The W7LPN 2 - 440 Vertical
Collinear Antenna Project
with a 6 Meter Surprise!
by W7LPN ~ Rick
Download the 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 hams:
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 practical.
You may immediately see the possibilities
of combining these two projects or meeting them in the middle.
more common coax collinear requires a PVC radome to give it rigidity and
weather proofing, and assembly can be difficult.
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 point.
Keep in mind that each 1/2 WL
section adds approximately 2.14dB.
Note in picture above,
the outer most portion of the antenna is the aluminum tubing.
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
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 of
A 12" section of 1" PVC glued over the bottom end of
the fiberglass flush with the end acts as a good mounting stub.
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
Then place #2 element a 38" X 0.79" section directly
above this, allowing access to the drilled whole.
Use Ox-Guard or
Penetrox and rivets or screws to secure the shield to the lower element
pulling it laterally and down.
Then pull the center conductor
through the hole using caution to separate them, pulling up and away from
the shield connection.
As in the drawing, pull the thin wire
through the hole with a hemostat, or tweezers and pull out a little
Cut a strip at both ends, attach by soldering
to the shielding near the connection you just made.
another hole between #2 & #3 elements, pull the wire snug and attach
the wire to the bottom end of #3 with screw or rivet.
process between #2 and #3 elements.
Attach a wire at top end of
Pull it through a whole between #3 & #4 elements.
trim and repeat this process and finish with 1/4 wl X 0.59" aluminum
connected only to the thin wire.
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:
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 SWR.
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.
Finished antenna in
picture above works fine... about 6.5 dB.
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
The Lime 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
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!
So you might call this project "The 2 Meter / 440 /
Magic Band / Surprise Antenna" HI!
on 6 meters in progress! More to come?
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