Revised November 7, 2020
Portable HF Antenna
(CHA EMCOMM II V2)
Operator’s Manual
Nevada - USA
WWW.CHAMELEONANTENNA.COM
VERSATILE – DEPENDABLE – STEALTH – BUILT TO LAST
CHA EMCOMM II V2 Page 2
Table of Contents
Introduction .............................................................................................................................................. 3
HF Propagation ......................................................................................................................................... 3
Parts of the Antenna ................................................................................................................................. 5
Antenna Configurations ............................................................................................................................ 7
Horizontal NVIS ..................................................................................................................................... 7
Sloping Wire .......................................................................................................................................... 9
Inverted “L” ......................................................................................................................................... 10
Recovery Procedure ................................................................................................................................ 11
Troubleshooting ...................................................................................................................................... 12
Specifications .......................................................................................................................................... 12
Accessories .............................................................................................................................................. 13
References .............................................................................................................................................. 15
Chameleon AntennaTM Products ............................................................................................................ 16
Be aware of overhead power lines when you are deploying the CHA EMCOMM II V2. You could be
electrocuted if the antenna gets near or contacts overhead power lines.
Photographs and diagrams in this manual may vary slightly from current production units due to manufacturing
changes that do not affect the form, fit, or function of the product.
All information on this product and the product itself is the property of and is proprietary to Chameleon
AntennaTM. Specifications are subject to change without prior notice.
CHA EMCOMM II V2 Page 3
Introduction
Thank you for purchasing and using the Chameleon Antenna
TM
Portable High Frequency (HF) Antenna
(CHA EMCOMM II V2). The CHA EMCOMM II V2 Antenna has been specially designed for backup
emergency HF systems or permanent installation. The integral broadband impedance matching network
transformer allows broadband antenna tuning. The antenna will operate from 1.8 - 54 MHz (including
160m – 6m amateur bands) without any adjustment with a wide range antenna tuner. The CHA
EMCOMM II V2 is the perfect backup antenna for military, government agencies, non-governmental
organizations (NGOs), Military Affiliate Radio System (MARS), Civil Air Patrol (CAP), Amateur Radio
Emergency Service (ARES) / Radio Amateur Civil Emergency Service (RACES), Salvation Army Team
Emergency Radio Network (SATERN), First Responders and especially for Emergency Preparedness. It is
also the ideal antenna for hams living in apartments and condominiums or developments with
homeowner’s associations, deed restrictions, or CCRs (Covenants, Conditions & Restrictions). The CHA
EMCOMM II V2 is configurable to facilitate Near-Vertical Incident Sky wave (NVIS) communication and is
totally waterproof. The CHA EMCOMM II V2 does not require any ground plane but will perform better
with one (a ground terminal is available for that purpose). This antenna requires a wide range antenna
tuner or coupler. Antennas built by Chameleon Antenna
TM
are versatile, dependable, stealthy, and built
to last. Please read this operator’s manual so that you may maximize the utility you obtain from your
CHA EMCOMM II V2.
HF Propagation
HF radio provides relatively inexpensive and reliable local, regional, national, and international voice and
data communication capability. It is especially suitable for undeveloped areas where normal
telecommunications are not available, too costly, or scarce, or where the commercial
telecommunications infrastructure has been damaged by a natural disaster or military conflict.
Although HF radio is a reasonably reliable method of communication, HF radio waves propagate through
a complex and constantly changing environment and are affected by weather, terrain, latitude, time of
day, season, and the 11-year solar cycle. A detailed explanation of the theory of HF radio wave
propagation is beyond the scope of this operator’s manual, but an understanding of the basic principles
will help the operator decide what frequency and which of the CHA EMCOMM II V2’s configurations will
support their communication requirements.
HF radio waves propagate from the transmitting antenna to the receiving antenna using two methods:
ground waves and sky waves.
Ground waves are composed of direct waves and surface waves. Direct waves travel directly from the
transmitting antenna to the receiving antenna when they are within the radio line-of-sight. Typically,
this distance is 8 to 14 miles for field stations. Surface waves follow the curvature of the Earth beyond
the radio horizon. They are usable during the day and under optimal conditions, up to around 90 miles,
see table (1). Low power, horizontal antenna polarization, rugged or urban terrain, dense foliage, or
CHA EMCOMM II V2 Page 4
dry soil conditions can reduce the range very
significantly. The U.S. Army found that in the
dense jungles of Vietnam, the range for ground
waves was sometimes less than one mile.
Frequency
Distance
Frequency
Distance
2 MHz
88 miles
14 MHz
33 miles
4 MHz
62 miles
18MHz
29 miles
7 MHz
47 miles
24 MHz
25 miles
10 MHz
39 miles
30 MHz
23 miles
Table 1. Maximum Surface Wave Range by
Frequency.
Sky waves are the primary method of HF radio wave propagation. HF radio waves on a frequency below
the critical frequency (found by an ionosonde) are reflected off one of the layers of the ionosphere and
back to Earth between 300 and 2,500 miles, depending upon the frequency and ionospheric conditions.
HF radio waves can then be reflected from the Earth to the ionosphere again during multi-hop
propagation for longer range communication. The most important thing for the operator to understand
about HF radio wave propagation is the concept of Maximum Usable Frequency (MUF), Lowest Usable
Frequency (LUF), and Optimal Working Frequency (OWF). The MUF is the frequency for which
successful communications between two points is predicted on 50% of the days of in a month. The LUF
is the frequency below which successful communications are lost due to ionospheric loses. The OWF,
which is somewhere between the LUF and around 80% of the MUF, is the range of frequencies which
can be used for reliable communication. If the LUF is above the MUF, HF sky wave propagation is
unlikely to occur.
The HF part of the Radio Frequency (RF) spectrum is usually filled with communications activity and an
experienced operator can often determine where the MUF is, and with less certainty, the LUF by
listening to where activity ends. The operator can then pick a frequency in the OWF and attempt to
establish contact. Another method is using HF propagation prediction software or an online service,
such as the Voice of America Coverage Analysis Program (VOACAP), which is available at no cost to
download or use online at www.voacap.com. The operator enters the location of the two stations and
the program shows either a chart or wheel with the predicted percentage of success based on frequency
and time. ALE, which is the standard for interoperable HF communications, is an automated method of
finding a frequency in the OWF and establishing and maintaining a communications link.
Even under optimal conditions, there is a gap between where ground waves end (around 40 to 90 miles)
and the sky wave returns to Earth on the first hop (around 300 miles). NVIS propagation can be used to
fill this gap. The frequency selected must be below the critical frequency, so NVIS can normally only be
used on frequencies from around 2 to 10 MHz. Frequencies of 2 – 4 MHz are typical at night and 4 – 8
MHz during the day.
CHA EMCOMM II V2 Page 5
Parts of the Antenna
The CHA EMCOMM II V2 is comprised of the following components, see plate (1):
Plate 1. EMCOMM II V2 Components.
a. Matching Transformer
The Matching Transformer, see plate (1), provides impedance matching for the CHA EMCOMM II V2.
b. Antenna Wire
The Antenna Wire, see plate (2), is a 60 foot length of insulated wire.
c. Isolation loop
Isolation loops (circular insulators) are permanently attached to the ends and middle (free floating)
of the Antenna Wire (b).
d. Carabiner
The Carabiner is a removable pear-shaped stainless steel hook with a spring-loaded gate.
e. Wire Connector
The Wire Connector is located at the end of the Antenna Wire (b) and is used to connect it to the
Matching Transformer (a).
CHA EMCOMM II V2 Page 6
Plate 2. Antenna Wire.
f. Line Winder
The Line Winder is used to store the Antenna Wire (b) when the EMCOMM II V2 is not deployed.
g. UHF Socket
The UHF Socket, SO-239, is located on the bottom of the Matching Transformer (a).
h. Top Transformer Connection
The Top Transformer Connection (marked “A” on the case) is located on the top of the Matching
Transformer (a).
i. Bottom Transformer Connection
The Bottom Transformer Connection is located on the bottom of the Matching Transformer (a).
j. Transformer Eyebolt
The Transformer Eyebolt is located on the top of the Matching Transformer (a).
CHA EMCOMM II V2 Page 7
Antenna Configurations
Using the supplied components, the CHA EMCOMM II V2 can be deployed into a number of useful
configurations. Three configurations, see table (2), are described in this manual, each with unique
performance characteristics. The table can assist the operator to quickly select the most appropriate
antenna configuration to meet their operational requirements.
Configuration
Ground
Short
Medium
Long
Directionality
Horizontal NVIS
↓ ↑
Omnidirectional
Sloping Wire
↓ ↕
Omnidirectional
Inverted “L”
↓ ↕
Unidirectional
Table 2. Antenna Configuration Selection.
To use the table, decide which distance column (Ground = 0 to 90 miles, Short = 0 - 300 miles, Medium =
300 – 1500 miles, Long > 1500 miles) best matches the distance to the station with whom you need to
communicate. Then, determine if the OWF is in the lower (↓ = 1.8 – 10 MHz) or upper (↑ = 10 – 30
MHz) frequency range. Finally, select the CHA EMCOMM II V2 configuration with the corresponding
symbol in the appropriate distance column. All CHA EMCOMM II V2 configurations provide some
capability in each distance category, so depending upon the complexity of your communications
network, you may need to select the best overall configuration. The directionality column indicates the
directionality characteristic of the antenna configuration. When using NVIS, all the configurations are
omnidirectional. Most configuration and frequency combinations will require a wide range antenna
tuner or coupler.
Horizontal NVIS
The CHA EMCOMM II V2 Horizontal NVIS configuration, see figure (1), is a special configuration designed
to provide good NVIS propagation on lower frequencies. It is predominately omnidirectional and
provides medium range sky wave propagation on frequencies above 10 MHz. It requires two supports
that will enable the antenna to be raised to a height of 10 – 12 feet. A counterpoise wire with a length
of 50 to 55 feet is recommended. If a counterpoise wire is not used, the coaxial cable must be 25 to 100
feet in length, as the shield of the coaxial cable provides the counterpoise. Use the following procedure
to install the Horizontal NVIS configuration.
Figure 1. Horizontal NVIS Configuration.
CHA EMCOMM II V2 Page 8
Site Selection and Preparation.
1. Select a site to deploy the CHA EMCOMM II
V2 Horizontal NVIS configuration. The site
must have two supports that will position
the Matching Transformer and the end of
the Antenna Wire to be at a height of
between 10 and 12 feet and 60 feet apart.
Higher or lower heights may be used, but
may reduce NVIS performance.
2. If not already attached, connect a Carabiner
(d) to the Wire Connector (e) end of the
Antenna Wire.
Connect the Matching Transformer. Refer to
plate (3) for steps (3) – (5).
Plate 3. Matching Transformer Electrical and
Mechanical Connections.
3. Connect the Carabiner from the Antenna
Wire to the Transformer Eyebolt (j).
4. Connect the Wire Connector from the
Antenna Wire to the Top Transformer
Connection (h). Tighten the wing nut finger
tight.
5. If using a counterpoise wire, connect it to
the Bottom Transformer Connection (i).
Tighten the wing nut finger tight.
6. Connect a CHA RFI CHOKE and coaxial cable
or the Integrated RF Choke end of the CHA
Coaxial Cable assembly to the UHF Socket
(g) on the Matching Transformer.
Raise the Antenna.
7. Using a Bowline or similar knot, tie the end
of a long length (25 feet or more) of
Paracord to the Carabiner from step (3).
8. Using a throw weight or other method, loop
the Paracord over the support that is
closest to where the radio set will be
located.
9. Raise the Matching Transformer end of the
antenna to a height of 10 to 12 feet and
secure it to the support using a Round Turn
and two Half Hitches, or similar knot.
10. Using a Bowline, or similar knot, tie another
long length of Paracord to the Isolation
Loop (c) at the end of the Antenna Wire.
11. Using a throw weight, or some other
method, loop the Paracord over the other
support.
12. Raise the end of the Antenna Wire to a
height of 10 to 12 feet, such that the
Antenna Wire is not quite taut, and secure
it to the support using a Round Turn and
two Half Hitches.
Extend the Counterpoise.
13. If using a counterpoise, extend it along the
ground under the raised portion of
antenna.
14. Perform operational test.
CHA EMCOMM II V2 Page 9
Sloping Wire
The CHA EMCOMM II V2 Sloping Wire configuration, see figure (3), is a broadband short to medium
range HF antenna. It is designed to provide acceptable ground wave and sky wave propagation. This
configuration is predominately omnidirectional, becoming slightly bidirectional towards both ends as
the frequency increases. The Sloping Wire requires one support and should be mounted at a height of
25 to 40 feet for best performance. A counterpoise wire, with a length of 20 - 40 feet, is recommended.
If a counterpoise is not used, the coaxial cable must be 25 to 100 feet in length, as the shield of the
coaxial cable provides the counterpoise. The “Half Sloper” is an alternate version of this configuration,
where the antenna is attached to a metal tower and the antenna is fed from the top.
Figure 3. Sloping Wire Configuration.
Site Selection and Preparation.
1. Select a site to deploy the CHA EMCOMM II
V2 Sloping Wire configuration. The site
must have a support that will position the
end of the Antenna Wire at a height of 25
to 40 feet. If the right support is
unavailable, any convenient object, such as
a fence post or the top of a vehicle, may be
used as a field expedient support with
reduced performance.
2. If not already attached, connect a Carabiner
(d) to the Wire Connector (e) end of the
Antenna Wire.
Connect the Matching Transformer. Refer to
plate (3) for steps (3) – (5).
3. Connect the Carabiner from the Antenna
Wire to the Transformer Eyebolt (j).
4. Connect the Wire Connector from the
Antenna Wire to the Top Transformer
Connection (h). Tighten the wing nut finger
tight.
5. If using a counterpoise wire, connect it to
the Bottom Transformer Connection (i).
Tighten the wing nut finger tight.
6. Connect a CHA RFI CHOKE and coaxial cable
or the Integrated RF Choke end of the CHA
Coaxial Cable assembly to the UHF Socket
(g) on the Matching Transformer.
Raise the Antenna.
CHA EMCOMM II V2 Page 10
7. Using a Bowline or similar knot, tie the end
of a short length (around 4 feet) of Paracord
to the Carabiner from step (3).
8. Drive a Stake into the ground closest to the
location of the radio set and tie the
Paracord from the Matching Transformer to
the Stake using two Half Hitches, or similar
knot.
9. Using a Bowline, or similar knot, tie a long
length (50 feet or more) of Paracord to the
Isolation Loop (c) at the end of the Antenna
Wire.
10. Using a throw weight or some other
method, loop the Paracord over the other
support.
11. Raise the end of the Antenna Wire to the
desired height, such that the Antenna Wire
is not quite taut, and secure it to the
support using a Round Turn and two Half
Hitches, or similar knot.
Extend the Counterpoise.
12. If using a counterpoise wire, extend it along
the ground in any convenient direction
away from the Antenna Wire.
13. Perform operational test.
Inverted “L”
The CHA EMCOMM II V2 Inverted “L” configuration, see figure (5), is a broadband short to medium
range HF antenna. This configuration tends to be unidirectional, favoring the horizontal end of the
antenna. It also provides effective ground waves communication during the day time on frequencies
between 1.8 – 4.0 MHz without using sky wave propagation. The Inverted “L” requires two supports
and should be mounted at a height of 25 feet for best performance. Though, it will provide good
performance at a height of 10 to 20 feet, and is usable when mounted as low as three feet. One
counterpoise wire, with a length of 20 - 40 feet, is recommended. If a counterpoise is not used, the
coaxial cable must be 25 to 100 feet in length, as the shield of the coaxial cable provides the
counterpoise.
Figure 5. Inverted “L” Configuration.
CHA EMCOMM II V2 Page 11
Site Selection and Preparation.
1. Select a site to deploy the CHA EMCOMM II
V2 Inverted “L” configuration. The site
must have two supports that will position
the corner of the “L” and the end of the
Antenna Wire at a height of 25 feet. If the
right supports are unavailable, any
convenient objects, such as fence posts or
the tops of vehicles, may be used as a field
expedient supports with reduced
performance.
2. If not already attached, connect a Carabiner
(d) to the Wire Connector (e) end of the
Antenna Wire.
Connect the Matching Transformer. Refer to
plate (3) for steps (3) – (5).
3. Connect the Carabiner from the Antenna
Wire to the Transformer Eyebolt (j).
4. Connect the Wire Connector from the
Antenna Wire to the Top Transformer
Connection (h). Tighten the wing nut finger
tight.
5. If using a counterpoise wire, connect it to
the Bottom Transformer Connection (i).
Tighten the wing nut finger tight.
6. Connect a CHA RFI CHOKE and coaxial cable
or the Integrated RF Choke end of the CHA
Coaxial Cable assembly to the UHF Socket
(g) on the Matching Transformer.
Raise the Antenna.
7. Using a Bowline or similar knot, tie the end
of a short length (around 4 feet) of Paracord
to the Carabiner from step (3).
8. Drive a Stake into the ground closest to the
location of the radio set and tie the
Paracord from the Matching Transformer to
the Stake using two Half Hitches, or similar
knot.
9. Using a Bowline or similar knot, tie a long
length (50 feet or more) of Paracord to the
Isolation Loop (c) at the end of the Antenna
Wire.
10. Using a throw weight or some other
method, loop the Paracord over the support
closest to the radio set.
11. Pull the Paracord and end of the Antenna
Wire over the support.
12. Using a throw weight or some other
method, loop the Paracord over the other
support.
13. Pull the Paracord, such that the Antenna
Wire is not quite taut, and secure it to the
support using a Round Turn and two Half
Hitches, or similar knot.
Extend the Counterpoise.
14. If using a counterpoise wire, extend it along
the ground under the antenna wire.
15. Perform operational test.
Recovery Procedure
To recover the CHA EMCOMM II V2, perform the following steps:
1. Disconnect the Coaxial Cable from the radio set.
2. Lower the antenna to the ground.
3. Disconnect the Coaxial Cable from the Matching Transformer (a).
4. Carefully roll (do not twist) the Coaxial Cable.
5. Untie the Paracord from the Matching Transformer and Antenna Wire (b), as applicable.
6. Disconnect the Antenna Wire and counterpoise wire, if used, from the Matching Transformer.
7. Roll the Antenna Wire onto the Line Winder (f) and secure with attached elastic cord.
8. Pull the Stakes from the ground.
CHA EMCOMM II V2 Page 12
9. Remove dirt from antenna components and inspect them for signs of wear.
10. Store components together.
Troubleshooting
1. Ensure Wire Connector is securely connected.
2. Inspect Antenna Wire for breakage or signs of strain.
3. Ensure UHF Plugs are securely tightened.
4. Inspect Coaxial Cable assembly for cuts in insulation or exposed shielding. Replace if damaged.
5. If still not operational, connect a Standing Wave Ratio (SWR) Power Meter and check SWR.
6. If SWR is greater than 10:1, check antenna tuner or coupler using the technical manual or
manufacturer’s procedure. Be sure to check the Coaxial Patch Cable that connects the radio set to
the antenna tuner or coupler.
7. If still not operational, replace Coaxial Cable assembly. Most problems with antenna systems are
caused by the coaxial cables and connectors.
8. Connect a Multi-Meter to the Antenna Wire to check continuity. Replace assemblies that do not
pass a continuity check.
9. If still not operational, replace Matching Transformer.
Specifications
• Frequency: 1.8 MHz through 54.0 MHz continuous (including all Amateur Radio Service bands
160m to 6m). Wide range antenna tuner or coupler required.
• Power: 250 W continuous duty cycle (CW, AM, FM, RTTY), 500 W intermittent duty cycle (SSB
and SSB-based digital modes)
• SWR: Subject to frequency and configuration, see red (bottom) line in figure (6).
Figure 6. SWR vs Frequency Graph.
• RF Connection: UHF Plug (PL-259)
• Length: 60 ft (maximum) and around 35 ft (minimum)
CHA EMCOMM II V2 Page 13
• Weight: 1 lbs.
• Personnel Requirements and Setup Time: one operator, less than 15 minutes.
• Color: Subdued Hues.
• Figures (7) through (9) show Far Field plots for the various antenna configurations
Accessories
The following accessories are available for purchase from Chameleon AntennaTM. Please contact us at
support@chameleonantenna.com for current prices and availability.
• Counterpoise Kit. The Counterpoise Kit is ideal for portable antenna deployment. The system
will create the ground-plane needed to any vertical antennas and will also play the role of guy
wires. It contains four 25 foot wire radials secured around plastic wire winders and four steel
tent stakes.
• 50’ Paracord and Line Winder Assembly. One assembly is recommended to enable installation
of the CHA EMCOMM II V2.
• Coaxial Cable Assembly. 50 feet of RG-58 with integrated RFI Choke. Used to connect the CHA
EMCOMM II V2 to the radio set. This is a highly recommended accessory if you are not using a
CHA RFI CHOKE.
• RF Choke Assembly. The CHA RFI CHOKE will prevent, greatly reduces or totally eliminates the
RFI carried by the coax cable. It can be installed either at the antenna feed point or right behind
the antenna tuner. This accessory is highly recommended if you are not using the Chameleon
AntennaTM Coaxial Cable Assembly.
Figure 7. Sloping Wire Far Field Plots, 7 (left) and 14 (right) MHz.
CHA EMCOMM II V2 Page 14
Figure 8 Inverted “L” Far Field Plots, 3.7 (left) and 7 (right) MHz.
Figure 9. Horizontal NVIS Far Field Plots, 3.7 (left) and 7 (right) MHz.
CHA EMCOMM II V2 Page 15
Recommended non-supplied accessories:
• Wide range antenna tuner or coupler. Required for most configurations.
• Flashlight.
• Multi-tool.
• Throwing weight and string.
• SWR Power Meter.
• Multi-Meter.
• One Tent Peg (if not purchasing optional counterpoise kit)
• Mallet.
• 20 – 50 ft. 18 gauge insulated stranded wire to be used as a counterpoise (if not purchasing
optional counterpoise kit)
• #10x24 stainless steel wing nut. Recommend one for use as a spare.
• Small canvas or nylon bag to store antenna components.
References
1. Silver, H. Ward (editor), 2013, 2014 ARRL Handbook for Radio Communications, 91st Edition, American Radio
Relay League, Newington, CT.
2. 1987, Tactical Single-Channel Radio Communications Techniques (FM 24-18), Department of the Army,
Washington, DC.
3. Turkes, Gurkan, 1990, Tactical HF Field Expedient Antenna Performance Volume I Thesis, U.S. Naval Post
Graduate School, Monterey, CA.
CHA EMCOMM II V2 Page 16
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TM
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