The following are simplified antennas based on the Dipole Antenna described at http://wireless.gumph.org/
The principle
The principle used in all these designs is to alternately expose each of
the two poles for half a wavelength.
The length of the half-wavelength is, as used in the "Gumph" designs,
i.e. 40.5mm because they all use copper elements.
General Properties
These antennas should be mounted with the elements vertical. That way their
"doughnut" shaped signal spreads out horizontally into the surrounding area.
When testing against an (Orinoco 802.11b WiFi) PC wireless card
it will be found that better
reception is obtained by orienting the card (and the laptop/computer/access point)
on its side rather than flat.
This is believed to be because of the polarisation produced by these dipoles.
Description
This is a single element dipole that is quicker to make
and avoids the time consuming soldering needed by the "Gumph" design.
It is (probably) similar to many of the commercial Dipole
antennas such as The ZoomAir 2.2 dBi Dipole Antenna Model #98110-02
and (probably) has the same gain of 2.2 dBi.
It works quite well with a maximum range of 300m with an
unobstructed line of sight.
The "doughnut" area that the signal covers is quite "deep"
so this antenna is suitable for mounting high up on a building
and the signal reaches downwards almost vertically below it.
Materials
As for the "Gumph" but needs a shorter piece of cable.
(1) (MIL-C-170-RG) RG213/U 10.1mm thick RF coaxial cable only 12cm long.
(Maplins order code XS66W, £1.29/Metre)
(2) N-Type Free Socket (Maplins socket type N011, order code FP01B, £2.29)
Total Cost: about £2.50
Time to Make: about 1 hour
Tools
Hack saw
Instructions
(1)Cut the end of the cable so that it fits the socket
which has a compression type fitting with a rubber washer
and a screw-up tightening action.
(2) mark up two lengths of 40.5mm (see "Gumph") beyond
a short length (about 2cm) for the socket fitting.
Cut through the PVC cover at these points (But not through the
woven copper outer conductor).
Cut right through the cable at the end of the antenna and strip off the black PVC cover of the second half-wave.
Strip off the woven outer copper conductor of the second half-wave.
Cut through the opaque inner polyethylene insulator at the half way point but do not cut through the inner copper conductor.
Strip off the opaque inner polyethylene insulator of the second half-wave leaving the inner copper conductor exposed. (If the insulator does not pull off easily, several cuts may be needed to pull it off bit-by-bit.)
Strip off the black PVC cover of the first half-wave.
Attach the socket and thats it. Ready to use. Note that in use the antenna should be oriented so that it is vertical. You can additionally put the antenna inside some sealed conduit for outside use.
Description
This is a simple dipole that is VERY quick and cheap to make
and it should be easy to produce a technical construction file
to document it.
The properties are similar to the coaxial dipole in that
it works quite well with a maximum range of 300m with an
unobstructed line of sight and
the "doughnut" area that the signal covers is quite "deep"
so this antenna is suitable for mounting high up on a building
and the signal reaches downwards almost vertically below it.
Materials
(1) Enamelled Copper Wire, two pieces each 60mm
(Maplins order code YN82D, 20 Guage, £3.79 for 42 Metres!!)
(2) N-Type Square Chassis Socket (Maplins order code FJ80B, £1.99)
(3) Nut and bolt
(4) A few cm of polyethylene insulator (e.g. leftover from making Coaxial dipole)
Total Cost: about £2.00
Time to Make: about half an hour
Tools
Wire cutter/scissors
Soldering Iron, Solder
Pliers
Instructions
Solder the first wire to the central pin of the chassis socket.
Thread a short piece of polyethylene insulator onto the wire
and then bend the wire at right angles to make an L shape.
Measure and cut the end of the wire at 40.5mm from the bend.
Bend the second wire into a small loop using the pliers
such that the bolt will pass through the loop (see below).
Thread a short piece of polyethylene insulator onto the wire
and then bend the wire at right angles to make another L shape.
Measure and cut the end of the wire at 40.5mm from the bend.
Attach the second wire to the frame of the chassis socket using the nut and bolt to secure.
Thats it. Note that in use the antenna should be oriented so that the wire is vertical. You can additionally put the antenna inside a sealed plastic box for outside use.
Other notes:
The ranges recorded were made by attaching the antenna by a short pigtail
to an Orinoco card (which has an inbuilt antenna with a range of about 30M.)
So both antennas were active during the tests.
11 Aug 02