ing. You are performing your own research with the data being gathered and visualized.
In the next chapter, we will switch gears a little and start working directly with access points.
You have plotted the location and signal strength of APs in your neighborhood. Now how
about finding a way to bring Wi-Fi to poor coverage areas? Read on to Chapter 8 to build your
own weather-resistant, outdoor access point.
in this part
Build Your Own Outdoor
Building a Solar-Powered
Creating a Free Wireless
Playing Access Point Games
Build Your Own
he neighborhood is mapped out in glorious color maps. Thereâ€™s
an antenna on your laptop, a cantenna on your desktop in the base-
in this chapter
ment, and an external antenna feeding them both. You can surf in
the backyard, the front yardâ€”but not quite from the park down the street.
Selecting the right
Your neighbors are starting to ask whatâ€™s going on. Theyâ€™re feeling left out. location
Thereâ€™s only one logical conclusion: Provide wireless Internet access for
everyone on your street. Hey, why shouldnâ€™t they reap the benefits of your
expertise? Besides itâ€™s a great way to introduce yourself: â€śHi, Iâ€™m the geek
parts youâ€™ll need
on your street. Would you like free high-speed Internet access?â€ť
Before long theyâ€™ll be throwing parties in your honor and waving as you Using Power-
walk down the street with your laptop openâ€”instead of looking at you
strangely and shaking their heads.
Or, maybe you just want to extend your range a little further, or you just Grounding your
like to climb up on your roof. Read on for how to get started. access point
You can build an outdoor access point using several different parts
(different enclosures, antennas, mounting hardware). To get started,
you will need the following items:
âž¤ Access point
âž¤ Power-over-Ethernet adapter
âž¤ Waterproof box
âž¤ Mounting hardware
âž¤ Lightning protector and grounding wire
âž¤ Antenna and mounting hardware (see Chapter 4) Building your own
âž¤ Matching pigtail (see Chapter 1)
âž¤ Ethernet cable
âž¤ Electrical tape
âž¤ Waterproof sealant
172 Part III â€” Playing with Access Points
Location, Location, Location
Wi-Fi range is all about line-of-sight. That is, if you can see the antenna, you can get online. If
you canâ€™t see it, all bets are off. Most of the time the antenna should be nice and high, where
everyone can see it. If you added an external antenna as described in Chapter 4, then you dis-
covered this during the site survey.
Thereâ€™s a Catch-22 with antenna placement. You need a longer cable to put the antenna in a
better place, but the longer the cable, the more signal you lose.
The solution? Move your access point closer to the antennaâ€”put it right on the pole. This
keeps the cable nice and short and transfers all the power where you want itâ€”into the air
instead of into the cables and connectors.
As discussed in Chapter 4, good line-of-sight is the best predictor of a successful installation.
The site in Figure 8-1 has clear line-of-sight.
Consider the following when trying to pick a good location for outdoor access:
Itâ€™s possible to get a good wireless connection through the outside walls of most
buildings, but rarely through multiple walls, and especially if there are no windows.
Big leafy trees absorb a lot of signal, especially when theyâ€™re wet. Remember trees if
youâ€™re choosing a location in winter, so it doesnâ€™t slowly stop working as spring arrives
and the leaves grow back.
FIGURE 8-1: No problem with line-of-sight here!
Chapter 8 â€” Build Your Own Outdoor Access Point
Use natural obstacles to block coverage where you donâ€™t want it to go. The side of a
building is better than the rooftop if you only want coverage in one area.
Remember, you can use an antenna to boost reception at the receiving end as shown in
Chapters 2 and 4. This is handy if youâ€™ve found the perfect location, except for that one
place where itâ€™s unreliable.
Prioritize within your coverage area. Sometimes there is no perfect solution, so knowing
whatâ€™s most important will help you make tradeoffs.
For example, if you only want coverage across the road, thereâ€™s no need to mount an omni
antenna on a high mast on the chimney. Instead, mount a directional antenna above your
(street-facing) garage door. Itâ€™s much easier to get at, and you wonâ€™t waste half the signal on an
area you donâ€™t need and create radio interference where itâ€™s not wanted.
Providing Power and Data
Your outdoor access point will need a source of power and a connection to the Internet. Weâ€™ll
get sneaky and provide both of those in a single cable using â€śPower-over-Ethernetâ€ť or PoE for
short. Running Ethernet cable is far easier than antenna cable. Itâ€™s much cheaper, more flexible
and can go up to 328 feet (100 m) without data loss.
PoE injects direct current (DC) into two of the unused wires in standard Cat-5 Ethernet cable. By
combining the power and data into a single cable, only one cable is needed for the longer runs
going outside to the access point.
One end of the cable will go into the outdoor box youâ€™ll build. The other end will go to your
digital subscriber line (DSL) or cable connection to the Internet (or an existing router). Youâ€™ll
need a power outlet at that location to provide power for the access point. See Figure 8-2 for an
example PoE setup.
Something else to consider is whether you want wired connections to the Internet as well as
wireless. A fully wireless system may give you more flexibility. You could relocate your cable or
DSL box away from your computer where itâ€™s more convenient for outside installation, such as
in the attic, an upstairs room, or the garage.
Lightning can strike almost anywhere, but it generally goes for high points, and if theyâ€™re
metal, then so much the better. You should take lightning protection seriously and plan for it in
your installation. Donâ€™t think, â€śCome on. The outdoor gear is only worth $100, Iâ€™ll take my
chances,â€ť because thatâ€™s not the issue. Even with good lightning protection, the outside gear is
likely to be toast anyway. You need lightning protection to prevent a fire, and to ensure the
safety of both the people and electronics inside the house.
174 Part III â€” Playing with Access Points
(To Access Point)
(To Wall Outlet)
(Up to 100 Meters)
Ethernet Plug Ethernet Plug
(To Access Point) (To Network Hub)
FIGURE 8-2: Internet access and Power-over-Ethernet in the same Ethernet cable.
You need to install lightning protection to protect against fire, and to reduce damage to people
and equipment inside the building.
Lightning protection is covered in more detail later in the chapter, but think about where the
copper grounding wire will go when youâ€™re planning the outdoor location. If electrical storms
are common in your area, and the mounting location is high and exposed, you must take this
very seriously indeed. See Figure 8-3 for a diagram on lightning strike protection.
Other common sources of accidents are ladders and high places. Be careful up there. No matter
how good a job you do the first time, chances are youâ€™ll be up there again to fix something, so it
might be worth compromising a little on the best location to provide safer and simpler access
to the equipment.
Balance the Trade-Offs
Thereâ€™s rarely a perfect place to put the outdoor access point and antenna. Itâ€™s a balance
between the following factors:
Line-of-sight to the desired coverage area
Physical access to the equipment for ease of installation or repair
Suitable route for Ethernet cable from inside
Suitable route for lightning ground cable
Protection from the elements (sun, rain, lightning, snow)
Aesthetic appeal: will the neighbors or landlord complain?
Chapter 8 â€” Build Your Own Outdoor Access Point
FIGURE 8-3: Lightning protection helps reduce property damage.
You can save some time, effort, and money by making an early decision about where the
antenna and box will go. For example, if you choose a sheltered location tucked under an eave,
you wonâ€™t need a more expensive highly waterproof enclosure. If you already have a mast with a
TV antenna, then half the job is over.
Choosing the Parts
The most time-consuming part of building your outdoor AP is getting all the parts
together. The actual assembly takes less than two hours once you have everything in one
There are no special tools required. A drill, some drill bits, a small handsaw, and a pair of pliers
or wrench to tighten everything onto the pole should be enough.
You may be surprised to find that the access point is less than half the total cost. Although
most parts cost about $20, thereâ€™re a few of them and they add up fast. The antenna is more
expensive and may cost up to $100 depending on your requirements.
176 Part III â€” Playing with Access Points
Research carefully and plan ahead to save on shipping costs. For example, the antenna, pigtail, and
lightning protector are all specialized items. Buying all of these online at the same time from a sin-
gle vendor may be cheaper than paying the best price plus shipping from three different suppliers.
Letâ€™s take a look at each of these items in detail.
The most important element is the access point. It is best (and cheapest) to choose an 802.11b
based device for outdoor use rather than the newer 802.11a and 802.11g equipment. The range
is better and there are more equipment choices. The exact type of access point you choose isnâ€™t
critical as long as:
It has a removable antenna (many do not)
You can find (or build) a matching PoE adapter, as discussed later in the chapter
The D-Link DWL-900AP is the device used in this chapter and shown in examples.
However there are many manufacturers of this type of equipment. Read reviews online or ask
friends for their recommendations. Figure 8-4 shows a common access point for outdoor use.
Some access points also include a four-port hub for connecting other computers via Ethernet.
Since the box will be up on the pole, it will be hard to use those extra ports, but apart from the
extra size, a combination router and access point will also work just fine.
FIGURE 8-4: A wireless access point with detachable antenna and standard accessories.
Chapter 8 â€” Build Your Own Outdoor Access Point
Be careful not to get a wireless Ethernet bridge, because they are not a complete access point.
Instead, they take a wireless signal from an access point in at one end and convert it to
Ethernet at the other. This is handy for getting computers online that only have an Ethernet
port (many older Macintosh computers for example) or to simplify installation.
Some access points are more reliable than others, so be sure to search online for comments
about specific models. Physically, most brands are quite reliable, but software quality varies a lot.
Look for reports of slow downs, hangs, reboots or spontaneous resets. Although resetting the
access point is easy enough via the PoE plug, it can be a chore to retrieve it to reconfigure it.
You need to get power to your equipment when itâ€™s up on the pole. A good way to do this is to
use â€śPower-over-Ethernetâ€ť or PoE. This adds power directly to unused wires in your Ethernet
cable to save running a separate power cable to your access point.
Ethernet cable is four twisted pairs, but only two pairs are used for data. Manufacturers real-
ized this years ago and started building proprietary solutions that add power to the unused
pairs. This has the advantage of halving the number of cables required. However, it was years
before they got together and agreed on a standard, so PoE is usually limited to high-end
commercial equipment and still isnâ€™t often found on consumer gear.
Now that a standard exists (802.3af ), companies are making converters that work with con-
sumer equipment, and sometimes itâ€™s possible to build your own adapter. Some background
on how it all works will help you decide on the best solution.
The challenge with sending low-voltage DC PoE cable is that voltage drops with distance.
Also, the amount of current is restricted by the small gauge wire used in the Ethernet cables.
Search online for â€śPoE calculatorâ€ť and youâ€™ll find resources like www.gweep.net/
˜sfoskett/tech/poecalc.html that estimate the voltage drop.
The PoE standard sends a much higher 48 VDC voltage over the wire. This requires less cur-
rent for the same amount of power, but the receiving equipment needs to be able to convert the
48 VDC to something usable.
Several companies now supply solutions for their consumer equipment. For example, D-Link
makes the DWL-P100 PoE adapter. This comes with a 48 V plug pack that runs on AC power
and is sent over the Ethernet cable to another box which converts the 48 V back into the
5 VDC needed by the access point.
The PoE adapter shown in Figure 8-5 combines Ethernet data and 48 VDC into a single
Ethernet cable and then splits it back to Ethernet and converts it down to 5 V at the other end.
If the access point operates at 12 V and itâ€™s a short Ethernet cable, the voltage drop may be small
enough to work with a simple splitter you can build yourself. Web sites like
www.nycwireless.net/poe/ provide detailed instructions on how to build one. Unfortunately, 5 V
is generally too low for this hack to work.
With some careful research, you could use this same adapter with other brandsâ€™ access points.
However, you need to be sure that the output voltage matches, that the current drawn is lower
178 Part III â€” Playing with Access Points
FIGURE 8-5: A Power-over-Ethernet adapter.
than the adapter rating, that the power plug is the same size, and that the plug uses the same
polarity. If in doubt, buy the access point and PoE adapter from the same manufacturer for the
Your access point has to stay dry and at a reasonable temperature to operate as expected.
Finding and building a case can be the most challenging part of this project, especially if you
donâ€™t want to spend more on the case than all the other equipment combined.
Your hardware manufacturer has already determined temperature range and humidity tolerance
for your product. Check the access pointâ€™s specification sheet or product manual for the exact
Ultimately the local weather conditions will dictate the type of case used. Other factors include
the ease-of-access and the expected installation lifetime.
Continuous below-freezing temperatures or snow and ice buildup can be challenging conditions
that require special solutions including box heaters and antenna de-icing. These are not
addressed here. More information on extreme-weather enclosures can be found online at
Tessco (www.tessco.com), Talley (www.talleycom.com), ElectroCom West
(www.ecwest.com), and other wireless equipment suppliers.
By far the cheapest and simplest box to work with is a plastic food container, as shown in
Figure 8-6. These are readily available in lots of sizes. Theyâ€™re easy to drill, cut and glue, and
Chapter 8 â€” Build Your Own Outdoor Access Point
FIGURE 8-6: A cheap, effective, easy-to-modify case.
are cheap. Their main downside is they can degrade quickly if theyâ€™re always in the sun. Donâ€™t
put one up and expect it to last for ten years. However, in most locations you should get a year
or so before it needs replacing.
The next step up is to visit a large hardware store, or better still an electrical supply store. They
usually stock outdoor â€śrainproof â€ť metal boxes in various sizes for under $20 (see Figure 8-7).
FIGURE 8-7: This 8 inch 8 inch metal case was $13.
180 Part III â€” Playing with Access Points
These metal cases are not completely waterproof, but theyâ€™ll withstand most weather, especially
if mounted in a sheltered location. The metal is harder to work with than plastic, but a metal
hacksaw and sharp drill bits will solve most modification needs.
The same stores also stock molded plastic junction boxes designed for burying in the ground.
These are completely waterproof, and as theyâ€™re made of plastic, theyâ€™re simple to modify. They
cost 50 to 100 percent more than the metal cases. Theyâ€™re air-tight, so they may get too hot if
you seal them completely. Some bottom ventilation holes may be needed for cooling.
Another source to explore is waterproof equipment carrying cases used for cameras or other
electronic gear. One large manufacturer is Pelican. They have a wide range of sizes, shapes, and
colors, and are completely waterproof. Prices are reasonable, though more expensive than junc-
tion boxes. The cases are plastic and fairly simple to modify, though the molded fittings and
indents can complicate internal mounting.
Last but not least, there are cases made especially for mounting electronic equipment outdoors-
on poles and walls. These usually have hinged doors, pole mounting points for U-bolts, rubber
gaskets for weather proofing, and cable through-holes. They range in cost from $50 to $100.
Thereâ€™s no single source for these as they tend to be custom made for specific industries. Search
for â€świsp outdoor enclosureâ€ť and similar to find suppliers online. (See Chapter 9 for an exam-
ple usage of one of these heavy-duty exclosures.)
Once youâ€™ve chosen your box, youâ€™ll need to figure out how to mount it to the pole or wall. A
good source of pole mounting hardware is the TV antenna section of your local hardware or
electronics store. An example is shown in Figure 8-8.
FIGURE 8-8: TV antenna mounting hardware like this pole and mounting bracket is