Variable permittivity dielectric material loaded stepped-horn antenna

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CHAPTER 5CONCLUSIONS AND FUTURE WORKStepped-horn antenna with variable permittivity dielectric material loading is proposed andanalyzed using hybrid numerical method. In the analysis, tapered region including steppedwaveguide section is divided into a number of rectangular waveguide sections filled withthe lossless dielectric material. Following the standard mode matching, a set of generalizedscattering matrix equations in each junction are obtained. The overall scattering matrixof the horn is evaluated by cascading the scattering matrices of individual steps. Thegeneralized reflection matrix of the aperture is determined using the method of moments.Then the generalized scattering matrix of the horn is combined with reflection matrix ofthe aperture. This analysis extended to determine yields the complex weighting coefficientof each mode at the horn aperture in terms of the power of the incident TE10 mode.Finally, the results are used to determine the input reflection coefficient of the antennaincluding the radiation patterns. Different dielectric materials are applied to achieve betterperformance characteristics. It was observed that the dielectric material loading improvesgain characteristics. Due to the optimization of stepped-horn antennas, aperture efficiency,cross-polarization and gain characteristics were improved. Dielectric material loading tostepped-horn antenna reduced of physical dimensions of the antenna and also improvedgain level. It is observed that for higher dielectric constant material and larger apertures,higher TEm0 modes are needed to be included into the optimization. However, undesiredmodes would also be excited at the aperture. For future work, multi-stepped horn antennaloaded with dielectric materials has to be investigated to excite the higher order TE m0modes and to cancel the undesired modes at the aperture.80
81Dielectric materials of various permittivities based on TiO2 has been fabricated andare currently being characterized. These materials will be used in optimum horn antennadesign to validate numerical results with the experimental measurements.
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Copyright Warning & RestrictionsThe
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VARIABLE PERMITTIVITY DIELECTRIC MA
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APPROVAL PAGEVARIABLE PERMITTIVITY
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To my parents, ..Tahsin and Güler
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TABLE OF CONTENTSChapterPage1 INTRO
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LIST OF FIGURESFigurePage2.1 Geomet
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FigureLIST OF FIGURES(Continued)Pag
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2field uniformity and this results
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4from improving the gain, dielectri
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Figure 2.1 Geometry of pyramidal a
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84Figure 2.4 Step discontinuity bet
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10section asFrom (2.4), the transve
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12and for the magnetic fieldIn the
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14where * shows complex conjugate.
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16where D is a diagonal matrix of t
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18Figure 2.6 Generalized reflection
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20aperture region and 11Ps is the m
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22where T; (x) and T: (y) are trian
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24where Γwghnk and r wg enk are th
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tiTo determine the unknown coeffici
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28An electric vector potential F an
Page 44 and 45: 30Using midpoint rule to evaluate i
Page 46 and 47: 32whereGreen function integrals, 4,
Page 48 and 49: 34taper and the phase distribution
Page 50 and 51: 36Even though, TE10 mode is an inci
Page 52 and 53: 38satisfy the amplitude ratio of 1/
Page 54 and 55: 40would be slight deviation from th
Page 56 and 57: 42increased to 15. Scattering matri
Page 58 and 59: 44Table 4.4 Amplitude and Phase of
Page 60 and 61: 46Figure 4.3, it is obvious that th
Page 62 and 63: 48al = 0.73A, b1 = 0.34A and apertu
Page 64 and 65: 50Table 4.7 Optimization Values of
Page 66 and 67: Figure 4.3 Input reflection coeffic
Page 68 and 69: Figure 4.5 Aperture efficiency vers
Page 70 and 71: Figure 4.7 Input reflection coeffic
Page 72 and 73: Figure 4.9 Aperture efficiency vers
Page 74 and 75: Figure 4.11 E-plane pattern versus
Page 76: 62Figure 4.13 Input reflection coef
Page 79 and 80: Figure 4.16 Aperture efficiency ver
Page 81 and 82: Figure 4.18 Amplitude of aperture m
Page 83 and 84: Figure 4.20 Amplitude of aperture m
Page 85 and 86: Figure 4.22 Input reflection coeffi
Page 87 and 88: Figure 4.24 Cross-polarization leve
Page 89 and 90: 751Figure 4.26 Amplitude of apertur
Page 91 and 92: 770.8Figure 4.28 Amplitude of apert
Page 93: Figure 4.30 Amplitude of aperture e
Page 97 and 98: The indefinite integrals associated
Page 99 and 100: BIBLIOGRAPHY[1] P. Clarricoats, A.
Page 101 and 102: 87[26] T. Bird and S. Hay, "Mismatc
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Variable permittivity dielectric material loaded stepped-horn antenna

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