By Nick Garner N3WG and George Zafiropoulos KJ6VU

By Nick Garner N3WG and George Zafiropoulos KJ6VU
Introduction
Over the last few years, there has been a significant increase in the number of radio amateurs interested
in portable operating. This is due to multiple factors including the availability of high quality portable
radio equipment, limitations to putting up large HF antennas at home, and the desire to travel and enjoy
the great outdoors. In most cases, portable operations impose some basic challenges, not least of which
is the need to run modest power and keep the size and weight of gear as low as possible.
Every year our club operates on Field Day and many of us enjoy taking our gear to the park or hitting the
hiking trail to operate far from the home station. Over the years, we have tried many different
antennas. We found that most commercial antennas are either too bulky and heavy to be easily hauled
around or are two small to be efficient, so idea of the PackTenna was born.
The challenges for coming up with the design for PackTenna included the following, somewhat
conflicting goals.
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Full size, no compromise performance, especially given the limitations of a quick portable setup.
Small enough when packed up for trail use (think SOTA) and air travel.
Quick to setup and take down.
A modular design that can evolve over time as your needs change.
An open design that makes it easy to make modifications and add your own options.
With these goals in mind, we decided to base the design on using wire elements and fiberglass
telescoping poles for the support. This combination allows us to construct full size antennas in many
configurations including horizontal dipoles, inverted vee, ground planes, long wires and resonate wires
to name a few. The rest of the PackTenna design includes all the hardware to make the system work.
We selected antenna hardware designed for backpacking which keeps the size and weight down and
then designed a unique feed point system that allows for quick setup and improved performance. We
hope you enjoy using the PackTenna as much as we enjoyed designing it.
73 de Nick Garner N3WG & George Zafiropoulos KJ6VU
The PackTenna System
The complete PackTenna system includes fiberglass support masts, wire antenna elements, base
mounting hardware, feed points and accessories. This section describes each piece of the system and
how it is used.
Complete System
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10 meter (32’) fiberglass mast
4x 20m quarter wave wire elements
1:1 Feed point choke, 9:1 feed point UNUN, in-line RF choke
Guy rings, guy lines, S-clips, ground stakes, mini bungee cords
Coax and carry bag
10 M (32’) Telescoping Fiberglass Support Mast
All antenna configurations require raising the antenna up in the air. The PackTenna mast telescopes out
to a maximum length of about 32 feet. When collapsed, the mast is only 26 inches long. This makes it
just the right size to stow in your luggage or strap to your backpack. Mast sections stay in place by
gently twisting the sections together when extended. It is important to not pull the elements too hard
so they don’t pop out the ends. If this happens, just unscrew the bottom and insert the sections back
where they belong.
The mast tapers to a very small diameter solid fiberglass rod at the tip. The top ¼ of the antenna, about
the last 8 feet are too light to mount a coax feed point but is normally used for the end of a quarter
wave ground plane wire or end-fed wire antenna.
TIP: An easy way to attach the wire to the tip of the mast is to remove the very last mast segment, the
4mm solid dowel, and slip the end of the wire element (with the female banana socket) into the end of
the last element tube. The crimped ferrule forms a natural bend in the wire and makes a great way to
secure the wire without any additional hardware.
When using the coaxial feed points, mount them ¾ the way up the mast. This is at about 21 feet above
the ground. At this point the mast diameter is about ½” and easily supports the coaxial balun feed
point.
TIP: If you are taking the mast on the trail and want to cut more weight, consider what antenna
configuration you need and only take the mast sections necessary. If you are using an inverted vee, you
can take out the last 4 or 5 sections because they cannot support the feed point balun anyway. If you
are using the mast to support the end of a wire element and don’t need the full 10 meter length, you
can remove the necessary mast sections and leave the larger, lower sections at home.
Wire Antenna Elements
The standard PackTenna elements are 16’ 10” and are designed to be a quarter wave on 20 meters. The
wire elements have strain relief loops and banana connectors on each end. The loops are attached with
S-clips which are in turn connected to the balun feed point, other elements or ground stakes. The basic
PackTenna is a linked dipole design. This makes it easy to clip multiple elements in series allowing for
easy band switching. The S-clips take the strain of the antenna and banana connectors. The banana
connectors are used to make the RF connection.
The banana connectors have a high surface area and are gold plated to make excellent RF connections.
For 20 meters, a pair of antenna elements can make a dipole, inverted vee, ground plane, etc. For 40
meters, simply clip two 20 meter elements in series. The high end that connects to the feed point uses a
male banana connector. The opposite end has a female banana connector. This makes it very easy to
tune the antenna in the field, if needed, by plugging in a short pigtail wire and trimming the length. This
way you can precisely tune the antenna while not cutting the 20m wire element. The antenna will work
reasonably well on 15m as well when configured as a 40m dipole or vee because 15m is the 3rd harmonic
of 40m.
A DIY antenna parts kit is also available with the same hardware to make it easy for you to make your
own antennas in any configuration you like for any band.
Base Mounting Hardware
The fiberglass mast must have a solid base to support the antenna. The PackTenna system includes a
guy kit for ground mounting the antenna. The guy system includes 8 guy lines. Each guy line is 10’ long
and has a line tensioner, and an S-clip. 3 guy lines are used to hold the base in place making the mast
self supporting. An additional four guy lines are included for the ends of the wire elements providing 20
feed of guy line on each side. One spare guy line is included because, well, you can always use more
hardware. . The guy kit includes 6 light weight ground stakes. Three for the mast support guy lines, two
for the wire element ends and a spare.
When using the PackTenna on hard ground, like an asphalt parking lot, it is much easier to use a
portable tripod mount. The PackTenna mast can be attached to the tripod with mini-bungee cords
included with the system. Just put at least two bungees around the mast and tripod center support.
Additional guying may be required depending on the antenna load and weather conditions.
Photo tripods or speaker stands can make good base mounts.
Guy Rings
Guy rings are available for various mounting points on the fiberglass mast. The largest guy ring will set
on the top of the 3rd section at about 5’ above the ground. This makes an excellent guyed base. For
many antenna configurations, no additional guying may be needed. Two other guy rings are available to
guy sections higher up the mast.
The smaller guy ring for the upper sections can also be used to make a double inverted vee with
elements going out at right angles similar to the famous military NVIS antenna model AS-2259.
Each guy ring has 4 guy line holes designed for S-clips to easily snap in place. Normally the mast is guyed
with 3 guy lines.
Base guying configuration
Guy line tensioner
3 sided aluminum ground stake with paracord loop
Feed Points
The feed point is where the coax cable and antenna element wire comes together. This is the heart of
the antenna. To deploy several different antenna configurations, the PackTenna system includes two
types of feed points. A 1:1 current balun and a 9:1 UNUN.
1:1 Feed Point Balun
A resonant antenna, like a half wave dipole, inverted vee or ground plane uses the balun to ensure there
is no common mode current flowing back down the coax shield to the transmitter. These antennas do
not require a tuner because the antenna is resonate for the band desired. The balun reduces or
eliminates RFI at the radio and helps make the antenna more efficient.
Standard PackTenna 1:1 Feed Point Balun
PackTenna feed points include multiple banana sockets to connect the balun to the wire antenna
elements. These connections are labeled “Ground” or “Center” The ground connections are connected
together and the center connections are connected to each other. S-clips connect to the side lobes or
top lobe and take the stress of the antenna element wire. The pigtail coming off the antenna wire
element plug into the banana sockets.
TIP: When fielding an inverted vee or dipole, plug one wire element into a ground jack and one wire
element into a center jack.
TIP: When setting up a long wire, sloper, or vertical, connect the vertical radiator element to the center
socket on the top and ground radials to one or more of the ground sockets.
9:1 UNUN
This type of feed point is used to match the coax to an end-fed high impedance antenna. These can be
either ½ wave resonate wires or random end fed wire antennas. The UNUN brings the feed point
impedance down closer to the transmitter’s 50 Ohm output impedance. A tuner is required to make
these types of antennas work.
9:1 Feed Point UNUN
Mounting the Feed Point
The feed point board mounts to the mast using mini bungee cords. This method allows you to attach
the board tightly to the mast without crushing the mast material. The bungees also grip the mast so the
feed point does not easily slide down the mast. There are six small holes that make convenient places to
attach the bungees. Connect one end to the PCB, wrap the cord around the mast several times and
connect the remaining end into another attachment point.
Three large loops are provided on the sides and top to allow the S-clips to connect to the board. The Sclips provide a mechanical connection from the wire elements to the feed point.
The wire elements plug into the feed point using mini banana plugs. There are 5 mini banana sockets
mounted to the feed point board. Three of them are bussed together to ground and two are bussed
together for the center wire of the feed line. The balun or UNUN on the feed point is between the feed
line and the wire element banana sockets. The wire loops at the end of the wire elements clip into the
S-clips and the male banana plugs plug into the sockets.
When using the PackTenna in a dipole or inverted vee, connect one wire element to a ground point and
the other wire element to the center point.
When using the PackTenna in an end-fed configuration, connect the long wire to one of the center
points and optionally add one or more ground wires to the ground points.
When using a vertical ground plane configuration, connect one or more ground radials to the ground
points and the vertical element to the top center socket.
The coax cable from the radio connects to the BNC connector at the bottom.
Coax Cable
We recommend 25’ lengths of RG58 coax with BNC connectors. Use one length of coax when operating
near the bottom of the mast. When operating farther from the mast, add another 25’ section of coax
with a BNC/BNC barred connector. Of course any 50 ohm coax will work. For general portable
operations, we recommend RG58 because it’s more robust than the thinner RG174 and it’s smaller and
lighter than the larger RG8X. For backpacking, while RG58 works fine, you may consider the thinner
cables. For these smaller cables, we recommend RG316 because of it’s mechanical strength. It is the
same size and performance as RG174. The downside to the smaller cable is the higher losses, even at HF
frequencies.
S-Clips
The S-clip is a universally useful piece of hardware. These non-conductive clips are true multi-taskers.
They are used to quickly connect wire elements to our feed points, connect guy lines together, and
suspend feed points from a tree limb. Your imagination is the limit. Notice the holes in the side… these
are very handy places where you can thread antenna wire in and out for quick setups or manually
tuning. You can also thread paracord through the hole and tie it off in a knot. Super light weight and
strong, these clips are a great addition to your portable station.
BNC Barrel Connector
We recommend using 25’ segments of RG58 coax with male BNC connectors on either end. The barrel
connector is used to link multiple 25’ segments together
Optional Switch Link
The switch link can be used instead of the banana connectors to make a linked dipole. The device is a
little PCB with a slide switch that makes / breaks the connection in the antenna wire. The isolation is
limited by the gap in the slides switches so care must be taken not to run very high power.
1:1 In-line current choke
Common mode current can flow on the outside of the shield from the feed point back down to the
shack. This can cause RF interference to your radios, accessories and other electronics. The 1:1 feed
point balun and a resonant antenna greatly reduce common mode currents and the in-line choke is not
typically needed for these configurations.
However, end-fed and non-resonant antennas tend to induce common mode current flowing back down
the coax shield. With these types of antennas we recommend using an in-line choke to minimize this
interference.
These problems are particularly common with higher power levels. Running QRP levels of 5 or 10 watts
usually does not present a problem. When the power level is much higher, say 50-100 watts, there is a
much higher chance of causing RF interference. This can also happen when the radio is in the near field
of the antenna. Moving away from the antenna and adding a choke will reduce the interference. It is
not always possible, at higher power levels, to completely eliminate the interference.
Antenna Configurations
The PackTenna system can be used to build many different antenna configurations. This section shows
some of the most popular antennas used in portable operations. The diagrams are provided to explain
the components needed and how to assemble them. These diagrams are not to scale but will give you
the general idea.
All the configurations only show the antenna components. It is assumed that there is some sort of base
support. This would be a low set of guy lines, typically at the top of the second or third mast section. A
ground stake or tripod can also be used as a base support. The base support method is not shown to
keep the diagrams from getting to cluttered.
So, which configuration of antenna is the best one? Every antenna configuration has pros and cons and
many books have been written to explain the differences in great detail. For the portable operator, here
is a very short set of recommendations
1.
Horizontal antennas (dipole, inverted vee) are lower noise than verticals. Elevation will
determine the angle of radiation. With a PackTenna the feed point will be at about 22 feet. For
20 meters and higher frequencies, this will provide good overall performance for both DX. On
40m with the antenna much closer to ground you will tend to have more local or regional
communications because the radiation pattern will be higher.
2. A quarter wave ground plane will have a low angle of radiation so it will perform well as a DX
antenna but tend to be noisier than a horizontal antenna. PackTenna is large enough to build a
full size quarter wave ground plane for 20m and higher frequencies. You can also make a
quarter wave ground plane for 40m but the feed point will be at the ground level. This will not
be as efficient as a raised feed point on the 20m configuration. You can overcome some of the
ground losses by adding several more ground radials on the ground itself.
3. End-Fed antennas, both the half wave and the non-resonant random wire have the big
advantage of being the easiest antenna to set up quickly and have a very small foot print. It’s
easy to see how these antennas are very popular for portable operations where quick setup and
take down is desirable. The disadvantage of these antennas is that they tend to be less efficient
as compared to a tuned resonant antenna. These antennas tend to induce common mode
current down the feed line back to the station. This is usually no problem at QRP levels but can
be a problem at higher power levels. Adding an in-line common mode current choke can reduce
this interference.
Inverted Vee
An inverted vee is a half wave dipole antenna with a single center support and the ends angled towards
the ground. This type of antenna performs similar to a traditional dipole in that it is horizontally
polarized with a fairly omni-directional pattern. Because of the horizontal polarization, the inverted vee
is typically quieter than a vertical.
Inverted Vee’s are popular for portable ops because, unlike a dipole, it only has one physical support
mast required. The angle of the V is typically between 90 and 120 degrees and care must be taken to
keep the ends of the elements off the ground by at least 2 to 3 feet and higher is better.
A 1:1 balun is recommended at the feed point to ensure an efficient coupling to the antenna elements
and to keep common mode currents from flowing back down the coax shield.
When setting up the inverted vee, extend the mast to about 22’. This is the point where the feedpoint
will be attached. This elevation works well on 20m and higher frequencies with little ground
interaction. It is also the point where the mast is still large enough to hold up the feed point and coax.
The antenna elements will act as a high level guy lines as well to keep the antenna in position.
The PackTenna elements are pre-cut as a quarter wave on 20 meters. On advantage of using a full size
half wave antenna is that they tend to be fairly broad band. This means if it’s tuned for the middle of
the band it will work pretty well across the whole band.
If you really want to tune the antenna even closer to your desired frequency you can add a tuning
whisker. The wire elements have a male banana plug that goes at the end closest to the feed point. The
opposite end has a female banana socket. This socket is used to link to another wire segment. You can
make a simple tunig wire by soldering a male banana plug onto about one foot of antenna wire. Plug
the short tuning wire at the end of the antenna and snip off an inch at a time until the antenna is
perfectly tuned.
The inverted vee configuration is also very good for a multi-band 20/40 antenna. In the diagram above,
you can see how putting two standard 20m quarter wave elements on each side and connecting the
dipole links between them wil make it easy to swtich between a full size 20m or 40m inverted vee.
When connecting the antenna elements to the feed point, insert one side into a banana socket marked
“Ground” and the other wire element into the banana socket marketd “Center”
Half Wave Dipole
The half wave dipole is the most common antenna found in ham radio and certainly the reference
against which just about all other antennas are measured against. A dipole must be suspended at either
end. This means you must find two strong anchor points. In addition to being a rather large antenna
compared to other configurations, dipoles are not as popular in the field as other configurations. The
PackTenna certainly can be deployed in a dipole configuration using the balun feed point and wire
elements. Two PackTenna 30’ fiberglass masts could be used to support a dipole as high up as about 22
feet. Beyond that point, the mast is too thin to provide enough support. The mast must be guyed very
close to the point where the dipole connects to the guy ring to avoid bending the mast.
We recommend that if you want to use the PackTenna in a dipole configuration you use a very rigid
anchor point for the ends of the dipole such as a tree or building.
Quarter Wave Ground Plane
The quarter wave ground plane has one quarter wave wire element in the vertical plane and one or
more ground radials forming the counterpoise of the antenna. The quarter wave has the advantage of a
low angle of radiation so it makes a good DX antenna. Although somewhat noisier than a dipole or
inverted vee, the ground plane is a good performing resonant antenna.
Ground planes can be ground mounted or elevated. Mounting the antenna with the base feed point at
the ground level causes significant ground losses and makes the antenna less efficient. Elevating the
whole antenna above ground so the feed point is at least 1/8 wave above the ground reduces ground
losses and makes the antenna more efficient.
From a practical point of view, with a 30’ tall PackTenna mast, you can make an elevated ground plane
for any band from 20 meters and up in frequency. This is the recommended configuration. It is an easy
configuration to setup and using 3 ground radials will double as your guy lines to hold up the antenna.
If you are making a larger antenna, say for 30m, 40m, or lower in frequency, you will have to put the
feed point much closer to ground. While this will certainly work, adding more radials will help reduce
ground losses. How many do you need? Ideally 8 or more would make a big difference so put out as
many as you can.
The length of radials for an elevated antenna makes a big difference in the tuning of the antenna. This
includes the length, angle and proximity to the ground. When ground mounting your vertical, the length
of the radials is not as critical.
End-Fed Half Wave
The end-fed half wave or random wire antenna is very popular. This is because it is very quick to set up
and take down and because it MUST be used with an antenna tuner, and can work on all bands. When
running a non-resonant end-fed wire, make sure the antenna is non resonant on ANY ham band. The
following lengths are good: 29’ 35.5’ 41’ 58’ 71’ because they don’t land in a ham band. With the
standard PackTenna wire element length of 16’ 10”, it is a quarter wave on 20m so you will want to add
additional wire. We recommend adding 12 feet of wire giving you a length of 29’ which is a nice, large
radiator and can be supported with a fully extended PackTenna mast.
The impedance of the antenna at the end is high, often between 1000-3000 Ohms, compared to the
transmitters expected load of 50 Ohms. These antenna benefit from using a 9:1 UNUN to transform the
impedance down to the range that your radio’s antenna tuner can match.
9:1 UNUN matching transformer
Typical configuration for an end-fed antenna would have the radiator plugged into the “Center”
connector and an optional ground wire connected to one of the “Ground” connectors.
PackTenna Hardware Pack
10’ guy lines with tensioners
S-clips
Ground stakes
Guy rings
Mini bungee cords
Reference
For the fanatic backpacker in all of us, here are the weights of each item in ounces…
1:1 feed point balun 2.6
9:1 UNUN with large core 4.4
4x 20m wire elements & winder 10.1
1x guy line 0.7
25' coax 9.7
Guy ring (each) 1.0
8 mini bungees 2.7
In line choke 2.7
10m mast 43.0