Variable permittivity dielectric material loaded stepped-horn antenna

More documents

Recommendations

Info

FigureLIST OF FIGURES(Continued)Page4.22 Input reflection coefficient versus frequency of the stepped-horn antennas for(εr1 = 1.0 5r2 = 1.0), (ε r1 = 1.4 5r2 = 1.4), (εr1 = 1.2 5r2 = 1.4),(εr1 = 1.4 εrg = 1.2) and empty horn antenna with L = 91.1 mm. . . . . 714.23 Gain versus frequency of the stepped-horn antennas for (ε r1 = 1.0 5 r2 = 1.0),(εr1 = 1.4 εrg = 1.4), (εr1 = 1.2 εrg = 1.4), (ε r 1 = 1.4 5r2 = 1.2) andempty horn antenna with L = 91.1 mm. 724.24 Cross-polarization level versus frequency of the stepped-horn antennas for(εr1 = 1.0 5r2 1.0), (εr1 = 1.4 5r2 = 1.4), (εr1 = 1.2 εrg = 1.4),(εr1 = 1.4 erg = 1.2) and empty horn antenna with L = 91.1 mm. . . . . 734.25 Aperture efficiency versus frequency of the stepped-horn antennas for ( εr1 =1.0 εrg = 1.0), (εr1 = 1.4 εrg = 1.4), (εr1 = 1.2 εrg = 1.4), (εr1 = 1.4εrg = 1.2) and empty horn antenna with L = 91.1 mm. 744.26 Amplitude of aperture modes versus frequency, for (εr1 = 1.4 5 r2 = 1.4)stepped-horn antenna. 754.27 Amplitude of aperture magnetic field distribution,Hx versus x and y for emptyhorn antenna with length L = 91.1 mm at f = 10GHz. 764.28 Amplitude of aperture electric field distribution,Ey versus x and y for emptyhorn antenna with length L = 91.1 mm at f = 10 GHz. 774.29 Amplitude of aperture magnetic field distribution, Hx versus x and y for (εr1 =1.0 εrg = 1.0) stepped-horn antenna at f = 10 GHz 784.30 Amplitude of aperture electric field distribution, Ey versus x and y for (εr1 =1.0 εrg = 1.0) stepped-horn antenna at f = 10 GHz. 79xi
CHAPTER 1INTRODUCTIONOne of the most widely used microwave antennas is the horn antenna. In general, itis a simple radiating aperture used to provide a smooth tapered transition for a wavetraveling from a feed waveguide into the free space. Horn antennas are used in satellitecommunications, as a feed element for radio astronomy reflector antennas and as a standardantenna for calibration and gain measurements in the laboratory. Horn antennas also finduse in aperture phase array systems. When used as radiating elements in an array, it isdesirable that a horn antenna have higher aperture efficiency in order to achieve favourablegain characteristics. Extensive research work has been made as a goal of improving thecross-polarization level and aperture efficiency of horn antennas. The use of dielectricloading, hybrid modes or multimodes, and corrugations on the walls of the horn are allconsequences of such research efforts [1] -[7]. Dielectric loading approach has the advantageover corrugated horns. It has comparable performance to corrugated horns but is muchsimpler to construct. In the work of Tsandoulas and Fitzgerald [3], dielectric loadingwas used to enhance the aperture efficiency of a rectangular horn antenna. In that work,dielectric material was only placed along the walls and assuming that only the dominantmode was propagating. Clarricoats et.al. [6] and Lier [8] have proposed inserting a conicaldielectric core inside the conical metal horn that is separated from the metal wall by adielectric layer with lower permittivity rather of the core material.In this thesis, loading the horn antenna with variable dielectric material is proposedto accomplish to improve cross-polarization, aperture efficiency and gain characteriscswithout increasing the size. Dielectric material is assumed to be filling the entire crosssectionof the part or the whole of the antenna structure. Multi-mode rectangular hornsemploy TEmo(m=1,3,5) modes with approximate amplitude 1/m to improve the aperture1
Page 1 and 2: Copyright Warning & RestrictionsThe
Page 4 and 5: VARIABLE PERMITTIVITY DIELECTRIC MA
Page 6 and 7: APPROVAL PAGEVARIABLE PERMITTIVITY
Page 8 and 9: To my parents, ..Tahsin and Güler
Page 10 and 11: TABLE OF CONTENTSChapterPage1 INTRO
Page 12 and 13: LIST OF FIGURESFigurePage2.1 Geomet
Page 16 and 17: 2field uniformity and this results
Page 18 and 19: 4from improving the gain, dielectri
Page 20 and 21: Figure 2.1 Geometry of pyramidal a
Page 22 and 23: 84Figure 2.4 Step discontinuity bet
Page 24 and 25: 10section asFrom (2.4), the transve
Page 26 and 27: 12and for the magnetic fieldIn the
Page 28 and 29: 14where * shows complex conjugate.
Page 30 and 31: 16where D is a diagonal matrix of t
Page 32 and 33: 18Figure 2.6 Generalized reflection
Page 34 and 35: 20aperture region and 11Ps is the m
Page 36 and 37: 22where T; (x) and T: (y) are trian
Page 38 and 39: 24where Γwghnk and r wg enk are th
Page 40 and 41: tiTo determine the unknown coeffici
Page 42 and 43: 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 and 94:
Figure 4.30 Amplitude of aperture e
Page 95 and 96:
81Dielectric materials of various p
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
show all

Variable permittivity dielectric material loaded stepped-horn antenna

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?