) FinalFinal antenna. antenna.antenna.

Proceedings 2020, 63, 36 4 of 9

The first step in the design of the proposed reconfigurable antenna is presented in Figure 3a. As can be seen from this figure, on the top side of the substrate four symmetrical circular-shaped microstrip parasitic patches are placed one opposite the other, and a circular-shaped patch is located at the center of the antenna, which is connected to the inner pin of the coaxial. On the bottom surface of the substrate, a square-shaped ground plane is printed. A resonant frequency at 3.93 GHz is created with −10 dB impedance bandwidth that ranges from 3.91 to 3.95 GHz as shown in Figure 4a. However, the maximum simulated gain value is 6.90 dB for the initial antenna at 3.93 GHz frequency as shown in Figure 3b. In order to enhance the impedance bandwidth, a change in the ground plane was implemented as shown in Figure 3b. Meanwhile, as in the case of the previous step, on the top side of the substrate, the antenna geometry remains unchanged. As given in Figure 4a, the improved antenna 1 resonates at 6.29 GHz with −10 dB impedance bandwidth that ranges from 5.83 to 7.27 GHz. Note that the improved antenna 1 has a bandwidth greater than that of the initial antenna. On the other Proceedingshand, the2020 maximum, 63, 36 simulated gain value is around 4.30 dB as shown in Figure 4b. 4 of 9

0 10

5 -10 0

-20 -5 Gain (dB) -10 -30 Iinitial antenna

Reflection coefficient (dB) Initial antenna Improved antenna 1 Improved antenna 1 -15 Improved antenna 2 Improved antenna 2 Final antenna Final antenna -40 -20 3456789 4567 Frequency (GHz) Frequency (GHz) (a) (b)

FigureFigure 4. Simulated4. Simulated reflection reflection coeffi coefficientcient and max and gain max of digainfferent of antennas:different (antennas:a) Reflection (a) coe Reflectionfficient, (bcoefficient,) Max gain. (b) Max gain.

TheIn order first step to improve in the design the impedance of the proposed bandwidth, reconfigurable a change antennain the parasitic is presented patch in geometry Figure3a. is Asimplemented. can be seen fromThe circular this figure, side onof the radiating top side ofcells the becomes substrate rectilinear four symmetrical as shown circular-shaped in Figure 3c. As microstripilluminated parasitic in Figure patches 4a, arethe placedimproved one oppositeantenna the2 resonates other, and at a 6.29 circular-shaped GHz with patch−10 dB is impedance located at thebandwidth center of thethat antenna, ranges from which 5.35 is connected to 7.33 GHz. to the Note inner that pin the of improved the coaxial. antenna On the 1 bottom has a surfacebandwidth of thegreater substrate, than athat square-shaped of the improved ground antenna plane is 1. printed. Meanwhile, A resonant the maximum frequency simulated at 3.93 GHz gain is createdvalue is witharound10 dB4.21 impedance dB as shown bandwidth in Figure that 4b. ranges from 3.91 to 3.95 GHz as shown in Figure4a. However, − the maximumTo make simulated the more value adapted, is 6.90 dB deformatio for the initialn at antenna the entry at 3.93 of GHzthe parasitic frequency patches as shown was incarried Figure 3outb. with slots in the form of triangles as shown in Figure 3d. The proposed reconfigurable antennaIn order becomes to enhance more the adapted. impedance The designed bandwidth, ante a changenna has in a thebandwidth ground planeof 5.31–6.95 was implemented GHz as shown as shownin Figure in Figure 4a. Note3b. Meanwhile, that the final as in antenna the case has of the a previousgain greater step, than on the that top of side the of other the substrate, antennas. theMeanwhile, antenna geometry the maximum remains simulated unchanged. gain Asvalue given at 5.8 in FigureGHz is4a, around the improved 6.0 dB as antenna shown 1in resonates Figure 4b. atThe 6.29 choice GHz withof the fan-shaped10 dB impedance design bandwidthis intended thatto cover ranges the from whole 5.83 azimuthal to 7.27 GHz. plane Note and thatto have the a − improvednew antenna antenna capable 1 has of ayielding bandwidth directive greater gain than patterns that ofin the azimuth initial antenna. plane. On the other hand, the maximum simulated gain value is around 4.30 dB as shown in Figure4b. 4. ParametricIn order to Study improve the impedance bandwidth, a change in the parasitic patch geometry is implemented. The circular side of the radiating cells becomes rectilinear as shown in Figure3c. A parametric study was achieved to comprehend the influence on the proposed antenna As illuminated in Figure4a, the improved antenna 2 resonates at 6.29 GHz with 10 dB impedance performance. Taking state 1 as an example, the parameters are optimized for antenna− performance bandwidth that ranges from 5.35 to 7.33 GHz. Note that the improved antenna 1 has a bandwidth and tabulated in Table 1. In this section, we study the effects of the main geometric parameters on greater than that of the improved antenna 1. Meanwhile, the maximum simulated gain value is around reflection coefficient (S11) and antenna gain. We present a parametric study of the proposed antenna 4.21 dB as shown in Figure4b. that is used to obtain the optimal values and the best performance by tuning one parameter at a time To make the antenna more adapted, deformation at the entry of the parasitic patches was carried while other parameters are left invariable. out with slots in the form of triangles as shown in Figure3d. The proposed reconfigurable antenna becomes more adapted. The designed antenna has a bandwidth of 5.31–6.95 GHz as shown in Figure4a. Note that the final antenna has a gain greater than that of the other antennas. Meanwhile, the maximum simulated gain value at 5.8 GHz is around 6.0 dB as shown in Figure4b. The choice of the fan-shaped design is intended to cover the whole azimuthal plane and to have a new antenna capable of yielding directive gain patterns in the azimuth plane.

4. Parametric Study A parametric study was achieved to comprehend the influence on the proposed antenna performance. Taking state 1 as an example, the parameters are optimized for antenna performance and tabulated in Table1. In this section, we study the e ffects of the main geometric parameters on reflection coefficient (S11) and antenna gain. We present a parametric study of the proposed antenna Proceedings 2020, 63, 36 5 of 9

Proceedings 2020, 63, 36 5 of 9 that is used to obtain the optimal values and the best performance by tuning one parameter at a time 4.1.Proceedings The Effect 2020, of63 ,the 36 Length L0 5 of 9 while other parameters are left invariable. 4.1. TheThe Effect antenna of the reflection Length L0 coefficient (S11) (dB) and the gain are simulated for different values of the 4.1.length The (L0) Effect of of fan-shaped the Length L0radiating cells and the other dimensions remaining constant are presented in The antenna reflection coefficient (S11) (dB) and the gain are simulated for different values of the FigureThe 5. antenna It can be reflectionseen that the coe impedancefficient (S11) bandwi (dB)dth and of the the gainproposed are simulated antenna remains for diff stableerent and values that length (L0) of fan-shaped radiating cells and the other dimensions remaining constant are presented in ofthe the frequency length (L0) resonances of fan-shaped are shifted. radiating As illustrate cells andd thein Figure other dimensions5a, when L0 remaining = 21 mm, constant the antenna are Figure 5. It can be seen that the impedance bandwidth of the proposed antenna remains stable and that presentedbecomes inmore Figure adapted.5. It can On be the seen other that hand, the impedance the antenna bandwidth gain remains of the almost proposed stable antenna for the remains 5.31–6.95 the frequency resonances are shifted. As illustrated in Figure 5a, when L0 = 21 mm, the antenna stableGHz band and that when the the frequency length L0 resonances = 21 mm as are shown shifted. in Figu Asre illustrated 5b. Therefore, in Figure the optimal5a, when value L0 of= 21length mm, is becomes more adapted. On the other hand, the antenna gain remains almost stable for the 5.31–6.95 theL0 antenna= 21 mm. becomes more adapted. On the other hand, the antenna gain remains almost stable for the GHz band when the length L0 = 21 mm as shown in Figure 5b. Therefore, the optimal value of length is 5.31–6.95 GHz band when the length L0 = 21 mm as shown in Figure5b. Therefore, the optimal value L0 = 21 mm. of length0 is L0 = 21 mm. 8

0 68

-10 46

-10 24 -20 Gain (dB) 02

-20

Gain (dB) -2 Reflection coefficient (dB) 0 -30 L0=20 mm L0=20 mm L0=21 mm L0=21 mm L0=22 mm -4-2 L0=22 mm Reflection coefficient (dB) -30 L0=20 mm L0=20 mm L0=21 mm L0=21 mm 45678 45678 L0=22 mm -4 L0=22 mm Frequency (GHz) Frequency (GHz) 45678 45678 Frequency(a) (GHz) Frequency(b) (GHz) Figure 5. Simulated( areflection) coefficient and max gain versus the length(b) L0: (a) Reflection coefficient, (b) Max gain. FigureFigure 5. 5.Simulated Simulated reflection reflection coeffi coefficientcient and maxand gain max versus gain theversus length the L0: length (a) Reflection L0: (a) coe Reflectionfficient, 4.2. (Thebcoefficient,) Max Effect gain. of ( bthe) Max Angle gain. β

4.2.4.2. The TheThe E Effectff ectantenna of of the the Anglegain Angle andβ β parameter (S11) (dB) are also simulated as a function of the angle β variation. As presented in Figure 6a, the frequency resonances are shifted. Meanwhile, the antenna TheThe antenna antenna gain gain and and parameter parameter (S11) (S11) (dB) are(dB) also are simulated also simulated as a function as a function of the angle of βthevariation. angle β becomes more adapted when β = 40°. Likewise, the antenna gain is larger at the 5.8 GHz frequency Asvariation. presented As in presented Figure6a, thein Figure frequency 6a, the resonances frequency are resonances shifted. Meanwhile, are shifted. the Meanwhile, antenna becomes the antenna more when the angle α increases from 36° to 44° as shown in Figure 6b. Therefore, the optimum value of adaptedbecomes when moreβ adapted= 40◦. Likewise, when β the= 40°. antenna Likewise, gain the is larger antenna at the gain 5.8 is GHz larger frequency at the 5.8 when GHz the frequency angle α this angle is β = 40°. increaseswhen the from angle 36 ◦αto increases 44◦ as shown from in36° Figure to 44°6 b.as Therefore,shown in Fi thegure optimum 6b. Therefore, value of the this optimum angle is β value= 40 ◦of. this angle is β = 40°. 8 0

68 0 -10

46 -10 -20 24

-20 -30 Gain (dB) 02 Gain (dB) Reflection coefficient coefficient (dB) Reflection -30 -20 -40 =36° =36° =40° =40° =44° -4 Reflection coefficient coefficient (dB) Reflection  -2 =44° -40 =36° =36° -50   =40° =40° 45678 45678 =44° -4 =44° Frequency (GHz) Frequency (GHz) -50 45678 45678 Frequency(a) (GHz) Frequency(b) (GHz) FigureFigure 6. 6.Simulated Simulated reflection (reflectiona) coe coefficientfficient and and max max gain gain versus versus the the angle angleβ β:(: a()a(b) Reflection )Reflection coe coefficient,fficient, (b()b Max) Max gain. gain. Figure 6. Simulated reflection coefficient and max gain versus the angle β: (a) Reflection coefficient, (b) Max gain.

Proceedings 2020, 63, 36 6 of 9 Proceedings 2020, 63, 36 6 of 9 5. Simulation Results and Discussion 5. SimulationBased on Resultsthe PIN and diode Discussion states, the different radiating elements of the antenna can be selectively poweredBased by on the the circular PIN diode patch. states, Therefore, the diff erenta series radiating of simulations elements was of theperformed antenna as can given be selectivelyin Table 2. poweredThe PIN bydiode the resistance circular patch. and capacitance Therefore, ain series the ON of and simulations OFF conditions was performed are 3 Ω, as0 pF, given and in 25 Table kΩ, 20.8. ThepF, PINrespectively diode resistance [18,19]. By and controlling capacitance the inbiasing the ON of andthe PIN OFF diodes, conditions the distribution are 3 Ω, 0 pF, of andthe antenna 25 kΩ, 0.8surface pF, respectively current will [18 be,19 modified;]. By controlling this will the deflect biasing the of direction the PIN of diodes, the antenna the distribution radiation. of The the radiating antenna surfacecells operate current either will beas modified;reflector(s) this or willdirector(s) deflect a theccording direction to the of the switches antenna states. radiation. This shows The radiating that the cellsproposed operate antenna either has as reflector(s) four operating or director(s) states named according as state to 1 (S1), the switches state 2 (S2), states. state This (S3) showsand state that 4 (S4). the proposed antenna has four operating states named as state 1 (S1), state 2 (S2), state (S3) and state 4 (S4). Table 2. The antenna operating states. Table 2. Operating States PIN DiodeThe 1 antenna PIN Diode operating 2 states. PIN Diode 3 PIN Diode 4 OperatingState States1 PIN Diode ON 1 PIN Diode ON 2 PIN Diode OFF 3 PIN Diode ON 4 StateState 1 2 ONON ONON OFFON ONOFF StateState 2 3 ON OFF ON ON ON ON OFF ON StateState 3 4 OFFON ONOFF ONON ON ON State 4 ON OFF ON ON The reflection coefficient (S11) (dB) of the proposed wideband reconfigurable antenna is presentedThe reflection in Figure coe 7.ffi cientThe simulated (S11) (dB) ofresults the proposed show that wideband the proposed reconfigurable antenna antenna has a bandwidth is presented of in26.75% Figure from7. The 5.31 simulated to 6.95 GHz results with show (S11) that less the than proposed −23 dB. antenna The simulated has a bandwidth results are of obtained 26.75% fromwhen 5.31the toantenna 6.95 GHz operates with in (S11) state less 1. The than same23 dB.result Thes are simulated given for results the other are obtainedthree operation when thestates. antenna − operates in state 1. The same results are given for the other three operation states.

0

-5

-10

-15

Reflection coefficient (dB) coefficient Reflection -20

-25 45678 Frequency (GHz) Figure 7. Simulated reflection coefficient S11 (dB). Figure 7. Simulated reflection coefficient S11 (dB). Far-field radiation patterns of the proposed antenna are simulated using an electromagnetic Far-field radiation patterns of the proposed antenna are simulated using an electromagnetic simulator. Figure8a–d show the simulated radiation patterns in the azimuth plane (XOY plane). simulator. Figure 8a–d show the simulated radiation patterns in the azimuth plane (XOY plane). The The main beam of the proposed antenna can be steered to approximate φ = 0◦, φ = 90◦, φ = 180◦ and main beam of the proposed antenna can be steered to approximate ϕ = 0°, ϕ = 90°, ϕ = 180° and ϕ = φ = 270◦, for State 1 to State 4, respectively. The radiation patterns in elevation are similar and the main 270°, for State 1 to State 4, respectively. The radiation patterns in elevation are similar and the main beam directions all point at θ = 36◦. Far-field radiation patterns at frequencies 5.8 GHz and 5.9 GHz in beam directions all point at θ = 36°. Far-field radiation patterns at frequencies 5.8 GHz and 5.9 GHz the azimuth plane show that the proposed wideband reconfigurable pattern antenna radiates in four in the azimuth plane show that the proposed wideband reconfigurable pattern antenna radiates in different directions as shown in Figures8 and9. four different directions as shown in Figures 8 and 9.

Proceedings 2020, 63, 36 7 of 9

Proceedings 2020, 63, 36 7 of 9 Proceedings 2020, 63, 36 : 5,8 GHz : 5,9 GHz 7 of 9

: 5,8 GHz : 5,9 GHz 0 0 0 330 30 330 0 (dB) 30 -5(dB0 ) -50 0 300 330-10 30 60 300330 -100 (dB) 30 60 -15-5(dB) -5-15 270300 -20-10 6090 270300 -10-20 60 90 -15 -15 270 90 270 90 240 -20 120 240 -20 120 240210 150 120 240 210 150120 180 180

210 150 210 150 180 180

(a) (b) 0(a) (b)0 0 0 330 (dB)0 30 330 0(dB) 30 -5 -5 330 0 (dB) 30 330 0 (dB) 30 300 -10-5 60 300 -5-10 60 300 -15-10 60 300 -10-15 60 270 -20-15 90 270 -15-20 90 270 -20 90 270 -20 90 240 120 240 120 240 120 240 120 210 150 210 150 210 180 150 210 180 150 180 180 (c) (d) (c) (d) Figure 8. Simulated radiation patterns of the proposed wideband reconfigurable antenna in azimuth FigureFigure 8. 8.Simulated Simulated radiation radiation patterns patterns ofof thethe proposedproposed wideband reconfigurable reconfigurable antenna antenna in inazimuth azimuth Plane: (a) State 1, (b) State 2, (c) State 3, (d) State 4. Plane:Plane: (a )(a State) State 1, 1, (b ()b State) State 2, 2, ( c()c) State State 3, 3, ((dd)) StateState 4.4.

((bb))

(c(c) ) (a()a )

(d) (d) Figure 9. Simulated 3D radiation patterns at 5.8 GHz: (a) State 1, (b) State 2, (c) State 3, (d) State 4. FigureFigure 9.9. Simulated 3D radiation patterns at 5.8 GHz: (aa) State 1, (bb) State 2, (cc) State 3, (dd) State 4. Simulated 3D radiation patterns at 5.8 GHz: ( ) State 1, ( ) State 2, ( ) State 3, ( ) State 4.

Proceedings 2020, 63, 36 8 of 9

To validate the proposed design, Table3 presents a comparison between our wideband reconfigurable antenna and other previously reported designs. It is clear that the impedance bandwidth of this antenna is higher than that of all published patterns reconfigurable antenna. According to Table3, the proposed antenna not only has pattern-reconfigurability and an enhanced bandwidth, but also possesses additional advantages—notably its smaller size.

Table 3. Comparison between recently proposed antennas and the proposed wideband reconfigurable antenna.

Impedance Ref. No. |S11| (dB) Peak Gain Azimuth Plane Beam-Scanning Switch No. Size (λ *) Bandwidth 0 [7] 18.6% 22 6~6.5 dBi 360 4 1.37 1.37 0.02 ◦ × × [18] 4.7% 40 8.22 dB 360 4 0.94 0.94 0.03 ◦ × × [19] 5.6% 20 4.7~7.3 dBi 180 8 1.17 1.17 0.08 ◦ × × This work 26.7% 23 5.95 dB 360 4 1.14 1.14 0.01 ◦ × × λ0* is the wavelength of the free space.

6. Conclusions In this work, a new wideband reconfigurable radiation pattern antenna using four fan-shaped radiation elements is simulated and studied. Based on the four PIN diode biasing, the nominated antenna can operate at four basic different modes and achieve radiation pattern reconfigurable characteristics. When the operation states of the proposed antenna steer sequentially, the main radiation beam can be changed in four different directions and can cover the whole azimuth plane. The designed antenna can supply a wideband ranging from 5.31 to 6.95 GHz. As is known, this band is exactly reserved for Wi-Fi, WiMAX, ITS and C-band satellite. Therefore, the proposed design fulfills the goal of this work absolutely.

Conflicts of Interest: The authors declare no conflict of interest.

References

1. Xie, P.; Wang, G.-M.; Li, H.-P.; Wen, T.; Kong, X. Frequency Reconfigurable Quasi-Yagi Antenna with a Novel Loading Four PIN Diodes. Frequenz 2018, 72, 189–195. [CrossRef] 2. Saeed, S.M.; Balanis, C.A.; Birtcher, C.R. Inkjet-Printed Flexible Reconfigurable Antenna for Conformal WLAN/WiMAX Wireless Devices. IEEE Antennas Wirel. Propag. Lett. 2016, 15, 1979–1982. [CrossRef] 3. Kim, J.; Sung, Y. Dual-Band Microstrip Patch Antenna with Switchable Orthogonal Linear Polarizations. J. Electromagn. Eng. Sci. 2018, 18, 215–220. [CrossRef] 4. Ramli, N.; Ali, M.T.; Islam, M.T.; Yusof, A.L.; Muhamud-Kayat, S. Aperture-Coupled Frequency and Patterns Reconfigurable Microstrip Stacked Array Antenna. IEEE Trans. Antennas Propag. 2015, 63, 1067–1074. [CrossRef] 5. Nguyen-Trong, N.; Hall, L.; Fumeaux, C. A Frequency- and Polarization-Reconfigurable -Loaded Microstrip Patch Antenna. IEEE Trans. Antennas Propag. 2015, 63, 5235–5240. [CrossRef] 6. Rahmani, F.; Touhami, N.A.; Kchairi, A.B.; Taher, N. Circular Planar Antenna with Reconfigurable Radiation Pattern using PIN Diodes. Procedia Manuf. 2020, 46, 760–765. [CrossRef] 7. Cheng, Y.-F.; Ding, X.; Wang, B.-Z.; Shao, W. An Azimuth-Pattern-Reconfigurable Antenna with Enhanced Gain and Front-to-Back Ratio. IEEE Antennas Wirel. Propag. Lett. 2017, 16, 2303–2306. [CrossRef] 8. Li, H.; Wu, M.; Yuan, S.; Zhou, C. Design of Off-Center Fed Windmill Loop for Pattern Reconfiguration. IEEE Antennas Wirel. Propag. Lett. 2019, 18, 1626–1630. [CrossRef] 9. Tran, H.H.; Park, H.C. Wideband Reconfigurable Antenna With Simple Biasing Circuit and Tri-Polarization Diversity. IEEE Antennas Wirel. Propag. Lett. 2019, 18, 2001–2005. [CrossRef] 10. Liu, B.-J.; Qiu, J.-H.; Wang, C.-L.; Li, G.-Q. Pattern-Reconfigurable Cylindrical Dielectric Resonator Antenna Based on Parasitic Elements. IEEE Access 2017, 5, 25584–25590. [CrossRef] 11. Jin, G.; Li, M.; Liu, D.; Zeng, G. A Simple Planar Pattern-Reconfigurable Antenna Based on Arc Dipoles. IEEE Antennas Wirel. Propag. Lett. 2018, 17, 1664–1668. [CrossRef] Proceedings 2020, 63, 36 9 of 9

12. Chen, S.-L.; Qin, P.; Lin, W.; Guo, Y. Pattern-Reconfigurable Antenna with Five Switchable Beams in Elevation Plane. IEEE Antennas Wirel. Propag. Lett. 2018, 17, 454–457. [CrossRef] 13. Tawk, Y.; Costantine, J.; Makhlouf, F.; Nassif, M.; Geagea, L.; Christodoulou, C.G. Wirelessly Automated Reconfigurable Antenna with Directional Selectivity. IEEE Access 2017, 5, 802–811. [CrossRef] 14. Tang, M.-C.; Zhou, B.; Duan, Y.; Chen, X.; Ziolkowski, R.W. Pattern-Reconfigurable, Flexible, Wideband, Directive, Electrically Small Near-Field Resonant Parasitic Antenna. IEEE Trans. Antennas Propag. 2018, 66, 2271–2280. [CrossRef] 15. Ma, W.D.; Wang, G.M.; Wang, Y.W.; Zong, B.F. Compact Microstrip Antenna with Pattern-Reconfigurable Characteristic. Radioengineering 2017, 26, 662–667. [CrossRef] 16. Khan, M.S.; Iftikhar, A.; Capobianco, A.-D.; Shubair, R.M.; Ijaz, B. Pattern and frequency reconfiguration of patch antenna using PIN diodes. Microw. Opt. Technol. Lett. 2017, 59, 2180–2185. [CrossRef] 17. He, X.; Gao, P.; Zhu, Z.; You, S.; Wang, P. A flexible pattern reconfigurable antenna for WLAN wireless systems. J. Electromagn. Waves Appl. 2019, 33, 782–793. [CrossRef] 18. Rahmani, F.; Touhami, N.A.; Kchairi, A.B.; Taher, N.; El Ouahabi, M. Reconfigurable Radiation Pattern Antenna Using Kite-Shaped Parasitic Patches for Wireless Access Applications. Int. J. Microw. Opt. Technol. 2020, 15, 187–195. 19. Deng, W.-Q.; Yang, X.-S.; Shen, C.-S.; Zhao, J.; Wang, B.-Z. A Dual-Polarized Pattern Reconfigurable Yagi Patch Antenna for Microbase Stations. IEEE Trans. Antennas Propag. 2017, 65, 5095–5102. [CrossRef] 20. Datasheet of Microsemi MPP4203 PIN Diodes. Available online: http://www.microsemi.com (accessed on 1 March 2020).

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