DIPED-2007 Proceedings

FEATURES OF RADIATION PATTERN FORMATION OF WIRE ANTENNALOCATED INSIDE H-FIGURATION CORNER REFLECTOR

Nadezhda P.Yeliseyeva

V. Karazin National University of Kharkov, 4 Svobody Sq., Kharkov, 61077, Ukrainee-mail: Nadezhda.P.Yeliseyeva ( univer. kharkov. ua

Abstract. Using the uniform geometrical diffraction theory (UGTD) method thealgorithms and computer codes for calculating and analyzing the directive patterns ofthe orthogonal components of the electric field intensity vector (EFIV) of the electricdipole located inside the fH - figuration finite size infinitely thin perfectly conductingcorner reflector were worked out. The influence of the diffraction effects on the ledgesin comparing with the ones in the case of the plane screen and the spatial distributionsof the diffracted fields on the transversal edges of analyzed system were investigated.

Statement of the problem. Withz 00=0 purpose of the redistribution of the

Kz _ 4 electromagnetic field energy in the2,Yx2 17 whole space the plane metal screens

5 Z5X55KB X AnRox widely are used. Additional possibilitiesto increase the radiation level in the one

, 900, sector of observation angles or to2t | Y Z1 XI 0 9 decrease - in other, to improve the

ZY, 03 directive gain and the Back to Front6,, 37J Y 3 D S K .L Ratio of the radiation system arise up at,6> 4 the use of more complete screens, in

Fig. 1 5 4 particular n - figuration type. Fromphysical reasons follows, that due to

screening parts of the space by the ledges it is possible to reduce the radiation in theappropriate areas and hereby to improve the Back to Front Ratio. Let's considerinfinitely thin perfectly conducting Hl - figuration reflector ABCDMKNL withdimensions L, H, W being excited independently by the electric dipoles 1, 2, 3 locatedin the point with coordinates (h, 0, 0) (Fig. 1). The investigated reflector has two lateral(1, 2) and six transversal edges on which owing to diffraction of the geometricaloptics(GO) waves the diffracted waves are formed. Within the frame of the UGTD methodthe directive patterns (DP) of the orthogonal components of the EFIV of analyzedsystem are determined as a sum of the GO fields Eo,,i (i=1 ... 6), fields diffracted onlateral Eo,tiK (K=1... 4) and transversal Eo,yim ( m=1... 6 ) edges. Each of the field isdefined by the equations of the light - shadow boundaries which were obtained by us.

6 4 6 6 6Eo (0 p) E EOii + Z Z (EOiKC22 + EpiKC32K)xiK +

EZ (EOimC22m + E(piMC32m)/im (1)

i=1 K=1i=1 m=1i=16 4 6 6 6

Ep(O,p) EZE(PIXI + EE (EOiKC23K +EPiKC33K)XiK +E E(E0imC23m +E(piMC33m)Xim (2)

i=l K=l i=l m=l i=l

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DIPED-2007 Proceedings

Here the coefficients Xi, XiK, Xim are equal to one or to zero in the light and shadowregion accordingly, C, are the elements of the transition matrix from own rectangularcoordinates systems on the edges of the reflector ABCDMKNL in the general XYZ [1].Numerical results. The reliability of the developed algorithms was verified by thecalculation of the spatial distributions of each part of the full field. In the Fig.2 thediffracted fields distributions on the transversal edges m=2, 3 (b, d, f, h, j, 1) and m=1,4 (a, c, e, g, i, k) for the reflector with sides L=H=0.52' and W=2' being exciting by thedipoles 1, 2, 3 placed above the midpoint of the screen at h=0.252' are presented. Atthis geometry the shadow cone angles are equal to 3=660 for all edges. Thus thesymmetry of the DP concerning (p = 0, 1800, 3600 and (p =900, 2700 for all dipoles andthe turn of the DP on A(p=900 for mutually orthogonal edges for the dipole 1 (Fig.2a, b,Fig.2c, d) and for mutually orthogonal dipoles 2 and 3 (Fig.2e, f, Fig.2g, h), (Fig.2i, j,Fig.2k, 1) follows. The maximum amplitudes of the field components from mutuallyorthogonal edges 1,4 and 2,3 are equal: for the dipole 1 Eolmax(l,4) =

E01max(2,3)=0.27E0, E(plmax( I ,4)=E(pImax(2,3)=0. IEo; for the dipoles 2 and 3 EO3max( 1,4)=E02max(2,3) =0.62Eo0 E(p3max(l,4) =Ep2max(2,3)=0.66E0, E02max(1,4)=EO3max(2,3)=0.64EO;E(p2max(1,4)=E(p3max(2,3)=0.34Eo. The diffracted field distributions in the Fig.2 and theequality of its maximum values verify it. In the Fig.3 the DP of the full field (curve 5)and its components - GO (1), diffracted on the lateral (2) and transversal m=2,3 (3)and m=1,4,5,6 (4) edges in the main observation planes are shown. Here the DP (6) ofthe full field in the case of the plane screen L=0.52', W=2' (H=0) is given also. It isseen, that for the dipole 1 in the plane 0 = 900 the main lobe width of the DP (5) on thelevel -3 dB decreases in comparison with a case of the screen (6). For the dipole 2 inthe forward half-space this effect is much less, however in the back half-space, due tothe ledges the radiation increases. For the dipole 1 the cross - polarized component E,(lis formed in the certain sectors of angles, as against a case with the screen, in bothmain planes due to cross edges 2,3 and 1,4,5,6. In a case with the screen the lateraledges cause cross-polarized component E02 in the plane (p = 00 [2]. For the HI - reflectorthe observation angles in the plane (p=00 lay on continuation of the lateral ledges(sliding observation), where owing to different boundary conditions for the dipoles 2and 3 E02=0. The cross - polarized component E,p3 in the certain sectors of angles isformed.Conclusions. The obtained numerical results have shown, that the use of the n-figuration reflector simultaneously enables to receive high coefficients of the directedand protective action, and also in essential limits to change the form of the dipole DPowing to additional possibilities varying dimensions of the lateral ledges.

REFERENCES

1. Yeliseyeva N.P. Pattern Analysis of an Arbitrarily Oriented Oscillator Placed abovea Flat Screen // Telecommunications and Radio Engineering . - 1999.- Vol. 53, N°1. - P. 43-53. (PaJHo4n3HKa H pajHoacTpoHoMHA. - 1998. -T.3, JNf 2.- C. 217-225.)

2. Gorobets N. N, Yeliseyeva N. P. 2003, 'Total Analysis of Radiation Characteristicsof Electric Dipole with Rectangular Screen', Proc. 4th International. Conf. onAntenna Theory and Techniques (ICATT'03), Sevastopol, 459- 464.

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DIPED-2007 Proceedings

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