CHAMELEON ANTENNA EMCOMM III Portable Antenna Instruction Manual
- June 15, 2024
- CHAMELEON ANTENNA
Table of Contents
CHAMELEON ANTENNA EMCOMM III Portable Antenna Instruction Manual
Nevada – USA WWW.CHAMELEONANTENNA.COM
WARNING! Never mount this, or any other antenna near power lines or
utility wires! Any materials: ladders, ropes, or feedlines that contact power
lines can conduct voltages that kill. Never trust insulation to protect you.
Stay away from all power lines.
WARNING! Never operate this antenna where people could be subjected to
high levels of RF exposure, especially above 10 watts or above 14 MHz. Never
use this antenna near RF sensitive medical devices, such as pacemakers.
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.
Introduction
Thank you for purchasing and using the Chameleon AntennaTM EMCOMM III Portable antenna. The EMCOMM III Portable antenna, see plate (1), is a portable High Frequency (HF) antenna specially designed for short to long range portable and man-pack HF communications. The EMCOMM III Portable antenna is ideal for hiking, backpacking, and both tent and Recreational Vehicle (RV) camping. It is also highly suitable 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), and amateur radio operators (hams) involved in field communication and disaster preparedness.
The EMCOMM III Portable antenna is configurable to facilitate Near-Vertical Incident Sky wave (NVIS) communication and will support most Automatic Link Establishment (ALE), frequency-hopping, and spread- spectrum modes and operations. An antenna tuner or coupler may be required for in some instances. The EMCOMM III Portable antenna can be deployed by the operator in the field in less than 15 minutes, using almost any available support, with no masts or guying required.
The EMCOMM III Portable antenna is comprised of a matching transformer, a 73-foot antenna wire on a line winder, and a 25-foot counterpoise – making a highly portable and effective HF antenna system.
Antennas built by Chameleon AntennaTM 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 EMCOMM III Portable antenna.
Plate (1). EMCOMM III Portable Antenna.
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 EMCOMM III Portable’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 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.
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.
Table 1. Maximum Surface Wave Range by Frequency.
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, 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 show a 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 is 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.
Parts of the Antenna
The EMCOMM III Portable antenna is comprised of the following components, refer to plate (2):
a. Matching Transformer
The Matching Transformer provides impedance matching for the EMCOMM III
Portable antenna. It is permanently affixed to the Line Winder (b).
b. Line Winder
The Line Winder is used to store the Antenna and Counterpoise Wires and
enables rapid deployment and recovery of the EMCOMM III Portable antenna. The
Matching Transformer (a) is permanently affixed to the Line Winder. The Line
Winder is also used as the end support for the erected antenna.
c. Antenna Connection
The Antenna Connection is the wing nut on the left side of the Matching
Transformer (a) marked “A”. It is used to connect the Antenna Wire (g) to the
Matching Transformer.
Plate 2. EMCOMM III Key Components.
d. Counterpoise Connection
The Counterpoise Connection is the other wing nut on the right side of the
Matching Transformer. It is used to connect the Counterpoise Wire (m) to the
Matching Transformer.
e. UHF Socket
The UHF Socket, SO-239, is located on the bottom of the Matching Transformer.
f. Suspension Attachment Point
The Suspension Attachment Point is a hole in the top of the Center Line Winder
(b) used to allow attachment of Paracord (k) for suspension of the erected
antenna.
g. Antenna Wire
The Antenna Wire consist of a 73-foot length of black insulated wire, wrapped
around the Line Winder (b).
h. Isolation Ring
An Isolation Loop is permanently attached to end of the Antenna and
Counterpoise Wires. There is also a floating Isolation Loop along the Antenna
Wire. They are used to attach Paracord (k) for suspension of the erected
antenna.
i. Wire Connectors
The Wire Connectors are wing nuts used to connect the Antenna and Counterpoise
Wires to the Antenna and Counterpoise Connections on the Matching Transformer.
j. Carabiner
The Carabiner is used to attach the Antenna Wire and Counterpoise Wires to the
Strain Relief Holes (n) in the Line Winder.
k. Paracord, 550
Paracord (not pictured, not supplied) is used to suspend components of the
EMCOMM III Portable antenna at the proper height or anchor it to the ground,
depending upon the antenna configuration.
l. Coaxial Cable Assembly
The Coaxial Cable Assembly (not pictured, not supplied) connects to the UHF
Socket (e) at one end and the Radio Set at the other. The use of an RF choke
at the feed point of the antenna will improve the performance of the antenna.
A 50-foot coaxial cable assembly, with an integrated RF choke, is available
purchase from Chameleon AntennaTM.
m. Counterpoise Wire
The Counterpoise Wire (not pictured) is a 25-foot length of black insulated
wire used in most configurations of the EMCOMM III Portable antenna. An
optional Counterpoise Kit, which contains four 25-foot wire radials secured
around Line Winders and four steel Tent Stakes is available from Chameleon
AntennaTM.
n. Strain Relief Hole
The two Strain Relief Holes are used to provide mechanical strain relief for
the Antenna and Counterpoise Wires.
Initial Assembly
Prior to first use, perform the following initial assembly procedure to prepare the EMCOMM III for field deployment. Refer to plates (2) and (3) during assembly.
-
Attach the Carabiner (j) which is fastened to the Antenna Wire (g) to the Strain Relief Hole (n) on the left side of the Line Winder
-
(b). The Antenna Wire is the longer of the two coils of wire.
Connect the Wire Connector (i) at the end of the Antenna Wire to the Antenna Connection (c) on the left side of the Matching Transformer (a). Tighten the wing nut finger tight. The Antenna Connection is marked with an “A”. -
Attach the Carabiner which is fastened to the Counterpoise Wire (m) to the Strain Relief Hole on the right side of the Line Winder. The Counterpoise Wire is the shorter of the two coils of wire.
-
Connect the Wire Connector at the end of the Counterpoise Wire to the Counterpoise Connection (d) on the right side of the Matching Transformer. Tighten the wing nut finger tight.
-
Wrap the Antenna Wire around the left side of the Line Winder using the grooves at the top and bottom of the Line Winder.
-
Wrap the Counterpoise Wire around the right side of the Line Winder using the groves at the top and bottom of the Line Winder.
Plate (3). Antenna Wire Connection.
The completed assembly should look similar to that pictured in plate (1). Once assembled it is not necessary to completely disassemble the antenna after use.
Antenna Configurations
Using the supplied components, the EMCOMM III Portable antenna can be deployed into a number of useful configurations. Three basic configurations are described in this manual, each with unique performance characteristics. Table (2) shows the antenna configurations described in this manual. The table can assist the operator to quickly select the most appropriate antenna configuration to meet their operational requirements.
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 EMCOMM III Portable configuration with the corresponding symbol in the appropriate distance column. All EMCOMM III Portable 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. “Hasty” and “Deliberate” in the deployment column indicate the relative complexity of site selection and setup for each antenna configuration.
To operate efficiently, all EMCOMM III Portable antenna end-fed configurations need one or more counterpoise wires. The single non-resonant counterpoise with a length of 25 feet, which is supplied, will provide satisfactory performance on most frequencies. However, increasing the number of counterpoise wires will increase the efficiency of the antenna, with four being a good compromise between performance and practicality. Chameleon AntennaTM offers a counterpoise kit (CHA COUNTERPOISE KIT), which consists of four 25 ft radials and Tent Stakes. Contact Chameleon AntennaTM for availability and price.
An antenna tuner or coupler may be required with some configurations and frequencies to obtain a suitable transmitter match.
Inverted “L” / Sloping Wire Configurations
The EMCOMM III Portable antenna, Inverted “L” and Sloping Wire configurations,
see figure (1), are medium to long range HF antennas. They should provide
acceptable ground wave and sky wave propagation. The Inverted “L” and Sloping
Wire configurations are excellent general-purpose antennas and are a good
choice when two supports are available (for the Inverted “L”) or one support
(for the Sloping Wire) and there is sufficient time for site selection and
installation. Installing the antenna at a height of around 25 feet or higher
will provide good performance. These configurations are predominately
omnidirectional on lower frequencies, slightly favoring the end of the antenna
on upper frequencies.
Figure 1. Inverted “L” and Sloping Wire (inset) Configurations.
Site Selection and Preparation.
-
Select a site to deploy the EMCOMM III Portable antenna Inverted “L” configuration, see figure
(1). The best site should have two trees or other supports where the height of the supports and the distance between the supports equal the length of the of the Antenna Wire. In the example configuration shown in figure (4), the height is 25 feet and the distance between the supports is 48 feet for a total of 73 feet. The Sloping Wire configuration requires only one support and is the easiest configuration to install. If tall supports are unavailable, any convenient object, such as fence posts or the top of vehicles, may be used as a field expedient supports with reduced performance. -
Unwind the Antenna Wire (g) from the Line Winder (b).
-
Unwind the Counterpoise Wire (m) from the Line Winder.
-
Using a Bowline or similar knot, tie one end of a short length of Paracord through the Suspension Attachment Point (f). This will be used to anchor the bottom end of the antenna to the ground.
Extend the Antenna Wire. -
Secure the Line Winder to the ground with the short length of Paracord and a Tent Stake (not supplied) or base of a small tree.
-
Extend the Antenna Wire to its full length to a position near the desired end point of the antenna.
Raise the antenna. Inverted “L” only, perform steps 7 through 9. Sloping Wire, skip to step 10. -
Using a Bowline or similar knot, tie a long length of Paracord to the floating Isolation Ring on the Antenna Wire.
-
Using a throw weight or some other method, loop the free end of the Paracord from the floating Isolation Loop on the Antenna Wire over the near end support.
-
Raise the floating Isolation Ring to the desired height and secure the free end of the Paracord to the support with a Round Turn and two Half Hitches or similar knot.
-
Tie a long length of Paracord to the Isolation Ring on the end of the Antenna Wire.
-
Using a throw weight or some other method, loop the free end of the Paracord from the end Isolation Loop over the far end support.
-
Pull the end Isolation Loop up to the desired height, such that the Antenna Wire is somewhat taut, but still has sufficient sag to allow for swaying. Secure the end of the Paracord to the end support using a Round Turn and two Half Hitches or similar knot.
-
Extend the Counterpoise Wire on the ground, in a mostly straight line, in any convenient direction. The end of the Counterpoise Wire may be left free or it can be secured to the ground using a Tent Stake (not supplied).
-
Connect the Coaxial Cable Assembly (l) to the UHF Socket (e) on the Matching Transformer.
-
Perform operational test.
End-Fed Inverted “V”
The EMCOMM III Portable antenna End-Fed Inverted “V” configuration, see figure
(2), is a medium range HF antenna. The End-Fed Inverted “V” is a good
compromise between performance and ease of installation since it requires only
one center support, has a reasonably small foot-print, and provides good sky
wave propagation. The center should be mounted at a height of around 25 feet
and when mounted at this height, the antenna will be omnidirectional at lower
frequencies and predominately bidirectional broadside to the antenna on upper
frequencies.
Figure 2. End-Fed Inverted “V” Configuration.
Site Selection and Preparation.
- Select a site to deploy the EMCOMM III Portable antenna End-Fed Inverted “V” configuration, see figure (2). The best site should have a tree or other support that would enable the center of the Antenna Wire to be raised to a height of around 25 feet. If tall supports are unavailable, any convenient object, such as a fence post or the top of a vehicle, may be used as field expedient supports with reduced performance.
- Unwind the Antenna Wire (g) from the Line Winder (b).
- Unwind the Counterpoise Wire (m) from the Line Winder.
- Using a Bowline or similar knot, tie one end of a short length of Paracord through the Suspension Attachment Point (f). This will be used to anchor the bottom end of the antenna to the ground. Extend the Antenna Wire.
- Secure the Line Winder to the ground with the short length of Paracord and a Tent Stake (not supplied) or the base of a small tree.
- Extend the Antenna Wire to its full length to a position near the desired end point of the antenna.
- Using a Bowline or similar knot, tie a long length of Paracord to the floating Isolation Ring on the Antenna Wire.
- Using a throw weight or some other method, loop the free end of the Paracord from the floating Isolation Ring on the Antenna Wire over the center support.
- Raise the floating Isolation Ring to the desired height and secure the free end of the Paracord to the support with a Round Turn and two Half Hitches or similar knot.
- Tie a short length of Paracord to the Isolation Loop on the end of the Antenna Wire.
- Pull the end Isolation Loop, such that the Antenna Wire is somewhat taut, but still has sufficient sag to allow for swaying. Secure the end of the Paracord to the ground using a Tent Stake (not supplied) or the base of a small tree.
- Extend the Counterpoise Wire on the ground, in a mostly straight line, in any convenient direction. The end of the Counterpoise Wire may be left free or it can be secured to the ground using a Tent Stake (not supplied).
- Connect the Coaxial Cable Assembly (l) to the UHF Socket (e) on the Matching Transformer
- Perform operational test.
Horizontal End-Fed (NVIS)
The EMCOMM III Portable antenna Horizontal End-Fed (NVIS) configuration, see
figure (3), is a short to medium range HF antenna. The Horizontal End-Fed
configuration will provide good NVIS propagation on lower frequencies and
medium range sky wave propagation on upper frequencies. It requires two
supports and should be mounted at a height of 25 feet for good overall
results. When mounted at this height, the antenna is omni-directional on the
lower frequencies and predominantly bidirectional towards the ends of the
antenna on the upper frequencies.
A special variation of this configuration is a high-gain long wire antenna for the 50 MHz (6 Meter) Amateur Radio Service band. In this configuration, the operator uses a 4 ft 8 in (56 in) wire and an insulator (not supplied) as the Antenna Wire and the supplied Antenna Wire as the counterpoise, as shown in the inset in figure (3).
Figure 3. Horizontal NVIS Configuration.
Site Selection and Preparation.
-
Select a site to deploy the EMCOMM III Portable antenna End-Fed Horizontal (NVIS) configuration, see figure (3). The best site should have two trees or other supports where the distance between the supports is at least 73 feet. If sufficiently tall supports are unavailable, any convenient object, such as fence posts or the top of vehicles, may be used as a field expedient supports with reduced performance.
-
Unwind the Antenna Wire (g) from the Line Winder (b).
-
Unwind the Counterpoise Wire (m) from the Line Winder.
-
Using a Bowline or similar loop knot, tie the end of a long length of Paracord to the Line Winder through the Suspension Attachment Point (f). This will be used to suspend the end of the antenna.
Extend the Antenna Wire. -
Extend the Antenna Wire to its full length to a position near the desired end point of the antenna.
-
Using a Bowline or similar knot, tie a long length of Paracord to the Isolation Ring on the end of the Antenna Wire. Raise the antenna.
-
Using a throw weight or some other method, loop the free end of the Paracord from the Line Winder over the near end support.
-
Connect the Coaxial Cable Assembly (l) to the UHF Socket (e) on the Matching Transformer.
-
Raise the Line Winder to the desired height and secure the free end of the Paracord to the support with a Round Turn and two Half Hitches or similar knot.
-
Using a throw weight or some other method, loop the free end of the Paracord from the end Isolation Ring over the far end support.
-
Pull the end Isolation Ring up to the desired height, such that the Antenna Wire is somewhat taut, but still has sufficient sag to allow for swaying. Secure the end of the Paracord to the far end support using a Round Turn and two Half Hitches or similar knot.
-
Extend the Counterpoise Wire on the ground, in a mostly straight line, in any convenient direction. The end of the Counterpoise Wire may be left free or it can be secured to the ground using a Tent Stake (not supplied).
-
Perform operational test.
Recovery Procedure
To recover the EMCOMM III Portable antenna, perform the following steps:
- Disconnect the Coaxial Cable Assembly from the radio set.
- Lower the antenna to the ground.
- Disconnect the Coaxial Cable Assembly from the Matching Transformer.
- Carefully roll (do not twist) the Coaxial Cable Assembly.
- Wind the Antenna and Counterpoise Wires onto the Line Winder and secure with attached shock cord.
- Remove dirt from antenna components and inspect them for signs of wear.
Troubleshooting
- Ensure Wire Connectors are securely connected.
- Inspect the Antenna and Counterpoise Wires for breakage or signs of strain.
- Ensure UHF Plug from the Coaxial Cable Assembly is securely connected to the UHF Socket.
- Inspect Coaxial Cable Assembly for cuts in insulation or exposed shielding.
- If still not operational, replace Coaxial Cable Assembly. Most problems with antenna systems are caused by the coaxial cables and connectors.
- If still not operational, contact Chameleon AntennaTM at support@chameleonantenna.com for technical support, be sure to include details on the antenna configuration, symptoms of the problem, and what steps you have taken.
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 for any EMCOMM III Portable end-fed antenna configuration. It contains four 25- foot wire radials secured around plastic wire winders and four steel Tent Stakes.
- Coaxial Cable Assembly. 50 feet of RG-58 with integrated RFI Choke. Used to connect the EMCOMM III Portable to the radio set. This is a highly recommended accessory if you are not using a CHA RFI CHOKE.
- RFI Choke. Used in conjunction with user furnished coax. This is a highly recommended accessory if you are not using the 50 ft. coax w/RFI Choke.
Specifications
- Frequency: 1.8 MHz through 55.0 MHz continuous (including all Amateur Radio Service bands 160m to 6m)
- Power: 100W SSB Phone, 50W CW, 25W High Duty Cycle Digital Modes
- RF Connection: UHF Plug (PL-259)
- SWR: Subject to frequency and configuration, as measured see table (4), but typically less than 2.0:1. An antenna tuner or coupler may be required.
- Length: 73 ft/25 ft
- Weight: Approximately 1 lbs.
- Ingress Protection comparable to IP42 standard (not tested). Ingress protection from most wires, screws or similar objects and from vertically dripping water when device is tilted at an angle up to 15 degrees
- Personnel Requirements and Setup Time: one trained operator, less than 15 minutes
- Far Field plots for the three basic and special EMCOMM III Portable antenna configurations are shown in figures (4) through (7)
Table 4. EMCOMM III Portable Antenna Measured SWR.
Figure 4. Inverted “L” Far Field Plot.
Figure 5. End-Fed Inverted “V” Far Field Plot.
Figure 6. Horizontal End-Fed Far Field Plot.
Figure 7. Six Meter Long Wire Far Field Plot.
References:
- Silver, H. Ward (editor), 2013, 2014 ARRL Handbook for Radio Communications, 91st Edition, American Radio Relay League, Newington, CT.
- 1987, Tactical Single-Channel Radio Communications Techniques (FM 24-18), Department of the Army, Washington, DC.
- Turkes, Gurkan, 1990, Tactical HF Field Expedient Antenna Performance Volume I Thesis, U.S. Naval Post Graduate School, Monterey, CA.
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