# Abstract—This and X Band frequencyoperations.Index Terms—Bandwidth, Cylindrical

Abstract—This paper represents the design and comparisonof Single Band Rectangular, Cylindrical and Triangular DielectricResonator Antenna. Three shapes of Dielectric ResonatorAntenna (DRA) were designed with similar feeding techniquei.e. Slot Aperture for C and X-Band frequency operations. Cand X Band are Microwave Band lies between frequency range4 to 8 GHz and 8 to 12 GHz. Antenna constraints such asdimensions and frequencies are determined using mathematicalformulation. The three shapes of DRA is simulated by electromagneticsimulator CST Microwave Studio.

The Bandwidth,Gainand Directivity of three shapes of DRA are evaluated and itis finally observed that the Triangular DRA has much widerbandwidth and have high value of Directivity and Gain thanRectangular and Cylindrical DRA at same Resonant frequency.The results of the present work may provide design guidelinesfor the development of efficient DRA at C and X Band frequencyoperations.Index Terms—Bandwidth, Cylindrical Dielectric ResonatorAntenna (CDRA), Dieletric Resonator Antenna (DRA), Directivity,Gain, Rectangular Dielectric Resonator Antenna (RDRA),Triangular Dielectric Resonator Antenna (TDRA).I.

INTRODUCTIONIn 1939, R. D. Richtmyer showed that un-metallized dielectricobjects could function similar to metallic cavities, whichhe called dielectric resonators 1.Dielectric resonators havereceived great interest in recent years for their potential applicationsin microwave and millimetre wave communicationsystems.

They have been widely used as a tuning componentin shielded microwave circuits such as filters7, oscillators,and cavity resonators8.With an appropriate feed arrangement, they can also beused as antennas, and they offer efficient radiation. Microstrip antenna at C and X-band application such as Radar andsatellite Communication offer high metallic losses due to thepresence of surface waves. So, the DRA overcome the problemof high metallic losses because it made of high permitivitydielectric material having less conductor losses8. DRA alsooffer advantages such as small size, high radiation efficiencydue to the absence of conductor losses, simple geometry, smallsize and flexible feed arrangement3-4.As compared with micro strip antenna, the DRA haswider impedance bandwidth and better efficiency and smallsize2. In this paper, the Bandwidth, Directivity and Gain ofSingle- Band Rectangular, Cylindrical and Triangular DRAare directly compared for C and X-Band applications.

Forthis purpose, Rectangular, Cylindrical and Triangular DRAwere designed for operation at 6, 7, 8, 9, 10 and 11 GHzwith the constraints that all antennas possess similar feedingmechanism. The Bandwidth, Directivity and Gain of the threeshapes of the DRA were measured.The result shows that not only the impedance bandwidthof the Triangular DRA is much wider than Rectangular andCylindrical DRA but also the Gain and Directivity of theTriangular DRA is noticebly higher than Rectangular andCylindrical DRA.In Section II, the configuration of Rectangular, Cylindrical andTriangular DRA are described.

In Section III , the simulationresults of the three shapes of DRA are discussed and presented.Finally, Section IV presents the conclusion of the presentedwork.II. ANTENNA CONFIGURATIONThis section describes the design configuration of Rectangular,Cylindrical and Triangular DRA.A. Retangular DRARectangular DRA is the most versatile shape of DRA. Thechosen configuration of RDRA is shown in fig.

1. RectrangularDRA were designed for 6, 7, 8, 9, 10 and 11 GHz in CSTMicrowave Studio. The dimensions of RDRA are length (l),width (w) and height (d)as shown in fig.

1.Rectangular DRAoffer two degree of freedom9 means that for any givenresonant frequency and fixed dielectric constant, any two ofthe three dimensions can be chosen randomly. Each designof Rectagular DRA has been etched from a Roger RO4000substrate material with a permitivty of 3.38 and thickness asshown in Table III and is common for Rectangular, Cylindricaland Triangular DRA at specified resonating frequencies. TheMC-20 ceramic material is taken as a dielectric material foreach design of Rectangular DRA having permitivity of 20.The Rectangular DRA was fed by 50 ohm standard microstripline coupled with slot Aperture of identical dimensions. Thedimensions of microstrip line coupled with slot aperture areshown in Table II and are common for Rectangular, Cylindricaland Triangular DRA at specified resonating frequencies.

Rectangular DRA support two types of modes TE10 andTM but TM mode has never been observed experimentally3.Therefore, the existance of TM mode is doubtful.ForTE mode, the resonant frequency are calculated by using thefollowing expression3fr =C2pqK2x + K2y + K2z (1)Kx =a; Ky =band Kz =2h(2)Fig. 1. Geometry of the RDRA!hTABLE IRECTANGULAR DRA DESIGN PARAMETERSRDRA Design Resonant Length Width HeightFrequency (mm) (mm) (mm)(GHz)Design I 6 10.68 8 5.

5Design II 7 8.128 7 5.5Design III 8 6.044 8 5.5Design IV 9 5.39 6 5.4Design V 10 4.

56 6 5.4Design VI 11 3.76 6.

9 5.5Where c is speed of light and is dielectric permitivity ofdielctric material. Where in eq (2), a is length , b is widthand h is height of the Rectnagular DRA. The values of thegeometric parameters are listed in Table I for the specifiedReosnant Frequencies.TABLE IISLOT APERTURE TECHNIQUE PARAMETERSRDRA,CDRA Resonant Slot Length Slot WidthTDRA Design Frequency (mm) mm(GHz)Design I 6 10 1.1Design II 7 8.

4 0.9Design III 8 7.4 0.81Design IV 9 6.6 0.72Design V 10 6 0.65Design VI 11 5.5 0.

6B. Cylindrical DRAThe geometry of microstip fed Cylindrical DRA as shownin fig.2. The dimensions of Cylindrical DRA are radius (r) andheight (h).It offer one degree of freedom means that for anygiven resonant frequency and fixed dielectric constant, one ofthe two dimension can be chosen randomly. It can designedfor 6, 7, 8 ,9, 10 and 11 GHz in CST Microwave STudio. Thedielectric layer used was Roger RO4000 material due to its lowcost and ability in reducing surface losses. The permitivty ofthe substrate material is 3.

38 and thickness as listed in table III.TABLE IIISUBSTARTE THICKNESSRDRA,CDRA Resonant ThicknessTDRA Design Frequency (mm)(GHz)Design I 6 0.42Design II 7 0.35Design III 8 0.

31Design IV 9 0.27Design V 10 0.25Design VI 11 0.24The MC-20 ceramic material is taken as a dielectric materialfor each design of Cylindrical DRA having permitivity of 20.The Cylindrical DRA was fed by 50 ohm standard microstripline coupled with slot Aperture of identical dimensions. Thedimensions of microstrip line coupled with slot aperture areshown in Table II and are common for Rectangular, Cylindricaland Triangular DRA at specified resonating frequencies.The Reosnant frequency is then determined as5fr =C2rp 1:71 +rh+ 0:1578(rh)2 (3)Where r and h represent its radius and height respectivelyand is the relative permitivity of dielectric material.

Fordifferent Resonant Frequency, the value of height and radiusare listed in Table IV.Fig. 2. Geometry of the CDRATABLE IVCYLINDRICAL DRA PARAMETERSCDRA Resonant Radius HeightDesign Frequency (mm) (mm)(GHz)Design I 6 5.26 6Design II 7 4.25 6Design III 8 3.51 6Design IV 9 3.04 6Design V 10 2.

68 6Design VI 11 2.40 6C. Triangular DRAThe advantage of Traingular DRA over rectangular andCylindrical DRA is that for a given resonant frequency andheight it offer smaller area than either Cylindrical and RectangularDRA. The geometry of the Triangular DRA as shownin fig.3. The dimension of Triangular DRA are heoght (h) andside length (Ls).

Length of all sides are same in all designs ofTriangular DRA. Triangular DRA were designed for resonantfrequency 6, 7, 8, 9,10 and 11 GHz in CST Microwave Studio.Each design of Triangular DRA has been etched from a RogerRO4000 substrate material having permitivty of 3.38 andthickness as listed in Table II.The MC-20 Ceramic materialis taken as dielectric material for each design of TriangularDRA having permitivity of 20.

The Triangular DRA was fedby 50 ohm standard microstrip line coupled with slot apertureof identical dimension. The dimensions of microstrip linecoupled with slot aperture are listed in Table III. The ResonantFrequency of TM mode is approximately given by 6fr =12p (43ls)2(m2 + mn + n2) + 0:1578(12h)212 (4)where c is speed of light, is the dielectric constt, ls isthe side length and h is the height of resonator.

The resonantFrequency indices m, n andl are used here instead of m,n andl because third index l is depemdant on the values of m andn. The indices l, m and n satisfy the condition l+m+n = 0 butthey all cannot be zero . The parameters of Triangular DRAare listed in Table V.

Fig. 3. Geometry of the TDRATABLE VTRIANGULAR DRA PARAMETERSTDRA Resonant Side HeightDesign Frequency Length (mm)(GHz) (mm)Design I 6 8.126 7Design II 7 6.965 6Design III 8 5.97 6Design IV 9 5.22 5.8Design V 10 4.

65 5.5Design VI 11 4.25 5III.

RESULTS AND DISCUSSIONA. Return Loss Vs Frequency CharacteristicThe simulation study of Return Loss versus Frequencycharacteristic of single band Rectangular, Cylindrical andTriangular DRA at resonating frequencies 6, 7, 8, 9, 10 and 11GHz has been carried out using CST Microwave Studio.TheSimulation result of Return Loss of Three shapes of DRAare shown from fig 4-9 for comparison purpose. From Fig 4-11, The resonant Frequency Range and -10 dB return lossBandwidth of three shapes of DRA are extracted and theresuts are given in Table VI .From Table VI .It can beenseen that the Triangular DRA has much wider Bandwidththan that of the Rectangular and Cylindrical DRA at sameresonating Frequency using same feeding technique, Dielectricmaterial and Substrate material. Fig.

4. shows that at 6 GHz, thebandwidth of Rectangular, Cylindrical and Triangular DRA is0.080, 0.131 and 0.

189 GHz which shows that the TriangularDRA has two times wider bandwidth than Rectangular DRAand one and half time wider than Cylindrical DRA at 6 GHz.Fig.4. shows that at 6 GHz, the bandwidth of Rectangular,Fig. 4. Variation in Bandwidth of RDRA,CDRA and TDRA at 6 GHzCylindrical and Triangular DRA are 0.

080, 0.131 and 0.189GHz and it is concluded that the Triangular DRA has twotimes wider bandwidth than Rectangular DRA and one andhalf time wider bandwidth than Cylindrical DRA at 6 GHz.

Fig.5. shows that at 7 GHz, the bandwidth of Rectangular,Fig. 5. Variation in Bandwidth of RDRA,CDRA and TDRA at 7 GHzCylindrical and Triangular DRA are 0.282, 0.

291 and 0.309GHz and it is concluded that the Triangular DRA has widerbandwidth than Rectangular and Cylindrical DRA at 7 GHz.Fig. 6. Variation in Bandwidth of RDRA,CDRA and TDRA at 8 GHzFig.6.

shows that at 8 GHz, the bandwidth of Rectangular,Cylindrical and Triangular DRA are 0.399, 0.397 and 0.722GHz and it is concluded that the Triangular DRA has twotimes wider bandwidth than Rectangular and Cylindrical DRAat 8 GHz.

Fig. 7. Variation in Bandwidth of RDRA,CDRA and TDRA at 9 GHzFig.7.

shows that at 9 GHz, the bandwidth of Rectangular,Cylindrical and Triangular DRA are 0.481, 0.477 and 0.488GHz and it is concluded that the Triangular DRA has widerbandwidth than Rectangular and Cylindrical DRA at 9 GHz.Fig.

8. shows that at 10 GHz, the bandwidth of Rectangular,Fig. 8. Variation in Bandwidth of RDRA,CDRA and TDRA at 10 GHzCylindrical and Triangular DRA are 0.

150, 0.156 and 0.533GHz and it is concluded that the Triangular DRA has threetimes wider bandwidth than Rectangular and CylindricalDRA at 10 GHz.Fig.9.

shows that at 11 GHz, the bandwidth of Rectangular,Cylindrical and Triangular DRA are 0.528, 0.501 and 0.578Fig. 9.

Variation in Bandwidth of RDRA,CDRA and TDRA at 11 GHzGHz and it is concluded that the Triangular DRA has widerbandwidth than Rectangular and Cylindrical DRA at 11 GHz.Fig.10.

and Table VI clearly shows that the Triangular DRAhas much wider bandwidth than Cylindrical and RectangularDRA at 6, 7, 8, 9, 10 and 11 GHz.TABLE VICOMPARISON OF BANDWIDTH OF SINGLE BAND RDRA,CDRA ANDTDRA.Resonant Rectangular DRA Cylindrical DRA Triangular DRAFrequency Frequency BW Frequency BW Frequency BW(GHz) Range (GHz) Range (GHz) Range (GHz)(GHz) (GHz) (GHz)6 5.960 – 0.080 5.934 – 0.

131 5.909 – 0.1896.040 6.066 6.0997 6.860 – 0.282 6.

859 – 0.291 6.907 – 0.3097.

143 7.151 7.2168 7.804 – 0.399 7.

803 – 0.397 7.606 – 0.

7228.203 8.200 8.3289 8.761 – 0.481 8.763 – 0.

477 8.776 – 0.4889.245 9.2407 9.26410 9.924 – 0.150 9.

924 – 0.156 9.732 – 0.53310.075 10.08 10.

26511 10.753 – 0.528 10.748 – 0.501 10.745 – 0.57811.281 11.

249 11.323Fig. 10.

Bandwidth Comparison of Single Band DRAB. Gain Vs Frequency CharacteristicThe Gain of the Antenna is the ratio of its radiation intensityto that of an isotrpic antenna radiating the same total poweras accpeted by real Antenna11. Fig 11 and Table VII showthe Gain result of comparison obtained from the simulationof Rectangular, Cylindrical and Triangular DRA at resonatingfrequency 6, 7, 8, 9, 10 and 11 GHz in CST Microwave Studio.The Gain of three shapes of DRA are extracted and are givenin Table VII.From Table VII and fig.11, it is clear that the Gainof Triangular DRA is higher than Rectangular and CylindricalDRA at C and X-Band.TABLE VIICOMPARISON OF GAIN OF SINGLE BAND RDRA,CDRA AND TDRA.Resonant Rectangular DRA Cylindrical DRA Triangular DRAFrequency Gain Gain Gain(GHz) (dB) (dB) (dB)6 5.

59 5.62 6.427 6.

03 6.02 6.738 6.27 6.27 6.

309 5.76 5.78 6.1410 6.17 6.18 6.2311 6.

56 6.35 6.59Fig. 11. Gain Comparison of Single Band DRAC. Directivity Vs Frequency CharacteristicDirectivity is the ratio of of radiation intensity ina givendirection to the average power radiation in all direction.

Fig11 and Table VIII show the Directivity result of comparisonobtained from the simulation of Rectangular, Cylindrical andTriangular DRA at resonating frequency 6, 7, 8, 9, 10 and 11GHz in CST Microwave Studio. The directivity of three shapesof DRA are extracted and are given in Table VIII.From TableVII and fig.11, it is clear that the directivity of TriangularDRA is higher than Rectangular and Cylindrical DRA at Cand X-Band.

Fig 12-17 show the simulated Gain result of Rectangular,Cylindrical and Triangular DRA for comparison purpose atresonating Frequencie 6, 7, 8, 9, 10 and 11 GHz.From fig.12-17, The Gain at different Resonanting Frequencies of threeshapes of DRA are extracted and are given in Table 7. Fromthe Table7 , The Directivty of Triangular DRA at C and XBand is hugher than that of the Rectangular and CylindricalDRA.

IV. CONCLUSIONThe performance of the Rectangular, Cylindrical and TriangularDRA has been compared at C and X Band bymeasuring six Rectangular, six Cylindrical and six TriangularTABLE VIIICOMPARISON OF DIRECTIVTY OF SINGLE BAND RDRA,CDRA ANDTDRA.Resonant Rectangular DRA Cylindrical DRA Triangular DRAFrequency Directivity Directivity Directivity(GHz) (dB) (dB) (dB)6 5.60 5.63 6.467 6.04 5.99 6.

738 6.25 6.34 6.369 5.76 5.77 6.

1810 6.23 6.24 6.2411 6.

68 6.44 6.69Fig.

12. Directivity Comparison of Single Band DRADRA. These eighteen antennas were designed on the samesubstrate material,fed by microsttrip line and having sameResonating Dielectric material. The simulated results showthat the bandwidth of Triangular DRA is much wider thanRectangular and Cylindrical DRA while the bandwidth ofCylindrical DRA is wider than Rectangular DRA.

Gain andDirectivit are alos measured and show that the gain anddiirectivity of Triangular DRA is higher than Rectangular nadCylindrical DRA while the gain and directivity of CylindricalDRA is higher than Rectangular DRA. The presented resultalso show that by changing shape of DRA, Bandwidth, Gainand Directivity changes. The presented results demonstratethat the Triangular DRA can be considered as a promisingalternative for antennas applied at C and X band frequencyoperations.