My Quad Project
A 2 Element Cubical Quad for the
10/11 Meter Band
I am a firm believer in the phrase,
" Why reinvent the wheel?".
This antenna is a
plumbers dream. Most
parts are available on the World Wide Web or at some larger hardware
stores. This two-element Cubical Quad antenna is designed for
use on either the 10-meter ham band or the 11-meter Citizen's
When all was said and done,
my SWR readings were 1.3 to 1.7 on the 10-meter band. At one
point during the tuning phase, I had a reading of 1 to 1 at about
29.5 MHz. I tried to stay with an age-old design but also used
commercially available parts. This kept the weight factor manageable
for a 10 or 11-meter size quad. My PVC version sports vertical
polarity plus an easy to change coaxial feed to the driven
The thing turned out quite well cosmetically
and I was very pleased with the electrical properties. I was
involved in building a similar antenna in the mid 60's. Back then, many of
us had a CB Radio. The basic design hasn't evolved much
but the construction material has. This antenna weighs just
about 20 pounds, the sixties version was nearly 45 lbs and all
The Boom is 63 inches from end
to end. I used 60 inches of 1 1/2 inch sch 40 PVC pipe. The
pipe is secured to the end hubs with 1/4 x 2 1/2 inch
stainless machine thread carriage bolts and nuts. By not cementing
these in place, it allowed me to construct each end section one at a
time. It also makes any future repair allot easier. The two 5 way
hubs that support the spreader arms are also PVC. These came from an
on-line greenhouse building supply company.
With the help of 8 reducers from an on-line
hardware company, the hubs will accept 1/2 inch sch 40 PVC pipe.
The ½ inch PVC pipe sections are 12 inches long
(15 inches for CB Band ). A 4-way one-inch slot is cut in one
These slots allow 1 1/2" stainless hose clamps to secure
the 1/2 inch dia by 72 inch solid fiberglass spreader arms.
This design makes for easy adjustment of the spreader
The fiberglass spreader arms were once
electric fence posts in a previous life. These too are from an
on-line electric fence supply Co. (See source
below) On the end of each spreader arm, I attached a
2-inch long by 1-inch diameter section of black nylon rod. I ordered
a 3-foot section from an On-Line plastic supply company and
cut them to length on my table saw. I drilled a 1/2 inch centered
1-inch deep hole in each. I secured the nylon tips with friction and
a dab of hot glue. These tips support the 12 ga. stranded
Primary wire that I purchased from a local automotive supply
opposite end of each nylon tip has a 1/8-inch dia hole drilled from
side to side for passing the wire through. I placed it 1/2
inches from the top of each piece.
I used the dimensions from an
on-line quad calculator to provide the exact length wire needed
for the reflector and the driven element. I measured these very
precisely but left about 6 inches of extra wire on each end. The wire has a white plastic
coating. I used a black marker to mark off each quarter length. I
colored 1/2 inches on either side of that mark with a red
marker. This made adjustment simple when I slid the fiberglass rods
out to their proper position.
I secured the wire in place with small nylon pull ties and a
dab of hot glue on either side of the nylon
The reflector wire is cut at the beginning
of the first red mark and at the end of the last. I striped the
coating back 1-inch on each end. I then overlapped and soldered the
two ends together.
(A second person here helps to flex the rod
to one side until the solder is cool.) With the soldered joint
securely inside the nylon tip, the fiberglass rods can be extended
to their proper length. The wire should be taut on all four
sections. After tightening the hose clamps, this completed the
Boom mounting plate (shown below) uses two stainless 1
7/8th" exhaust clamps and two 1 1/4" mast clamps.
This picture shows a piece of aluminum plate 1/4" X 4" X
12". I drilled and attached the plate to the boom
centered and plumbed. The aluminum plate and the
stainless clamps came from "That"
on-line auction or buy-now web company.
Moving to the
business end of the boom, the supporting structures are exactly the
same as the reflector end with only one minor change. The beginning
and end of the driven element are attached at either of the
horizontal spreader arms. At this tip, I expanded the 1/8th
hole to a 3/8th hole. I placed a 2 1/2 by 3/8th inch machine
thread nylon retaining bolt here as an attachment point for either
end of the wire. I needed a thin machine thread nut so I sawed one
in half. After tapping the bolt into place, I was left with one half
of the nut on either side of the nylon tip. I secured the nut with a
small bit of hot glue. I drilled 1/8th inch holes through the nylon
bolt on either side of the nuts parallel to the boom to secure the
element wires. Now I threaded the wire through the
I placed the black mark at the center of the
nylon tip then carefully held the wire in-place and passed the
correct amount of wire through the 1/8 inch hole and secured it in
place with a pull tie and hot glue. I repeated this on the opposite
side of the tip. I did this to make certain each wire was the same
length as the other 2 sections. It only took seconds to do this but
it takes a lot of words to describe the
After securing the wires with wire ties and
hot glue, I was left with 2 short ends. I stripped the covering off
each end exposing copper to the black marks. At this point, I slid
the last spreader arm out to take up the slack in the wires and
tightened the stainless hose clamp.
If you look at the next to last picture
above, you will see a small aluminum project box.
I attached an
SO 239 at one end and drilled two holes and installed rubber
grommets to the other end of the box to protect the feed wires. I
also installed one U bolt to attach the box to the spreader arm just
below the attachment points.
optional balun could be installed here in place of the simple
I stripped out about 6 inches of coax shield
from some spare RG58 cable and divided this in two. I drilled a
small hole next to each grommet as attachment points for small ring
connectors. I secured these with sheet metal screws. I slid a section of shield
down each short feed wire and soldered part of the shield to the
ring connectors. I slid a piece of shrink tubing down each wire. I
soldered each wire to a feed point and slid the shrink tubing over
the joints. I slid the braid up to the beginning of the plastic
coating on one of the element wires and secured it with a pull tie.
Feed Point Drawing here!
At this point,
I attached my SWR meter and started adjusting the braid exposing
more or less of the unshielded portion of the remaining feed wire
until I achieved the lowest SWR. I used another pull tie and covered
the braids with electrical tape. This completed the antenna.
Either one of the charts below should give you the needed
dimensions for the 11Meter CB band or 10 meter dimensions for hams
that hold Tech class privileges and above.
I used the first
chart below for the 10 meter band.
10 Meter Quad length chart:
10 Meter Ham Center Freq: 28.4Mhz
Total Arm Dimension In
From Boom Center Line to End of Tips
Total Length (Inches)
(Boom length = 60 inches)
Reflector: 108 13/16
Quad length chart:
11 Meter CB Center Freq: 27.205Mhz
Total Arm Dimension In
From Boom Center Line to End of Tips
Total Length (Inches)
(Boom length = 62
Reflector: 113 5/8
Driven: 78 3/8
One last thing, I had
to buy a short piece of clear 1/2" dia. plastic tubing and cut
it into 2 inch sections. I slid two pieces onto each of the
fiberglass spreaders before inserting them into the 12-inch spreader
supports. Seems the 1/2 inch dia. PVC pipe, isn't 1/2 inch
inside, its 5/8th".
One of those small problems a person
building something from scratch runs into from time to
Note: There is an optional
balun that might replace the direct connection project box.
It should give acceptable SWR readings on either the 10 or 11
meter version. It uses the same SO 239 52 ohm input and the
output uses two thumbscrew connections. The net weight is 3.9
pounds. The weight could be a problem if installed where
the project box is connected. Another challenge would be
designing a mounting plate with U-bolts to attach it to the
Fiberglass spreader. If I decide to upgrade the RF feed, I will do a
bit more research before ordering this item. It looks a bit
pricy but I also believe "you get what you pay for". This
upgrade should improve reception a bit and also refine the signal
radiation pattern. N1UUE - 73's
Balun - 2:1, High Power, 1.8 to 30 MHz, Cast
Aluminum Gasketed Enclosure - DXE-BAL100-H11-C. I located this item on the
"If one person takes
a chance and builds one and enjoys the project, it would make
Bob Eastman "
Happy building and 73!
N1UUE Mexico, Maine. (See his website for
any updates to this project)
Email Bob for questions: eastcom 1 at gwi.net (remove
a few links you might use. This is where I ordered some of my
These links may be useful to
Some suggested sources for
Megastore PVC 5 way connector
Plastic Nylon rod
Hardware Store.com PVC reducing bushing
Farm Fence Supplies Fibergalss rods
Aluminum Plate, 1/4" x 4" x 12"
Local hardware stores, auto parts stores, etc