How to Install Wireless Amplifiers

July 10, 2013 at 10:00 AM

 Setting up a WiFi Booster for an Indoor Wireless System

 

An Assortment of WiFi Amplifiers

If you do not work with wireless components every day, the prospect of adding a new component to boost the power of your signal may seem daunting. While we always recommend you have a professional install communications equipment to ensure it is done correctly, this brief tutorial will give you the basic steps to set up a simple WiFi booster. If it helps, you can also take a look at the video in this post or visit our complete tutorial here.

 

 

 

If you have a WLAN setup that requires a stronger signal, a simple WiFi booster may do the trick. Due to FCC regulations, if you are doing this installation in the United States, you need FCC approval to buy the amplifier. If you don't need an amplifier with power over 1 Watt, you can purchase an FCC certified amplifier kit which requires no special operator's license. Either way, most setups follow this simple procedure.

 

Diagram of an RF amplifier setup

On the amplifier, you will typically see two coaxial cable jacks, one labeled "Antenna" and the other labeled "Radio". There should also be a power jack (usually a DC jack requiring an external power adapter), which is where the amplifier gets the power to repeat the signal.

 

Using low-loss coaxial cable, simply connect the antenna to the antenna jack on the amplifier, and the radio (or access point or router, etc) to the radio jack. Then, after the two sides are hooked up, attach the power adapter and plug it in. Most amplifiers have LED lights to indicate activity, which helps you to see if it is working.

 

It's that easy!

 

Quick note: L-com has a huge selection of top-quality wireless RF amplifiers for the 2.4 GHz WiFi band and 5.8 GHz WiFi band, as well as 900 MHz, 3.5 GHz, and 4.9 GHz frequencies. These ampifiers feature HyperLink's® Active Power Control (APC), which automatically maintains a constant output power regardless of the length of the attached cables. Aside from the indoor wireless amplifiers, L-com also carries HyperLink® brand outdoor wireless amplifiers for all-weather operation.
 

Low Loss Coaxial Cable for Wireless Applications

June 26, 2013 at 10:00 AM

 

Closeup of Low Loss Coaxial Cable Stripped to Show Components

Even in a wireless network, cables and wires are still used to connect components together (access points to amplifiers, amplifiers to antennas, etc). Each component needs cabling to interact.

 

If you are a wireless engineer and need to interconnect components, chances are you are using low loss coaxial cabling. While 50 Ohm RG-style coax is sometimes used, the attenuation is usually too much for any length over just a few feet. This is where low loss coaxial cable comes in.

 

 

Coaxial Cable and RG-Style Coax

 

All coaxial cable works the same way: the signal is run over two "axes" (thus the name). Coaxial technology is one of the oldest signal cabling types, and is still used today for a specific reason: it is robust and can carry a signal very well over a long distance. In general, the thicker the cable, the less "loss" or attenuation of signal there is over the length of the cable.

 

The original standards for coaxial cable were set forth by the US military. These cables used the term "RG" (for "Radio Guide" or "Radio Government") followed by a number to designate the standard. This worked well at the time, but as technology became more and more utilized in commercial and non-military applications, the restrictions of the standard became less rigid (to the point where RG316, for instance, may have very different properties today depending on who manufactures it).

 

 

Times Microwave LMR® Cables

 

No matter who makes the RG-style cables, they have one fundamental problem: the signal degrades over the length of the cable until it is no longer useable. For shorter use in labs or machine-to-machine applications, this is not a problem. But in wireless applications, the signal integrity up until it is broadcast through the antenna is critical.

 

For that reason, Times Microwave Systems developed a low loss version of coax that it branded as its LMR® series coax. The newly-engineered solution offered far lower loss and better RF shielding, making them a much better choice for wireless systems than the RG styles.

 

Outside of Times Microwave Systems' product (the term LMR® refers specifically to Times Microwave Systems product and is trademarked for their use), several other companies now offer low-loss coaxial cables. These generally follow a similar naming convention as what Times Microwave Systems uses: a three-digit "series" number that refers to both the thickness of the cable and the low loss properties.

 

For instance, 100-series low loss coax is thinner and has greater loss than 200-series, which is thinner and has greater loss than 400-series, etc.

Diagram of most common low-loss coaxial cables

Note that with thicker cable factors such as cable weight and flexibility must be considered. However, there are now ultra-flex versions of thicker series like the 400-series that offer similar loss characteristics but are far more flexible.

 

Quick note: L-com has been manufacturing high-quality coaxial cables and components for over thirty years.
 

Tutorial on Wireless Networking

June 12, 2013 at 10:00 AM

 

Wireless network antenna and devices

Entire cities and even countries are looking into ways to expand communications access for their residents as the Internet has shifted from a luxury to an imperative. The most promising solution: wireless networking.

 

Why? Wireless networking allows a non-physical (well, at least non-cabled) connection to a wireless LAN (WLAN) and onto the World Wide Web for users. So what are you waiting for? Cut the cord!

 

Be mindful of this though- issues such as network and band congestion, security, signal range and propagation, power demands, and more make WLANs tricky to implement for all but the most informed network engineers and IT professionals. Yet there's no stopping this technology in its rapid advance, with solutions such as distributed antenna systems (DAS) and MESH networks beginning to show promise. For you to get started, here's a basic wireless tutorial on terminology and concepts.

 


Wireless Standards

 

Radio frequency signals can take a lot of different forms, so in order for devices made by different manufacturers to communicate, the IEEE has provided several standards including the mainstay for wireless Ethernet: 802.11.

 

The 802.11 standard specifies the band and IP protocol used to transmit data, and provides guidelines to maximize the speed of transmission. 802.11a, for instance, uses the 5Ghz band and can typically transmit at speeds up to 54 Mbps in shorter ranges. 802.11b, 802.11g, 802.11n, and the new 802.11ac all use various methods to increase the speed and range. The latest IEEE wireless standard, 802.11ac boasts transmission speeds of up to 1 Gbps!

 

Each standard typically requires wireless routers, access points, and other transmission equipment to match its designation, though there are many that can operate in multiple standards (such as routers that are 802.11b/g/n compliant).

 


Wireless Bands

 

In attempt to maintain order within the entire radio frequency spectrum that is available to us, the FCC and other global communications standardization organizations have designated or set aside specific ranges of frequencies for specific uses. We call these "ISM bands". ISM stands for industrial, scientific and medical to denote where these frequencies are used.  ISM bands (specifically the 2.4 GHz and 5 GHz frequencies) are also used in commercial wireless networks. 

 

Typically access points, antennas, and amplifiers all use either the 2.4 GHz band, 5.8 GHz band, or both for WiFi. Other ISM bands have been set aside for things like cell phone use, RFID chips, emergency/municipal use, and military use.

 


Wireless Security

 

As mentioned previously, one of the big emerging issues with wireless networking is security. Without a physical cable that can be plugged and unplugged, the only method to control who can do what on a network is to build it into the software and protocol. That means it is critical to set up a wireless network with appropriate security measures and to be aware of the security status of any network you connect to.

 

For most small networks, methods such as WPA, WPA2, or WPA-PSK allow the safe identification of nodes that should be allowed on a network with passwords and other controls. Wireless routers can also use access passwords to allow administrators to adjust or update security features as required.

 
If you have questions about a wireless project or application, contact L-com's technical support line for a live response and expert advice!
 

Picking the Right Antenna for Your Application

May 29, 2013 at 10:00 AM

 

How-To 

 

A log periodic antenna mounted on a pole or mast

If you are new to wireless technology, the multitude of antenna shapes, sizes, styles and gains can be bewildering at first. Will you need a dish antenna, a grid, a Yagi or just a rubber duck?

 

Fortunately, by following a few rules of thumb, you can get a hang of the different styles and the applications they fill. It starts with a complete survey of the area where you need coverage: its shape, size and obstructions found within it. With these details on hand, you'll need to consider the following factors:


 

Beam Width


One of the key differences between antenna styles is the "beam width" and direction. In general, the narrower the beam width the more powerful the signal is in a particular direction. That's not to say Omni directional antennas are weak, but merely that the signal strength is spread in a different way (which may or may not be appropriate for your application).

 

Read this article for more information on signal gain patterns and wireless network design.

 

Vertical and horizontal beam patterns
Beam Pattern of a Log Periodic Antenna

 

 

Antenna Polarity

 

Another aspect of antennas to keep in mind is the polarity. While wireless signals travel, they move as a wave. Just like ripples on the surface of water, waves that move in the same direction cancel each other out. Waves in different directions do not. In a similar way, too many antennas set up in a vertical polarization in an area can cancel each other out, resulting in extremely poor signals.

 

In the case where a lot of wireless signals in the same band may be required, setting up antennas with different polarities can improve the performance of each signal. In some instances, you may want to set up "dual polarized" antennas, which include both vertical and horizontal polarities. These and other types of polarities (such as "cross polarized" and "circular polarized") can improve the strength and distance of signals in multiple ways.

 

This article offers some great information on antenna polarization.

 

Antenna Polarization Diagrams
WiFi Antenna Polarization Schemes

 

 

Antenna Gain

 

The final consideration for choosing your antenna is antenna gain. Measured in decibels (dB), it is commonly written as a number followed by "dBi" (the "i" at the end is for "Isotropic", and indicates that the number is relative to an imaginary, "perfect" dipole radiation). In general, the higher the dBi the stronger the signal in whatever direction it is going.

 

While it may seem tempting to simply buy the antenna with the highest gain for your beam width and polarization, it may not be relevant for your application. You should seek a dBi relative to the size of the space that the signal needs to cover. In many cases, a high gain will provide poor coverage closer to the antenna and better coverage further away.

 

For instance, setting up an Omni directional antenna in the center of a small cafe would require a smaller gain. If you use an antenna with too large a gain, people using devices in the street outside of the cafe would have better signal than those in the cafe itself because the total signal would be stretched.

 

This article explains why too much gain is a bad thing.

 

Small gain antenna used in 300-foot courtyardLarge gain antenna used in 1000-foot courtyard
An 8 dBi Omni directional antenna is more appropriate for a 300' space in a cafe courtyard than a 14 dBi antenna.
 

Quick note: L-com's technical resources section has tons of helpful information for the WiFi newbie or established expert alike. Also, for help selecting an antenna, try the Antenna Product Wizard.

 

How To Amplify Wireless Signals without an FCC Operators License

May 1, 2013 at 10:00 AM

 

Example of a Wireless Amplifier Setup for a Laptop

Do you need a wireless amplifier but can't get one?

 

That's because the Federal Communications Commission (FCC) Part 15 regulations dictate the use of RF power amplifiers in the United States. Individual RF power amplifiers are not offered for general sale within the United States and must be part of a wireless system previously certified by the FCC.

 

Customers in the US that are inquiring about purchasing individual amplifiers must first be prequalified to see if they meet certain requirements. Those who qualify are typically Federal Government agencies, Department of Defense (DOD) and FCC licensed operators. This is obviously not ideal for the typical home or commercial business user.

 

So how can you get one?

 

L-com carries FCC-certified amplifier kits. These kits are complete 2.4 GHz wireless systems that feature a wireless USB adapter, rubber duck antenna and amplifier. Since FCC ID numbers have been granted to these kits, prequalification is not required in order for them to be sold.

 

L-com carries three types of FCC-certified WiFi boosters: standard, economy grade, and PoE compliant. Available with amplifiers ranging from 100 mW to 1 Watt, they provide exactly the boost your signal needs.

 

Click here for a helpful video on how to setup a laptop WiFi booster kit:

 

Wireless Amplifier Video

 
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