NTIA-REPORT"-80-39

Effect of Small Frequency

Changes on the Radiation

Patterns of MF (AM)

Directional Antennas

A. c. Stewart

J. B. Heffelfinger

u.s. DEPARTMENT OF COMMERCE

Philip M. Klutznick, Secretary

Henry Geller, Assistant Secretary

for Communications and Information

MAY 1980

TABLE OF CONTENTS

Page

LIST OF FIGURES v

LIST OF TABLES v

ABSTRACT 1

1. INTRODUCTION 1

2. THEORETICAL RADIATION PATTERNSf

4

3. MEASURED PATTERNS 11

4. 1430 KHZ CALCULATIONS 21

5. SUMMARY AND CONCLUSIONS 24

6. ACKNOWLEDGMENTS 25

7. REFERENCE"S 26

APPENDIX 27

1. REFERENCES 27

i. i i

Table 1.

Table 2.

Table 3.

Table 4.

Table 5.

Table 6.

Table 7.

Table 8.

Table 9.

Table 10.

LIST OF TABLES

Suggested 9 kHz Allocation Plan

Computed Radiation Pattern for WLBH

Computed Radiation Pattern for KLAK

Computed Radiation Pattern for WELO - Nighttime

Comp~ted Radiation Pattern for WELD - Daytime

Measured F~'el d Strengths for WLBH

Measured Field Strengths for KLAK

Measured Field Strengths for WELO -Night Pattern

Measured Field Strengths for WELD - Day Pattern

Measurement Assignments of Engineers

v

3

5

8

10

12

14

17

19

22

23

EFFECT OF SMALL FREQUENCY CHANGES ON THE

RADIATION PATTERNS OF MF (AM) DIRECTIONAL ANTENNAS

Arthur C. Stewart* and John B. Heffelfinger**

The pressure to provide additional full-time' facilities in

the AM (standard broadcasting) band in the United States

resulted in a rulemaking petition filed. with the Federal

Communications Commission (FCC) by the National Telecommunications and Information Administrc:tion (NTIA). The petition proposed the reduction of the AM channel spacing from 10 to

9 kHz. According to the suggested frequency allocation plan, the maximum frequency change required for any standard AM

broadcast station would be ±4 kHz. At the Institute for

Telecommunication Sciences, in addition to investigation of

several impacts which would result fran the change,a study was

conducted both theoretically and experimentally to detennine the magnitude of the radiation pattern changes that would be

caused by a ±4kHz frequency change for stations using directional antenna arr-ays. The doll ar cost to broadcasters

because of the proposed change is directly tied to the

engineering costs that would be required in achieving compliance with directional arrays. Additionally, a computer study of the 1430 kHz regional channel, using standard patterns for all occupants of the. channel, was conducted to determine

the effects of a ±4 kHz frequency change on the interference

levels suffered by co-channel stations. The results of the

study demonstrate that the effects of small frequency changes on the radiation patterns of directional antenna arrays are

greater in practice than theoretical predictions would

indicate, but that required pattern corrections could probably be quickly and easily effected.

Key Words: AM broadcast band; allocation bandwidth;

directional antennas; frequency allocations

1. INTRODUCTION

Because of the number of requests for additional full-time facilities in

the AM (standard broadcast) band, different means for providing additional

channel space have been considered. Proposals for the addition of new

channel s by extending the high frequency 1imi t of the present AM broadcast

band (535 to 1605 kHz) have not been popular because existing radio. receivers

*Mr. Stewart is with the u.s. Department of Commerce, National Telecommunications and Information Administration, Institute for Telecommunication

Sciences, Boulder, Colorado 80303.

**Mr. Heffelfinger is a consulting communications engineer, 9233 Ward Parkway, Suite 285, Kansas City, Missouri 64114.
do not cover the extended range, and the time requi red for repl acement of

existing receivers because of obsolescence would be too long to justify the

expenditure for new broadcast stations in the extended portion of the band.

Twelve new channels could be provided in the spectrum space presently

occupied by the AM standard broadcast band by the simple expedient of changing

the allocation channel ,spacing from 10 to 9 kHz. This reduced channel spacing

is already in use in other regions of the world (ITU regions 1 and 3), but not

in the Americas (region 2). This scheme for increasing the number of AM

channels has had the support of a portion of the broadcast industry and was

the subject of a rulemaking petition filed with the Federal Communications

Commission (FCC) by the National Telecommunications and Infonnation Administration (NTIA). A suggested allocation plan is shown in Table 1. According

to this plan, the maximum frequency change required of any presently. operating

broadcast station is 4 kHz. ,It will be noted that some broadcast stations

would not be required to change their frequency, some would be required to

move 1 kHz, some 2 kHz, some 3 kHz, and some 4 kHz.

Studies have been conducted to determine what effect the change in allocation bandwidth would have on adjacent channel interference with existing

receivers and what changes in receiver characteristics would be desirable with

the reduced channel widths.

The frequency -chanqe for broadcaststati ons empl oying omnidirectional

antennas would be a simple operation of changing the crystals in the transmi tterand monitoring equipmentto crystals for the new frequency, some

slight retuning of the transmitter and antenna matching network, and a new

measurement of antenna impedance, though the current antenna measurements

would cover the new frequency.

In the case of broadcast stations which use directional antenna arrays

(of which there are a great many) either for the protection of ot-her stations

on the same frequency or to achieve a desired coverage area, the problem is

more compl ex. The desired radiation pattern for an array is determined by the

orientation of the array, the spacing betweenrthe elements of the array, and

the ratios of the currents and phase relationships between the elements. With

changes in frequency, the electrical heights of the radiators and the electrical spacing between the elements of the array will be different than the

parameters used by the designer of the array. The electrical lengths of

transmission lines will be different and will contribute diff.erent phase

2
Table 1. Proposed 9 kHz Frequency Allocation Plan

Nearest Nearest Nearest

Present f New * f ~f Present f New * f ~f Present f New * f Af

kHz kHz kHz kHz kHz kHz kHz kHz kHz

540 540 0 900 900 0 1260 1260 0

550 549 -1 910 909 -1 1270 1269 -1

560 558 -2 920 918 -2 1280 1278 -2

570 567 -3 930 927 -3 1290 1287 -3

580 576 -4 940 936 -4 1300 1296 -4

585 945 1305

590 594 +4 950 954 +4 1310 1314 +4

600 603 +3 960 963 +3 1320 1323 +3

610 612 +2 970 972 +2 1330 1332 +2

620 621 +1 980 981 +1 1340 1341 +1

630 630 0 990 990 0 1350 1350 0

640 639 -1 1000 999 -1 1360 1359 -1

650 648 -2 1010 1008 -2 1370 1368 -2

660 657 -3 1020 1017 -3 1380 1377 -3

670 666 -4 1030 1026 -4 1390 1386 -4

675 1035 1395

680 684 +4 1040 1044 +4 1400 1404 +4

690 693 +3 1050 1053 +3 1410 1413 +3

700 702 +2 1060 1062 +2 1420 1422 +2

710 711 +1 1070 1071 +1 1430 1431 +1

720 720 0 1080 1080 0 1440 1440 0

730 729 -1 1090 1089 -1 1450 1449 -1

740 738 -2 1100 1098 -2 1460 1458 -2

750 747 -3 1110 1107 -3 1470 1467 -3

760 756 -4 1120 1116 -4 1480 1476 -4

765 1125 1485

770 774 +4 1130 1134 +4 1490 1494 +4

780 783 +3 1140 1143 +3 1500 1503 +3

790 792 +2 1150 1152 +2 1510 1512 +2

800 801 +1 1160 1161 +1 1520 1521 +1

810 810 0 1170. 1170 0 1530 1530 0

820 819 -1 1180 1179 -1 1540 1539 -1

830 828 -2 1190 1188 -2 1550 1548 -2

840 837 -3 1200 1197 -3 1560 1557 -3

850 846 -4 1210 1206 -4 1570 1566 -4

855 1215 1575

860 864 +4 1220 1224 +4 1580 1584 +4

870 873 +3 1230 1233 +3 1590 1593 +3

880 882 +2 1240 1242 +2 1600 1602 +2

890 891 +1 1250 1251 +1

* According to the 9 kHz spacing plan used in Regions 1 and 3.

3
shi f ts, Phase shi fts in phasi ng and matchi ng networks in the antenna system

will also change. The greater the frequency change, the greater the change in

electrical lengths and phase changes in the array. In the study, the maximum

frequency change (±4 kHz) was used since this will cause the greatest change

in the parameters. The purpose of this study was to detennine whether

existing directional antenna arrays could accommodate this amount of frequency

change and still provide the required protection to co-channel stations

without redesign. It was also the purpose of the study to determine the

probable complexity and likely cost to broadcasters of making the frequency

change.

This report deals with the theoretical studies made on several directional antenna systems 'and with experiments with four directional systems at

three broadcast stations when the operating frequency was changed 4 kHz both

above and below their normal frequency. Additionally, a computer analysis of

the station-to-station interference on the 1430 kHz channel and comparison

with the interference that' would exist if the frequency were changed to

1426 kHz and 1434 kHz is presented.

2. THEORETICAL RADIATION PATTERNS

Radiation patterns were calculated for a number of broadcast station

directional antennas at their present operating frequency and at frequencies

from 1 to 4 kHz both above and below. Standard patterns were also calculated

for all stations on 1430kHz with directional antennas and for all of these

stations if they were operating on 1426 kHz and 1434 kHz. The licensed

design parameters for the antennas were used for the offset frequencies with

only the electrical heights of the antennas and the electrical spacing between

el ementsof the array changed to confonn to the offset frequencies. Changes

in the radiation patterns of all of the stations were minor.

Radi ation patterns were al so cal cul ated for the four directi onal arrays

which were measured as described in Section 3. The calculations were made at

the assigned frequency and at frequencies 4 kHz above and below. Licensed

field ratios and phases were used, with the spacing between elements and

antenna heights changed to the electrical lengths they would be at the offset

frequencies.

Table 2 shows the computed, horizontal-plane, standard pattern for Radio

Station WLBH in Mattoon, Illinois. Also shown are the fields that would be

4
Tab1 e 2. \~LBH - Standard Hori zonta 1 Plane Pattern

Field Strength mV/m Ratios Azimuth 1166 kHz 1170kHz 1174kHz AlB CIS A B C

0 74.85 75.13 75.46 0.996 1.004

10 73.46 72.66 71.89 1.011 0.989

20 89.24 88.35 87.45 1.010 0.990

30 95.32 94.83 94.34 1.005 0.995

40 78.22 78.03 77.85 1.002 0.998

50 60.51 60.13 59.75 1.006 0.994

60 86.49 85.84 85.20 1.008 0.993

70 112.78 112.10 111 .42 ".006 0.994

80 97.56 96.85 96.14 1.007 0.993

90 88.24 88.13 88.02 1.001 0.999

100 215.52 216.16 216.78 0.997 1.003

110 406.63 407.47 408.29 0.998 1.002

120 606.44 607.23 607.98 0.999 i .001

130 782.95 783. 51 784.03 0.999 1.001

140 916.77 917.04 917.24 1.000 1.000

150 998.85 998.86 998.81 1.000 1.000

160 1026.35 1026.27 1026.12 1.000 1.000

170 998.85 998.86 998.81 1.000 1. 000

180 916.77 917.04 917.24 1'.000 1.000

190 782.95 783.51 784.03 0.999 1.001

200 606.44 607.23 607.98 0.999 1.001

210 406.64 407.47 408.29 0.998 1.002

220 215.52 216.16 216.78 0.997 1.003

230 88.24 88.13 88.02 1.001 0.999

240 97.56 96.85 96.14 1.007 0.993

250 112.78 112.10 111.41 1.006 0.994

260 86.49 85.84 85.20 1.008 0.993

270 60.51 60.13 59.75 1.006 0.994

280 78.22 78.03 77.85 1.002 0.998

290 95.32 94.83 94.34 1.005 0.995

300 89.24 88.35 87.45 1.010 0.990

310 73.46 72.66 71.89 1.011 0.989

320 74.85 75. 13 75.46 0.996 1.004

330 91.30 92.47 93.70 0.987 1.013

340 99.69 101 . 13 102.62 0.986 1.015

350 91.30 92.47 93.70 0.987 1.013

NOTE: Maximum deviation occurs at 3400 (1.5%) at 00 elevation.

5
produced by the array if the frequency were shifted to 1166 kHz and

1174 kHz. The ratios between the 1170 kHz fields and those at 1166 and

1174 kHz are shown in the right hand columns. Note that the maximum deviation

in the fields at the offset frequencies is 1.5%.

The antenna array at Radio Station WLBH consists of four radiators

arranged in a line oriented 3400 true (Figure 1). The radiators are spaced

210 feet apart. The southeast radiator is 525 feet high and is used to

support an FM antenna. The other three towers are 210 feet high. The design

parameters for the array at 1170 kHz are as follows:

Tower Spaci ng from Beari ng from Field

Tower Height Reference Tower Reference Tower Phase Ratio

1 900 00 00 -133.10 1

2 900 900 3400 76.070 1.764

3 900 1800 3400 -76.10 1.493

4 2250 2700 3400 133.10 0.578

3400 T

0.587 / 133.1 0

No.3 1.493 / -76.1°

No.2 1.764 / 76.07°

No. 1.0 / -133.1°

Figure 1. WLBH antenna array.

6
Table 3 is a similar computation of the standard radiation pattern for

Radio Station KLAK in Denver, Colorado. The antenna array at Radio Station

KLAK consists of four elements located essentially at the corners of a

rectangle with dimensions of 325 feet by 154 feet (Figure 2).. The long

dimension is oriented at approximately N 950 E. The northeast tower is 360

f~et in height, and is used for daytime operation. It also supports an

auxiliary FM antenna. The other three towers are 185 feet high. The design

parameters at 1600 kHz are shown.

Tower Spaci ng from Bearing from Field

Tower Height Reference Tower Reference Tower Phase Ratio

1 212.50 0 a a 1

2 1090 91.2420 1850 1000 0.55

3 1090 210.40 249.30 980 0.5

4 1090 189.5870 2750 _90 0.89

No. 4 0.89 I _9°

r No. 1 / 0°

N 275° E

I N 185°

L I No. 3 0.5 / 98° ----0

No. 2 0.55·/ 100°

Spacing

No. 1 to No. 4 325' (190°)

No. 3 to No. 2 325' (190°)

No. 4 to No. 3 154- (90°) H

1 = 360' (212.5°)

No. 1 to No. 2 154- (90°) H2, H3, H4 = 185- (1090)

Figure 2. KLAK antenna array.

7
Table 3. KLAK - Standard Horizontal Plane Pattern

Night Pattern

Field Strength mV/m Ratios Azimuth 1596 kHz 1600 kHz 1604 kHz AlB CIS A S C

0 1165. 57 1167 . 67 1169.73 0.998 1.002

10 1146.77 1148.79 1150.77 0.998 1.002

20 1033. 71 1035.06 1036.37 0.999 1.001

30 846.47 846.73 846.94 1.000 1.000

40 617.97 616.94 615.87 1.002 0.998

50 386.26 384.05 381 .81 1.006 0.994

-60 188.41 185.52 182. 61 1.016 0.984

70 76.71 76.03 75.51 1.009 0.993

80 105.27 108.14 111 . 07 0.974 1.027

90 131.50 134.59 137.70 0.977 1.023

100 120.04 122.65 125.28 0.979 1.021

110 85.90 87.66 89.46 0.980 1.020

120 57.08 57.38 57.74 0.995 1.006

130 65.75 64.75 63.76 1.015 0.985

140 101.85 100.80 99.76 1.010 0.990

150 156. 13 155.57 155.00 1.004 0.996

160 226.74 226.91 227.08 0.999 1.001

170 298.62 299.51 300.41 0.997 1.003

180 350.00 351 .27 352.74 0.996 1.004

190 365.11 366.54 367.98 0.996 1.004

200 342.31 343.38 344.45 0.997 1.003

210 294.11 294.55 294.99 0.999 1.002

220 238.79 238.57 238.23 1.001 0.999

230 188.02 187.26 186.50 1.004 0.996

240 141.82 140.66 139.50 1.008 0.992

250 98.75 97.35 95.95 1.014 0.986

260 69.93 69.02 68.16 1.013 0.988

270 68.08 68.50 69.04 0.994 1.008

280 72.11 72.81 73.65 0.990 1.012

290 80.32 79.05 77 .91 1.016 0.986

300 , 51 . 96 149.00 146.05 1.020 0.980

310 299.76 297.00 294.22 1.009· 0.991

320 499.17 497.32 495.43 1.004 0.996

330 720.96 720.31 719.62 , .001 0.999

340 929.51 930.10 930.65 0.999 1.001

350 1087.80 1089.39 1090.93 0.999 1.001

Note: For fields in excess of 10% of the horizontal plane rms value, the

maximum deviation of 7.47% occurs at an azimuth of 70° and an

elevation angle of 15°.

8
The maximum difference between the offset frequency fields and the 1600 kHz

fields is 2.7%.

Table 4 is a computation of the nighttime pattern for Radio Station WELO

in Tupelo, Mississippi. The antenna array at Radio Station WELO consists of

four elements arranged in a parallelogram with dimensions of 1320 feet by 566

feet (Figure 3). The long dimension is oriented 00 true. The antennas are

305 feet high. A 500-foot tower supporting an FM antenna is located in the

vicinity of the No.1 and No.2 towers. This tower has been detuned at

580 kHz. Shown are the. design parameters at the assigned frequency of

580 kHz.

Tower Spacing from Beari ng from Field

Tower Height Reference Tower Reference Tower Phase Ratio

1 64.80 0 0 -1520 1

2 64.80 1200 200 0 1.6667

3 64.80 2800 0 -152° 0.65

4 64.80 394.90 5.9660 0 1.0833

Spacing

No. 1 to No. 3 1320 - (280°)

No. 2 to No. 4 1320- (280°)

No. 1 to No. 2 566- (120°)

No. 3 to No. 4 566- (120°)

H, , H

2, H3, H

4 = 305- (64.8°)

I

0° T

I

I No.2 1.6667 / 0°

No.4 1.0833 I 0°

;f

/1

No.3 0.65 I -152°

No.1 1 / -152°

Figure 3. WELD antenna array.

9
Table 4. WELD - Standard Horizontal Plane Pattern

Ntqhtt'ime

Field Strength mV/m Ratios Azimuth 576 kHz 580 kHz 584 kHz

A B C AlB CIB

0 190.38 192.65 194.81 0.988 1.011

10 192.86 195.26 197.55 .0.988 1.012

20 176.23 178.83 181.33 0.986 1.014

30 139.46 142. '4 144.75 0.981 1.018

40 86.82 89.09 91.34 0.975 1.025

50 49.04 48.92 48.92 1.003 1.000

60 81.56 80.18 78.78 1.017 0.983

70 116.48 115.75 114.98 1.006 0.993

80 119.00 118.70 118.38 1.003 0.997

90 97.34 96.91 96.46 1.004 0.995

100 84.48 83.61 82.74 1.010 0.990

110 84.94 83.79 82.64 1.014 0.986

120 67.94 66.45 64.96 1.022 0.978

130 46.01 45.73 45.55 1.006 0.996

140 89.41 91.45 93.47 0.978 1.022

150 154.92 157 .42 159.83 0.984 1.015

160 208.95 211.34 213. 61 0.989 1.011

170 243.67 245.79 247.77 0.991 1.008

180 258.63 260.61 262.42 0.992 1.007

190 254.56 256.64 258.56 0.992 1.008

200 '230.43 232.83 235.09 0.990 1.010

210 184.04 186.78 189.42 0.985 1.014

220 117.84 120.40 122.94 0.979 1.021

230 69.77 69.31 69.01 1.007 0.996

240 125.41 122.76 120. 11 1.022 0.978

250 199.36 197.29 195. 18 1.011 0.989

260 234.06 232.68 231.26 1.006 0.994

270 214.66 213.59 212.49 1.00·5 0.995

280 154.22 153. 11 151 •98 1.007 0.993

290 84.95 83.80 82.65 1.014 0.986

300 37.52 36.60 35.70 1.025 0.975

310 21.58 21.46 21.40 1.006 0.997

320 45.74 46.92 48.11 0.975 1.025

330 90.57 92.41 94.21 0.980 1.020

340 135.74 137.87 139.93 0.985 1.015

350 170. 61 172.83 174.96 0.987 1.012

Note: For any azimuth angle or elevation angle through 70°, the maximum deviation occurs at 304° azimuth and 0° elevation (2.76%).

10
The maximum deviation in fiel d strength at 576 kHz and 584 kHz from that at

580 kHz is 2.5%.

Table 5 is a computation of the daytime pattern for Radio Station WELO.

This array uses two elements of the four-tower nighttime array with the

following design parameters at 580 kHz.

Tower Spaci ng from Beari ng from Field

Tower Height Reference Tower Reference Tower Phase Ratio

1 64.80 a 0 0 1

2 64.80 1200 200 -900 2.222

The maximum deviation of field strength at 576 kHz and 584 kHz from the value

at 580 kHz is <1%.

Though the tabulations in Tables 2 through 5 are for azimuthal increments

of 100 for the horizontal plane standard pattern, the computations were made

with azimuth increments of 20 and for vertical angles from a to 700 in 50

increments. The maximum percentage deviation of the f i eld at the offset

frequencies from the field at the licensed frequency is given in the note at

the bottom of the table for the nighttime arrays at KLAK and WELD. These

represent very sma11 deviations in the actual fields since they are in

directions where the fields are small. It appears that wide-spaced arrays

with elements not in line and with mixed tower heights are apt to produce

variations of 10 to 15% in radiated fields at certain of the higher vertical

angles when the frequency is shifted ±4 kHz.

3. MEASURED PATTERNS

In order to obtain some IIhands onll experience with the problems that

might arise in connection with the proposed cha~ge to a 9 kHz allocation

bandwi dth and to provide some veri ficati on of the theoreti cal cal cul ati ons,

the frequencies of three radio stations with directional antennas were

changed. These stations were WLBH, 1170 kHz in Mattoon, Illinois; KLAK,

1600 kHz in Denver, Colorado; and WELD, 580 kHz in Tupelo, Mississippi.

Since the maximum frequency shift that would be required to implement the

proposed 9 kHz allocation plan is ±4 kHz, and ·since this would result in the

largest change in the electrical spacing of elements in an array, the frequency of each of the stations was changed to 4 kHz above and 4 kHz below

their assigned frequency. The new frequencies were obtained from a very

11
Table 5. WELD - Standard Horizontal Plane Pattern

Daytime

Field Strength mV/m Ratios Azimuth 576 kHz 580 kHz 584 kHz

A B C AlB CIB

0 250.36 250.38 250.38 1.000 1.000

10 248. 18 248.12 248.03 1.000 1.000

20 247.35 247.25 247 . 13 1.000 1.000

30 248. 18 248. 12 248.03 1.000 1.000

40 250.36 250.38 250.38 1.000 1.000

50 252.90 253.05 253. 18 0.999 1.000

60 254.33 254.62 254.90 0.999 1.001

70 252.86 253.28 253.70 0.998 1.002

80 246.75 247.25 247.75 0.998 1.002

90 234.70 235.21 235.71 0.998 1.002

100 216.33 216.74 217 . 15 0.998 1.002

110 192.40 192.63 192.86 0.999 1.001

120 165.04 165.04 165.04 1.000 1.000

130 137.65 137.44 137.23 1 002 0.999

140 114.67 114.37 114.07 1.003 0.997

150 100.47 100.30 100. 14 1.002 0.998

160 96.68 96.85 97.03 0.998 1.002

170 100.37 100.89 101.44 0.995 1.005

180 106.56 107.35 108. 17 0.993 1.008

190 111 . 52 112.48 113.45 0.992 1.009

200 113.37 114.37 115.39 0.991 1.009

210 111 . 52 112.48 113.45 0.992 1.009

220 106.56 107.35 108. 17 0.993 1.008

230 100.37 100.89 101 .44 0.995 1.006

240 96.69 96.85 97.03 0.998 1.002

250 100.47 100.30 100. 14 1.002 0.998

260 114.67 114.37 114.07 1.003 0.997

270 137.65 137.44 137.23 1.002 0.999

280 165.04 165.04 165.04 1.000 1.000

290 192.40 192.63 192.86 0.999 1.000

300 216.33 216.74 217 . 15 0.998 1.002

310 '234.70 235.21 235.71 0.998 1.002

320 246.75 247.25 247.75 0.998 1.002

330 252.86 253.28 253.70 0.998 1.002

340 254.33 254.62 254.90 0.999 1.001

350 252.90 253.05 253. 18 0.999 1.001

12
stable commercial frequency synthesizer. At WLBH and KLAK, this frequency

source was used in place of the crystal oscillator in the transmitter. At

WELD, the synthesizer was used in place of the crystal in the transmitter

osci 11 ator .

The first experiment was conducted at radio st~tionWLBH. Conduct of the

tests was authorized by the FCC during the test period, 1:00 to 5:00 A.M. on

the nights of July 12 and 13. The frequency of WLBH was changed to 1174 kHz

on ~uly 12, 1979, and the directional antenna was adjusted to the licensed

parameters. An in-line bridge was installed at the common point and the

common point impedance was returned to its 1170 kHz value at each of the

offset frequencies. The power input at the common point was held constant for

all of the tests on the three frequencies. Field strength readings were made

at three points on each of the 12 radials used for the original proof of

performance. The same points were measured during the daytime with the

station operating on 1170 kHz. During the test period on July 13, the

operation was repeated with the station operating on 1166 kHz with the

directional antenna adjusted to the licensed parameters.

The measurements were made by three engineers, each with a field strength

meter, making measurements on four of the radials. The same engineer and the

same field strength meter made the measurements on the same four radials in

each of the tests.

The measured field strengths and the ratios between the field strengths

on the offset frequencies and the 1170 kHz fields are shown in Table 6. The

differences between the offset frequency field strengths and the fields at

1170 kHz are much greater than were expected and will be discussed at the end

of the section.

Adjustment of the phase and field ratios at the offset frequencies were

made by thestation1sengineering personnel. About 1.5 hours were required to

adjust the directional antenna to the licensed parameters on 1174 kHz and

about 0.5 hour to obtain the licensed parameters on 1166 kHz.

The indicated field ratios and phases at WLBH for the three frequencies

were as follows:

1170 kHz Field Ratio Phase

Tower No. 1 0.55 -1100

Tower No. 2 0.91 -152.50

Tower No. 3 1.00 0

Tower No. 4 0.64 148.50

13
Table 6. Measurements on Radio Station WLBH - 07/12 &13/79

Field Strength mV/m Ratios Point 1166 kHz 1170 kHz 1174 kHz A/B C/B A B C

6° Radial

8 43 51 62.5 0.843 1.226

17 19.5 27 36.5 0.722 1.352

18 10 14 19.5 0.714 1.393

27° Radial

9 63 56 68 1. 125 1.214

17 29.5 25 27 1.180 1.080

19 19.5 18 21.5 1.083 1.194

50° Radial

16(MP-1) 29 25 23.5 1.160 0.940

17 22 19 16 1.158 0.842

19 13 12 12 1.083 1.000

70° Radial

12 65 62 52 1.048 0.839

17 35 32 24 1.094 0.750

19(MP-2) 31 28.5 23.5 1.088 0.825

870 Radial

12 54 58 70 0.931 1.207

18 27 25 23 1.080 0.920

X 26 23 29 1.130 1.261

125° Radial

15 325 320 315 1.016 0.984

17 190 180 190 1.056. 1.056

18 160 150 150 1.067 1.000

1600 Radial

MP-3 600 580 585 1.034 1.009

233° Radial

11 72 63 74 1.143 1.175

16 86 79 89 1.089 1. 127

17 33.2 29.5 32.2 1. 125 1.091

2500 Radial

11 62.5 52.5 41.5 1.190 0.790

17 27 25.2 22.6 1.071 0.897

19 22.8 17.7 16.2 1.288 0.915

2700 Radial

10 44 32.2 35.2 1.366 1.093

17(MP-4) 17.2 17. 1 24.8 1.006 1.450

18 11 5.9 13. 1 1.864 2.220

293 0 Radial

12 63 50 55.5 1.260 1.110

17 35.5 25.2 25.5 1.409 1.021

18 27 29.5 24.9 0.915 0.844

3140 Radial

13 24 24.5 30 0.980 1.224

17 14.8 19.5 23 0.759 1.179

18 9.6 13.5 15.5 0.711 1.148

3400 Radial

8 49 45.5 70.0 1.077 1.538

17(MP-5) 47 45.5 47.5 1.033 1.044

18 32 32.5 35 0.985 1.077

14
1174 kHz Field Ratio Phase

Tower No. 1 0.522 -109.90

Tower No. 2 0.89 -151.90

Tower No. 3 1.00 a

Tower No. 4 0.633 147.90

1166 kHz Field Ratio Phase

Tower No. 1 0.538 -1100

Tower No. 2 0.90 -1520

Tower No. 3 1.00 a

Tower No. 4 0.64 148.50

Due to limitations on time and resources, it was decided that we should

1imit our measurement program to two additional stations, one close to either

end of the broadcast band. It also seemed advisable to choose arrays with a

wide spacing between elements since the change in electrical spacing would'be

greater with changes in frequency. Radio Station KLAK at 1600 kHz and Radio

Station WELO at 580 kHz were selected. Both stations had fairly wide-spa~ed,

parall el ogram, antenna arrays.

The tests at KLAK, in Denver, Colorado, were conducted on September 12

and 13. Tests were authorized during daytime hours by the FCC, who also

provided three engineers and field strength meters to assist with the measurements. Field strength measurements were made at three points on each of the

12 radials used in the original proof of perfonnance. Since six engineers and

field intensity meters were available, each engineer was assigned two radials,

and all measurements on each of the radials were made by the same engineer and

with the same equipment. A commercial in-line bridge was connected at the

common point, and the same input power to the phasor ;was maintained for all

measurements.

The field strength at each of the selected measurement points was

measured with the transmitter on 1600 kHz and the directional antenna adjusted

to the licensed parameters. The frequency was then changed to 1596 kHz, and

the field strength at the measurement points was measured with no adjustment

of the directional antenna. The antenna was then adjusted to the licensed

parameters with the frequency at 1596 kHz, and another set of measurements was

made. The frequency was then returned to 1600 kHz, and the antenna ~djusted

to licensed parameters. The measurement sequence was repeated with the transmitter frequency at 1604 kHz. The points were first measured with no

15
adjustment of the directional anterina, and then measured with the antenna

adjusted to licensed parameters.

The measurements at KLAK are shown in Table 7 with the ratios; between the

field intensities at the offset frequencies and the 1600 kHz values in the

right hand columns. Again, the measured field strengths deviate from the

predicted values by a larger amount than had been expected.

Adjustment of the phasing equipment to" restore the licensed parameters at

the offset frequencies was achieved with the front panel controls of the

phasor by th~station engineering personnel. No more than one-half hour was

required for each adjustment.

The indicated field ratios and phases for the three frequencies and modes

of operation at KLAK are given below.

1600 k~z - Night Pattern - aligned

Field Ratio Phase

1596kHz - Night Pattern - not adjusted

Field Ratio

1596 kHz - Night Pattern - adjusted

Field Ratio

1604 kHz - Night Pattern - not adjusted

Field Ratio

Tower No. 1

Tower No.2

Tower No. 3

Tower No. 4

Tower No. 1

Tower No.2

Tower No. 3

Tower No.4

Tower No. 1

Tower No. 2

Tower No. 3

Tower No.4

Tower No. 1

Tower No. 2

Tower No. 3

Tower No. 4

1.00

1.253

1.164

1.698

1.00

1.203

1.141

1. 715

1.00

1.265

1.157

1.715

1.00

1.272

1.158

1.645

16

Phase

o

119.30

109.50

7.40

Phase

o

116.40

106.80

7.40

Phase

o

1120

102.50

7.80
Table 7. Measurements on Radio Station KLAK - 09/12 &13/79

Field Strength mV/m Ratios

Points A B C D E B/A CIA D/A EfA

Radial B - 25°

B 1.7 400 410 417 415 408 1.025 1.042 1.037 1.020

B 2.6 268 270 275 272 275 1.007 1.026 1.015 1.026

B 3.0 225 238 237 232 232 1.058 1.053 1.053 1.031

Radial C - 45°

C 1.5 288 285 288 287 284 0.990 1.000 0.996 0.986

C 2.0 207 212 213 212 208 1.024 1.029 1.024 1.005

C 2.5 139 144 143 138 142 1.036 1.029 0.993 1.022

Radial D - 71°

D 1.7 34 27 3205 45 35. 1 0.794 0.956 1.323 1.032

o 2.4 13.5 13.7 16.5 19.5 16 1.015 1.222 1.444 1.185

o 2.85 13 10.8 13.5 18.2 15.2 0.831 1.038 1.400 1.169

Radial E - 91°

E 1.6 49 49 53 51 45 1.000 1.082 1.041 0.918

E2.3 32 30.9 31 .3 35 33 0.966 0.978 1.094 1.031

E 2.9 30.8 28.8 29.8 32.7 30.6 0.935 0.967 1.062 0.993

Radial F - 121 °

F 1.62 13 13.5 13 11 15 1.038 1.000 0.846 1. 154

F 2.5 14 16 19 14 14 1. 143 1.357 1.000 1.000

F 3.2 7.9 10 10.5 6.4 5.8 1.266 1.329 0.81 0.734

Radial G - 155°

G 1 87 120 110 64 75 1.379 1.264 0.736 0.862

G 1.5 54 70 60 40 45 1.296 1. 111 0.741 0.833

G 2.4 27 39 32 22 23 1.444 1.185 0.815 0.852

Radial H - 1900

H 1 93 120 105 46 98 1.290 1.129 0.495 1.054

H 2 71 90 81 37 70 1.268 1. 141 0.521 0.986

H 3 51 63 54 37 50 1.235 1.059 0.725 0.980

Radial I - 2200

I 1 46 43 46.5 50 46 0.935 1.011 1.087 1.000

I 2 34 31 31.5 26 28 0.912 0.926 0.765 0.823

I 3 24 22 21 22 25 0.917 0.875 0.917 1.042

Radial J - 2490

J 0.9 60 59 62 62 60 -0.983 1.033 1.033 1.000

J 2.8 29 32.5 31.5 29 26 1. 121 1.086 1.000 0.897

J 3.3 22.5 20.5 22 20 19.5 0.911 0.978 0.889 0.867

Radial K -2750

K 1.55 14 10 11 16.5 16 0.714 0.786 1.179 1.143

K 2.37 16 12.2 14.5 17.5 16 0.762 0.906 1.094 1.000

K 5.85 2.3 1.52 1.95 3.8 3.2 0.661 0.848 1.652 1.391

Radial L - 301 0

L 1 70 68 69 54 54 0.971 0.986 0.771 0.771

L 2 78 71 71 61 60 0.910 0.910 0.782 0.769

L 3 62 52 52 43 46 0.839 0.839 0.693 0.742

Radial M- 3300

r~ 3.3 155 125 128 100 105 0.806 0.826 0.645 0.677

M4 92 85 85 68 69 0.924 0.924 0.739 0.750 ~1 4.5 90 88 85 66 65 0.978 0.944 0.733 0.722

A - 1600 kHz - aligned

B - 1596 kHz - not aligned

C - 1596 kHz - licensed parameters

D - 1604 kHz - not aligned

E - 1604 kHz - licensed parameters

17
Tower No. 1

Tower No. 2

Tower No. 3

Tower No.4

1604 kHz - Night Pattern - adjusted

Field Ratio

1.00

1.251

1.177

1.67

Phase

o

115.90

106.40

7.70

Phase

-150.40

o

-149.40

+ 0.3 0

0.595

1.00

0.393

0.65

Tower No. 1

Tower No. 2

Tower No. 3

Tower No.4

Measurements were made at Radio Station WELD in Tupelo, Mississippi, on

September 25 and 26. WELD operates on 580 kHz using a two-tower directional

array for its daytime operation and a four-element parallelogram array at

night. Authorization to make the measurements during the daytime was granted

by the FCC, who also assigned three of their engineers equipped with field

strength meters to assist with the measurements. The nighttime four-element

array was measured following the same procedure used at KLAK. Three points

were measured on each of the 12 radials used for the original proof of

performance. Measurements were first made on 580 kHz, the frequency was then

cha~ged to 584 kHz, and measurements made without realigning the array to

licensed parameters. Licensed parameters were then restored, and measurements

made at 584 kHz. This operation was repeated at 576 kHz. The results are

shown in Table 8. Parameters of the array are given in Section 2.

It was not possib1e to obta in the 1icensed parameters wi th the front

panel controls at the 584 kHz frequency. Taps were changed in the phasor

duri ng the test peri od on September 27. About two hours were requi red to

establish the licensed parameters at this frequency. About one-half hour was

required to obtain the licensed parameters at 576 kHz using front panel

controls.

The indicated field ratios and phases at WELD for the different

frequencies and modes of operation are given below.

580 kHz - Night Pattern - aligned

Field Ratio

18
Table 8. Measurements on Radio Station WELO - 09/25 &26/79

Nighttime Pattern

Distance Field Strength mV/m Ratios

Points Miles A B C 0 E B/A CIA O/A E/A

25° Radial

Pt. 20 2.23 50.1 56.4 51'.6 66 57.6 1.126 1.030 1.317 1.150

Pt. 21 2.68 43.2 44 36 50.2 45.5 1.019 0.833 1. 162 1.053

Pt. 22 3.35 27 29.1 22 28.1 32.4 1.078 0.815 1.041 1.200

52° Radial

Pt. 21 3.0 14 19.8 11 .2 10.9 15.0 1.414 0.800 0.779 1.071

Pt. 22 3.4 15.2 20.4 12.6 11 .2 15.4 1.342 0.829 0.737 1.013

Pt. 23 3.65 10.8 14.5 8. 1 7.6 10.8 1.343 0.750 0.704 1.000

750 Radial 3

Pt. 22 3.38 28.5 30.2 39.0 27.2 28.6 1.060 1.368 0.954 1.004

Pt. 23 3.62 27.2 29.0 37.8 26.0 27.2 1.066 1.390 0.956 1.000

Pt. 24 3.95 22.5 23.5 31.4 21.8 22.6 1.044 1.396 0.969 1.004

960 Radial

Pt. 20 2.60 15.5 11 .5 26.2 26.5 19.5 0.742 1.690 1.710 1.258

Pt. 22 3.85 12.3 10.5 19.5 15.5 15.5 0.854 1.585 1.260 1.260

Pt. 23 4.2 10.7 6.3 15.5 19.5 13.0 0.589 1.449 1.822 1.215

1300 Radial

Pt. 21 2.13 13.5 8.6 29 21 14 0.637 2.148 1.556 1.037

Pt. 23A 3.0 9.6 5. 1 19 15.8 10.5 0.531 1.979 1.646 1.094

Pt. 26 3.51 9.2 5.2 19.1 14.5 10 0.565 2.076 1.576 1.087

1550 Radial

Pt. 23 3.15 52 50 53 55 52 0.962 1.019 1.056 1.000

Pte> 24 3.40 41.5 40 41 44 41.5 0.964 0.988 1.060 1.000

Pt. 25 4.05 28.5 27 30 29.5 28 0.947 1.053 1.035 0.983

2000 Radial

Pt. 20 2.09 84 80 83 80 78 0.952 0.988 0.952 0.929

Pt. 21 2.20 66 65 70 68 67 0.985 1.061 1.030 1.015

-Pt. 23 2.61 64 60 64 64 63 0.938 1.000 1.000 0.984

2280 Radial

Pt. 20 2.03 32.8 26 46.8 34.8 32.1 0.793 1.427 1.061 0.979

Pt. 21 2. 15 25.1 19.8 37.5 28.1 25.2 0.789 1.494 1.120 1.004

Pt. 22 2.30 24.4 19.6 39.2 27.2 24.2 0.803 1.607 1.115 0.992

Pt. 24 3.7 14.5 11 . 1 24.0 16.2 14.5 0.766 1.655 1.117 1.000

2450 Radial

Pt. 21 2.39 46.5 44.7 36.5 48 47 0.961 0.785 1.032 1.011

Pt. 22 3.65 33.8 32.9 27.8 33.2 34·.5 0.973 0.823 0.982 1.021

Pt. 23 4.4 30.8 29.7 24.8 30.3 31.4 0.964 0.805 0.984 1.020

2780 Radial

Pt. 18 2.03 63 61 42 63 64 0.968 0.667 1.000 1.016

Pt. 25 4.75 24.2 24 16 25.8 25.9 0.992 0.661 1.066 1.070

Pt. 26 4.95 24.0 23.2 15 25.2 25.3 0.967 0.625 1.050 1.054

3100 Radial

Pt. 23 3.0 7.3 11.8 9 9.8 8.1 1.616 1.233 1.343 1.110

Pt. 24 3.20 8.4 12.5 6.5 9.0 8.5 1.438 0.774 1.071 1.012

Pt. 30 6.65 2.5 5.2 2.95 2.7 2.62 2.080 1. 18 1.08 1.048

358° Radial

Pt. 19 2.13 72 71 76 79 77.5 0.986 1.056 1.097 1.07'6

Pt. 21 2.51 63.2 63.1 66.2 71.2 68.1 0.998 1.048 1. 127 1.078

Pt. 22 2.64 55 53.2 55.1 61 .3 57.2 0.967 1.002 1.115 1.040

A - 580 kHz, aligned, 535 watts

B - 584 kHz, not aligned, 535 watts

C - 584 kHz, licensed parameters, 535 watts

o - 576 kHz, not aligned, 535 watts

E - 576 kHz, licensed parameters, 535 watts

19
584 kHz - Night Pattern - not adjusted

Field Ratio Phase

Tower No. 1 0.662 -160.3 0

Tower No. 2 1.00 0

Tower No. 3 0.455 -143.1 0

Tower No. 4 0.671 - 5.1 0

584 kHz - Night Pattern - adjusted

Field Ratio Phase

Tower No. 1 0.594 -150.20

Tower No • 2 1.00 0

Tower No. 3 0.406 -149.80

Tower No. 4 0.655 + 0.40

576 kHz - Night Pattern - not adjusted

Fiel d Ratio Phase

Tower No. 1 0.502 -143.40

Tower No. 2 1.00 0

Tower No. 3 0.371 -156.0°

Tower No. 4 0.637 + 5.3 0

576 kHz - Night Pattern - adjusted

Field Ratio Phase

Tower No. 1 0.60 -150.40

Tower No. 2 1.00 0

Tower No. 3 0.40 -149.2°

Tower No. 4 0.657 + 0.6 0

580 kHz - Day Pattern - al i gned

Field Ratio Phase

Tower No. 1 0.48 83.8 0

Tower No. 2 1.00 0

584 kHz - Day Pattern - not adjusted

Field Ratio Phase

Tower No. 1 0.387 69.3°

Tower No. 2 1.00 0

576 kHz - Day Pattern - not adjusted

Field Ratio Phase

Tower No. 1 0.55 104.90

Tower No. 2 1.00 0

20
The daytime array for WELD was also measured at the licensed frequency

and at 584 kHz and at 576 kHz without adjusting the array. Since monitoring

equipment was located in the transmitting building and phasing equipment was

located at the tower bases, it was decided not to attempt to adjust the twotower array to licensed parameters at the offset frequencies. The measurements are shown in Table 9.

The measurements made at Radio Station KLAKandat Radio Station WELD"

without any adjustments to the array demonstrate that frequency changes of

±4 kHz do not cause serious changes in radiation patterns. The changes were

greater at WELD than at KLAK. Field ratio changes and phase changes were

greater at WELD. These changes are due to changes in the electrical lengths

of transmission lines and phase shifts in phasing and matching networks. The

changes are proportional to the percentage change in frequency and are greater

at the lower end of the band.

The measured field intensities of the directional antennas when the

frequency was changed ±4 kHz and the antenna aligned showed markedly greater

changes than were predicted by the theoretical calculations. The explanation

of the larger deviations may lie in the fac~that the assumption that the

array was al igned to the design parameters when it was in compl i ance wi th the

construction permit is not true. No attempt was made to bring the stations

monitor points to the permitted values, but it is believed that this could

have been done with minor changes in the field ratios and phases.

Table ID is a list of the engineers who made the field strength measurements on the radio stations and the radials for which they were responsible.

4. 1430 kHz CALCULATIONS

To evaluate the impact of chahging frequencies as much as"±4kHz on the

nighttime interference level, a model system at 1430 kHz was set up on a

computer. Existing licensees or permittees* in the continental U.S. were

assigned a standard pattern utilizing the presently licensed antenna system

parameters at the presently licensed sites. The standard pattern was computed

using Sec. 73.150 of the FCC Rules and Regulations (1976). A loss resistance

of one ohm at the current loop was assumed for each element of the array. The

*Radio Station WBRB, Mt. Clemens, Michigan, was not included in the study.

21
Table 9. Measurements on Radio Station WELD - 09/26/79

Daytime Pattern

Distance Field Strength mV/m Ratios

Points Mile A B C B/A CIA

250 Radial

Pt. 20 2.23 93.1 100.8 109.2 1.083 1.173

Pt. 21 2.68 82.8 78.1 95 0.943 1. 147

Pt. 22 3.35 55.2 51.2 59.2 0.928 1.073

520 Radial

Pt. 21 3.0 72 66 82 0.917 1'.139

Pt. 22 3.4 70 64.5 86 0.921 1.143

Pt. 23 3.65 60.5 56 67.5 0.926 1.116

750 Radial

Pt. 22 3.38 66.5 64.5 72 0.970 1.083

Pt. 23 3.62 66.5 64 70 0.962 1.053

Pt. 24 3.95 55.5 54.5 58.5 0.982 1.054

960 Radial

Pt. 20 2.60 76 72 70 0.947 0.921

Pt. 22 3.85 47 47 46 1.000 0.979

Pt. 23 4.2 39.5 40 36 1.013 0.911

1300 Radial

Pt. 21 2.13 56 64 55 1. 143 0.982

Pt. 23A 3.0 41 49 34 1.195 0.829

Pt. 26 3.51 38 44 31 1. 158 0.816

1550 Radial

Pt. 23 3.15 30.5 38.5 26 1.262 0.853

Pt. 24 3.40 23 33 21 1.435 0.913

Pt. 25 4.05 17 23 14.5 1.353 0.853

2000 Radial

Pt. 20 2.09 41 39 50.5 0.951 1.232

Pt. 21 2.20 32.5 32 41 0.985 1.262

Pt. 23 2.61 30 30.5 37 1.017 1.233

2280 Radial

Pt. 20 2.03 34.2 39.2 36.1 1. 146 1.056

Pt. 21 2. 15 27.6 31.8 30.8 1. 152 1. 116

Pt. 22 2.30 28.9 35.0 31.8 1.211 1.100

Pt. 24 3.7 17.2 20.2 20.3 1.174 1. 180

2450 Radial

Pt. 21 2.39 27.2 38.0 20.1 1.397 0.739

Pt. 22 3.65 18.2 24.8 15.6 1.363 0.857

Pt. 43 4.4 18.7 23.5 16.2 1.257 0.866

2780 Radial

Pt. 18 2.03 62 71 50.5 1. 145 0.815

Pt. 25 4.75 26.6 29.9 21.4 1.124 0.805

Pt. 26 4.95 24.8 28.0 20.3 1. 129 0.819

3100 Radial

Pt. 23 3.0 69 71 67 1.029 O.g]l

Pt. 24 3.20 63 65 60 1.032 0.952

Pt. 30 6.65 27.6 30 27.2 1.087 0.986

3580 Radial

Pt. 19 2. 13 106.8 108 111 1.011 1.039

Pt. 21 2.51 93.1 90.1 101 0.968 1.192

Pt. 22 2.64 73.2 77.4 98 1.057 1.339

A - 580 kHz, aligned, 1080 watts

B - 584 kHz, not adjusted, 1080 watts

C - 576 kHz, not adjusted, 1080 watts

The daytime patterns were not adjusted to the

licensed parameters on 576 and 584 kHz since

the monitoring equipment was located in the

transmitter building and the phasing networks

were at the antenna bases.

22
Assignment

Table 10. Measurement Assignments

E,ngi neer

RaQio Station WLBH Measurements

233° 250° 270° 293° Radials

50°: 70°: 87°' 125° Radials

314°, 340°, 6°: 27° Radials

Radio Station KLAK Measurements

35° (B), 450(C) Radials

71° (D), 91 0(E) Radials

121° (F), 1550(G) Radials

190° (H), 220°(1) Radials

249.30(J), 2750(K) Radials

301° (L), 3300(M) Radials

Radio Station WELD Measurements

25° 3580 Radials

52°: 75° Radials

96°, 130° Radials

155°, 200° Radials

228°, 245° Radials

310°, 278° Radials

John B. Heffelfinger

Ray Livesay

Arthur C. Stewart

John B. Heffelfinger

Larry Brock

Don Wyatt

Brion C. Gilbert

Girard M. Westerberg

Arthur C. Stewart

Bill Simpson

Bob Bradl ey

George J. Bourda, Jr.

Arthur C. Stewart

John B. Heffelfinger

Billy Joe Crabb

23

Consultant/NT1A

WLBH

NT1A/1TS

Consul tant/N.T1A

FCC

FCC

FCC

KLAK

NT1A/1TS

FCC

FCC

FCC

NT1A/1TS

Consultant/NT1A

WELD
site-to-site 50% RSS interference free signal level for each station was

calculated using Figures 2 and 6a of the FCC Rules and Regulations.

Using the FCC soil conducivity map, Figure M3, and Graph 18 of the FCC

Rules and Regulations, the standard horizontal plane pattern for each station

was computed and used to obtain the location of the 1430 kHz, 50% RSS (siteto-site), interference-free ,5i gnal contour at points along 36 radials spaced

10° apart at each station. The geographical coordinates for each of these

points were cal cul ated usi ng fonnul as contai ned in Special Publ icati on #8

(U.S. Coast and Geodetic Survey, 1933). For frequencies of 1426 and 1434 kHz,

the 50% RSS interference-free signal value was recomputed at each of the 36

points for each licensee.

Appendix A tabulates the results of the above described computations. An

examination of the data in the appendix shows that variations in the fields at

the interference-free contours at the offset frequencies are minimal.

5. SUMMARY AND CONCLUSIONS

Theoretical calculations of radiation patterns for directional antenna

arrays indicate that frequency changes of up to 4 kHz have only minor effects

on radiated fields. The fact that measured fields on radio station antennas

showed greater changes with frequency than the computed values may be due to

initial misalignment of the array. It should be possible to bring the fields

at monitor points within limits with minor adjustments of the phasing equipment.

The study comparing the interference levels at 1426 kHz and 1434 kHz with

the interference which exists at 1430 kHz when all nighttime occupants of the

band are considered shows only minimal changes in the levels of interference

at any station. This may not be true for all channels; however this was a

randomly chosen, heavily populated, regional channel.

If some regulations were relaxed for the transition period, it should be

possible to make the change to a 9 kHz allocation bandwidth overnight without

a disruption of present service and without undue overload to the consulting

engineering community. The proposed frequency changes are small, and station

engineering personnel could, in most cases, restore the licensed parameters

for the antenna wi thout troubl e. Power could be detenni ned by the indi rect

method until input impedances could be measured and approved. Some adjustment

period could be established to allow time to bring the monitor point fields to

24
authorized limits. This work could be performed by engineering personnel at

the stations in the majority of cases. There would undoubtedly be some

problem cases, and the consulting engineers could concentrate on these,

resolving less critical cases later and measuring input impedances as time

permitted. Most stations would be able to make .partial proofs of performance

using station personnel.

The cost to broadcasters of making the change to a 9 kHz allocation

bandwidth is dependent on the requirements of the FCC. The cost of making

input impedance measurements is about $500 to $750 plus expenses. The time

required for making a partial proof of performance on the average directional

array would be .about six man-days. This assumes no problems with alignment to

reestablish the approved fields in the protection directions and should be

true for the majority of stations. A full proof of performance would require

a maximum of 21 man-days for the average station with a single DA pattern.

Many stations would be able to perform part of the requirements using their

own personnel. No redesign of directional antennas should be required except

in the case of a very few critical arrays.

6. ACKNOWLEDGMENTS

The authors wish to thank the management and engineering staffs of the

radio stations who cooperated in the experimental phase of the project. This

part of the project would have been impossible without their help. In

particular, Ray Livesay, owner and Technical Director of Radio Station WLBH;

Girard Westerberg, Chief Engineer of Radio Station KLAK; Bi1.1y Jrie Crabb,

Chief Engineer of WELO; and Watt Hairston, Technical Advisor for Fritts

Broadcasting.

The conduct of the experiments was greatly expedited by the FCC engineers

who assisted with the field strength measurements. These engineers were Brion

C. Gilbert, Don Wyatt, and Larry Brock from the Denver office and Bill

Simpson, Bob Bradley, and George Bourda, Jr., from the New Orleans office.

The work of Christopher Brooks from the University of Colorado, Stephen

Stewart from the Mine Safety and Health Administration, and Nancy Madonna and

Duane Hyovalti from NTIA/ITS in adapting computer programs developed by one of

the authors (John B. Heffelfinger) for the CDC 6600 computer and processing

the large amount of data required for the interference analysis on 1430 kHz is

also gratefully acknowledged.

25
7• REFERENCES

Federal Communication Commission (1976), Rules and Regulations, Volume III,

Part 73, August.

U.S. Coast and Geodetic Survey (1933), Fonnulas and tables for the computation of geodetic positions, Special Publication #8, 7th Edition,

(Superintendent of Documents, U.S. Government Printing Office).

26
APPENDIX. COMPUTATIONS OF INTERFERENCE FREE SIGNAL CONTOURS

FOR RADIO STATIONS OPERATING ON 1430 KHZ

The attached computations were made for night operation on 1430 kHz and

1430 kHz ±4 kHz. All computations were made using standard patterns with a

loss resistance of one ohm per element at the current loop. Site-to-site

interference levels (50% RSS) were used to determine the interference-free

signal contour of each station. The FCC soil conductivity map and the

computed standard hori zontal plane. pattern were used to detennine the location

of the interference-free contour at 1430 kHz. Points on the interference-free

signal contour were computed using azimuthal increments of 100 beginning at

N 00 E. For the differential frequencies (±4 kHz), the standard patterns were

recomputed usi n9 the present operati ng parameters except for antenna heights

and spacings, and the interference to each of the previously located "poin"ts on

the interference free signal contour (50% RSS value on 1430 kHz) were

recalculated and the comparisons made. Figure 2 and 6a of the FCC Rules and

Regulations (1976) were used to compute the interference signals, and Graph 18

of Section 73.184 of the FCC Rules and Regulations (1976) was used to compute

the location of the interference-free"signal contours. The Andoyer-Lambert

fonnul a (Cl arke Spheriod 1866) wa s used to detenni ne the beari ng and distance

between stations and between stations and points on the interference-free

signal contour. Formulas contained in special publication #8 (U.S. Coast and

Geodetic Survey, 1933) were used to determine the geographic coordinates of

points on the interference-free signal contour.

1. REFERENCES

Federal Communications Commission (1976J, Rules and Regulations, Volume III,

Part 73, August.

U.S. Coast and GeOdetic Survey (1933), Formulas and tables for the computation of geodetic positions, Special Publication #8, 7th Edition,

(Superintendent of Documents, U.S. Government Printing Office).

27
Table A-l

(Si te.~ to-Si te)

Interference Limit50%RSS Values

50%

RSS Values

Station 1434 kHz 1430 kHz 1426 kHz

KELI 2.574486 2.572259 2.572837

KALV 9.068736 9.084286 9.118945 '

WVAM 4.649008 4.793371 4.775929

KLO 2.708158 2.699287 2.692089

WEIR 4.537801 4.544997 4.552867

WJRB 22.i29698 22.28698 22.27692

KRGI 16.76261 16.75473 16.67028

KEES 27.41962 27.47289 27.41640

KBRC 3.929017 3.933098 3.956561

WBEV 32.81107 32.82299 32.77194

KARM 2.230129 2.2266001 2.315314

KALI 25.02177 25.03202 25.04111

KNTA 22.98419 23.09384 23.20038

WQOI 8.600525 8.599298 8.598017

WQPO 8.737696 8.760033 8.7]3349

WWGS 22.21879 22.27990 22.34040 WW~Q 15.4,4082 15.40918 15.37186

WIRE 3.744660 3.740293 3.755180

WYMC 20.75804 20.65408 20.61676

WIL 5.215959 5.232283 5.225892

WNJR 2.428348 2.709657 2.433308

KKAT 15.32290 15.34355 15.32989

WENE 8.387507 8.396380 8.405075

WMNC 22.74791 22.41471 22.71842

WFOB 13.95319 13.95677 13.96034

WNAV 15.75850 15.87456 15.98863

KOSI 6.334624 6.330468 6.332558

I')Q

'- '..;
Table A-2

Station Call: KELI

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 35.34 2.85 2.84 2.84

10 32.27 2.76 2.75 2.75

20 27.92 2.66 2.65 2.66

30 26.44 2.62 2.61 2.61

40 24.08 2.59 2.58 2.58

50 20.63 2.57 2.57 2.57

60 18.70 2.59 2.59 2.59

70 19.57 2.62 2.62 2.61

80 23.93 2.68 2.69 2.68

90 27.81 2.77 2.78 2.77

100 31.14 2.60 2.62 2.60

110 33.76 2.73 2.75 2.74

120 35.50 2.84 2.86 2.84

130 37.24 2.93 2.95 2.93

140 38.37 2.96 2.99 2.97

150 39.08 2.95 2.97 2.95

160 39.52 2.89 2.92 2.90

170 39.75 2.82 2.84 2.83

180 39.83 2.73 2.76 2.74

190 39.75 2.63 2.65 2.64

200 34.74 2.78 2.79 2.78

210 31.91 2.71 2.71 2.71

220 30.54 2.66 2.66 2.66

230 28.30 2.63 2.62 2.63

240 26.72 2.60 2.60 2.60

250 25.36 2.58 2.58 2.58

260 23.21 2.57 2.57 2.57

270 20.97 2.56 2.56 2.56

280 18.39 2.56 2.56 2.56

290 15.83 2.56 2.56 2.56

300 15.02 2.56 2.56 2.56

310 16.89 2.56 2.56 2.56

320 19. 14 2.58 2.58 2.58

330 37.91 2.87 2.86 2.86

340 36.24 2.87 2.86 2.86

350 36.81 2.89 2.88 2.88

*1430 kHz 50% RSS site-to-site value.

29
Table A~·3

Station Call: KALV

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 1.38 8.95 8.91 8.90

10 0.87 8.99 8.96 8.94

20 0.73 9.04 9.01 8.99

30 1. 21 9.00 8.96 8.95

40 1.56 8.97 8.94 8.92

50 1.56 8.98 8.95 8.93

60 1. 21 9.03 8.99 8.98

70 0.73 9.08 9.04 9.02

80 0.87 9.08 9.05 9.03

90 1.38 9.12 9.08 9.07

100 1.56 9.14 9.10 9.09

110 1.09 9.16 9.13 9·. 11

120 0.98 9.15 9.11 9.10

130 3. 14 9.34 9.30 9.29

140 5.82 9.64 9.60 9.59

150 8.56 9.80 9.76 9.75

160 11 . 13 10.20 10.16 10.15

170 13.25 10.50 10.46 10.45

180 15.05 10.95 10.92 10.91

190 16.30 11 .01 10.98 10.96

200 17.08 10.94 10.91 10.90

210 17.53 10.95 10.92 10.91

220 17.73 10.72 10.69 10.67

230 17.73 10.45 10.42 10.41

240 17.53 10.14 10. 11 10.09

250 17.08 9.79 9.76 9.74

260 16.30 9.48 9.45 9.43

270 15.05 9.18 9.15 9.13

280 13.25 8.94 8.91 8.89

290 11 . 13 8.79 8.76 8.74

300 8.56 8.74 8.71 8.69

310 5.82 8.79 8.76 8.74

320 3. 14 8.83 8.80 8.78

330 0.98 9.01 8.98 8.96

340 1.09 8.99 8.96 8.94

350 1.56 8.94 8.90 8.89

*1430 kHz 50% RSS site-to-site value.
Table A-4

Station Call: WVA~1

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 4.66 4.70 4.72 4.58

10 4.77 4.71 4.73 4.59

20 4.92 4.74 4.75 4.61

30 7.23 4.78 4.79 4.65

40 7.38 4.81 4.83 4.69

50 7.27 4.84 4.86 4.72

60 6.78 4.86 4.89 4.74

70 5.69 4.88 4.90 4.75

80 3.80 4.85 4.87 4.72

90 3.91 4.86 4.88 4.73

100 6.34 4.21 4.26 4.10

110 8.07 4.28 4.32 4. 16

120 9.28 4.34 4.39 4.22

130 10.12 4.39 4.44 4.27

140 10.75 4.43 4.48 4.31

150 11 .10 4.45 4.49 4.33

160 11.30 4.46 4.50 4.34

170 11.40 4.41 4.45 4.28

180 11 .40 4.38 4.42 4.26

190 11.30 4.40 4.44 4.28

200 11 .10 4.91 4.93 4.78

210 10. 75 4.85 4.87 4.72

220 7.20 4.79 4.81 4.66

230 6.57 4.76 4.78 4.63

240 5.69 4.73 4.75 4.61

250 4.52 4.76 4.78 4.64

260 2.79 4.77 4.79 4.65

270 2.71 4.77 4.78 4.64

280 4.03 4.73 4.74 4.61

290 4.80 4.71 4.72 4.59

300 5.11 4.69 4.71 4.57

310 5.19 4.69 4.70 4.57

320 5.08 4.70 4.71 4.58

330 4.92 4.71 4.72 4.59

340 4.77 4.67 4.69 4.55

350 4.66 4.69 4.70 4.57

*1430 kHz 50% RSS site-to-site value.

31
Table A-5

Station Call: KLO

Interference I Imi t

Azimuth Distance to Interference 50% RSS Value (mVjm)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 30.96 2.68 2.70 2.72

10 31.42 2.66 2.68 2.70

20 32.83 2.64 2.66 2.68

30 30.67 2.63 2.64 2.66

40 28.52 2.62 2.63 2.65

50 25.60 2.62 2.63 2.64

60 21.59 2.63 2.64 2.65

70 21 . 16 2.95 2.96 2.65

80 18.07 2.97 2.97 2.98

90 15.21 2.98 2.98 2.99

100 11.72 2.67 2.99 3.00

110 10.98 2.68 2.69 2.69

120 14.47 2.71 2.71 2.71

130 17.55 2.74 2.73 2.73

140 19.02 2.77 2.77 2.76

150 20.75 2.81 2.80 2.80

160 25.31 2.87 2.86 2.86

170 28.95 2.93 2.92 2.91

180 24.05 2.88 2.87 2.87

190 17.70 2.83 2.'82 2.82

200 12.55 2.78 2.78 3.79

210 13.58 2.79 2.79 2.79

220 14.91 2.79 2.79 2.79

230 14.48 2.78 2.78 2.79

240 15.55 2.77 2.78 2.79

250 19.74 2.78 2.79 2.80

260 25.78 2.79 2.80 2.81

270 30.08 2.50 2.52 2.54

280 32.86 2.52 2.54 2.57

290 34.04 2.53 2.55 2.58

300 33.49 2.52 2.55 2.58

310 30.72 2.78 2.81 2.54

320 24.70 2.74 2.76 2.79

330· 13.99 2.69 2.71 2.73

340 22. 14 2.69 2.71 2.73

350 28.50 2.69 2.71 2.74

*1430 kHz 50% RSS site-to-site value.

3i."
Table A-6

Station Call: WEIR

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 8.22 4.84 4.84 4.83

10 8.00 4.85 4.84 4.84

20 7.55 4.82 4.82 4.81

30 6.77 4.78 4.77 4.77

40 5.65 4.64 4.63 4.62

50 4.43 4.59 4.58 4.57

60 3.50 4.55 4.54 4.54

70 3.43 4.54 4.53 4.52

80 3029 4.52 4.51 4.51

90 3.60 4.51 4.51 4.50

100 5.23 4.52 4.51 4.50

110 6.95 4.49 4.48 4.47

120 8.35 4.49 4.47 4.46

130 9.42 4.47 4.46 4.45

140 10.18 4.47 4.46 4.45

150 10.75 4.47 4.46 4.45

160 11 .06 4.47 4.45 4.44

170 11 .20 /I /1/1 /I /I') I • II ~.~v 4.41

180 11 .22 4.42 4.40 4.39

190 11 . 13 4.39 4.38 4.36

200 10.90 4.44 4.43 4.42

210 10.45 4.42 4.41 4.40

220 9.75 4.40 4.39 4.39

230 8.79 4.41 4.40 4.39

240 7.56 4.43 4.42 4.41

250 5.94 4.47 4.46 4.45

260 4.19 4.50 4.49 4.48

270 3.24 4.53 4.52 4.51

280 3.41 4.54 4.53 4.52

290 3.41 4.56 4.55 4.54

300 3.94 4.58 4.57 4.57

310 5.18 4.62 4.61 4.61

320 6.34 4.67 4.67 4.66

330 7.27 4.74 4.73 4.73

340 7.85 4.79 4.78 4.78

350 8.17 4.83 4.82 4.82

*1430 kHz 50% RSS site-to-site value.

33
Table A-7

Station Call: WJRB

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free CQntour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 0.95 22.33 22.34 22.35

10 0.86 22.33 22.34 22.35

20 1.24 22.34 22. 35 . 22.36

30 1.46 22.34 22.35 22.36

40 1.24 22.34 22.35 22.36

50 0.92 22.34 22.35 22.36

60 1.81 22.36 22.36 22.37

70 2.78 22.37 22.38 22.39

80 3.46 22.39 22.40 22.41

90 3.84 22.34 22.35 22.36

100 3.96 22.34 22.35 22.36

110 3.93 22.29 22.30 22.31

120 3.81 22.23 22.24 22.25

130 3.68 22.22 22.23 22.24

140 3.61 22.45 22.46 22.47

150 3.65 22.44 22.45 22.46

160 3.79 22.43 22.45 22.46

170 3.98 22.37 22.38 22.39

180 4.27 22.36 22.37 22.38

190 4.52 22.29 22.31 22.32

200 4.73 22.28 22.29 22.30

210 4.83 22.32 22.33 22.34

220 4.77 22.31 22.32 22.33

230 4.47 22.35 22.37 22.38

240 3.90 22.12 22.13 22.14

250 3.07 22.18 22. '9 22.20

260 2.01 22.19 22.20 22.21

270 1. '9 22.26 22.27 22.28

280 1.30 22.25 22.26 22.27

290 1.34 22.25 22.26 22.27

300 1.00 22.26 22.27 22.28

310 0.52 22.27 22.28 22.29

320 0.90 22.32 22.33 22.34

330 1.29 22.32 22.33 22.34

340 1.43 22.32 22.33 22.34

350 1.27 22.32 22.33 22.34

*1430 kHz 50% RSS site-to-site value.

34
Table A~8

Station Call: KRGI

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 12.48 17.12 17.20 17.21

10 12.39 17.23 17. 31 17.32

20 12.10 17.30 17.39 17.39

30 11 .53 17.35 17.44 17.44

40 10.72 17.33 17.41 17.42

50 9.60 17.28 17.37 17.38

60 8.06 17. 19 17.28 17.29

70 6. 18 17.05 17.14 17. 14

80 3.99 16.92 17.00 17. 01

90 1.75 16.75 16.83 16.84

100 1.61 16.75 16.83 16.84

110 2.56 16.76 16.85 16.85

120 2.80 16.75 16.83 16.84

130 2.44 16.71 16.80 16.80

140 1.72 16.68 16.76 16. 77

150 1.21 16.66 16.74 16.75

160 1.58 16.63 16.72 16.73

170 2.09 16.62 16. 70 16.71

180 2.26 16.60 16.68 16.69

190 2.09 16.56 16.64 16.65

200 1.58 16.58 16.67 16.68

210 1. 21 16.59 16".68 16.68

220 1.72 16.58 16.66 16.67

230 2.44 16.53 16.61 16.62

240 2.80 16.49 16.58 16.59

250 2.56 16.52 16.61 16.61

260 1.61 16.59 16.67 16.68

270 1.75 16.60 16.68 16.69

280 3.99 16.49 16.58 16.58

290 6.18 16.44 16.52 16.53

300 8.06 16.44 16.52 16.53

310 9.60 16.49 16.58 16.58

320 10.72 16.59 16.68 16.68

330 11 .53 16. 71 16.79 16.80

340 12.10 16.86 16.94 16.95

350 12.39 16.99 17.07 17.08

*1430 kHz 50% RSS site-to-site value.
Table A~9

Station Call: KEES

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mVjm)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 1. 11 27.48 27.54 27.49

10 0.98 27.48 27.54 27.48

20 0.62 27.41 27.47 27.42

30 0.48 27 . 41 27.47 27.42

40 1.26 27.47 27.53 27.48

50 2.13 27.47 27.52 27.47

60 2.93 27.46 27 .51 27.46

70 3.66 27.38 27.44 27.39

80 4.28 27.38 27.43 27.38

90 4.72 27.30 27.36 27.31 .

100 4.99 27.24 27.29 27.24

110 5.13 27.17 27.23 27 . 18

120 5.15 27.11 27 .17 27.11

130 5.06 27.12 27.17 27.12

140 4.92 27.06 27.11 27.06

150 4.75 27.06 27 . 12 27.07

160 4.59 27.07 27.13 27.08

170 4.47 27.08 27 .14 27.08

180 4.43 27.15 27.21 27.16

190 4.47 27 .16 27.22 27 .16

200 4.59 27.17 27.22 27.17

210 4.75 27 ..17 27.23 27.18

220 4.92 27.25 27.30 27.25

230 5.06 27.32 27.38 27.32

240 5.15 27.32 27.38 27.33

250 5.13 27.39 27.45 27.40

260 4.99 27.46 27.52 27.46

270 4.72 27.53 27.58 27.53

280 4.28 27.52 27.58 27.52

290 3.66 27.58 27.64 27.58

300 2.93 27.57 27.63 27.57

310 2.13 27.56 27.62 27.57

320 1.26 27.49 27.55 27.49

330 0.48 27.42 27.47 27.42

340 0.62 27.42 27.47 27.42

350 0.98 27.48 27.54 27.49

*1430 kHz 50% RSS site-to-site value.

36
Table A~10

Station Call: KBRC

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 9.55 3.76 3.74 3.73

10 9.74 3.75 3.72 3.72

20 9.85 3.75 3.72 3.72

30 9.87 3.75 3.73 3.73

40 9.75 3.76 3.74 3.73

50 9.45 3.79 3.76 3.76

60 8.92 3.82 3.79 3.79

70 8.34 3.85 3.82 3.82

80 7.60 3.89 3.86 3.86

90 6.79 3.S2 3.90 3.90

100 6.06 3.95 3.93 3.92

110 5.57 3.97 3.95 3.95

120 5.42 3.99 3.97 3.97

130 5.43 4.01 3.99 3.98

140 5.45 4.03 4.01 4.00

150 5.43 4.05 4.03 4.02

160 5.41 4.06 4.03 4.03

170 5.52 4.07 4.05 4.05

180 5.94 4.08 4.06 4.06

190 6.63 4. 11 4.08 4.08

200 7.44 4.12 4.10 4.09

210 8. 19 4.13 4. 11 4.11

220 8.82 4. 14 4. 11 4.11

230 9.37 4.13 4.10 4.10

240 9.70 4.10 4.08 4.08

250 9.85 4.08 4.06 4.06

260 9.87 4.04 4.02 4.02

270 9.77 4.01 3.99 3.98

280 9.59 3.97 3.95 3.95

290 9.37 3.94 3.92 3.91

300 9. 14 3.90 3.88 3.87

310 8.98 3.87 3.85 3.84

320 8.91 3.85 3.83 3.82

330 8.95 3.82 3.80 3.79

340 9. 11 3.79 3.77 3.77

350 9.32 3.74 3.75 3.75

*1430 kHz 50% RSS site-to-site value.

37

Table A~12

Station Call: KARM

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 14.97 2.53 2.47 2.43

10 17.23 2.55 2.49 2.45

20 22.69 2.61 2.55 2.51

30 15.98 2.51 2.46 2.42

40 14.76 2.47 2.42 2.38

50 12.63 2.42 2.36 2.33

60 13.90 2.40 2.35 2.31

70 18.30 2.67 2.63 2.60

80 22.47 2.65 2.61 2.58

90 26.13 2.64 2.60 2.57

100 27.64 2.58 2.54 2.52

110 33.34 2.53 2.50 2.48

120 34.68 2.46 2.43 2.43

130 34.42 2.37 2.35 2.35

140 30.74 2.05 2.02 2.25

150 29.34 2.03 2.00 1.99

160 27.40 2.03 1.99 1.98

170 25.09 2.04 2.00 1.98

180 23.09 2.07 2.03 2.00

190 21.48 2.09 2.05 2.02

200 20.55 2. 11 2.06 2.03

210 20.55 2.13 2.09 2.06

220 21.48 2.15 2.10 2.07

230 23.09 2.17 2.13 2.10

240 25.09 2.21 2.16 2. 13

250 27.40 2.25 2.20 2.17

260 29.34 2.31 2.26 2.22

270 30.74 2.37 2.32 2.28

280 31.41 2.43 2.38 2.34

290 31.40 2.50 2.44 2.40

300 30.62 2.56 2.50 2.46

310 32.45 2.63 2.57 2.53

320 31.92 2.69 2.63 2.59

330 28.21 2.68 2.62 2.58

340 22.79 2.63 2.58 2.53

350· 13.90 2.51 2.46 2.42

*i430 kHz 50% RSS site-to-site value.
Table A-13

Station Call: KALI

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 0.58 25.06 25.05 25.04

10 1.00 25.09 25.08 25.07

20 1.58 25.21 25.20 25.19

30 1. 91 25.25 25.24 25.23

40 1. 91 25.18 25.17 25.16

50 1.58 25.16 25.16 25.15

60 1.00 25.12 25.11 25.10

70 0.58 25.01 25.00 24.99

90 0.96 25.04 25.03 25.02

90 1. 12 25.05 25.04 25.03

100 0.69 25.01 25.00 24.99

110 1.36 25.04 25.03 25.03

120 3.13 24.95 24.94 24.93

130 4.92 24.81 24.80 24.79

140 6.50 24.62 24.61 24.60

150 7.78 24.47 24.46 24.45

160 8.79 24.86 24.86 24.85

170 9.58 24.65 24.65 24.64

180 1, . 17 24.48 24.47 24.46

190 11.65 24.32 24.31 24.30

200 12.46 24.22 24.21 24.20

210 13. 17 23.58 23.56 23.55

220 12.63 23.67 23.65 23.64

230 12.46 23.76 23.75 23.73

24,0 11 .65 24.01 24.00 23.98

250 10.12 24.29 24.27 24.25

260 9.58 23.84 23.82 23.80

270 8.79 24.02 24.00 23.98

280 7.78 24.22 24.20 24.18

290 6.50 24.36 24.35 24.33

300 4.92 24.51 24.49 24.47

310 3.13 24.48 24.46 24.44

320 1.36 25.09 25.08 25.07

330 0.69 25.04 25.03 25.02

340 1. 12 25.13 25.12 25.11

350 0.96 25.06 25.06 25.05

*1430 kHz 50% RSS site-to-site value.

40
Table A-14

Station Call: KNTA

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mVjm)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 0.55 23.18 23.08 22.97

10 0.47 23.18 23.08 22.97

20 0.47 17.02 16.87 16. 71

30 0.54 17.02 16.87 16. 71

40 0.56 17.02 16.87 16.71

50 0.50 17.03 16.87 16.71

60 0.45 17.03 16.87 16.71

70 0.51 17.03 16.87 16.72

80 0.57 17.03 16.87 16.72

90 0.54 17.03 16.88 16.72

100 0.46 17.03 16.88 16.72

110 0.46 17.04 16.88 16.72

120 0.46 17.04 16.88 16.72

130 0.82 17.04 16.89 16.73

140 1.87 17.13 16.97 16.81

150 3.11 17.22 17.06 16.90

160 4.41 17.25 17.09 16.93

170 5.48 17.27 17 . 12 16.95 ., nn

I~U 6.40 17.22 17.07 16.91

190 7.02 17 . 16 17. 01 16.85

200 7.49 23.38 23.27 23.16

210 7.73 23.30 23.20 23.09

220 7.77 23.15 23.04 22.93

230 7.61 23.06 22.95 22.84

240 7.23 23.04 22.93 22.82

250 6.69 22.94 22.83 22.72

260 5.88 22.90 22.80 22.69

270 4.86 22.95 22.84 22.73

280 3.63 22.99 22.89 22.78

290 2.35 23.05 22.94 22.83

300 1. 19 23.12 23.01 22.90

310 0.50 23.19 23.09 22.98

320 0.46 23.19 23.09 23.98

330 0.45 23.19 23.08 22.97

340 0.50 23.19 23.08 22.97

350 0.57 23.18 23.08 22.97

*1430 kHz 50% RSS site-to-site value.

41
Table A-15

Station Call: WQDI

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mVjm)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 6.98 8.76 8.76 8.76

10 7.55 8.76 8.76 8.76

20 7.89 8.76 8.76 8.76

30 8.10 8.73 8.73 8.73

40 8.21 8.68 8.68 8.68

50 8.25 8.65 8.65 8.65

60 8.27 8.63 8.63 8.63

70 8.25 8.67 8.67 8.67

80 8.21 8.64 8.64 8.65

90 s. 10 8.62 8.62 8.62

100 7.89 8.57 8.57 8.57

110 7.55 8.57 8.57 8.57

120 6.·98 8.54 8.54 8.55

130 6.29 8.54 8.54 8.55

140 5.46 8.57 8.57 8.57

150 4.97 8.57 8.57 8.57

160 5.22 8.57 8.57 8.57

170 5.98 8.54 8.54 8.55

180 6.74 8.54 8.54 8.55

190 7.31 8.54 8.54 8.55

200 7.73 8.57 8.57 8.57

210 7.97 8.59 8.59 8.60

220 8.12 8.62 8.62 8.62

23-0 8.19 8.64 8.64 8.65

240 8.21 8.67 8.67 8.67

250 8.19 8.63 8.63 8.63

260 8.12 8.65 8.65 8.65

270 7.97 8.71 8.71 8.71

280 7.73 8.73 8.73 8.73

290 7.31 8.73 8.73 8.73

300 6.74 8.76 8.76 8.76

310 5.98 8.76 8.76 8.76

320 5.22 8.73 8.73 8.73

330 4.97 8.73 8.73 8.73

340 5.46 8.76 8.76 8.76

350 6.29 8.76 8.76 8.76

*1430 kHz 50% RSS site-to-site value.

l' '1 rL
Table A-16

Station Call: WQPD

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mVjm)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 4. 14 8.81 8.82 8.84

10 4.14 8.81 8.83 8.84

20 4.14 8.82 8.83 8.84

30 4.14 8.80 8.82 8.83

40 4.14 8.81 8.82 8.83

50 4.14 8.80 8.81 8.82

60 4.14 8.78 8.79 8.80

70 4.14 8.77 8.78 8.80

80 4.14 8.75 8.77 8.78

90 4.14 8.74 8.75 8.76

100 4.14 8.72 8.74 8.75

110 4.14 8.71 8.72 8.73

120 4.14 8.68 8.69 8.71

130 4. 14 8.67 8.69 8.70

140 4.14 8.66 8.67 8.68

150 4.14 8.65 8.66 8.67

160 4.14 8.63 8.64 8.66

17 n /I 1 /I n r" n rll

I U '1'.I'"t o.o~ 0.0"1- 8.65

180 4.14 8.62 8.63 8.64

190 4.14 8.6.3 8.64 8.65

200 4. 14 8.63 8.64 8.65

210 4.61 8.62 8.64 8.65

220 4.61 8.63 8.65 8.66

230 4.61 8.63 8.64 8.66

240 4.61 8.65 8.66 8.67

250 4.61 8.67 8.68 8.69

260 4.14 8.69 8.70 8.72

270 4.61 8.70 8.72 8.73

280 4.14 8.72 8.73 8.74

290 4.14 8.74 8.75 8.77

300 4.14 8.75 8.77 8.78

310 4.14 8.77 8.78 8.79

320 4.14 8.78 8.79 8.81

330 4.14 8.79 8.81 8.82

340 4. 14 8.80 8.81 8.82

350 4.14 8.81 8.82 8.83

*1430 kHz 50% RSS site-to-site value.
Table A~17

Station Call: WWGS

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 0.88 22.12 22.06 22.00

10 0.95 22.13 22.07 22.00

20 0.41 22.22 22.16 22.10

30 1. 15 22.18 22.12 22.05

40 2.42 22.04 . 21 .98 21.92

50 3.51 21.84 21.78 21 .71

60 4.39 21 .96 21.89 21.83

70 5.00 22.19 22.13 22.07

80 5.43 22.43 22.37 22.31

90 5.59 22.66 22.60 22.53

100 5.55 22.88 22.82 22.76

lTO 4.54 23.05 22.99 22.93

120 4.19 23.12 23.06 23.00

130 3.66 23.12 23.06 23.01

140 3.06 23.00 22.94 22.88

150 1.93 22.80 22.74 22.68

160 0.69 22.49 22.43 22.37

170 0.57 22.47 22.41 22.35

180 0.88 22.51 22.45 22.39

190 0.77 22.46 22.40 22.34

200 0.47 22.41 22.35 22.29

210 0.27 22.37 22.31 22.25

220 0.30 22.36 22.30 22.24

2310 0.68 22.36 22.30 22.24

240 1.24 22.38 22.31 22.25

250 1.74 22.29 22.23 22.16

260 2.02 22.24 22. 18 22.12

270 2.00 22.13 22.07 22.00

280 1.67 22.12 22.06 22.00

290 0.97 22.16 22.10 22.04

300 0.32 22.27 22.21 22.15

310 1.03 22.11 22.05 21.98

320 1.25 22.04 21.98 21.92

330 1. 12 22.08 22.01 21.95

340 0.61 22.21 22.15 22.09

350 0.38 22.27 22.21 22.15

*1430 kHz 50% RSS site-to-site value.

4·4
Table A-18

Station Call: WWWQ

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(Ndegrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 1.40 15.40 15.44 15.47

10 1.08 15.41 15.44 15.47

20 1. 16 15.39 15.43 15.46

30 1.75 15.39 15.43 15.46

40 1.69 15.39 15.43 15.46

50 1.00 15.37 15.40 15.44

60 3.17 15.36 15.40 15.43

70 4.57 15.34 15.38 15.41

80 5.29 15.32 15.36 15.39

90 5.21 15.28 15.32 15.35

100 4.32 15.28 15.31 15.34

110 2~68 15.30 15.34 15.37

120 1.09 15.33 15.37 15.40

130 1.83 15.31 15.35 15.38

140 1.04 15.33 15.37 15.40

150 1.69 15.30 15.33 15.37

160 2.66 15.28 15.31 15.35

170 3.13 15.28 15.32 15.35

180 3.24 15.28 15.32 15.35

190 3.01 15.30 15.33 15.36

200 2.36 15.32 15.35 15.39

210 1.00 15.35 15.39 15.42

220 1.54 15.35 15.39 15.42

230 1.75 15.35 15.39 15.42

240 1.31 15.37 15.41 15.44

250 3.43 15.39 15.43 15.46

260 4.77 15.42 15.46 15.49

270 5.34 15.45 15.49 15.52

280 5.08 15.48 15.52 15.55

290 4.09 15.47 15.51 15.54

300 2.43 15.43 15.47 15.50

310 0.93 15.40 15.43 15.46

320 1.83 15.42 15.46 15.49

330 1.57 15.42 15.46 15.49

340 0.94 15.41 15.45 15.48

350 1.25 15.41 15.44 15.48

*1430 kHz 50% RSS site-to-site value.
Table A-19

Station Call: WIRE

Interference Limit

Azimuth Di·stance to Interference 50% RSSValue (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 26.72 . 3.67 3.65 3.66

10 26.86 3.64 3.63 3.63

20 26.19 3.64 3.62 3.63

30 25.71 3.63 3.61 3.62

40 21.63 3.64 3.62 3.63

50 20.10 3.64 3.62 3.63

60 17.57 3.64 3.62 3.63

70 13.62 3.65 3.64 3.64

80 7.90 3.69 3.67 3.68

90 12.37 3.66 3.26 3.65

100 16.75 3.65 3.67 3.65

110 19.33 3.67 3.72 3.67

120 20.97 3.70 3.79 3.69

130 21.85 3.73 3.85 3.33

140 22.27 3.37 3.91 3.36

150 22.48 3.40 3.95 3.39

160 22.57 3.43 3.98 3.42

170 22.57 3.45 3.99 3.44

180 22.48 3.47 3.99 3.46

190 22.27 3.47 3.97 3.46

200 21.85 3.47 3.94 3.46

210 20.97 3.46 3.90 3.46

220 19.33 3.45 3.45 3.44

230 16.75 3.84 3.43 3.83

240 12.37 3.83 3.82 3.82

250 7.90 3.81 3.80 3.80

260 13.62 3.85 3.83 3.84

270 17.57 3.88 3.86 3.87

280 20.09 3.89 3.87 3.88

290 21.63 3.88 3.86 3.87

300 22.31 3.86 3.84 3.85

310 23.29 3.84 3.83 3.83

320 22.67 3.81 3.80 3.80

330 24.90 3.77 3.76 3.76

340 25.95 3.73 3.72 3.72

350 26.60 3.70 3.68 3.69

*1430 kHz 50% RSS site-to-site value.

46
Table A-20

Station Call: WYMC

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 1.06 20.61 20.65 20.75

10 1.08 20.59 20.63 20.73

20 1.08 20.59 20.63 20.73

30 1.06 20.60 20.64 20.74

40 1. 12 20.61 20.64 20.75

50 1. 21 20.61 20.65 20.75

60 1.20 20.62 20.66 20.76

70 1.04 20.62 20.66 20.76

80 1. 13 20.63 20.67 20.77

90 1.67 20.65 20.68 20.79

100 2.04 20.65 20.69 20.79

110 1.98 20.67 20.71 20.81

120 1.33 20.65 20.68 20.79

130 1.52 20.65 20.68 20.78

140 2.95 21 .57 21 .61 21.72

150 4.04 21.59 21.63 21.74

160 4.83 21.59 21.63 ?1 7/1. '- I • I I

170 5.35 21.59 21.63 21.75

180 5.65 21.58 21.62 21.73

190 5.83 21.58 21.62 21.74

200 5.83 21.59 21.63 21.75

210 5.65 21.58 21.62 21.74

220 5.35 20.82 20.86 20.96

230 4.83 20.82 20.86 20.96

240 4.04 20.81 20.85 20.96

250 2.95 20.80 20.84 20.94

260 1.52 20.80 20.84 20.95

270 1.33 20.61 20.64 20.75

280 1.97 20.60 20.64 20.75

290 2.04 20.58 20.62 20.72

300 1.67 20.58 20.61 20.72

310 1. 13 20.59 20.62 20.73

320 1.04 20.62 20.66 20.76

330 1.20 20.60 20.64 20.75

340 1.21 20.60 20.64 20.74

350 1-. 12 20.60 20.64 20.75

*1430 kHz 50% RSS site-to-site value.

47
Table A-21

Station Call: WIL

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 33.21 7.36 7.37 7.36

10 30.54 6.78 6.79 6.78

20 26.53 6.16 6.16 6.15

30 20.33 5.56 5.56 5.54

40 13.96 5.25 5.25 5.24

50 5.97 5.19 5.19 5.18

60 5.86 5.18 5.19 5.17

70 5.26 5.18 5.18 5.17

80 6.06 5.18 5.18 5.17

90 8.20 5.19 5.20 5.18

100 7.04 5.20 5.21 5.19

110 5.99 5.22 5.22 5.21

120 13.42 5.44 5.45 5.43

130 18.49 5.81 5.82 5.81

140 22.11 6.17 6.18 6.17

150 24.42 6.47 6.48 6.48

160 25.07 6.49 6.51 6.50

170 24.42 6.35 6.36 6.35

180 22.11 6.14 6.15 6.13

190 18.49 5.80 5.80 5.79

200 13.42 5.50 5.50 5.49

210 5.99 5.27 5.28 5.26

220 7.04 5.27 5.28 5.26

230 8.20 5.30 5.31 5.29

240 6.06 5.25 5.26 5.24

250 5.26 5.25 5.26 5.24

260 5.86 5.27 5.27 5.26

270 5.96 5.28 5.28 5.27

280 13.96 5.46 5.47 5.45

290 20.33 5.77 5.77 5.76

300 26.53 6.25 6.26 6.25

310 30.54 6.77 6.78 6.77

320 33.21 7.24 7.26 7.25

330 34.63 7.52 7.53 7.52

340 35.05 7.69 7.70 7.70

350 34.63 7.61 7.62 7.62

*1430 kHz 50% RSS site-to-site value.

48
Table A~22

Station Call: WNJR

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mVjm)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 14.50 2.61 2.65 2.60

10 16.25 2.69 2.90 2.68

20 17.61 2.66 2.80 2.65

30 18.75 2.61 2.69 2.60

40 19.42 2.56 2.66 2.55

50 19.71 2.50 2.59 2.49

60 19.73 2.45 2.58 2.43

70 19.54 2.42 2.71 2.40

80 19.21 2.44 2.80 2.42

90 18.83 2.48 2.61 2.46

100 16.66 2.49 2.68 2.47

110 15.37 2.53 2.74 2.50

120 15.36 2.58 2.77 2.56

130 15.47 2.64 2.77 2.62

140 14.83 2.60 2.73 2.58

150 14.63 2.63 2.73 2.61

160 14.36 2.65 2.72 2.63

170 19.7i 2.54 2.73 2.53

180 19.74 2.54 2.98 2.55

190 19.51 2.55 2.92 2.55

200 18.92 2.51 2.85 2.51

210 17.82 2.40 2.69 2.41

220 16.58 2.60 2.64 2.59

230 14. 91 2.53 2.63 2.52

240 12.82 2.47 2.69 2.46

250 10.61 2.42 2.70 2.41

260 8.27 2.42 2.49 2.42

270 7.30 2.43 2.54 2.42

280 7.98 2.44 2.56 2.43

290 8.63 2.45 2.58 2.45

300 8.69 2.47 2.61 2.46

310 8. 16 2.48 2.64 2.47

320 7.37 2.48 2.64 2.47

330 7.88 2.50 2.65 2.49

340 10.06 2.53 2.66 2.53

350 12.40 2.58 2.68 2.57

*1430 kHz 50% RSS site-to-site value.

49
Table A-23

Station Call: KKAT

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 3.06 15.34 15.35 15.33

10 2.79 15.35 15.36 15.34

20 0.98 15.34 15.36 15.34

30 3.05 15.37 15.38 15.36

40 4.61 15.38 15.40 15.38

50 4-.58 15.42 15.43 15.41

60 2.51 15.37 15.39 15.36

70 2.92 15.38 15.39 15.37

80 7.10 15.45 15.47 15.45

90 10.31 15.53 15.54 15.52

100 12.63 15.58 15.59 15.57

110 13.78 15.55 15.57 15.55

120 14.32 15.51 15.53 15.51

130 14.32 15.47 15.49 15.47

140 13.78 15.43 15.45 15.43

'50 12.63 15.39 15.40 15.38

160 10.31 15.34 15.36 15.34

170 7.10 15.33 15.34 15.32

180 2.92 15.32 15.33 15.31

190 2.51 15.31 15.33 15.30

200 4.58 15.29 15.31 15.29

210 4.61 15.27- 15.29 15.27

220 2.60 15.30 15.32 15.30

230 0.90 15.31 15.33 15.31

240 2.40 15.30 15.31 15.29

250 3.06 15.28 15.30 15.27

260 2.71 15.30 15.31 15.29

27D 1.48 15.31 15.32 15.30

280 1.42 15.31 15.32 15.30

290 2.80 15.30 15.31 15.30

300 3.49 15.29 15.31 15.29

310 3.49 15.30 15.32 15.29

320 2.80 15.31 15.32 15.30

330 1.42 15.33 15.34 15.32

340 1.48 15.33 15.34 15.32

350 2.71 15.33 15.35 15.33

*1430 kHz 50% RSS site-to-site value.

50
Table A-24

Station Call: WENE

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 8.91 8.83 8.83 8.82

10 10.80 8.78 8.77 8.77

20 12. 15 8. 71 8.70 8.70

30 13.08 8.63 8.63 8.62

40 13.66 8.55 8.55 8.54

50 13.85 8.48 8.48 8.47

60 13.73 8.41 8.41 8.40

70 13.23 8.36 8.36 8.35

80 12.32 8.21 8.21 8.20

90 11 .01 8.22 8.21 8.21

100 9.03 8.28 8.28 8.27

110 6.61 8.15 8.15 8.14

120 3.61 8.27 8.26 8.25

130 1.86 8.34 8.33 8.32

140 2.02 8.34 8.33 8.32

150 2.62 8.33 8.32 8.31

160 3.68 8.32 8.31 8.30

170 4.35 8.33 8.32 8.31

180 4.17 8.35 8.34 8.33

190 3.61 8.38 8.37 8.36

200 2.97 8.41 8.40 8".39

210 2.48 8.42 8.41 8.40

220 2.24 8.44 8.43 8.42

230 2.21 8.45 8.44 8.43

240 2.37 8.46 8.45 8.45

250 2.68 8.48 8~47 8.46

260 3.05 8.50 8.49 8.48

270 3.51 8.52 8.51 8.50

280 4.12 8.54 8.54 8.53

290 4.69 8.57 8.56 8.55

300 4.94 8.57 8.56 8.55

310 4.88 8.55 8.54 8.53

320 4.71 8.54 8.53 8.52

330 4.75 8.52 8.51 8.50

340 5.34 8.66 8.65 8.64

350 6.97 8.65 8.64 8.63

*1430 kHz 50% RSS site-to-site value.

51
Table A~25

Station Ca11: WMNC

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mVjm)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 1.25 22.76 22.46 22.79

10 1. 15 22.76 22.46 22.79

20 1. 17 22.76 22.46 22.79

30 1.25 22.76 22.46 22.79

40 1.06 22.73 22.42 22.76

50 0.65 22.73 22.43 22.76

60 1.69 22.73 22.42 22.76

70 2.55 22.71 22.40 22.74

80 3.18 22.69 22.38 22.72

90 3.55 22.66 22.35 22.69

100 3.82 22.61 22.31 22.64

110 3.95 22.62 22.31 22.65

120 4.02 22.60 22.29 22.63

130 4.01 22.59 22.28 22.62

140 3.94 22.59 22.29 22.62

1"50 3.78 22.61 22.30 22.64

160 3.49 22.61 22.31 22.64

170 3.07 22.65 22.34 22.68

180 2.40 22.66 22.36 22.69

190 1.48 22.71 22.40 22.74

200 0.61 22.72 22.42 22.75

210 1.14 22.74 22.43 22.77

220 1.25 22.74 22.43 22.77

230 1.15 22.74 22.43 22.77

240 1. 17 22.73 22.42 22.75

250 1.26 22.76 22.46 22.79

260 1.24 22.76 22.45 22.79

270 1.06 22.75 22.45 22.78

280 0.88 22.75 22.45 22.78

290 0.92 22.75 22.45 22.78

300 1.02 22.77 22.47 22.80

310 1.01 22.77 22.46 22.80

320 0.90 22.77 22.46 22.80

330 0.90 22.77 22.46 22.80

340 1.10 22.76 22.46 22.79

350 1.25 22.76 22.46 22.79

*1430 kHz 50% RSS site-to-site value.

52
Table A~·26

Station Call: WFOB

Interference Ljmjt

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 13.38 15.43 15.42 15.42

10 12.85 15. 12 15. 11 15. 11

20 11.89 15.26 15.26 15.26

30 10.45 14.89 14.89 14.89

40 8.65 14.10 14.10 14.09

50 6.35 13.90 13.89 13.89

60 3.90 13.80 13.80 13.80

70 1.72 13.83 13.83 13.83

80 1.50 13.84 13.83 13.83

90 1.56 13.79 13.79 13.79

100 1.44 13.77 13.76 13.76

110 2.88 13.52 13.52 13.51

120 4.74 13.21 13.20 13.20

130 6.26 12.91 12.90 12.90

140 7.44 12.69 12.69 12.69

150 8.18 12.57 12.57 12.56

160 8.50 12.56 12.56 12.55

170 8.37 12. 11 12. 11 12.10

180 7.78 12.33 12.32 12.31

190 6.79 12.59 12.58 12.57

200 5.42 12.87 12.87 12.86

210 3.64 13.12 13.11 13.10

220 1.87 13.27 13.27 13.26

230 1.42 13.34 13.33 13.32

240 1.61 13.38 13.37 13.36

250 1.37 13.41 13.41 13.40

260 2.93 13.57 13.57 13.56

270 5.44 13.93 13.92 13.92

280 7.76 14.34 14.33 14.32

290 9.77 14.74 14.73 14.72

300 11 .33 15~1 0 15.09 15.08

310 12.54 15.30 15.29 15.28

320 1'3.21 15.37 15.36 15.35

330 13.56 16.10 16.09 16.09

340 13.69 15.92 15.92 15.92

350 13.63 15.71 15. 71 15.70

*1430 kHz 50% RSS site-to-site value.

53
TableA-27

Station Call: WNAV

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mVjm)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 4.30 15.84 15.72 15.61

10 4.01 15.88 15.76 15.64

20 3.59 15.93 15.81 15.69

30 2.98 15.94 15.82 15.70

40 2.17 15.98 15.86 15.74

50 1.80 15.98 15.87 15.75

60 2.69 15.99 15.87 15.76

70 3.65 16.02 15.90 15.79

80 4.42 16.05 15.93 15.81

90 4.99 16.09 15.98 15.85

100 5.46 16. 14 16.02 15.90

110 5.81 16. 19 16.07 15.95

120 6.08 16.78 16.66 16.55

130 6.26 16.81 16.70 16.58

140 6.38 16.83 16. 71 16.60

150 6.47 17.83 17.72 17.62

160 6.51 17.81 17.70 17.60

170 6.50 17.77 17.67 17.56

180 6.46 17 . 17 17.06 16.95

190 6.36 17 . 12 17 .01 16.. 90

200 6.23 17.09 16.98 16.87

210 6.04 17.05 16.94 17.83

220 5.74 17.00 16.89 16.79

230 5.38 16.95 16.85 16.74

240 4.90 16.93 16.83 16.72

2.50 4.29 16.92 16.81 16.71

260 3.47 16.90 16.79 16.69

270 2.48 16.91 16.80 16.69

280 1.75 16.88 16.77 16.66

290 2.34 16.86 16.75 16.64

300 3. 12 15.92 15.80 15.69

310 3.70 15.88 15.77 15.66

320 4.08 15.86 15.75 15.63

330 4.33 15.84 15.73 15.62

340 4.44 15.82 15.71 15.60

350 4.43 15.85 15.73 15.62

*1430 kHz 50% RSS site-to-site value.
Tab1 e A~,28

Station Call: KOSI

Interference Limit

Azimuth Distance to Interference 50% RSS Value (mV/m)

(N degrees E) Free Contour* (miles) 1426 kHz 1430 kHz 1434 kHz

0 33.91 6.24 6.25 6.30

10 34.31 6.26 6.27 6.32

20 33.91 6. 19 6.20 6.25

30 32.57 6.76 6.78 6.81

40 30.12 6.50 6.52 6.55

50 26.23 6.22 6.23 6.26

60 19.96 5.94 5.94 5.96

70 13.80 5.77 5.78 5.79

80 6.09 5.66 5.66 5.67

90 4.51 6.32 6.32 6.32

100 4.40 6.31 6.31 6.32

110 4.69 6.32 6.31 6.32

120 4.54 6.31 6.31 6.31

130 8.31 6.31 6.31 6.31

140 12.66 6.31 6.31 6.31

150 14.81 6.34 6.33 6.33

160 15.60 6.38 6.37 6.36

170 15.39 6.40 6.39 6.39

180 14.82 6.41 6.40 6.39

190 14.52 6.42 6.41 6.40

200 14.82 6.44 6.42 6.42

210 15.39 6.4.5 6.43 6.43

220 15.60 6.43 6.42 6.41

230 14.81 6.40 6.39 6.38

240 12.66 6.36 6.35 6.35

250 8.31 '6.33 6.32 6.32

260 4.54 6.32 6.32 6.32

270 4.69 6.32 6.32 6.32

280 4.40 6.32 6.32 6.32

290 4.51 6.32 6.32 6.33

300 6.09 6.68 5.67 5.68

310 13.80 5.76 5.76 5.77

320 19.96 5.93 5.93 5.95

330 26.23 6.21 6.22 6.24

340 30.12 5.81 6.51 5.86

350 32.57 6.05 6.06 6. 11

*1430 kHz 50% RSS site-to-site value.

55

FORM OT-29

(3-73)

u.s. DEPARTMENT OF COMMERCE

OFFICE OF TELECOMMUNICATIONS

BIBLIOGRAPHIC DATA SHEET

1. PUBLICATION OR REPORT NO.2. Gov't Accession No.3. Recipient's Accession No.

NTIA Report 80-39

4. TITLE AND SUBTITLE 5. Publication Date

Effect of Small Frequency Changes on the Radiation

Patterns of MF (AM) Directional Antennas

Mav 1980

6. rffiAiTTsrganization Code

7. AUTHOR(S)

Arthur C. Stewart and John B. Heffelfinger

9. Project/Task/Work Unit No.

10. Contract/Grant No.

8. 'PERFORMING ORGANIZATION NAME AND ADDRESS U. S. Department of Commerce

National Telecommunications & Information Administration t---------------4

Institute for Telecommunication Sciences

Boulder, CO 80303

11. Sponsoring Organization Name and Address 12. Type of -Rep or t and Period Covered

Same

13.

14. SUPPLEMENTARY NOTES

l 5. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

Th:ip~~SSn~~¥orprovfdeYadd{tidh~ie1ulltime facilities in the AM (standa~d broadcasting) band in the United States resulted in a rulemaking petition filed with the

Federal Communications Commission (FCC). The petition proposed the reduction of

the AM channel spacing from 10 to 9 kHz. According to the suggested frequency allo

cation plan, the maximum frequency change required for any standard AM broadcast

station would be +4 kHz. A study was conducted both theoretically and experimentally to determine the magni tude of ·the radi ati on pattern changes that would be

caused by a +4 kHz frequency change for stations using directional antenna arrays.

Additionally: a computer study of the 1430 kHz regional channel was conducted to

determine the effects of a +4 kHz frequency change.on the interference levels

suffered by co-channel statlons. The results of the study demonstrate that the

effects of small frequency changes on the radiation patterns of directional antenna

arrays are greater in practice than theoretical predictions would indicate, but

that the required pattern corrections could probably be quickly and easily effected

16. Key \l'ords (Alphabetical order, separated by semicolons)

AM broadcast band; allocation bandwidth; di rec t ional antennas; frequency

allocations

17. :\ V AI LABI LITY STA TE~fENT 13. Se c ur l t y Class (Thi s report) 20. \umber 1.)[ p a ze s

LX] UNLIMITED. Unclassified

o FOR OFFICIAL DISTRIBUTIO~.

19. Sc c ur It y C la S s (Th is pod f.,ic j

Unclassified

21. Price:

~u.s. GOVERNMENT PRINTING OFFICE: 1980-0-678-572/402