Boost your wifi with this unique helical wifi antenna that can greatly extend your wireless networking
range and speed. When built with ten or more turns, this wifi booster antenna vastly outperforms the cantennas and wi fi
wok tops often seen on the internet. A short five turn helical makes a very good feeder for a
wifi parabolic dish antenna.
A special quality of this antenna is that it radiates and receives a circularly polarized signal. It does not favor vertically
or horizontally polarized signals. Thus, this antenna works well with wifi signals reflecting off of buildings, moving vehicles,
or antennas oriented at odd angles. Circularly polarized signals are less affected by rain, so you can reach distant access
points in stormy weather. There is a 3 dB loss of gain when using this antenna with linearly polarized signals; high gain is
maintained by making the antenna long - at least ten turns for stand-alone usage.
Before we get into the building the wifi booster antenna, consider a wireless bridge first. If your goal is to transfer
wireless internet from another building and use it indoors, you should instead use a wireless bridge. If you want to
provde STRONG wireless internet coverage to an area, but cannot provide a fiber optic or ethernet cable to your wireless
router, again consider using a wireless bridge to substitute for the unavailable cable, and connect the bridge to the router.
A wireless bridge is a better solution for situations such as:
Wireless bridges work like a long run of ethernet without cable...
- Providing internet connectivity from one building to users in a remote house or office.
- Providing internet connectivity from one highrise building to another across town.
- Providing internet connectivity from an onshore location to users on an island.
- Sharing connectivity between two locations which can't be linked by cable.
Design parameters for this helical wifi antenna were calculated using the
online helical antenna calculator and was inspired
by similar designs used for the
AMSAT OSCAR 40 satellite.
PARTS REQUIRED FOR THE HELICAL WIFI ANTENNA:
- one square piece of copper sheet metal or single sided PC board for a ground plane.
- one PVC kitchen drain tailpiece (3.8 cm /
1.5" diameter) to hold the helical windings
- six 1/8" plastic cable ties
- a length of copper circuit tape (adhesive backed,
width 3mm or 1/8") or #14 copper wire
- one suitable chassis connector (I used a reverse
sma type matching the connector on my adaptor)
- one 90 degree angle bracket with screws and bolts
- Center the tailpiece on the PC board, copper side,
and mark the circumference in ink.
- Mark four locations on the circumference, spaced 90
degrees, where the cable ties will hold down the PVC
- Mark one location on the circumference, exactly
between two 90 degree markings, where the coaxial
connector will be mounted.
At this point you should have a PC board with a
circle in the center, four tick marks on the circle at
90 deg intervals, and one tick mark exactly between two
- Drill 1/8" holes on the inside and
outside of the circumference at the cable tie
- Drill a hole directly on the circumference suitable
for the chassis connector. Carefully measure and drill
other holes for this connector if necessary.
- Drill four holes, spaced 90 deg apart near the
bottom end of the PVC tailpiece.
- Drill holes to accomodate a small 90 degree corner
- Drill holes on opposite side of board to accomodate
USB wifi adapter that will be affixed with cable
- Tin the copper around the connector mounting hole,
then mount the connector. Clip the center pin to keep
it only long enough for connection to the helix
- Cut out a notch to accomodate the connector; it
should clear center conductor, but avoud cutting out
excess PVC material.
- Feed cable ties through from the back side of the
board, through holes in the tube, and back through the
board. Tighten the cable ties, making sure the tube is
firmly held to the copper ground plane.
- Use a ruler and the edge of a sheet of paper to
create a template for positioning the windings on the
PVC tube. Distance zero represents the ground plane,
then add the feedpoint distance, then ticks matching
the turns spacing. Use the template to mark your tube
on both the feedpoint side and the opposite side.
The objective is to precisely wind the helical wifi antenna
using an accurate guide...
Space the turns 2.5 cm on a
tube of 3.9cm outer diameter.
Here is a table used for my prototype helical wifi antenna
and its connector. Note that turn 1 starts at 0.8 cm (height
above ground plane of feedpoint). Turns Spacing is 2.5
cm, and the diameter is 3.9 cm (close enough for 1.5"
PVC tailpiece). If your connector can be
trimmed to allow a feed connection closer to the ground
plane than 0.8CM, then simply run the helix as low as
necessary. Most impartant is keeping the proper spacing
(fits 1.5" PVC
Height (cm) above
- Carefully wind the helix, using circuit
tape or wire, then solder to center conductor of
chassis connector. Double check against the turns
template. Polarization will be right-handed if the
turns spiral clockwise (looking outward from
- Attach the angle bracket and wifi
adapter, making sure all parts are secure and ready for
service, as seen in the images below.
The high gain wifi helical antenna.
10 turn stand alone version
Cable losses avoided by
mounting wifi adapter
at base of antenna.
Short wifi helix feeding a long range parabolic wifi
At this point, helical wifi antenna is ready for its
smoke test...plug in the cables and look for some
signals! Theoretical gain of the prototype helical was
about 18 dB over an isotropic radiator; it beat my biquad by
about 7 to 13 RSSI units, and indeed seemed less
sensitive to polarization and rainfall. Signals still
seem to fluctuate much from second to second. If your
antenna is functioning satisfactorily at this point, I
suggest spray painting three layers of clearcoat onto the
windings and groundplane for stability and corrosion
If you are interested in yet another wifi range extending antenna I have built
and tested with excellent results, look at this
wifi booster yagi antenna which you may attach to a USB dongle or a wifi
router if it has an external antenna connector.
©2005 - 2023 AB9IL.net, All Rights Reserved.