What is a wireless bridge:
A wireless bridge is used to connect two or more LAN segments (buildings). A wireless bridge provides the same functionality as being connected using Ethernet cable, though eliminates the need to run cable between locations as well as eliminating the maximum distance limitation of Ethernet cable (328'). The bridge essentially converts a wired connection to wireless at one end and then converts the wireless signal back to a wired connection at the other end. By bridging multiple AP's you can connect several remote locations to your wireless network and you can roam freely between all AP's in the network. When connecting multiple locations you will need an AP/Bridge, an outdoor antenna, a switch (optional) and the necessary low loss cable between the antenna and the access point for each location, and of course a router is also needed if you intend to share a high-speed Internet connection. Most wireless routers have a built-in switch, but the access point may not support bridging, therefore may not be suitable for this use. For this reason I recommend using a wired router, such as the Netgear RP614 - Cable/DSL Web Safe Router, and separate access points to create your wireless bridge. You can also apply this logic to a simple home wireless network. Most people purchase a wireless router, not knowing what the limitations are. Purchasing a wired router and a separate access point gives you much more flexibility plus the ability to expand the network at a later time. A common question we frequently are asked is can I use my existing wireless router? The answer is YES...but there are additional setup concerns that must be addressed. The main purpose of a router is to provide a shared connection to the Internet (WAN port). Both wired and wireless routers have a WAN port, therefore function the same as far as providing a connection to the Internet. The difference is that a wireless router also has a built-in access point that is proprietary to that device, therefore there will be two wireless systems that must function independently of each other. This is accomplished by programming the two systems to operate on non-interfering channels. There are a total of 11 channels (1-11), though only 3 non-interfering channels (1, 6 & 11). If the existing wireless router is operating on channel 11 simply setup the bridge to operate on channel 1 or channel 6.

If the power output, antenna and cable combination is incapable of reaching the distance, amplifiers may be required. When an amplifier is needed it is usually required at both ends to insure that both the transmitting (TX) and receiving (RX) signals are amplified. Remember, a wireless connection is a two-way street; it does no good to transmit a signal without being able to get it back. Once a wireless bridge is established between locations, a wired or wireless network (or both) can be utilized at each location. An existing high-speed Internet connection (router) will be shared across the entire network. Wireless client adapters can access the network within range of any AP/Bridge with an Omni-directional antenna.

Range and choosing the right antennas:
The range of the signal will depend on several factors, including power output of your wireless access point, receive strength of the wireless card or cards you are transmitting to, obstructions, buildings or trees which may be in the way of your transmitting path, walls, etc. Since there are so many factors which can determine the overall range of your wireless system, it is impossible to cover it in this simple article. A rule of thumb however is to always choose an antenna which you think may be an overkill. Why? Because the power output is extremely small it is necessary to have as much gain as possible. Most wireless cards have a power output of 32 mW (+15dBm), which is roughly the same amount of power it takes to light a high power LED (Light Emitting Diode). LEDs are bright, but imagine trying to see one from a distance or through a building or trees. This is why the antenna is critical for amplifying the signal so it is as strong as possible. Why is the power output so small? Because 802.11 works at the same frequency as a microwave oven (2.4 GHz) and if it put out a large amount of power…well…Microwave popcorn! enough said. Directional antennas are best for longer distance as they focus all energy in one direction. Omni-directional antennas are best for wide area coverage as they transmit and receive from all directions (360°). A typical wireless bridge configuration will consist of an outdoor Omni-directional antenna at the base and a directional antenna at the remote locations (see above picture). If your point-to-point connection is over 1000' or line-of-sight is limited, circular polarity antennas are recommended. A high-speed Internet connection can be located at any one of the AP/Bridges in the network and is connected via a router (WAN port). The use of an outdoor Omni-directional antenna will greatly enhance the wireless communication capabilities in and around that location, as well as providing a hot-spot that can be accessed from other remote locations. Using a directional antenna at a remote location will provide longer range between antennas, though would require additional equipment if wireless access is desired at that location. It is possible to use a directional antenna at each location to achieve even greater distance between locations, but you would be limited to two locations since the directional antennas would be precisely aimed at each other. This limitation could be eliminated by using a 2-way splitter and both a directional antenna and Omni-directional antenna array. Omni-directional antennas can also be used at all locations, but would result in a shorter range than when using a directional antenna, though using Omni-directional antennas would provide wireless capability without any additional equipment.

Point-to-point vs. Point-to-multipoint:
Now for the AP/Bridge, you will need an access point that has a removable antenna and capable of bridging mode. An access point is referred to as a bridge (or repeater) when it is setup in point-to-point or point-to-multipoint mode. In point-to-point mode, two access points are programmed to talk to each other, therefore bridging two locations. In point-to-multipoint mode, one access point is programmed to talk directly to multiple remote access points that are programmed in point-to-point mode, therefore bridging multiple locations. Some AP's use a chain method where one AP is bridged (chained) to another, then another...etc., though point-to-multipoint works best as you can see from the above picture. Bridging mode is programmed through the normal setup/configuration (usually advanced settings) by giving each AP/Bridge the MAC address of a remote AP/Bridge. In point-to-point mode each AP/Bridge would be given the MAC address of the other AP/Bridge. When setting up point-to-multipoint, one AP/Bridge would be programmed with as many remote AP/Bridge MAC addresses you may have (note that some AP's are limited to how many AP's can be bridged together). Normally only one AP/Bridge in the network can be programmed to point-to-multipoint mode, and all others must be programmed to point-to-point. It is impossible to compare all AP's, but to provide a sample of how this is done I have included a link to a simplified procedure for programming the Netgear WG602.

WDS Bridging/Repeating Wireless Distribution System (WDS) is a feature supported by an increasing number of access points. Simply put, it enables single radio APs to be wirelessly connected instead of using a wired Ethernet connection. There are certain disadvantages to consider when using WDS: There is considerable wireless throughput loss when using multiple "hops" (transmitting between multiple "chained" APs). Dynamically assigned and rotated encryption keys (WPA and others) are not supported in a WDS connection. Only static keys (WEP) can be used in a WDS connection. Point-to-multipoint (above example) mode provides the best performance simply because one AP is a central point to which all remote APs are communicating (only 1 hop). Often it is impossible to utilize point-to-multipoint due to the inability to acquire line-of-sight (no central point that can be seen from all remote locations). The best solution for this situation is to use a "dual radio" access point. The wireless throughput is not sacrificed because the APs are capable of communicating on a separate channel between each hop (see example below).

NETGEAR WG602 54Mbps Wireless - G Access Point NETGEAR's future-ready WG602 Wireless Access Point connects to all IEEE 802.11b wireless networks. And it lets you add new clients based on the forthcoming, screaming-fast IEEE 802.11g standard at 54 Mbps, while it maintains support for your existing 802.11b network - taking care of today's needs as well as tomorrow's. With its high-speed data transmissions of up to 54 Mbps, you accomplish a lot of work in a short amount of time. Network users can share a broadband Internet connection, access e-mail, download large files, videoconference, and distribute and play digital images, videos, and MP3 files. Easy to set up and use, NETGEAR's intuitive Install Assistant makes driver installation a cinch. And with up to 128-bit WEP encryption, you can rest assured that your wireless network communications are private.

Dual Radio Access Points

Choosing the right cables; putting it all together:
The antennas are connected to the AP/Bridge using low loss 50 ohm cable - FREE SHIPPING is available with purchase of antenna. It is important to use the correct type (low loss) cable for best performance...DO NOT use RG type cable as it is considerably more lossy. It is also very important to weatherproof all outdoor exposed connections to prevent corrosion and loss of signal. Each remote antenna MUST have a clear line-of-sight to the base antenna. You should locate the AP/Bridge near the location of where the antenna cable will enter the building, yet easily accessible for running LAN cable. If the distance from the AP/Bridge to the antenna is under 10 feet, you can use a 200 series pigtail cable only. If the distance is over 10 feet, I recommend using the lower loss 400 series cable (N-Male to N-Female) and a short pigtail between the 400 cable and the AP/Bridge. Why two cables? Simply because wireless devices use very small connectors and the 400 type cable is quite rigid. The pigtail will provide the connection to the wireless device using a much more flexible cable, resulting in less stress on the wireless device. Only one AP/Bridge is connected to an Internet router using LAN cable (Cat5 or better). Any additional available LAN ports can be used for connecting wired (LAN connected) computers. I suggest using a wired Cable/DSL router, such as the Netgear RP614 - Cable/DSL Web Safe Router, simply because wireless routers are useless for this type of wireless network expansion. Remote AP/Bridge(s) are connected to a switch, such as the Netgear 5 Port 10/100 Desktop Switch - FS605NA -OR- the Netgear 8 Port 10/100 Desktop Switch - FS608NA, to permit multiple computers to be connected to the network. You then connect computers at each remote location to the switch using Ethernet cable. Wireless access is automatically provided at any location where an Omni-directional antenna is used. The easiest way to provide wireless access at a remote location when using a directional antenna is by using a 2-way splitter. The splitter allows you to connect two antennas to a wireless radio, such as both a directional antenna and an Omni-directional antenna (see illustration). It is important to consider the following issues when choosing a location for each AP/Bridge. LAN cable has a maximum length limit of 100 meters (328 feet) for each device connected, including jumper/patch cables. Low loss antenna cable should be kept as short as possible to reduce signal loss and eliminate the need for an amplifier. When the antenna cable length exceeds 50 feet, a coax amplifier is recommended as cable loss becomes much higher. When transmitting beyond 1000 feet, an amplifier is also recommended at both ends so that both transmit (TX) and receive (RX) signals are amplified.

Aiming the antennas:
Now that you have configured and deployed your wireless bridge(s) we're ready for aiming the antennas. Directional antennas must be aimed toward the Omni-directional base (source) antenna. For shorter distances (under 500 feet) this most likely can be done from eyesight. Simply make both vertical and horizontal adjustments to the antenna aiming it toward the base (Omni) antenna. For distances over 500 feet I recommend using Netstumbler software to obtain the best signal (download Netstumbler). Netstumbler provides a graph that is updated every second making it possible to make fine tuning adjustments. Netstumber works with a wide selection of wireless adapters, both notebook and desktop (check compatibility list). You will temporarily disconnect the antenna from the AP/Bridge (make sure you also power off the AP/Bridge, otherwise it may cause interference) at each remote location and connect it directly to a notebook or desktop wireless adapter (note that not all notebook adapters have external antenna connectors). Once you lock-in the best signal from each remote antenna, reconnect the antenna to the AP/Bridge. That's it, you are ready to share drives, printers, and high-speed Internet between locations and across the entire network.

Protect your investment; It is a good idea to protect all AP/Bridges by installing a lightning protector on both the power and antenna cable. Lightning surges are the most common cause of equipment problems and can lead to service interruptions, reprogramming, or even costly replacement of equipment. We provide high quality coax lightning protectors that are comparable to ones made by Huber Suhner® or Radiall®, though are less than half the price. They are easily installed either directly on the antenna or between the 400 series cable and the pigtail.

Making it safe and secure:
I highly recommend using WEP (wired equivalent protection) as well as turning off SSID broadcast. This will prevent unauthorized use of your wireless network, as well as making it much more safe and secure. For an additional layer of security, you can restrict wireless access by adapter MAC address. Simply follow the setup procedure for enabling and disabling these features. Enabling WEP when using Netstumbler will ensure you are locking into your signal, not just any.

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Whether you are building a home network or an enterprise network, equipment choices are very critical. We manufacture and distribute a wide range of high quality antennas, cable assemblies and many other accessories, though we do not provide electronic devices such as routers, access points, wireless adapters, etc. Be sure to research the product specifications before purchasing to make sure it has the power output and features you need.