While many cities and organizations offer free Wi-Fi Internet to anyone who is within range of their transmitters, the coverage can sometimes be spotty, weak or blocked by structures that interfere with the line-of-sight transmission requirements of Wi-Fi. If you are close enough to an open Wi-Fi area to receive a weak signal, however, you may be able to increase its strength enough using Wi-Fi extenders to achieve a reliable signal.

Types of Extenders

The basic Wi-Fi extender, also called a repeater, is a device that plugs into an outlet and has a radio with built-in antennas that receive a signal from the closest router, amplify it and rebroadcast it locally. Advanced models may have replaceable antennas, with options for directional and high-gain versions for increased range. Some manufacturers also offer outdoor extenders, powered by Power over Ethernet, or PoE, which can be mounted to a pole, roof or wall to receive a weak outdoor signal and rebroadcast it locally. In addition, you can typically configure standard routers and access points as extenders, and they may offer other options to improve signal quality.

Placement

If you are using a single extender, place it as close to the signal's transmission point as possible, preferably in front of a window or another area that does not impede the signal's path. You can then add more extenders to increase the indoor range, if needed. Especially weak signals or ones that are blocked by adjacent structures may improve with an outdoor extender, which you can combine with an indoor extender to further increase the range. An outdoor extender requires an Ethernet cable to be run from inside the home to the extender's outside location -- possibly through a wall -- to deliver power.

Configuration

Many of the Wi-Fi extenders on the market come with software for your computer to automatically configure them. If you have to manually configure the extender, find the extender's network IP address, username and password in its documentation, and then type the IP address into your browser's address bar. Enter the username and password, when prompted, to enter the extender's configuration interface. To function correctly, the extender should use the same SSID, wireless channel, security type and passphrase as the open Wi-Fi network. Find these settings in the configuration interface and set them to match. You also have to set the extender to a suitable IP address for the network. Find the IP address setting, which is the current address of the extender, and choose DHCP, or dynamic addressing, to obtain a new IP address from the Wi-Fi network automatically.

Effects on Network Speed

When using a Wi-Fi extender, the speed of the network may be reduced by half or more, due to the latency introduced by repeating the signal and other factors. For Internet access, this should not make much of a difference, because Internet speeds are much slower than the speed of a typical wireless network. Transferring files between computers on the Wi-Fi network, however, may be much slower when you use extenders.