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External WiFi Antennas

Take Full Advantage of Your External WiFi Adapter

AIR802 Parabolic Antenna

The antennas built-in to portable WiFi devices work surprisingly well considering their small size and how weak most WiFi signals are. But beyond the coffee shop or fast food restaurant hot spots, they often don’t work well enough. For your signal to really “get out”, you need an external WiFi antenna.

If you invested in an external WiFi adapter hopefully you followed my advice and got one with an antenna connector. This will allow you to experiment with bigger, more efficient antennas. Don’t be too concerned about getting the most powerful adapter made. You should realize, once you have the same transmit power as the device on the other end (and a similar performing antenna), any more is redundant. The reason is high output power only helps on the transmit side. You still need to do something about the receive side. Antenna gain helps equally in both transmit and receive so that is the place to concentrate your efforts.

External WiFi antennas are usually connected with coaxial cable. Coaxial cable, or coax (pronounced ko-axe), is a 2 conductor cable with a copper wire inner conductor surrounded by a braided copper shield and an insulating material separating them. The outer shield is supposed to keep the signal on the inner conductor from escaping thus reducing signal loss. This works good at lower radio frequencies but at the frequencies used by WiFi, signal loss is a problem. It’s posible cable losses could be more than that gained by the antenna. Therefore it’s a good idea to keep coax cable runs as short as possible.

If a long coax run is unavoidable, you have two options. First, you can choose a higher gain antenna to make up for the loss. Higher gain for antennas usually means bigger. If this is not practical, the second option is to mount the WiFi adapter right on the antenna. This avoids the loss of signal problem because the data from the radio can be sent to and from the computer via a USB or Ethernet cable that effectively has no signal loss because the data at this point has already been converted to digital format. A USB adapter can handle a cable length of 15 feet (3 meters). A 15 foot USB cable should be enough for most RV or marine applications. If you need more length, there are USB extenders with built-in boosters. Ethernet cable specs allow much longer lengths. Having a high-gain antenna with the WiFi radio mounted on it is a double bonus.

A typical USB WiFi adapter is not designed for outdoor use. But there’s nothing stopping you from mounting one on an antenna for temporary outdoor use in fair weather. Just bring it inside when not in use or if the rain threatens. If you’re set up in one spot for an extended period consider a WiFi adapter designed for outdoor use.

Select a place for your coax or USB cable to exit the RV or boat. Sealable feed-through fittings are available for more permanent installations. This avoids the hassle of cable routing every time you stop. Ideally, the exit point should be near the antenna mount location. Bring the antenna out and mount it to solid point on the vehicle. Stainless steel U-bolts on the back ladder or roof racks work good. Aim if necessary and you’re good for the duration of your stay. When it’s time to leave protect your system by storing the antenna inside and securing and sealing the end of the USB or Ethernet cable, if permanently installed.

Good quality outdoor antennas are usually equipped with N-Type connectors. USB type WiFi adapters will have SMA type connectors so you may have to mate different connector types with adapters or cables with different connectors on each end. There will also be connector gender issues. When ordering, make sure you have the right combination. Luckily, picture ads on Amazon have a zoom feature so you can look closely and confirm the type and gender of connector on your equipment. They also list suggested adapter and cable combinations that might be purchased together. These suggestions usually take into account the type of connectors used.

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