The W7LPN 2 - 440
Vertical Collinear Antenna Project
with a 6 Meter Surprise!
W7LPN ~ Rick Frazier
updated and easier to
build (12-08) version
It is a pdf file and is under
1 meg file size. Adobe Reader
I would like to share
with you my findings and my design of the well known vertical
collinear antenna, by looking at the work of two other
morphed these two ideas and came up with a truly commercial grade
antenna you can build at home.
The simple colinear
antenna is honestly too long, gangly and tall to be
You may immediately see the
possibilities of combining these two projects or meeting them in the
The more common coax collinear requires a PVC radome
to give it rigidity and weather proofing, and assembly can be
The "Simple Collinear" is very long, gangly, and
heavy, requires several guys, and is difficult to raise.
The 2 - 440
Collinear vertical in this project is simple to build and expand,
semi rigid, self supporting, water tight, electrically sound, and a
professional appearance when completed.
First look at my drawing
below, and decide how long an antenna you want to have up,
approximately. Then sketch it out. Start at the bottom with a 1/4
wave 19" section and a 1/2 wave 38" section separated by the feed
Keep in mind that each 1/2 WL section adds approximately
Note in picture
above, the outer most portion of the antenna is the aluminum
I started with 3/4" and 1/2"
fiberglass tubing from Max-Gain and 0.79" and 0.59" aluminum antenna
stock from MFJ.
Assemble 0.79" fiberglass tubing sections
with 2 part epoxy (not putty), with short sections of 1/2"
fiberglass inserted to reinforce the joints.
Run a long #22
wire inside the entire length of fiberglass while assembling. It is much more difficult to thread afterwards if you
don't. When soldering or attaching #22 wire ends, remove any
coating down to bare wire.
Leave plenty extra length at each
end for pulling and attaching at each section. Too much epoxy can
gum up your project and hang up the thin wire.
NOTE: Element sections are numbered starting at bottom
A 12" section of 1" PVC glued over the bottom
end of the fiberglass flush with the end acts as a good mounting
Directly above that, place #1 element, a 19" X 0.79"
aluminum tubing (1/4 wl) section. Directly above this, drill a hole
in the fiberglass large enough to pull the shield and center
conductor of your coax through.
Then place #2 element a 38"
X 0.79" section directly above this, allowing access to the drilled
Use Ox-Guard or Penetrox and rivets or screws to
secure the shield to the lower element pulling it laterally and
Then pull the center conductor through the hole
using caution to separate them, pulling up and away from the shield
As in the drawing, pull the thin wire through
the hole with a hemostat, or tweezers and pull out a little working
Cut a strip at both ends, attach by soldering
to the shielding near the connection you just
Drill another hole between #2 & #3 elements,
pull the wire snug and attach the wire to the bottom end of #3 with
screw or rivet.
Repeat the process between #2 and #3 elements.
Attach a wire at top end of #2.
Pull it through a whole
between #3 & #4 elements.
Cut an trim and repeat this process
and finish with 1/4 wl X 0.59" aluminum connected only to the thin
Thus you can see #1 skips to #3, #2 skips to #4 etc,
until you terminate at the 19" end stub.
Some final construction notes:
with 1/4wl -19" at the bottom and end with 1/4 wl -19" at the top,
the middle is expandable. I placed ferrite beads over the coax about
38" below the base of the antenna, adjust distance for best
Keep in mind, the greater the difference between the
diameter of the
tubing and the size of the thin wire, and the
larger the tubing, the lower the SWR, broader the bandwidth, and the
easier the tuning.
Sealing each joint.
I used hot
glue and shrink tubing. The tip:
I filled with hot
glue and pulled a short piece of heat shrink inside itself and
to the side, then shrunk it over the end.
in picture above works fine... about 6.5 dB.
I wasn't completely satisfied, leaning toward the side
of perfection, so I did take it back down, took some pictures
and added another 1/2 wave element and ran the coax thru the
ferrite beads 3 times at 38" as per the calculator on the other
collinear site linked earlier in this article, and then tied down
the coax firmly. I won't make any other adjustments.
The photo you should see above is of
the antenna with 4 sealed joints, 1/4 wave at top and bottom, and 3
X 1/2 wave elements in the middle (14ft.total).
mountain repeater is 100 miles away from my QTH and my ham friend
says my signal is full quieting on 5
I was honestly pleasantly surprised by the performance
of this antenna.
Resonant on 6 meters too! Really!
It has very low swr on 6! Cool eh? My ham partner lives about 10
miles away and with the power all the way down we talked thru the
repeater and simplex on 6 meters. Cool!
you might call this project "The 2 Meter / 440 / Magic Band
/ Surprise Antenna" HI!
Further testing on 6
meters in progress! More to come?
There's something about the simplicity of
alternating thin wire and large tubing which goes together so easily
with good results. One thing I've learned is the greater the
difference between the sizes of tubing vs. the wire, the better the
SWR and broader the bandwidth.
This appears to be a truly high-gain home-brew
project well within the abilities of the average home-brew
tinkerer and the surprising ability to also be used on 6 meters was
certainly an unexpected plus!
like the fact that it is easily expandable, and a relatively simple
design and each time you add another 1/2 wave section....more
Editors Note: Upon doing some math, it appears that the entire
length (14 feet) is acting as a (near) 3/4 wavelength antenna on 6
meters! Further testing in
Radiation pattern and gain on 6 meters