Construye Una Antena Wifi(Build A Wifi Biquad Dish Antenna)

How-To: Build a WiFi biquad dish antenna

Wireless enthusiasts have been repurposing satellite dishes for a couple years now. This
summer the longest link ever was established over 125 miles using old 12 foot and 10 foot
satellite dishes. A dish that big is usually overkill for most people and modern mini-dishes work
just as well. The dish helps focus the radio waves onto a directionalantenna feed. We're
building a biquad antenna feed because it offers very good performance and is pretty forgiving
when it comes to assembly errors. Follow along as we assemble the feed, attach it to a DirecTV
dish and test out its performance.
Why? With just a handful of cheap parts, a salvaged DirecTV dish and a little soldering, we
were able to detect access points from over 8 miles away. Usingconsumer WiFi gear we picked
up over 18 APs in an area with only 1 house per square mile.

Building the antenna
Biquad antennas can be built from common materials, which is nice because you don't have to
scrounge around for the perfectly-sized soup can. We did have to buy some specialized parts
before getting started though.

The most important part here is the small silver panel mountN-connector in the center of the
picture; the entire antenna will be built on this. We purchased it from S.M. Electronics, part#
1113-000-N331-011. The "N-connector" is standard across the majority of commercial antennas
and you can connect them to your wireless devices using "pigtails." The longer pigtail in the
picture is a RP-TNC to N-Male pigtail that we'll use to connect our antenna to aLinksys
WRT54G access point. The short pigtail is a RP-MMCX to N-Male pigtail so we can connect to
our Senao 2511CD PLUS EXT2 WiFi card which is pictured. We also purchased 10 feet of WBC
400 coax cable so we wouldn't have to sit with the dish in our lap. We got our surplus DirecTV
dish from Freecycle. We'll cover the reason for the mini butane torch later.
Trevor Marshall built one of thefirst biquad WiFi antennas found on the internet. We followed
the slightly more thorough instructions found at martybugs.net. Here are the raw materials we
started with:

The wire is standard solid-core 3-conductor wire used for most house wiring. We didn't have
any copper printed circuit board material laying around so we used this thin sheet of copper
and supported it using the 1/4-inchthick black plastic pictured.
The first step in building the element was stripping and cutting a 244mm length of wire.

We marked the wire every 31mm with a permanent marker and began bending the wire into a
double diamond shape. We tried to make the length of each leg 30.5mm.

The easiest way to make really sharp bends in the solid copper wire is to use two pairs of pliers.
With the pliersheld perpendicular to each other bend the wire against one of the sets of jaws.

The element with all bends completed:

Next we cut out a 110mm square of black plastic to use as a base for the reflector. We drilled a
hole in the center to clear our connector.

We then soldered a piece of copper wire to the center pin of
our N-connector.
Next we soldered a piece of of wire to the outside ofthe
connector. We ran into some trouble here. Our cheapy iron
was not capable of getting the connector's base hot enough to
make a good solder joint. We bought a butane torch and used
that to heat up the surfaces. This worked pretty well except it
desoldered our center pin. We recommend you solder the
outside piece of wire first before doing the center one.

After the connector had cooledit was attached to the black
plastic base using epoxy. The thin copper sheet was attached
to the front with epoxy and trimmed to fit.
We let the epoxy cure for a while before proceeding. The next
step was to solder our bow tie shaped element to the vertical
wires. The element was supported by two pieces of scrap
copper trimmed to 15mm to ensure proper positioning.

Then the extra wire...