collinear antenna is several antennas all fed in phase in a
It could be a folded dipole array or just
a straight dipole array fed with different lengths and different
impedance of coax. It can be made of alternating coax pieces cut to
the 1/2 wave length for the frequency.
It can be half wave elements or five eight
wave elements, even seven eights wave radiators but fed from one end
of the antenna array with phasing coils or stubs between the
A folded dipole collinear array is fed
from one point with various lengths of coax and of different
impedances. This is the design of many commercial antennas used on
By feeding the antenna with the J feed
design the only coax needed is your 50 ohm coax from your
The advantages of my
collinear design is higher gain than a single antenna and a
broader frequency response and very low angle of radiation
at the horizon for
reaching out much further vs the standard ground plane or J
pole antenna types!
The 2 Meter 5
element collinear I designed has 9.7 dBd
(more than many Yagi types.)
The 2 Meter 10
element collinear has a whopping 13 dBd
(more than most Yagi types.)
My 70cm 5
element collinear has 9.7 dBd
My 70cm 10 element
collinear has 13 dBd gain
All gain is referenced to a dipole
[Notice all gain figures in dBd, not
All antennas are omni-directional, no rotor
THE WB3AYW ANTENNAS
TYPICAL RADIATION PLOT
Typical radiation plot---showing
very low 5 degree angle.
(This plot is typical of both the
2 meter and 70cm versions)
My design uses one half wave
radiators and when using five eight wave radiators, after 3
elements, the radiation starts to go very
With the half wave elements you can
actually stack how ever many you want to, and the radiation angle
stays at the horizon or where you set it at.
This design was developed as I tried to
pull another collinear up in a tree with a rope up to a limb,
and the rope kept cutting into the tree limb.
The weight stopped my progress of putting
This prevented me from getting the
commercial design up to the height that I
So I came up with this light
weight wire collinear antenna for my repeater in Blairsville
Georgia. I now live in the Dawsonville
It took me a while to develop the phasing
coil so the antenna radiated at the horizon. The first
ones were large and very visible.
I kept working on the
A couple years later I figured out how to
shrink the coils even farther, and this design was
Now as for being invisible,
(well almost), in deed restricted locations / neighborhoods,
painting the coil form flat
gray made the antenna almost disappear to people at about 20 to 30
feet away when mounted in a tree. The antenna is very difficult to
see as shown in photos below against the shadow of the trees on the
wall and against tree and sky backgrounds! "Stealth" depends much on
angle of sun, background behind antenna and many other
44605 (70cm 5
element) hanging beside my rv garage in
Pic 2. (left)
Pic 3 (right)
Pic 2 above....44605 (70cm 5 element) hanging from
rv garage door
Pic 3 above....44605 (70cm
5 element) phasing coil on
(left) Pic 5 (right)
above....44605 (70cm 5
element) laying on driveway
Pic 5 above....44605 (70cm 5
element) phasing coil on antenna.
The two meter coils
have more turns and are 6 inches long.
All of the fiberglass antennas like
commercial types are wire antennas inside of a radome for support,
and protection up on a high mountain top.
All commercial antennas used for repeaters
are wire antennas hidden in the fiberglass radome, and are very
visible to the eye.
The cost of the radomes is very high, as
they need to withstand high wind and ice loads up on the mountain
My antenna design is
not for a repeater in a high wind area or with ice loads. The
antennas are NOT inside a radome!
The are for the average ham with
trees or a tower, used for there antennas.
The commercial antennas are usually not
more than 20 to 22 feet long because if used on a commercial tower
they can not be more than about 22 feet above the light on the top
of the tower. FAA regulations I
When hanging an antenna from a large tree
it can be any length under the tree limb used for the support. Thus
a 10 element of my design is possible for two
After about 15 elements the radiation
pattern gets very flat.
My antennas are designed to have
there maximum radiation at the horizon.
They can have down-tilt built in if
ordered when placing the order. You must state this WHEN YOU
Once the tilt is built in it can not be
changed unless a new phasing coil is
By feeding the antenna with the J feed at
the bottom, it uses a shorter coax thus, less feed line loss,
not at the center a folded dipole array like the commercial
types that is up higher on the
The phasing coils insure that the complete
antenna array radiates at the horizon
unless ordered with tilt.
The antenna weight is 3 pounds or less,
this means a light rope will only be needed to hang this
Wind resistance is very low as the
radiators are made from #12 stranded wire.
This collinear radiates all along the
complete antenna array at the horizon.
The Two meter and Seventy Centimeter, 446
design, has the same radiation pattern, for each band at the
These are single band
antennas, NOT dual band designs. Dual band antennas are a compromise
These antennas can be put up and taken
down in less than 5 minutes as they are held up with a small
diameter rope, say over a tree limb, or a yard arm on a
Cost of my antennas are quite a bit lower
as the radome is not needed.
Thus big savings, as no rotor or
radome is needed for a NON DIRECTIONAL
They have the gain
of a beam without the cost of a beam and
Questions you might have!
Can I put the
antennas you offer inside PVC tubing for support so I can mount it
on top of a mast and if I can mount it inside PVC tubing, will this
change the swr readings? I don't have any way to support it from the
Answer--- Definitely NOT ! This will change
the complete frequency of the antenna. This antenna was
designed for light weight and stealth to be held up with a
light rope from the
is pre tuned without a radome.
How far away
from any metal surfaces does it have to be mounted? Example, like
aluminum siding of a house or mobile home or other metallic
Answer---About 12 inches
from a tower and farther away from a house with aluminum siding or
if it has aluminum backed insulation. I suggest hanging it from
a deciduous tree limb. Not a Pine tree, as they have a lot of
moisture in them and also attract
stated swr plots change when mounted higher than 3 feet above the
Answer---No, but the
bottom of the antenna will NOT handle the WEIGHT of extra coax.
(The matching J pole is
made from 300 OHM Ladder line which is #18 or #20 in size. I am
looking for ladder line made from #16 wire, but can not find
Question? Are the swr plots on this
web page done with the antenna at 3 feet above the
Answer---Yes and No, also
hanging from a tree limb with the MFJ 269 analyzer. The plots are
generated with W7EL's 5.0 antenna program.
I also check each
antenna as they are built, with the analyzer on my work bench inside
of the shed and it is aluminum sided. Antennas are about 18 inches
away from the siding when being tested. When hung with Dacron/nylon
rope in a tree the VSWR does not
2 meter version of this antenna also "work" on the 440
Answer---Yes, but the
radiation angle and VSWR will be higher. I do
not recommend this type of
What type of coax should I use
with these antennas?
Answer---52 OHM coax RG8X
is a good choice if kept to short lengths of under about 15 feet
total. Cheap coax is asking for trouble. I use 100% copper inner and
outer braid coax with a clear jacket. At vhf and uhf, low loss 50
ohm coax is recommended like LMR-400.
I cut the coax pigtail 4
feet long but I advertise it as 3 feet on the antenna, since part of
the coax is up inside the lower sleeve. The pl 259 is
only soldered on the pin, the braid is connected by compression in