R

PUBLICATION NUMBER: 10515-0040-4200

MARCH 2004
Rev. -

RF-1940/RF-1941 SERIES
HF MANPACK ANTENNA
INSTRUCTION MANUAL

The material contained herein is subject to U.S. export approval. No export or

re-export is permitted without written approval from the U.S. Government.
 PUBLICATION NUMBER: 10515-0040-4200
MARCH 2004
Rev. -

RF-1940/RF-1941 SERIES
HF MANPACK ANTENNA
INSTRUCTION MANUAL
The material contained herein is subject to U.S. export approval. No export or
re-export is permitted without written approval from the U.S. Government.

Copyright  2004
By Harris Corporation
All Rights Reserved

HARRIS CORPORATION RF COMMUNICATIONS DIVISION

1680 University Avenue Rochester, New York 14610-1887 USA
Tel: 585-244-5830. Fax: 585-242-4755. http://www.harris.com
 TABLE OF CONTENTS

Paragraph Page

CHAPTER 1 – GENERAL INFORMATION

1.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.2 GENERAL INSTALLATION GUIDELINES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2.1 Antenna Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2.2 RF Radiation Hazards from Radiating Antennas . . . . . . . . . . . . . . . . . . . . . . 1-2

CHAPTER 2 – INSTALLATION

2.1 DIPOLE DEPLOYMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.2 ANTENNA CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2.2.1 Ground Wave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2.2.2 Short-To-Medium Skywave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2.2.3 Long Skywave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2.3 PERFORMANCE OF ANTENNA CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . 2-11
2.3.1 3 MHz Best Configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11
2.3.2 7 MHz Best Configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
2.3.3 11 MHz Best Configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
2.3.4 15 MHz Best Configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18
2.4 GROUNDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21

iii
 TABLE OF CONTENTS – Continued

Paragraph Page
CHAPTER 3 – REFERENCES

3.1 TAKE-OFF-ANGLE VERSUS PATH DISTANCE CHART. . . . . . . . . . . . . . . . . . . . . . 3-1

3.2 REFERENCES FOR ADDITIONAL INFORMATION ON HF PROPAGATION
AND ANTENNA CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

APPENDIX A

A.1 TECHNICAL SPECIFICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

iv
 LIST OF FIGURES

Figure Page

1-1 Distance Chart in Feet showing Minimum Safety Distances from HF Radiation
Hazard for Various RF Power Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1-2 Distance Chart in Meters showing Minimum Safety Distances from HF
Radiation Hazard for Various RF Power Levels . . . . . . . . . . . . . . . . . . . . 1-4
2-1 RF-1940 and RF-1941 Dipole Configuration . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2-2 Ground Wave Antenna Configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
2-3 Short to Medium Skywave Antenna Configurations . . . . . . . . . . . . . . . . . . . . 2-9
2-4 Long Range Skywave Antenna Configuration . . . . . . . . . . . . . . . . . . . . . . . . 2-10
2-5 Gain (dBi) versus Antenna Configuration and Range (km) at 3 MHz. . . . . . . 2-13
2-6 Gain (dBi) versus Antenna Configuration and Range (km) at 7 MHz. . . . . . . 2-15
2-7 Gain (dBi) versus Antenna Configuration and Range (km) at 11 MHz . . . . . . 2-17
2-8 Gain (dBi) versus Antenna Configuration and Range (km) at 15 MHz. . . . . . 2-20
3-1 Take-Off-Angle Versus Path Length for F2 Layer at 320 km . . . . . . . . . . . . . 3-1

LIST OF TABLES

Table Page

2-1 Marker Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

v
 This page intentionally left blank.

vi
 ABOUT THE MANUAL

This manual contains information for the RF-1940/RF-1941

Series HF Manpack Antenna. It its divided into the
following sections:
• Section 1, General Information: introduction
and general installation guidelines.
• Section 2, Installation: general antenna
deployment, antenna configurations, and
grounding.
• Section 3, Reference Material
• Appendix A, Technical Specifications

WARNING
The installation of antennas and their associated support
structures requires specialized skills. These installations
should only be made by experienced personnel, and only after
they have thoroughly read and understood the supplied
documentation. Failure to do so could result in serious damage
to the equipment and injury to personnel both during and after
installation. Upon request, Harris Corporation can supply
training in the techniques required. Harris Corporation
assumes no responsibility or liability for any damage or injury
that may occur as the result of any installation.
vii
 WARNING
When used with an antenna coupler, the voltage on the
RF-1940/RF-1941 HF Manpack Antenna may exceed 7,000
volts. Verify that transmitter power is off before proceeding
with antenna assembly or disassembly. Electrical burns will
result if you touch the antenna or transmission cable
conductors when the transmitter is keyed.

WARNING
Ensure that there are no power lines nearby before erecting the
antenna. Allowing the antenna to touch overhead power lines
can result in injury or death.

viii
 CHAPTER 1

GENERAL INFORMATION
1.1 INTRODUCTION
The RF-1940/RF-1941 Series of antennas are lightweight, portable dipole antennas for use in single-frequency
applications. The RF-1940 can be adjusted to resonant lengths from 3 to 30 MHz, while the RF-1941 covers the
complete 2 to 30 MHz band. Both are designed for transportability and used with Harris RF-5800H and AN/PRC-
150 High Frequency (HF) transceivers. The antennas can be used with external power amplifiers with power levels
up to 500 watts.
The antenna is stored on self-contained, flat spools which form an integral part of the antenna. During operation, the
unused portion remains stored on the storage spool. Each spool also contains 60 feet (18 meters) of throwing line
which can be connected to masts, trees, buildings, poles, etc. The RF-1940/RF-1941 antennas are supplied with type
BNC input connectors.
1.2 GENERAL INSTALLATION GUIDELINES
1.2.1 Antenna Deployment

WARNING
ALWAYS USE EXTREME CARE WHEN DEPLOYING
ANTENNAS! Care should be taken to deploy the antenna
away from electrical wires, electrical machinery, or other
potential sources of electrical shock. Antennas should not be
deployed in areas where people or animals may come in
contact with them.
1-1
The most critical factors in determining the performance of an HF communications system are the deployment of
the antenna and the effectiveness of the ground system. Since the RF-1940 and RF-1941 are designed for quick
deployment in emergency, disaster, and other portable applications, a well-designed and well-planned antenna site
will seldom be possible. However, use of the guidelines in this manual will allow the user to set up the best antenna
system for the circumstances, providing the user with a communications range of up to several thousand miles.

Refer to Paragraph 3.2 in References for Additional Information on HF Propagation and Antenna Considerations.
Because HF propagation is dependent upon time of day, weather conditions, time of the year, and sunspot activity,
this data is published periodically by radio amateur magazines and available at web sites. In general, lower
frequencies are not usable during daylight hours and higher frequencies are not usable at night. During periods of
sunspot activity, maximum usable frequencies will have to be determined by the operator.

In addition to safety considerations, the location of all antenna systems should be chosen to be clear of obstructions
and electromagnetic noise sources such as high-tension lines or electrical machinery.

1.2.2 RF Radiation Hazards from Radiating Antennas

Potential radiation hazards exist with any antenna that radiates RF energy. Guidelines recommending safe distances
from radiating antenna are summarized in the graphs shown in Figure 1-1 and Figure 1-2. The graph indicates the
recommended minimum safe distance for various RF power levels at various frequencies in an uncontrolled
environment with the equipment operating in a continuous duty mode. These conditions are for the maximum
permissible level for human exposure to RF radiation averaged over any six-minute period.

Refer to the Institute of Electrical and Electronics Engineers, Inc. (IEEE) C95.1-1991, IEEE Standard for Safety
Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz, for a
detailed explanation on this topic. Actual radiation levels are dependent on many factors, including soil conditions,
adequacy of the grounding system, the antenna type, operating frequency, and power level. Refer to Chapter 3,
References, for additional information concerning safe levels of human exposure of RF electromagnetic fields.

1-2
 HF RADIATION HAZARD
SAFE DISTANCE FOR 6 MINUTE PERIOD
12

11

10

9 1000W

6 500W

3
100W
2

2 6 10 14 18 22 26 30
FREQUENCY (MHz)
1000W, ANTENNA 500W, ANTENNA 100W, ANTENNA
CL-0040-4300-0001

Figure 1-1. Distance Chart in Feet showing Minimum Safety Distances from HF Radiation Hazard
for Various RF Power Levels
1-3
 HF RADIATION HAZARD
SAFE DISTANCE FOR 6 MINUTE PERIOD
3.75

3
DISTANCE (m) 1000W

2
500W

1
100W

2 6 10 14 18 22 26 30
FREQUENCY (MHz)
1000W, ANTENNA 500W, ANTENNA 100W, ANTENNA
CL-0040-4300-0002

Figure 1-2. Distance Chart in Meters showing Minimum Safety Distances from HF Radiation Haz-
ard for Various RF Power Levels
1-4
 CHAPTER 2

INSTALLATION

2.1 DIPOLE DEPLOYMENT

The RF-1940 and RF-1941 portable dipoles are antennas which are fully field deployable by one person, and no
additional mounting hardware is required. These antennas can be deployed in many configurations such as
half-wave dipole, sloping-vee, or inverted-vee. These instructions will describe the deployment of a half-wave
dipole.

The antenna assembly consists of a center insulator and three winders. The winders contain rope, dipole element
wire, and a feedline. General procedural steps for erecting a dipole antenna follow:

WARNING
When used with a coupler, the voltage on the RF-1940 or the
RF-1941 HF Antenna may exceed 7,000 volts. Verify that
transmitter power is off before proceeding with antenna
assembly and connection. Electrical burns will result if the
antenna or transmission cable conductors are touched while
keying the transmitter.

2-1
 WARNING
Ensure that there are no power lines nearby before erecting the
antenna. Allowing the antenna to touch overhead power lines
can result in injury or death.

a. Unroll an amount of element wire from the winder equal to the desired frequency that is being used. The
wire has markers attached so the correct length can be easily determined. The placement of the markers
along the elements are given in Table 2-1.
b. To ensure correct marker placement, wrap element wire around the boss at the top of the winder. See
Figure 2-1.
c. Attach the strain relief hooks from each element wire to each side of the center insulator, and attach each
spade lug at the end of the wire to the insulator via the wing nut.

NOTE
It is important that the marker position is just touching the
edge of the winder.

d. Connect the coax feedline BNC connector to the insulator, and attach the strain relief to the loop
provided on the insulator.
e. Unwind as much rope as required, and secure both ends of the antenna to the supports. Note that a
throwing weight is attached to the free end of the rope for convenience. The optimum height is a
function of communication range and frequency. In general, the desired height is between 3 and 10
meters.

2-2
 Table 2-1. Marker Placement
Frequency RF-1940 RF-1941
(MHz) (in meters) (in meters)
2.0 N/A 35.07
2.1 N/A 33.18
2.2 N/A 31.48
2.3 N/A 29.94
2.4 N/A 28.64
2.5 N/A 27.42
2.75 N/A 24.80
3.0 22.86 22.64
3.25 21.21 20.84
3.5 19.56 19.33
3.75 18.22 17.92
4.0 16.80 16.66
4.5 14.94 14.72
5.0 13.39 13.16
5.5 12.09 11.87
6.0 10.87 10.87
6.5 10.11 10.01
7.0 9.29 9.28
8.0 7.97 7.94
9.0 7.12 6.98

2-3
 Table 2-1. Marker Placement (Continued)
Frequency RF-1940 RF-1941
(MHz) (in meters) (in meters)
10.0 6.25 6.17
12.0 5.10 4.98
14.0 4.27 4.14
16.0 3.61 3.54
18.0 3.12 3.04
20.0 2.75 2.67
22.0 2.42 2.36
26.0 1.86 1.78
30.0 1.45 1.30

2-4
Figure 2-1. RF-1940 and RF-1941 Dipole Configuration

2-5
2.2 ANTENNA CONFIGURATIONS

This section describes the possible approaches to configuring the antenna system for optimum performance. The
decision of which antenna to employ is primarily based on the distance of the communications. Other factors such
as available supports, deployment area, and erection time need to be considered before a decision can be made.

For discussion purposes, the scenarios are divided into three classes: ground wave, short to medium skywave, and
long skywave. Ground wave is possible to 80 kilometers over land and 480 kilometers over water. Short skywave
(Near Vertical Incidence Skywave [NVIS]) paths are those under 300 kilometers and generally involve a single hop
from the ionosphere. Medium skywave also involves a single hop from 300 to 1200 kilometers. Long skywave paths
are greater than 1200 kilometers and may involve multiple hops.

2.2.1 Ground Wave

Ground-wave propagation involves the transmission of a radio wave signal along or near the surface of the earth.
This requires the antenna to aim the radio wave at the horizon (low take-off angle). Ground-wave distances within
line-of-sight communication is easily achieved. Distance beyond the horizon is a function of frequency,
conductivity, polarization, and antenna height.
The simple horizontal dipole configuration is impractical for ground-wave propagation. The preferred setup is to use
a single support and to deploy an antenna that provides vertical polarization, e.g., “L” configuration antenna, or
vertical dipole. These antennas have radiation characteristics necessary for ground-wave paths, although the vertical
dipole is preferred. Figure 2-2 provides examples of these types of antennas.
Regardless of which antenna configuration is used, the height of the antenna is important for successful
communication; for example, increased height equates to increased range.

2-6
2.2.2 Short-To-Medium Skywave

Short-to-medium skywave paths require that the radio wave be directed upwards. The RF-1940/RF-1941 antennas,
configured as a horizontal dipole or inverted dipole, are the best choice for this path. The antenna should be sized
for the lowest frequency to be used and erected as high as practical.

For short ranges, the bearing is not critical, as the antenna is essentially omnidirectional for high take-off angles. For
this type of path, excessive height beyond 1/4 of a wavelength is not recommended as it tends to lower the take-off
angle below that which is required. Figure 2-3 describes the horizontal dipole and the inverted dipole configurations.

2.2.3 Long Skywave

Long skywave paths require that the take-off angle of the radio wave be directed at low take-off angles, similar to
ground-wave.

The RF-1940/RF-1941 antennas can be used in the dipole configuration if a height between one-fourth and one-half
wavelength can be achieved. Orient the antenna such that the desired station is perpendicular (broadside) to the
antenna. Alternately, a vertical dipole can be erected if only one support exists.

If the communication is to a specific direction, several types of directional antennas can be made from the
RF-1940/RF-1941; these are the sloping vee, long wire, vertical rhombic, and inverted “L”. The sloping vee is made
similarly to a dipole, except a single support is used and the two ends are swung around to form a vee, the apex of
which points in the favored direction. A long wire is formed by joining the two wire elements and laying out the
wire in an elevated straight line. This antenna is directional, and the wire should be pointed about 20° away from
the desired direction. A vertical rhombic antenna is configured by the entire length of wire running up and over a
single mast. Figure 2-4 illustrates these options.

2-7
 WINDER WINDER

λ/2 λ/4
+

COAX TO TRANSMITTER
COAX TO TRANSMITTER
+

TO TRANSMITTER TO TRANSMITTER
WINDER

VERTICAL DIPOLE "L" ANTENNA

CL-0040-4300-0004

Figure 2-2. Ground Wave Antenna Configurations

2-8
 90 TO 120

λ/4
λ/4

NON-METALLIC
SUPPORT
HEIGHT = 10 m
WINDER WINDER
TO TRANSMITTER

INVERTED VEE ANTENNA

WINDER WINDER
λ/2

9.2 m
4.2 m
1.0 m COAX

DIPOLE CL-0040-4300-0005

Figure 2-3. Short to Medium Skywave Antenna Configurations

2-9
 ANTENNA WIRE INSULATED FROM
SUPPORTS

ANTENNA WIRE -
INVERTED “L” NON-METALLIC
COAXIAL - SUPPORTS HEIGHT
LONG WIRE 5 TO 10 m
TRANSMITTER

LONG-WIRE ANTENNA AND INVERTED “L”

MAXIMUM RADIATION

INSULATOR APEX ANGLE

30° TO 90° INSULATOR
MAST
9.2 m

INSULATOR
COAXIAL

9.2 m (VEE)
TRANSMITTER 1.0 m (SLOPING VEE)

CL-0040-4300-0006
VEE AND SLOPING VEE

Figure 2-4. Long Range Skywave Antenna Configuration

2-10
2.3 PERFORMANCE OF ANTENNA CONFIGURATION

Three-dimensional diagrams provide gain versus Take-Off-Angle (TOA) for each antenna configuration. The
antenna configurations are listed along the diagram's floor. The height of each curve displays antenna gain, while
depth displays propagation distance as a function of TOA.

2.3.1 3 MHz Best Configurations

The following information lists the 3 MHz best configurations. See Figure 2-5 for gain versus antenna configuration
and range at 3 MHz.

• Best overall antenna for 3.0 MHz is the λ/2 dipole at 9.2 meters high.
• 0 to 160 km (> 4.0 dBi)
λ/2 dipole at 9.2 meters high
'V' at 9.2 meters high, 90°
Inverted 'L' at 9.2 meters high
Long wire antenna
• 160 to 320 km (> 4.0 dBi)
λ/2 dipole at 9.2 meters high
'V' at 9.2 meters high, 90°
Long wire antenna

2-11
 • 320 to 520 km (> 1.0 dBi)
λ/2 dipole at 9.2 meters high
'V' at 9.2 meters high, 90°
'V' at 9.2 meters high, 60°
Inverted 'L' at 9.2 meters high
Long wire antenna
• Gain falls off as take-off-angle decreases
• Significant decrease in high-angle gain as a resonant dipole is lowered from 9.2 m to 4.2 m to 1.0 m.

2-12
Figure 2-5. Gain (dBi) versus Antenna Configuration and Range (km) at 3 MHz

2-13
2.3.2 7 MHz Best Configurations

The following information lists the 7 MHz best configurations. See Figure 2-6 for gain versus antenna configuration
and range at 7 MHz.

• Best overall antenna for 7 MHz is the 'V' dipole at 9.2 meters high with 90° vertex angle.
• 0 to 160 km (> 5.0 dBi)
λ/2 dipole at 9.2 meters high
Inverted λ/2 dipole
'V' at 9.2 meters high, 90°
• 160 to 320 km (> 5.0 dBi)
λ/2 dipole at 9.2 meters high
Inverted λ/2 dipole
'V' at 9.2 meters high, 90°
Inverted 'L' at 9.2 m
Long wire antenna
• 320 to 520 km (> 6.0 dBi)
λ/2 dipole at 9.2 meters high
'V' at 9.2 meters high, 90°
Inverted 'L' at 9.2 m
Long wire antenna
• 520 to 900 km (> 4.0 dBi)
λ/2 dipole at 9.2 meters high
'V' at 9.2 meters high, 90°
Long wire antenna
2-14
Figure 2-6. Gain (dBi) versus Antenna Configuration and Range (km) at 7 MHz

2-15
2.3.3 11 MHz Best Configurations
The following information lists the 11 MHz best configurations. See Figure 2-7 for gain versus antenna
configuration and range at 11 MHz.
• Best high angle (> 75°) antenna configuration is the λ/2 dipole at 4.2 meters high and low-angle antenna is
the 'V' dipole at 9.2 meters high with 90° vertex angle.
• For 0 to 160 km (> 5.0 dBi)
λ/2 dipole at 4.2 meters high
Inverted 'V'
• For 160 to 320 km (> 4.0 dBi)
λ/2 dipole at 9.2 meters high
λ/2 dipole at 4.2 meters high
Inverted 'V'
• For 320 to 900 km (> 5.0 dBi)
λ/2 dipole at 4.2 and 9.2 meters high
Inverted 'V'
'V' at both 90° and 60° vertex
Sloping 'V' at 9.2 with 90° vertex
Inverted 'L' at 9.2 meters
Long wire at 9.2 meters high
• For 900 to 1250 km (> 5.0 dBi)
λ/2 dipole at 4.2 and 9.2 meters high
'V' at both 90° and 60° vertex
Long wire at 9.2 meters high
2-16
• The dipole at 4.2 meters out performs a dipole at 9.2 for less than 320 km links.

Figure 2-7. Gain (dBi) versus Antenna Configuration and Range (km) at 11 MHz
2-17
2.3.4 15 MHz Best Configurations

The following information lists the 15 MHz best configurations. See Figure 2-8 for gain versus antenna
configuration at 15 MHz.

• Best high angle (> 75°) antenna configuration is the λ/2 dipole at 4.2 meters high and low-angle antenna is
the 'V' dipole at 9.2 meters high with 90° vertex angle
• For 0 to 320 km (> 5.0 dBi)
λ/2 dipole at 4.2 meters high
• For 320 to 520 km (> 4.0 dBi)
λ/2 dipole at 4.2 meters high
λ/2 dipole at 9.2 meters high
Inverted 'V'
• For 520 to 900 km (> 6.0 dBi)
λ/2 dipole at 9.2 meters high
Inverted 'V'
'V' at both 90° and 60° vertex
Sloping 'V' at 9.2 with 90° and 60° vertex
Inverted 'L' at 4.2 and 9.2 meters
Long wire at 9.2 meters high

2-18
• For 900 to 1250 km (> 6.0 dBi)
λ/2 dipole at 9.2 meters high
Inverted 'V'
'V' at both 90° and 60° vertex
Sloping 'V' at 9.2 with 90° and 60° vertex
Long wire at 9.2 meters high
• For 1250 to 3500 km (> 2.0 dBi)
'V' at both 90° and 60° vertex

2-19
 Figure 2-8. Gain (dBi) versus Antenna Configuration and Range (km) at 15 MHz

2-20
2.4 GROUNDING

The importance of grounding cannot be overemphasized. Inadequate grounding degrades system operation and
causes RF voltages to be present on the chassis of the connected transmitter or transceiver. These voltages can cause
equipment damage and present a serious personnel hazard. Grounding also provides a path for lightning to minimize
the potential damage from overvoltage and overcurrent.

WARNING
Inadequate or defective grounding presents a personnel
hazard that could result in serious injury or death.

CAUTION
Inadequate or defective grounding could damage the
equipment.
The HF transmitter/transceiver's ground terminals should be connected directly to ground, using the shortest and
thickest (low inductance) possible wire. All ground cables should be as short as possible, ideally less than 30
centimeters. Paint, grease, rust, etc. must be scraped away so that only bare metal is visible at grounding points.
Ground cables can be fabricated from tinned, braided copper of the correct length. Ground terminals are provided
on the transceiver such that shock mount action is not inhibited.

2-21
Ideally, the transceiver ground terminal could be connected to a grounded pipe (such as a cold water pipe), preferably
where the pipe enters the ground, or a steel or copper rod driven at least one meter into the soil. In situations where
the water table is far below the surface (such as desert or mountainous terrain), it may be necessary to create an
artificial ground (counterpoise).

A counterpoise system significantly improves ground wave performance and can be created by using as many radial
wires as possible spread out like the spokes of a wheel. A ground connection to a vehicle body provides another
effective counterpoise system. Even a single wire laid on the ground or a connection to any mass of metal, such as
a wire fence, improves the R/T's performance.

2-22
 CHAPTER 3

REFERENCES

3.1 TAKE-OFF-ANGLE VERSUS PATH DISTANCE CHART

See Figure 3-1 for Take-Off-Angle versus path length for F2 layer at 320 km.

Figure 3-1. Take-Off-Angle Versus Path Length for F2 Layer at 320 km

3-1
3.2 REFERENCES FOR ADDITIONAL INFORMATION ON HF PROPAGATION AND ANTENNA
CONSIDERATIONS

The following listings are sources of additional reference information on HF propagation and antennas:

• Field Antenna Handbook, consulting report prepared by James A. Koch for the Department of Defense,
Electromagnetic Compatibility Analysis Center, Annapolis, Maryland 21402; Report number
ECAC-CR-83-200
• The Radio Amateur's Handbook, American Radio Relay League: Newlington, CT 06111; ISBN:
0-87259-160-3
• The ARRL Antenna Book, American Radio Relay League: Newlington, CT 06111; ISBN: 0-87259-414-9
• Reference Data for Radio Engineers, Howard W. Sams & Co., Inc., Indianapolis, Indiana 46268; ISBN:
0-672-21218-8
• Basic Radio Propagation Predictions, CRPL-D, published monthly, US Government Printing Office,
Washington, DC 20402
• Institute of Electrical and Electronics Engineers, Inc. (IEEE) C95.1-1991, IEEE Standard for Safety Levels
with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz.
• Web Sites
1. www.rfcomm.harris.com - Harris RF Communications web page

2. www.ngdc.noaa.gov/stp/IONO/ionohome.html - Ionosphere data

3. www.ips.gov.au - Ionosphere data

4. www.sel.noaa.gov - Ionosphere data

5. http://elbert.its.bldrdoc.gov/ - HF propagation prediction software (VOACAP and ICEPAC)

3-2
 APPENDIX A

A.1 TECHNICAL SPECIFICATIONS

The following lists the specifications for the RF-1940/RF-1941 HF Manpack Antenna.

ELECTRICAL
Frequency: 3.0 MHz - 30 MHz (RF-1940)
2.0 MHz - 30 MHz (RF-1941)
Maximum Power Rating: 500 Watts at 2.0 MHz to 30 MHz
VSWR: 1.7:1
Polarization: Horizontal (Dipole Configuration)
Input Impedance: 50 Ohms nominal
Input Connector (at center): BNC Female
RF INPUT CABLE
RF Input Cable: RG-58C/U (or equivalent)
Length: 10 meters
MECHANICAL
Overall Element Length 46.4 meters (RF-1940)
74.6 meters (RF-1941)
Weight: Approximately 2.3 kg (5.0 lbs)
Stored Size: 34 cm x 17 cm x 7 cm

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RF Communications Division ½ 1680 University Ave ½ Rochester, NY USA 14610

Tel: 585-244-5830. Fax: 585-242-4755 www.harris.com