IEEE TRANSACTIONS ON BROADCASTING, VOL.35, N0.2 , JUNE 1989 227

COMPUTER ANALYSIS OF VERTICAL RADIATION PATTERNS OF DIPOLE PANEL ARRAY ANTENNAS

C. Pantsios Markhauser (x) & F. Pantsios Markhauser (xx) , IEEE Member

(x), (xx) Department of Electrical Engineering, University Simon Bolivar, Caracas-Venezuela

(xx) Eng. Dept. Radio Caracas Television, Caracas-Venezuela

ABSTRACT :

A GW Basic computer program has been developed in this paper in order to analyze any azimuth vertical radiation pattern of a dipole panel array antenna, fixed on a square tower structure, under different conditions of horizontal progressive quadrature current phase shifting, mechanical panel displacement, beam tilt, feeding current coefficients (null filling) and asymmetric arrangements with and without panel centering. The final effects are singled out by comparing vertical radiation pattern diagrams corresponding to each of the forementioned cares.

The result obtained in regard to simultaneous horizontal progressive current phase and mechanical shift show appreciable variations in the vertical radiation patterns, corresponding to arrays of one or two dipole per tower face (omnidirectional arrangement), while for more elements there is a negligible effect on the main beam, but noticeable changes on the sidelobes.

On the other hand, for any omnidirectional arrangements, under the forementioned conditions of current phase and mechanical shift, almost no vertical radiation at a=o degrees along the tower exists (compensation effect).

It has also been demonstrated that for an array with binomial current coefficients, almost no changes on the beam pattern has been observed.

So far as beam tilt is concerned, drastic pattern displacement appear for mechanical panel tilt, while the effect is softer in the electrical case (current phase shift).

In relation with the feeding current coefficient variations, zero shifts in vertical radiation pattern can be accomplished in case null filling or elimination of sidelobes are required.

Finally, some interesting results have been obtained with respect to asymmetric dipole arrangements on square tower structures.

The V-pattern corresponding to the shortest array shows ripple due to adjacent face panels interaction.

In case horizontal progressive shift is used, the ripples swing around the V- pattern corresponding to the single array.

Panel centering reduces the number of ripples but increases the swing.

ARRAY

0018-9316/89/0600-0227$01.00 0 1989 IEEE

228

I. -INTRODUCTION

In a previous paper [I], two programs where developed in order to analyze the compensations of the mechanical panel displacement and electric progressive current phase shift technique (HPS) has on the horizontal radiation patterns of dipole panel array antenna mounted on a square tower.

In this paper, the behavior of the vertical radiation pattern is analyzed under different conditions, by conveniently adapting the directivity program shown in [2].

The actual program was derived from the forementioned directivity program by fixing the azimuth angle I1Xt1 to the desired value and summing up vectorially in l 1 Y l 1 , the E-field contributions of the corresponding panel arrays on each face of the tower structure, in order to obtain the total electrical field pattern.

The conditions considered in the program for rendering the corresponding vertical pattern are the following: 1. -Horizontal progressive quadrature feeding current phase shift and mechanical panel displacement (HPS);2.- Electrical and mechanical beamtilt: 3.- Non uniform panel excitation; 4.- Asymmetric dipole arrangements: 5.- Tower width.

As can be inferred, the program offers great flexibility in order to adapt the antenna to almost any practical requirements.

11. ANALYSIS OF THE EFFECTS THE CONSIDERED CONDITIONS HAVE ON THE VERTICAL PATTERN

Figure la and lb show the rectangular coordinate system as well as the selected antenna parameters used in the program.

111. HORIZONTAL PROGRESSIVE QUADRATURE CURRENT PHASE SHIFT AND MECHANICAL PANEL DIS- PLACEMENT EFFECTS

The vertical radiation pattern on Figure 2 belongs to a single dipole mounted on a tower facts. The observations point is located at an azimuth angle of X=O degrees. As shown in the figure, the E-field maximum occurs at 8=0 degrees and gets cancelled out by the image dipole at 8=90 degrees (finite conducting surface along the tower axis).

Figure 3A shows the V-pattern of an omnidirectional array of one dipole per face, at X=O degrees. In this case, a field maxima appears at an elevation of 0-50 degrees. This occurs due to absence of image dipoles on faces B and D for X=O (finite conducting surfaces on B and D).

The V-pattern of the forementioned omnidirectional array with HPS appears on Figure 3B and shows remarkable similitude to Figure 2 , which corresponds to one single array. As a difference comparing with Figure 3A, the E-field goes to zero at 8=90 due to field cancellation effect of the dipoles of faces B,C and D which are all fed in quadrature phases. Figure 3C depicts the v-pattern at X=45, where again, the E-field is zero at 8=90. Additionally, the field maximum occurs off the boresight due to adjacent panel interaction.

The pattern on Figure 4A belongs to a single array of eight dipoles, at X=O degrees. In this case, as has been commented before, regarding Figure 2 (one single dipole) , the E-field has a maximum at 8=0 degrees, but additionally showing three sidelobes.

I n Figures 4 0 and 4C the corresponding v-patterns of an omnidirectional array of eight dipoles, with and without HPS respectively, are shown. As already mentioned in Figures 2 , 3A and 3B, the same is true for Figures 4A, 4B and 4C respectively, with the difference that figure 4B presents relatively less radiation along the tower axis and sidelobe attenuation. Figure 4D shows the E-field maximum at 8=0 degrees and higher sidelobe levels in regard to the pattern of Figure 4A. Additionally, all the forementioned Figures show the same zeros as expected.

IEAH TIL1 (mchic,): 0 C~:l;Cl:Cz:C3:0 -VERTICAL RADIATION OF AN ANTENNA WITH ONE

DIPOLE I N A R R A Y A .

229

p I 8 B& VERTICAL RADIATION OF AN ANTENNA WITH A DIPOLE PER TOWER FACE.

k 0 1 4 -

e12 3

\

11. 2-BEAMTILT EFFECTS

A) MECHANICAL BEAMTILT

In this case, tilt of the pattern is accomplished by vertical and mechanical skew of the panels corresponding to one tower face (see Fig. 1B). The skew angle is denoted at O=GAM degrees.

Figure 5 illustrates the effect a panel tilt of GAM=30 degrees has on the v-pattern of a single eight dipole panel array, observed at X=O. Comparing with Figure 4A, a phase shift of the whole pattern results with no sidelobe deformation.

B) ELECTRICAL BEAMTILT

Figures 6A and 6B shown v-patterns of the same forementioned array but with electrical phase shift A>-10 and AL=-30 respectively, where AL is the phase angle contained in PSI (array progressive phase). By comparing Figures 5 and 6B it can be observed that the mechanical beamtilt produces more pattern shift than the electrical, for the same angle. Additionally, the electrical shift deforms the pattern and reduces the number of sidelobes. Figure 6A illustrates less beamtilt and pattern deformation.

11. 3-NON UNIFORM PANEL EXCITATION EFFECTS

On Figures 7A, 7B, 7C and 8 the effects of the non uniform panel excitation can be noted. On Figure 7A,

230

again appears the v-pattern corresponding to the single eight dipole array with uniform excitation CO=(l,l,l,l,l,l,l,l). In Figure 7B the four center dipole feeding currents have been changes to twice the former amplitude. In this case, this leads to reduction of the center sidelobes as well as center zero shift and wider main beamwidth. By increasing the four center currents up to 3 , the center sidelobes totally disappear, as shown in Figure 7C. Figure 8 depicts a v-pattern of a binomial array, with only a wider main lobe left.

F I G 4 q V E R T I C A L RADIATION OF AN ANTENNA WITH ONE A R R A Y OF ElOHT D I P O L E S .

11. 4-EFFECTS OF ASYMMETRIC DIPOLE ARRANGEMENTS

In this case, antennas with different number of dipoles per tower face are considered.

Asymmetric arrangements are very useful in directing radiation to a specific direction in space, in order to provide efficient coverage.

An example of asymmetric dipole arrangements effects on a vertical radiation pattern are shown on Figure 9A, for an arrangement of eight dipoles on faces A and C and two dipoles on B and D, respectively. The observation point on the antenna is located on X=90 degrees (perpendicular to face D, which supports two dipoles). The vertical radiation pattern shows clearly the effects of the two adjacent eight dipole arrays, producing oscillations on the pattern.

"tn

k 0 , I \ -I \ A

verticil angle I; ,6rl Dl: ,27 D2: ,I( MO): 8 A(1): 8 DI; ,86 D3: 0 ~(2): 8 ~(3): 8

FW 0 0 AZIHUTH ANGLE 0

BUH TILT (electric,): 0 W): 0 r(3): 0 BUH TILT (mechanic,): 0 ~:~l,l,l,l,l,l,l,l~:

Cl:a:c3 F I 0 4 8 VERTICAL RADIATION O F AN ANTENNA

wiin AN B DIPOLE ARRAY PER TOWER FACE

k 0 , I ::1\ vertical angle

L- ,I4 01: ,2? D2: ,46 D k ,86 D3:-,1768 AZIMTH AHUk 0 BDN 1111 (electric,): 0

RW: 8 A(1): 8 R(2): 8 A(3): 8 I(@): 0 F(1): 90

F(2): 180 F(3): 270 BUH IILI (mechanic,): 0 Co:(lil~~~l,l~l~l)~

I 6 4c THE SAME AS 1 8 BUT WITH SIMULTANEOUS PANEL AN0 CURRENT SWIFTS.

23 1

F I 0 ,4 D THE SAME AS 40 BUT WITH D 2 . 0 . 6 ~ .

5

Figure 9B shows the vertical radiation pattern corresponding to the same antenna and at X=-90 degrees, but with simultaneous mechanical horizontal panel shifting and progressive quadrature feeding currents. In this case, the oscillations follow the envelope corresponding to the pattern of a single array of two dipoles as shown in Figure 9C.

Figure 9C illustrates the vertical radiation pattern of the same antenna abut with only progressive quadrature feeding current phase shift. The diagram coincides wit the one belonging to an array of only two dipoles due to effective compensation effect between the adjacent eight dipole arrays (phase opposition) .

All the cases described until now have not taken into account the centering of the two dipole arrays of the antenna. When this is done, the results that appear on Figures 10A, 10B and lOC, show the effects of the two dipole arrays center shifted. Comparing 10A and 10B, the same conclusion is valid as in 9A and 9B. The result in 1OC is identical to the one in 9C, as expected.

It is important to notice, that when array centering is considered, the corresponding vertical radiation patterns show deeper oscillation effects with less ripple and flatter E-field for angles close to 0=0 degrees.

I 0 e VERTICAL RADIATION OF AN 0 DIPOLE ARRAY ANTENNA WITH A PANEL TILT OAM.+50°

vertical angle k ,64 D1: ,27 D2: ,46 1W: 8 A(1): 1

232

OI2 -1 I A

vertical angle Ok , I 4 11: ,I7 D2: ,5 fi(k 8 Mi): 1

Dk ,Y D3:-,1768 ~ 2 ) : I ~ 3 ) : 1 121MIH LNctE= 0 F(N: 0 F(1): 0 BWH Ill1 (electric.1: 0 0 F(3): 0

BWH 1IM (mechanic,): 0 Co: ~ l , l , l , l l l l l , l , l ~ ; Cl:C2:C3:0

f I 0 7 A VERTICAL RADIATION OF AN e DIPOLE ARRAY ANTFWYA WITH CURRENTS l ~ l ~ l ~ l ~ l : l ~ l ~ l

233

BUM IIM (mechanic,): 0 Co:(1,1,21,35,35,217,1) Cl:C2:c3=0

F I 0 8 VERTICAL RADIATION OF AN 0 DIPOLE ANTENNA WITH BINOMIAL CURRENT coir,

8 FICIENTS.

11. 5-TOWER WIDTH EFFECTS

Figure 11 depicts the vertical radiation pattern for X=-90 degrees (perpendicular to the two dipole array), for a tower width of TD=2 lambda. As can be noted by comparison of this figure with Figure 1 0 A , deeper ripple oscillations occur at close to 0 degrees.

11. 6-CONCLUSIONS

Throughout this paper, it has been shown that HPS, feeding current amplitude and phase, beamtilt and array centering have sensible effects on the vertical radiation pattern of the antenna, at any azimuth angle.

For any omnidirectional array, HPS assures minimum adjacent panel interaction (minimal mutual coupling) leading therefore to optimize impedance matching.

Effective sidelobe and zero shift control has been demonstrated by suitable selection of dipole excitation.

In regard to panel centering, flatter patterns can be achieved for angles closer to 0 degrees.

On the other hand, horizontal tower sections bigger than panel width are not practical.

Finally, a tradeoff between H and V -patterns as well s impedance matching has to be considered in order to obtain optimal antenna performance.

WM Ill1 (electric,): 0 F(2): 0 P(3): 0 IIM (mechanic,): Q d(O):d(l)=d(2):d(3):0

F I 0 9 A VERTICAL RADIATION OF AN ANTENNA WITH 8 DIPOLES IN FACES A AND C AND 2 IN BAND D

I \ k e, 2 \

D k J6 D3:-11768 ~(2): a ~(3): 2 AZlMIH ItlGk-90 FW: 0 F(1): 90 BUM IILI (electric,): 0 F(2): 160 F(3): 270 BUM Ill1 (mechanic,): 0 d(O):d(l):d(2)=d(3):0

F l G 9 & THE SAME AS OB BUT WITH SIMULTANEOUS PANEL AND CURRENT SHIFTS.

234

e, 2 L

\

IERM IIM (mclunic,): 0 d(Okd(2):O 1(1):6(3): 1 , s 619108 THE SAME AS IN SA DUT WITH TWO

DIPOLE ARRAYS CENTERED.

0,2 4 \

DI; ,06 D3: 0

lZInlTW lW-YO BUN Ill1 (electric,): 0 I(!): 118 270 Ell IlM (mechanicl): 0 1(0):d(2):0 d ( lkd(3 ) : lJ

P(2k 8 1(3): 2 ?(e): 0 !(I): 90

+ I 0 I O C THE SAME AS IN SC BUT WITH TWO DIPOLE ARRAY8 CENTERED.

F

L: ,64 D1: ,21 D2: , 5 DL: ,06 D3: 0 TD:S,Q I(0): 8 A(1): 2 M2): 8 M3): 2

P ( B k Q P(1k Q P(2): Q P(3k 0 AZIIIIlIH INCLE:-90 BMH IILT (electric,): 0 BHH IILT (mechanic,): 0 d(0):d(2): d(l):d(3):1,5

k

vertical angle

1 G I I VERTICAL PATTERN OF AN ANTENNA WITH 8 DIPOLES I N FACES A AND C AND 2 IN B AND D , W I T H A TOWER WIDTH TD = 2 WAVE LENGTH

APENDlX NO1 VERTICAL RADIATION PATTERN ?ROORAY FOR DIPOLE ?ANEL ARRAY ANTENNAS

150 REM VERTlClV PATTERN I b O REM FIELD CALCUL1TlON 161 DIM k1360) 163 PI-3.14159 la4 BCREEN 0 . 0 , O Ib6 CL6 l b7 K l - 0 170 READ TD,L. DI, 02. DL, D3. AL. O&M I75 DATA . A4. .&e, .27, .SO. .Ob.- . 1760. 180 FOR 1-0 TO 3 190 READ A ~ l l , F ~ l ~ , D l l ~ 192 DEF FNFH(I)-F(II/10O*PI 19s FOR K-1 TO A t 1 1 197 READ C ( K . 1 ) 199 NEXT K

0.0

200 NEXT I 220 DATA b,O,O,l,l,l,l,l,l,l,l, 2.90.1.59

1.1, 0.180.0.1.1. I r l , l , I , I . 1.2.270.1.5 I. I 225 INPUT "1ZIIUITH-"tR 230 FOR V-0 TO 90 KTEP 2 235 V R - ( ( Y + O M ) 1 1 B 0 ) * F I 240 CT-0 245 CF-0 2b0 67-0 265 SF-0 ZB0 FOR J-0 TO 3 290 X-R.J.90 295 XR-X/IBO*PI

302 UR-u/p

310 0-0

BOO a-o 010 m-cz 02u I-N 0'0 **-I 8 4 0 QOSUb 1340 050 I-INT((L/2-LOlIDZ) E L 0 K-1 070 DOSUB 1340 ~ 0 0 EZ-SQRIA^Zrb"2).ABS 881 BOTO 1431 900 GOSUB I410 910 0010 330 920 A-0 930 6-0 940 1-INT((L-LO)/DI) 950 K--1 9b0 GOSUB 1340 970 GOTO BBC' 980 1-0 990 B-0 1000 I-N 1010 K-0

1030 E1-2rABS(A*PI 1040 GI-U I050 E2-0

1020 Gosum 1340

1051 62-0 1060 GOSUB I410 1070 0010 330 IOBO 6-0 1090 B-0 1100 LO-DI.A6StTAN(XhlI 1110 IF LO\L/2 THEN 1230 1120 I-N I l a u K - I 1140 GOSUC 1340 115U I-INT((L0-L/~)/oz) I I b 0 K m - 1 1170 GOSUC 1 3 4 0 llB0 EI-GBSISOh(1 2*6 Z I * F l 1190 GOTO 14Sb lZU0 €2-0 1210 GOSUB 1410 1220 GOTO 330

1240 K - I 1250 GOSUB 1340 1260 E1-1BSlS~h(A^2+~'2~~F~ 1270 S O T 0 1441 1260 E2-0 I290 GOSUB 1410 13u0 G O T 0 330 I310 c -0 132u 5-0

$230 I-INT(LOIDZ)

1330 SOTO 330

580 I F ABS(COS(XR))<-tl THEN 980 590 I F M<COS(XR) W COS(XR)<MI

610 8-0 620 I - N 630 U-0 6 4 0 00SUB 1 3 4 0 650 EI-Z*.QBStA*FI 660 G I - 0 670 E 2 - E l 680 02-61 690 GODUS 1410 700 GOT0 330 7 1 0 LO-DI*ABS(TW(XR))

?U) 0-0 7 4 0 I -N ?so U-0 7H) BOW0 1 3 4 0 710 E1-2.A86(A*P) 700 01-0 790 IF L O > L / 2 THEN 920

LOO a-o

720 a-o

1 4 3 7 G I - A T N ( S / ~ ) 1 4 3 8 GO10 1200 14'9 GI-0 1440 GOTO I200 1441 I F E l - V THEN 1444 1 4 4 2 Gl-ATN(BfA) 1 4 4 3 GOTO I280 1 4 4 4 G I - 0 1 4 4 5 GOTO 1280 1 4 5 0 RETURN 1 4 6 0 GOTO 230 1 4 0 0 P I - 3 . 1 4 1 5 9 1490 REM DRAW GRID I500 SCREEN 2.0.0 1510 VIEW (262.20)-(638.162) 1520 WINDOW (-2,-2)-(92.56) I540 FOR J-0 TO 90 STEP I 0 1550 L I N E (J,O)-(J,-ll 1560 NEXT J 1561 PSET ( 0 . 0 ) 1 5 7 0 L I N E (90.0)-(0,0) 1580 FOR J-0 TO 50 STEP 10 1590 L I N E (O.J)-(-Z,J) 1600 NEXT J 1601 PSET ( 0 , O ) 1610 L I N E ( 0 , 0 ) - ( 0 . 5 0 ) 1 6 4 5 FOR 1-0 TO 5 165C1 LOCATE 5+1+ 3.30 I 6 6 0 PRINT USING "# .N" ; l -(.2).1 1665 NEXT I 1670 LOCATE 14,261PRINT " h " 1680 LOCATE 21.35 1690 PRINT "0 1 0 20 30 40 1700 LOCATE 2.27sPRINT "VERTICAL RADlATION PATTERN" 1701 LOCATE 5.1 l P R l N T "L~"L;"DI- "Dl ; "D2-"D2 1 7 0 2 LOCATE 7,1 #PRINT "DL="DL;"D3="DS 1703 LOCATE 9,1 I P R I N l "A (O)="A(0) 8 * ' A ( l )=" ;A( 1)

1705 LOCATE 15, 1 ,PRINT " F ( D ) - " ; F ( 0 ) ; " F ( I ) - " F ( l ) 1 7 0 6 LOCATE 15.1 r P R l N T " F ( Z ) r " ; F ( Z ) ; " F ( 3 ) I " F ( 3 ) 1707 LOCATE 19.1 i P R l N T "BEAM T I L T (electric. )=";AL 1708 LOCATE 21.1 *PRINT '"BEAM T I L T (mechanic.)-";GAM 1709 LOCATE 23,39 I PRINT ' " v r r t z c r l angle" 1710 LOCATE 17, I :PRINT '"IZIMUTH PNGLE-";R 171 1 LOCATE 23.1 I PRINT " d (Cl)=d (2)-0;d ( 1 )=d (3) -0.5" 1 7 1 2 PSET ( 0 . 0 ) 1715 FOR Y-0 TO 90 STEP 1 172CJ K-(K(90-YI ) /U1 *SO 1730 L I N E - ( V , K ) 1 7 4 0 NEXT V 1 7 4 1 PSET ( 0 . 0 ) 17LCI END

1704 LOCATE I I , I I PRINT *-A ( z ) - " a (2) ; ts)=";a (3)

REFERENCES

Carl and Fred Pantsios, ;Smoothing of Omnidirectional Horizontal Radiation Patterns of TFD TV Panel Antenna Arrays with Progressive Current Phase Shift Feeding; IEEE Transactions on Broadcasting, BC-31,No 2.

Fred and Carl Pantsios,; Computer Programs for the Calculation of the HorizonLa1 Far Field Radiation Pattern and Directivity of Full Wave Dipole Panel Antennas; IEEE Transac- tions on Broadcasting 1984, Vol. BC-30, No 3.

1 4 2 2 NEXT Il 1 4 2 5 C-0tCI*D-BNGI*E* 1427 S-GlSI*D+GNCI*E 1 4 3 0 RETWlN 1 4 3 1 I F E2-0 T M N 1 4 5 4 1 4 3 2 O2-ATN(B/Al 1 4 3 3 GOT0 900 l a 4 G2-0