National Bureau of Standards
library, N.W. Bldg ^
MAY 1 1 1962
Basic Radio
Propagation
Predictions
FOR AUGUST 1962
Three Months in Advance
r*\ 1 X*
t-'J'i j,Q
h OiiOO ch> U J i \
taken from tha Z:m.
Issued May 1962
CRPL Series D
Number 213
The Central Radio Propagation Laboratory
The propagation of radio waves over long distances depends on their reflection from the ionosphere, the
electrically conducting layers in the earth’s upper atmosphere. The characteristics of these layers are continually
changing. For regular and reliable communication, it is therefore necessary to collect and analyze ionospheric
data from stations all over the world in order that predictions of usable frequencies between any two places at
any hour can be made. During the war, the United States Joint Communications Board set up the Interservice
Radio Propagation Laboratory at the National Bureau of Standards to centralize ionospheric work and predic¬
tions for the Armed Forces of the United States.
On May 1, 1946, this activity returned to peacetime status as the Central Radio Propagation Laboratory of
the National Bureau of Standards. Designed to act as a permanent centralizing agency for propagation pre¬
dictions and studies, analogous in the field of radio to the reports of the Weather Bureau in the field of meteor¬
ology, the Central Radio Propagation Laboratory was established in cooperation with the many government agencies
vitally concerned with communication and radio propagation problems. These agencies are represented on an
Interdepartmental Council on Radio Propagation and Standards, which assists in furthering the work of the
Laboratory; included are the Departments of State, Army, Navy, and Air Force, United States Information
Agency, United States Coast Guard, Civil Aeronautics Administration, and Federal Communications Commission.
Observers have been designated by the Air Navigation Development Board, Interdepartment Radio Advisory
Committee, United States Coast and Geodetic Survey, and United States Weather Bureau. The Council works
in cooperation with a Technical Advisory Committee appointed by the Institute of Radio Engineers at the request
of the Director, National Bureau of Standards.
The Central Radio Propagation Laboratory receives and analyzes data from approximately 120 stations
located throughout the world, including 8 domestic and 17 overseas stations which are operated either directly
or under contract by the National Bureau of Standards. Ionospheric data and predictions are disseminated to
the Armed Forces, commercial users, scientists, and laboratories. The basic ionospheric research of the Labora¬
tory includes theoretical and experimental studies of maximum usable frequencies, ionospheric absorption, long¬
time variations of radio propagation characteristics, the effects of the sun on radio propagation, and the relation
between radio disturbance and geomagnetic variation. In the microwave field, the Laboratory is investigating the
relation between radio propagation and weather phenomena, as well as methods by which predictions can be made
and radio communications improved in this portion of the radiofrequency spectrum. Another phase of the Lab¬
oratory’s work is the development and maintenance of standards and methods of measurement of many basic
electrical quantities throughout the entire frequency spectrum.
Basic Radio Propagation Predictions
The CRPL Series D, Basic Radio Propagation Predictions, is issued monthly as an aid in the determination
of the best sky-wave frequencies over any path at any time of day for average conditions for the month of
prediction, 3 months in advance. Charts of extraordinary-wave critical frequency for the F 2 layer, of maxi¬
mum usable frequency for a transmission distance of 4,000 km, and of percentage of time occurrence for
transmission by sporadic E in excess of 15 Me, for a distance of 2,000 km, are included.
Beginning with the January 1960 issue (CRPL-D185) the CRPL-R series, “Basic Radio
Propagation Predictions,” is available on a purchase basis from the Superintendent of Docu¬
ments, U. S. Government Printing Office, Washington 25, D. C., on the following terms:
Single copy . . . . . . . 15 cents
Annual subscription (12 issues) . $1.50
(To foreign countries, $2.00)
The rules of the Superintendent of Documents require that remittances be made in
advance either by coupons sold in sets of 20 for $1 and good until used, or by check or
money order payable to the Superintendent of Documents. Currency, if used, is at sender’s
risk. Postage stamps, foreign money, and defaced or smooth coins are not acceptable. Re¬
mittances from foreign countries should be by international money order payable to the
Superintendent of Documents or by draft on a United States bank.
Address subscriptions, remittances, and all inquiries relating thereto, to the Superintendent
of Documents, U. S. Government Printing Office, Washington 25, D. C.
The printing of this publication has been approved by the Director of the Bureau of the Budget, June 19, 1961.
271954— Type C— 62
MAY
19 6 2
U. S. DEPARTMENT OF COMMERCE
Luther H. Hodges, Secretary
NATIONAL BUREAU OF STANDARDS
A. V. Astin, Director
CRPL Series D
NUMBER 2 TTI
BASIC RADIO PROPAGATION PREDICTIONS
FOR AUGUST 1962 THREE MONTHS IN ADVANCE
Introduction
The CRPL-D series, “Basic Radio Propagation Predictions,” issued by the National Bureau of
Standards, contains contour charts of monthly median F2-zero-MUF and F2-4000-MUF for each of
four zones, W, I (Afro-European), E, I (Pacific), (figs. 1 to 8) ; a worldwide contour chart of
monthly median U-2000-MUF (fig. 9) ; a contour chart of median fE s (fig. 10) ; and a chart
showing percentage of time occurrence for Fs-2000-MUF in excess of 15 Me (fig. 11). Local
time used for North Pole: 75° W; for South Pole: 105°E.
Methods for using these charts are given in Circular 465 of the National Bureau of Stand¬
ards, entitled “Instructions for the Use of Basic Radio Propagation Predictions,” and available
from the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C.,
price 30 cents (to foreign countries, 40 cents). Procedures described in this manual should be
modified to take into account the separate contour charts for the two I zones. Zone boundaries
are the same as shown in figure 1 of Circular 465. ' . _ .
|
Requests for the manual of instructions and for the basic predictions from members of the
Navy or Air Force should be sent to the proper service address as follows. For the Navy : The-
Director, Naval Communications. For the Air Force: Directorate Telecommunications, Depart¬
ment of the Air Force, Washington 25, D. C., Attention: AFOAC-FC.
Following figure 11 of each issue, sets of auxiliary figures (nos. 1, 2, 11, 12 of NBS Circular
465) or forms CRPL-AF and AH are given in rotation, two in each issue of CRPL Series D.
They are necessary or useful for the preparation of tables and graphs of MUF and FOT (OWF),
as explained in NBS Circular 465. . - ,
The charts in this issue were constructed from data through February 1962, together with
the smoothed 12-month running-average Zurich sunspot number 31, centered on August 1962. The
provisional mean number fer the year 1961 was 52.
Information concerning the theory of radio-wave propagation, measurement technics, struc¬
ture of the ionosphere, ionospheric variations, prediction methods, absorption, field intensity,
radio noise, lowest required radiated power, and lowest useful high frequency is given in Circular —
462 of the National Bureau of Standards, “Ionospheric Radio Propagation.” This circular is
available from the Superintendent of Documents, price $1.25 (to foreign countries, $1.65). Addi¬
tional information about radio noise may be found in NBS Circular 557, “Worldwide and Radio
Noise Levels Expected in the Frequency Band 10 Kilocycles to 100 Megacycles,” also available from _
the Superintendent of Documents, price 30 cents (to foreign countries, 40 cents) and in C.C.I.R.
Report No. 65, “Revision of Atmospheric Radio Noise Data,” International Telecommunication
Union, Geneva, 1957.
NORTH
LATITUDE
SOUTH
o
o
FIG. I MEDIAN F2 - ZERO - MUF , IN Mc,W ZONE, PREDICTED FOR AUGUST 1962
O
O
LOCAL TIME
NORTH
LATITUDE
SOUTH
LOCAL TIME
NORTH
LATITUDE
SOUTH
ooooooooo ooooooooo
OOOOOOOOOo ooooooooo
FIG. 3. MEDIAN F2 - ZERO - MUF, IN Me, I ZONE ( AFRO - EUROPEAN ), PREDICTED FOR AUGUST 1962
LOCAL TIME
NORTH
LATITUDE
SOUTH
ooooooooo ooooooooo
QOOOOOOOOo ooooooooo
— O — CMro^-inoh-coo
LOCAL TIME
NORTH
LATITUDE
SOUTH
ooooooooo ooooooooo
OOOOOOOOOo ooooooooo
LOCAL TIME
NORTH
LATITUDE
SOUTH
LOCAL TIME
o
o
o
NORTH
0
O
LATITUDE
o
o
o
o
o
o
SOUTH
o
O
o
o
o
LOCAL TIME
NORTH
LATITUDE
SOUTH
ooooooooo ooooooooo
OOOOOOOOOo ooooooooo
CnOOh-tDlO^rrOCM — O — <\irO^-lDCD(^CDCT>
LOCAL TIME
NORTH
LATITUDE
SOUTH
o
ooooooooo ooooooooo
OOOOOOOOOo ooooooooo
cnoor^iDiri'^rocvJ — O — ojro^mo^-aDCD
cm
CM
o
C\J
CD
CD
CM
O
CD
O
CD
O
O
CM
O
FIG. 9. MEDIAN E - 2000 - MUF, IN Me, PREDICTED FOR AUGUST 1962
O
O
LOCAL TIME
north latitude south
o
O
00
o
o
h-
0
o
co
0
O
LO
0
O
0
O
ro
o
O
00
0
O
o
o
O
o
o
00
o
o
O
ro
o
O
'O'
o
O
in
o
o
O
CD
o
O
h~
0
O
00
0
O
(T>
5
o
O
00
o
h-
o
O
ED
o
lO
O
o
ro
o
00
o
O
o
O
00
o
rO
O
^r
o
o
in
o
CD
o
L-
o
00
0
o
o
CD
o
O
CO
0
O
L-
0
O
CD
0
O
LO
O
o
rO
o
<\J
o
O
o
O
o
o
O
00
O
ro
o
o
m
o
CD
O
O
00 LU
LOCAL TIME
NORTH
o
O
o
O
o
o
o
O
0
O
o
O
h-
ED
in
FT
ro
C\J
o
o
o
o
o
O
o
O
O
o
O
00
h-
CD
in
FT
rO
o
o
o
0
o
o
O
o
O
O
O
O
CD
00
L-
CD
m
FT
LATITUDE
O
o
O
oOl
O
CM
O
o
o
o
CM
O
O
o
O
ro
o
O
CM
o
O
o
O
SOUTH
o
0
o
o
O
O
O
O
rO
FT
m
CD
o
q
o
O
0
O
o
O
CM
rO
o
fT
o
m
o
o
O
O
O
O
CM
ro
FT
o
O
o
O
O
CO
CD
$
o
o
0
O
O
O
CD
T-
00
—
0
o
0
o
O
O
O
O
in
CD
r-
00 LU
OJ
CM
O
CM
CO
CD
M"
CM
o
00
O
CD
O
O
CM
O
FIG. II. PERCENTAGE OF TIME OCCURRENCE FOR Es-2000-MUF IN EXCESS OF 15 Me, PREDICTED FOR AUGUST 1962
1
o
o
LOCAL TIME
o
MUF FOT
— 15
- 5
5
NOMOGRAM FOR TRANSFORMING F2-ZER0-MUF AND F2-4000-MUF TO EQUIVALENT MAXIMUM
USABLE FREQUENCIES AT INTERMEDIATE TRANSMISSION DISTANCES, CONVERSION SCALE
FOR OBTAINING OPTIMUM TRAFFIC FREQUENCY (FOT).
E- Layer 2000-muf
50-q
45-=
40-
35-
30 —
25-
15-
io-
9-
8-
7-
6-
I km = 0.62137 mile = 0.5 39 61 nout. ml.
I mile = l.60935km = 0-86836naut.mL
I nout. ml. = l.85325km=|. 1516 ml.
MUF
Me
50—
40 —
30-
20—
15—
10—
^.9 :
6—
5—
4~
3-r
2.5- r
2—
1.5—
Distance,
Kilometers
_ 2500-4000
=- 2000
— 1500
— 1000
— 900
— 800
— 700
— 600
— 500
— 400
— 300
— 200
— 100
0
4-
Exomple shown by
doshed lines:
Distance = 500 Kilometers
2 000- km E muf = 20 Me
Combined E-ond F,-Loyer mut = 8 4 Me
NOMOGRAM FOR TRANSFORMING E-LAYER 2000-MUF TO EQUIVALENT MAXIMUM
USABLE FREQUENCIES AND OPTIMUM TRAFFIC FREQUENCIES DUE TO COMBINEO
EFFECT OF E LAYER AND Ft LAYER AT OTHER TRANSMISSION DISTANCES.
Notes on Use of Predictions
It is believed that these predictions are reasonably accurate for vertical incidence and for one-hop F 2 trans¬
mission for average layer height for 4000-km distance over a great circle path. In practice, the picture is often
more complicated. The effective antenna-radiated power at low angles of departure may not be sufficient for maxi¬
mum single hop distance. Also, for a given distance various modes, or combinations of modes, of propagation are
often possible, including combinations of E- and F-layer single or multiple hops. Ionospheric forward scatter, back-
scatter, off -great-circle transmission, and sporadic E may increase the actual MUF for a given circuit over that
expected for the simplest great circle mode. Sporadic E may be particularly important during night hours in
auroral zones, and during the middle of the day in the summer in temperate zones. Ionospheric layer tilt, hori¬
zontal ionization gradients, meteoric or auroral propagation may play an important part.
For many circuits, these may explain why the median MUF may give a better estimate of the FOT than the
usual procedure of percentage reduction of the MUF. Use of operating experience in conjunction with these
predictions will aid in maintaining the highest possible circuit efficiency.
Reports to this laboratory of discrepancies between predictions and experience are helpful in improving these
predictions. Communications should be addressed to Central Radio Propagation Laboratory, National Bureau of
Standards, Boulder, Colorado. Please note this is not an address for subscriptions. Subscription information is
given elsewhere in this report.
UNITED STATES penalty for private use to avoid
GOVERNMENT PRINTING OFFICE payment of postage, $300
DIVISION OF PUBLIC DOCUMENTS (GPO)
WASHINGTON 25, D. C.
OFFICIAL BUSINESS
CRPL Reports
[A detailed list of CRPL publications is available from the Central Radio Propagation Laboratory upon request]
Daily :
Radio disturbance forecasts, every half hour from broadcast stations WWV and WWVH of the National
Bureau of Standards.
Telephoned and telegraphed reports of ionospheric, solar, geomagnetic, and radio propagation data.
North Atlantic Radio Propagation Forecast.
North Pacific Radio Propagation Forecast.
Semimonthly Frequency Revision Factors For CRPL Basic Radio Propagation Prediction Reports.
Basic Radio Propagation Predictions — Three months in advance. (Dept, of the Army, TB 11 —
499 — , monthly supplements to TM 11 — 499; Dept, of the Air Force, TO 31 — 3 — 28 series).
On sale by Superintendent of Documents. Members of the Armed Forces should address
cognizant military office.
(Part A). Ionospheric Data.
(Part B). Solar-Geophysical Data.
Limited distribution. These publications are in general disseminated only to those
individuals or scientific organizations which collaborate in the exchange of iono¬
spheric, solar, geomagnetic, or other radio propagation data.
Catalog of Data:
A catalog of records and data on file at the U. S. IGY World Data Center A for Airglow and Ionosphere,
Boulder Laboratories, National Bureau of Standards, which includes a fee schedule to cover the cost of sup¬
plying copies, is available upon request.
The publications listed above may be obtained without charge from the Central Radio Propagation Laboratory,
National Bureau of Standards, Boulder Laboratories, Boutder, Colorado, unless otherwise indicated. Please note
that the F series is not generally available.
CRPL— J.
CRPL — Jp.
Semimonthly :
CRPL— Ja.
Monthly :
CRPL— D.
CRPL— F.
NBS Circular 465.
NBS Circular 557.
NBS Circular 582.
Circulars of the National Bureau of Standards pertaining to Radio Sky Wave Transmission:
NBS Circular 462. Ionospheric Radio Propagation. $1.25
Instructions for the Use of Basic Radio Propagation Predictions. 30 cents.
Worldwide Radio Noise Levels Expected in the Frequency Band 10 Kilocycles to 100
megacycles. 30 cents.
Worldwide Occurrence of Sporadic E. $3.25.
These Circulars are on sale by the Superintendent of Documents, U. S. Government
Printing Office, Washington 25, D.C. Members of the Armed Forces should address
the respective military office having cognizance of radio wave propagation.
Selected Technical Notes of the National Bureau of Standards :
World Maps of F2 Critical Frequencies and Maximum Usable Frequency
$3.50 PB 15136 1-2. $3.50.
Technical Considerations Leading to an Optimum Allocation of Radio
in the Band 25 to 60 Me. $2.50.
Radio Noise Data for the IGY. $2.50.
. Quarterly Radio Noise Data (Mar.-May 1959). $1.00.
(June-Aug. 1959). $1.00.
, etc. (Sept.-Nov. 1959). $1.50.
An Atlas of Oblique-Incidence Ionograms. $2.25.
Mean Electron Density Variations of the Quiet Ionosphere, 1: March
25.
, etc. 2: April 1959. $1.25.
Variations in Frequency of Occurrence of Sporadic E, 1949 — 1959. $0.75.
These Technical Notes are on sale by the Office of Technical Services, U. S. Depart¬
ment of Commerce, Washington 25, D. C. Order by PB number.
NBS
Tech.
Note
o
PB151361.
Factors.
NBS
Tech.
Note
13.
PB151372.
F requeneies
NBS
Tech.
Note
18.
PB151377.
18-2.
PB151377-2.
18-3.
PB151377-3.
18-4.
PB151377-4.
NBS
Tech.
Note
31.
PB151390.
NBS
Tech.
Note
40-1.
PB151399-1.
1959. $1.;
40-2.
PB151399-2,
NBS
Tech.
Note
117.
PB161618.
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