Design Of A Novel UWB Hexagonal Patch Antenna Having Three Notched Band .

Technical Journal, University of Engineering and Technology (UET) Taxila, PakistanVol. 22 No. II-2017Design of a Novel UWB Hexagonal PatchAntenna having Three Notched Band FeaturesR. Amin1, M. I. Khattak2, R. M. Edawrds3, G. Ahmad4, M. K. Shreen5, A. Basit61,2,4,5,63Electrical Engineering Department, UET, Peshawar, PakistanElectrical Engineering Department, Loughborough University, UK2m.i.khattak@uetpeshawar.edu.pk5.35 GHz and 5.72 to 5.8 GHz) and ITU (7.95 to 8.4GHz).One solution, to get rid of interference problem,is to use filter but it may add up to the expenditure andincrease the multifaceted nature and sophistication ofthe system [iv]; a simpler technique which could beimplied is the use of antenna in order to overcome thisconundrum. There are varied methods and techniquesemployed with a specific end goal to accomplish theobjective of band notching. One being the use ofparasitic element in order to stop the undesired range offrequencies [v-vi]. Another method being theintroduction of fractal geometry in the designing ofantenna which notches specific frequencies and thusenlists itself in the category of notching techniques[vii]. Yet another method could be acquired where bandnotch UWB antenna is outlined by utilizing split-ringresonator. The dimensions of the rings determine notchfrequency [viii]. Additionally, open loop, closed loop,open-circuited and short-circuited coplanar waveguideresonators are used to design band notch UWB antenna[ix-x]. Apart from the above mentioned procedure, yetagain, Computer auto-design technique is one of theprocedures in which optimization process is used todesign band stop antenna [xi-xii]. Last but not the least,Cuts or slots of various geometrical shapes are driven inthe radiator to achieve band notch characteristics.Current flows mainly on the surface of patch feedingline and ground plane and thus, cuts in these portionstrap the current. The dimensions of the cuts areproportional to the notch frequency and its bandwidth[xiii-xiv]. This paper is based on slot technique of bandnotching which uses CST Microwave Studio Suite forsimulation. Triple stop band characteristic has beenachieved by introducing 'I' shaped and 'C' shaped slotsand an inverted 'U' shaped cut in the radiating element.The excitation given here is microstrip line in nature.Abstract-A UWB hexagonal patch antenna with threeband-stop features is suggested in this article having ahexagonal shaped radiator fed with microstrip line with“I”, “C” and Inverted “U” shaped slots to attain theband notch characteristics. The dimensions of thesuggested antenna are 30mm 28mm 1.6mm. Thedesign is printed on FR4 substrate of permittivity 4.6and loss tangent 0.02. The antenna reports a substantialbandwidth from 2.65 GHz to 11.3 GHz. Out of this 8.65GHz range, the VSWR is less than 2 except at threenotch bands for WiMax system (3.3 to 3.7 GHz),WLAN system (5.15 to 5.85 GHz) and ITU (7.95 to 8.4GHz). The proffered antenna has a stable gain in theentire range of 8.65 GHz except the notch bands. Theradiation pattern of this antenna is nearly omnidirectional.Keywords-Ultra-Wide Band, ITU Frequency Band,WLAN, VSWR, WiMAX, HFSS.I. INTRODUCTIONUltra wideband (UWB) is a rapidly emergingtechnology with enhanced features for example lowpower utilization, high data rate, minimal effort andenhanced resolution of multipath [I]. This is a peerlessand unrivalled technology for implementation in highspeed and short range transmission. It is highlyrecommended for its utilization in the field of medicalsuch as high precision cancer detection [ii]. Highresolution ground penetrating radar also uses UWBtechnology. In 2002, the Federal CommunicationCommission (FCC) in America completelytransformed and revolutionized it by approving theunlicensed utilization of UWB range from 3.1 to 10.6GHz [iii]. Since then, an elevated and enlarged numberof research labs, academic institutions andgovernmental agencies have been trying to amplify thelatent potentials of this technology and actualize it intoreality. Its maximum power is restricted to 41dBm/MHz. UWB implies time shifting mechanismto broadcast binary data having rate in million pulsesper second. In this 7.5 GHz bandwidth, several narrowband systems pre-exist. Interference problems emanatefrom these narrow band systems. UWB system isaffected by WiMax(3.3 to 3.7 GHz), WLAN (5.15 toII. ANTENNA DESIGNUWB monopole antennas employ variousgeometrical shapes but in our propounded design,hexagonal geometrical structure has been brought intoservice. The desired antenna is formulated on FR-4substrate. Its thickness (h) is taken to be 1.6 mm so as toachieve the relative permittivity ( r ) of 4.6. Thedimensions of the substrate are 30 x 28mm. The41

Technical Journal, University of Engineering and Technology (UET) Taxila, PakistanVol. 22 No. II-2017wdimensions of the ground plane are 8 x 28mm. It alsohas a slot in the top mid of ground which has a length of3.5mm and width of 3.3mm. The desired antenna isprovided with a 50 Ω micro strip feed which has alength of 8mm and width of 3mm. The length of eachside of the hexagon is 10 mm. The resonating range ofthis antenna varies from 2.65 to 11.3 GHz. Differentslots are exploited to stop various bands to side-stepinterference. WiMax band (3.3 to 3.7 GHz) is thwartedby 'I' shaped slot of dimension 12.5 mm x 0.3mm. 'C'shaped slot having length 18.7 mm and width 0.5mm ismade use of to stop the band in the range of 5.15 to 5.8GHz used for WLAN application. The ITU frequencyband (7.95 to 8.4 GHz) has been stopped by inverted 'U'shaped slot of dimension 12.28 mm x .60mm in feederline and lower portion of the patch. Notch frequencyand substrate permittivity determine dimensions of theslots. At notch frequencies, length of the slots is quarterwavelength or half wavelength. The followingpostulates define length of the slots (Ls) [15].H1L4H2LH4LgH6WgLfBack viewL3Front viewL1H3H5L2Inverted U slotC slotFig. 1. Design of Novel Hexagonal AntennaIII. DISCOURSE/DEBATE ON FINDINGS(1)orIn this portion, the findings of UWB monopoleantenna with triple notch bands are put forward. TheS11 (dB) characteristic of the suggested antenna isdisplayed in Fig. 2. This graph reveals the widebandbehavior of the antenna in which 2.65 to 11.3 GHzportion of S11 (dB) is less than -10dB which standsperfectly in line with the criterion set by FCC.(2)Whereas c is the relative dielectric constant of FR-4 substrateLs is length of slot in mm,8C is the speed of light and its value is 3 x 10 m/sandfn is notch frequency in Ghz.S-Parameter [Magnitude in dB]-2S1,1-4-6-8-10-12The above equations are used to determine thedimensions of the design. By careful analysis andparametric study of the proposed model, the finalstructure of the antenna is obtained which is displayedin illustration 1. The length of 'I' shaped slot is 12.5mmand its width is 0.3mm. The length of 'C' shaped slot is18.7 mm and its width is 0.5mm. The inverted 'U'shaped slot is 12.28 mm long and its width is 0.6mm.The other parameters are recorded inTable 1.-14-16-18-20-22234567Frequency / GHz89101112Fig. 2. S11(dB) of the novel Antenna covering thewhole UWB BandFig. 3 shows the VSWR plot without notchedcharacteristics.Voltage Standing Wave Ratio (VSWR)7TABLE IDIMENSIONS OF THE VARIOUS PARAMETER OF THENOVEL ANTENNA 5H68Wg3.3321234567Frequency / GHz89101112Fig. 3. VSWR plot of the novel antennaFig. 4 shows the notched characteristics of theantenna at three different communications bands andfrom VSWR plot it is clear that the three bands centeredat 3.48, 5.52 and 8.15 GHz have been halted by theantenna.42

Technical Journal, University of Engineering and Technology (UET) Taxila, PakistanVoltage Standing Wave Ratio (VSWR)Vol. 22 No. II-2017To discuss notching characteristics of thesimulated antenna, the surface current circulations atvarious bands are depicted in Fig. 9(a), (b) and 3917911959.70123456789101112Frequency / GHzFig. 4. VSWR plot of the antenna with triple stopband featuresIn the entire 8.65 GHz bandwidth VSWR 2 exceptat notch bands.Fig. 5, Fig. 6 and Fig. 7 represents the stepwisereturn loss of the proposed antenna with three notchbands. Fig. 8 is showing all the results in one plot.S-Parameter [Magnitude in 0116713410066.933.50-4023456789101112Frequency / GHzFig. 5. S11(dB) of the antenna with first notch ofWiMAX band.S-Parameter [Magnitude in 112Frequency / GHzFig. 6. S11(dB) of the antenna with first and secondnotch of WiMAX and ISM bands.(b)S-Parameter [Magnitude in dB]-2S1,1-4A/m-631-8456728344-1012345678( 2.652, -10.196 )( 11.43, -9.537 )( 3.2108, -10.061 )( 3.6699, -10.003 )( 5.0936, -10.106 )( 5.4895, -9.9269 )( 7.892, -9.9878 )( 8.3119, -10.159 )313281456789101125012Frequency / GHz219Fig. 7. S11(dB) of the antenna with first, second andthird notch of WiMAX, ISM and ITU bands.188156125S-Parameter [Magnitude in dB]0S1,193.8S1,1 1-5S1,1 2-1062.5S1,1 3-1531.3-20-250-30-35(c)-4023456789101112Frequency / GHzFig. 9. Current circulations at stop bands of(a) 3.48GHz, (b) 5.52GHz and (c) 8.15GHzFig. 8. Progressive S11(dB)of the proposed antennawith all three notches.43

Technical Journal, University of Engineering and Technology (UET) Taxila, PakistanWhile Fig. 10 (a) and (b) highlights the currentcirculations at 4.5 GHz and 7 GHz which areconsidered as present in pass bands.The results presented in Illustration 9 and 10signify that energy is concentrated around the slot anddoes not radiate into the space. At stop band, the currentcirculation is dominant in the area encapsulating theslots which enhances near field radiation counteractedand thus enhanced power is bounced back to theincoming terminal. This way the band notchingcharacteristics of antenna can be achieved [xvi]. Whilecurrent distribution at pass bands show that slots havenegligible effect on the radiations.Vol. 22 No. II-2017bands. The 3-dimensional (Directivity) radiationpattern of the propounded antenna is displayed inFig. 13 with 6.8dBi at 9 GHz of directivity.00330303060300-512024015060300270 901090-20330270-40-55-70240120210150210180180(a) E & H plane at 3.48 70 9086270-52 -50 -48 -46 b) E & H plane at 5.52 Ghz18.903012.6330606.29030300330300600270 90-48 -46 -44 -42 529.223.317.511.75.840270-48 -46 -44 -42 -40150180210180(c) E & H plane at 7 GhzFig. 11. Radiation pattern (E and H-plan) at(a) 3.48GHz, (b) 5.52 GHz and (c) 7GHzGain (IEEE),3DMax. Value (Solid Angle) 176543210-1234567Frequency / GHz8910Fig. 12. Gain versus Frequency plot(b)Fig. 10. Current circulations at pass bands of(a) 4.5GHz and (b)7GHzThe radiation pathways at varied frequencies aredisplayed in Fig. 11. Fig. 12 describes the gain of theantenna. The gain increases with increase in frequency.However, there is a sharp decrease in gain at notch441112