There may be a wireless internet host in your house, at a club house or in your development that you would be free to use, if only you had a way to access the signal from your current location. Most PC Wireless connections are too week to pick up a signal more than about 50 feet away.
What we are going to describe in this document is how to send and receive a signal to and from a central base wireless internet system that is near by. Maybe you are trying to get signal between buildings at work, buildings at school, on your personal property, or in our case trying to communicate from our RV with a wireless internet Router in the RV park club house half a mile away. The solution is not that difficult as long as you know what to buy, know the FCC laws regarding signal out put, and have clear line of site access to the WiFi Source you are trying to acquire.
We are going to configure a system that will tap into a Wireless b/G system. Wireless N is the new standard being used today, but we do not need to worry about that, as the N routers will scale back to b/g , we save lots of money on equipment, and could never use the N benefits from these distances in a shared environment anyway.
In our scenario, we travel in an RV from RV park to RV park, and never know what we are going to find as far as public wireless internet is concerned. So we need a very generic, powerful, and flexible system.
Here are the ground rules of wireless internet.
Your Antenna cannot transmit more the 4 watts of power with out risk of persecution from a group called the FCC. These guys have tons of enforcement power and are not afraid to use it. Do not exceed 4 watts. (The 2.4Ghz spectrum in low wattage’s does not require a license, but it is regulated.) Know the Law! Here is a tutorial: http://www.afar.net/tutorials/fcc-rules/ . If you are installing the system in a location that does not move, unlike our RV, here are some helpful tips on FCC rules, and directional antennas that will get you a little more distance and a clearer signal. http://www.seattlewireless.net/InterpretingFccRegulations -chart of power and antenna combinations. Point to Point installs, can get around these 4 watt laws a bit using 100% directional antennas which is too cumbersome for RV use.
Get some calculators for wattage, we want to throw 4 watts of power in long distance situations. Since we are designing for a mobile installation, we need to get a system that is adjustable.
Note: typical wireless access routers you have in your house on a cable modem serving your wireless PC’s run at a fixed wattage of 100mw, 1/10 the legal limit, but handy in a neighborhood where everyone has a router in their home. This low wattage leaves dead space between homes so we do not stomp on each other signals.
To reach a long distance, we need to step up the wattage, also referred to (dBm) (30 dBm is the currently the maximum legally allowed input wattage to an antenna.) The Antenna has rating called gain, this is measured in dbi. Typically and antenna used for long range jobs would be rated between 6 and 15dbi gain. The dBm and the dBi numbers must be fed into a formula get EIRP (Effective Isotropic Radiated Power (EIRP) ) The EIRP emitted wattage is limited to 4 watts or 36dBm. In the End 4 watts is our magic number, we can’t under any circumstances exceed it. (Now you know why WiFi does not have the power to travel great distances like other radio waves do, and why you need to know something before your build your transceiver.) Here is a calculator to help you understand antenna gain vs power output at the booster. http://www.csgnetwork.com/antennaecalc.html
We installed a minimal system on our RV and are pulling data at 1/4 mile through lightly forested air space. The lodge is about 50′ lower in elevation than we are, but yet, we found the higher we mount the antenna, the better the signal. (If you never move, get a directional antenna, it has better signal qualities.)
We installed a 7dbi antenna at the end of a PVC pipe. We elevated the antenna 6′ above the roof of the RV, giving an effective height of 18′. We can see the antenna from quite a distance. Next to the antenna is an omni directional trucker antenna made by Wilson Electronics for the MiFi card. This allows us to switch between the public WiFi and the Verizon Mifi with a slight change in the routers programming any time we want to.
A closer photo of the antennas. The black one is the trucker antenna. The trucker antenna’s performance is hindered by the grey 2.4ghz WiFi antenna a bit, it needs more separation. We have our system running 1/4 of the legal limit, because we did not have the money to buy new, and bought used equipment that we thought would get us by.
Wireless Internet Technical Jargon to keep you legal, and to help you choose the right equipment:
These antennas are connected to an access point client router and a wireless router like what is found in most people’s homes today. Now let’s go back to theory again, as this will help us know what kind of equipment to buy. We know we want to run at 4 watts, and be able to scale wattage down in places where we might accidentally step on our neighbor’s equipment. We don’t want to throw a wave big enough to take down our neighbor’s router, that would be evil on our part. We believe the right way to begin, is to buy a good solid 15dbi antenna, then look for your signal booster. Getting an adjustable booster will allow you lots of flexibility. An under powered antenna will limit any power your booster may have, and antennas are not typically adjustable. The next few images are sample calculations of wattage and gain. The input and output is logarithmic and you will see exponential power changes with very little change in input wattage and gain.
This image is what what we were running until we could buy a good antenna. Notice the transmitter power is .2watts or (23dBm) or 200mw.
We have an antenna with 7dbi of gain. We click calculate and find that we are broad casting about 1 watt of EIRP which is 1/4 of the legal limit. You will see this number on the bottom right of the picture above. Our internet reception suffers unnecessarily because of the antenna’s dbi.
The calculator above tells us if we buy a 15dbi antenna and turn our booster down to 125milliwatts we would be broadcasting at 3.95 watts at the antenna. This would be perfect. We can scale down if required by our location, or we can run at max speed without over taxing our WiFi booster heat wise. (The higher the power setting on your WiFi booster, the more network outages you will have due to component over heat.)
Here is a sample of what not to do:
If you do what all of us want to do, and go get the highest gain antenna you can find, and the highest output router you can get, you get in trouble fast! In this example we are sending 28dBm (600mw) from our signal booster, this is perfectly legal as we are allowed to send 30dBm (1000mw or 1watt) to the antenna. The antenna is rated at 15dbi gain. We bought both pieces of equipment legally, but because we are bad at math, we paired them up without making any adjustments. Now we are 4.25 times the legal antenna output. I do not want to be around when Mr. FCC law man shows up the door with those new steel hollow tip bullets they bought.
We now know that with 15dbi antenna’s being available, we do not need to buy any equipment sporting more than 600milliwats in power. One more word of caution here, if your wireless router, or USB adapter for your PC has an antenna output on it that you plan to screw the booster to, you also have to add its output to the output of the booster to be sure you are not exceeding legal specs. If you hard wire your booster to a non adjustable USB wireless device, or router, you may in some cases need to subtract 100mw from the power you send at your booster level.
Two good systems you can use to transmit point to point, or receive, or share wireless internet
There are two brands of the client routers, one is Ubiquity, and one is Engenius. Engenius is the brand we show here. After about 3 months experience with Engenius, having a unit fail, spending weeks trying to get support, we given up an tossed the access point in a drawer until we can figure out why we can’t log in to it any more. We replaced it with the Ubiquity Bullet M2 You can read about it here. It has about the same range as the Engenius, more tools, about the same cost, and requires fewer parts to get up and running.
Now it is time to assemble the wireless internet booster system.
We acquire a wireless antenna. (Shown above) – We wanted a 15dbi, but since we could not afford a new one, this used 7dbi would have to suffice.
We drilled out the bracket, and screwed the bracket directly to a 3/4″ PVC pipe. Due to the height one needs and the weight of the antennas. We would recommend 1.5″ diameter pipe. – When we get time, we will swap this pipe out.
Notice the LM-400 wire connecting the antenna. This wire has a type N connection on each end. One connects the directly to the antenna, the other will require an adapter as most boosters have a very small SMA connector on them.
This is referred to as a male N to Female SMA adapter.
Since the cable and N adapter are female we had to get a barrel connector to screw the adapter to the cable and the SMA adapter
The SMA adapter that is now attached to the black cable has to be screwed on to the booster. You will see the brass male SMA connection in this picture. Screw all this together.
Here is the model number of the booster we are using.
Front view of the booster. After we attached the black cable and put the antennas on the roof, this booster is placed in an outside lockable compartment on the RV. The beige cable is the Ethernet cable that we hooked to our in house router that is used to connect the PC’s together in the house.
This plug goes in your in house router. We use a Netgear 3500 series router in our house to connect all of our pc’s together. This router allows us to share one internet connection with every net-workable device we own. Plug this into the hole marked internet. The booster has an IP address of 192.168.1.1 from the factory. If your network router cant see that address, you may have to configure the booster from a PC.
We installed a 7dbi antenna at the end of a PVC pipe. We elevated the antenna 6′ above the roof of the RV, giving an effective height of 18′. We can see the antenna from quite a distance. Next to the antenna is an omni directional trucker antenna made by Wilson Electronics for the MiFi card. This allows us to switch between the public WiFi and the Verizon Mifi with a slight change in the routers programming any time we want to. We now have connected the wireless devices all together. The Netgear router is placed in a compartment in the RV, no equipment went into the house. All this is accessed via a wireless connection.
Netgear router and beige Ethernet cable coming into the compartment from the booster which we mounted in a separate compartment. Now it is time to configure all the software on this equipment and set the power outputs to the antenna.
We will go through the setup screens for the EnGenius booster and the Netgear 3500 router as if they were purchased new.
Connect a cable from your PC to the Netgear router, set your PC’s IP address 192.168.1.10, network to 255.255.255.0, and default gateway to 192.168.1.1 type 192.168.1.1 into internet explorer then logon to the netgear router usually admin and password. Then click on Basic settings and make them match the image above. Save the settings
Click on LAN setting and make this screen match yours. The router will now be at 192.168.20.1 – You will need to remember this for future access. You may want to find the wan settings and set the access password as well if you do not want to share the connection with your neighbors.
If you are interested in building a Wifi solution for your RV Please consider buying your equipment from the links below. The purchases allow us to pay for the internet usage, and enable us to further obtain content. If you have any questions, please use the comment form.