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| Wireless technology |
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| What is wireless technology? |
| Wireless technology uses radio waves to transmit information without cables or wiring. Although wireless communications have been used since 1876, the technology is becoming widely used in the creation of wireless computer networks. |
| There are many standards for wireless communications, including Bluetooth, DECT and WiMax. WiFi or 802.11 is a set of standards designed for wireless ethernet LANs and is the protocol used by all of our miniPCI wireless cards. |
| The table below summarises the features of the 802.11a, 802.11b and 802.11g standards, which are most commonly used in wireless networking. |
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| The 802.11n standard is currently under development, and is expected to offer a theoretical maximum speed of 540 Mbps and a better operating distance than the current standards. |
| The current estimate for approval of the new standard is July 2007. Although many vendors claim to have 'pre-n' products, there is no guarantee that these will comply with the standard when it is finally released. |
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| Why would I want to use wireless technology? |
| There are two main advantages of using wireless technology for computer networks - mobility and cost-savings. |
| Using a wireless network means that you can move about freely, within your home, business or even your city, and still maintain a connection to other computers on the same network. |
| Installing cabling can be expensive, especially over long distances, in difficult terrain, or in established buildings, so it can mean considerable cost-savings to use a wireless network instead, provided the environment is suitable. |
| For WANs, using wireless technology also removes the need to pay for access to existing telecommunications infrastructure. |
Typical uses of wireless technology include:
- a home or small business wireless access point that gives access to the internet for one or more computers
- linking two buildings (business premises, farm buildings, temporary or mobile sites) that are physically separate
- hot spots in public places such as hotels, restaurants, marinas, caravan parks
- wireless ISP infrastructure (network backbones and customer services)
- remote access to equipment, such as remote sensors or device controllers (e.g. irrigation systems, temperature sensors, security cameras)
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| What do I need to use wireless technology? |
| To build your own wireless network, you'll need the following: |
| 1. Computers |
| To make use of a wireless network, you'll need wireless-capable computers and devices such as wireless access points or wireless routers. You can build your own access point or router using dedicated hardware, like the ALIX and net computers that we sell, or you can buy an off-the-shelf product. |  |
| 2. Wireless cards |
| Wireless expansion cards (also called wireless adapters) handle the processing of the data that is transmitted or received over a wireless network. Each card supports one or more of the 802.11 standards, and has different characteristics with regard to the chipset used, maximum output power, speed, receive sensitivity, etc. Wireless adapters are available in a variety of formats, including miniPCI and PCI, PCMCIA (CardBus) and USB. All of our wireless cards are miniPCI type 3A or 3B. |  |
| 3. Antennas |
| As with other radio devices, wireless computers can use antennas to improve reception and transmission quality. Each antenna has a distinctive pattern of radiation, with omni-directional (360°) being the most common. Antennas can also be directional or sectorised, with transmission and reception occurring in a narrower, more specific direction. The gain of an antenna in combination with the output power of the wireless card, determine the output power (EIRP) of a wireless device. |  |
| 4. Pigtails |
| A pigtail is used to connect a wireless card to an antenna. Some pigtails connect directly from the wireless card to the antenna, while others connect from another pigtail to the antenna, allowing for more distant placement of the antenna from the wireless card. With these longer pigtails, loss of signal can occur, so using special low-loss cable (LLC or LMR) is recommended. |  |
| It's important to make sure you have compatible connectors on your card, pigtail and antenna. The wireless card connectors are usually u.fl (or I-PEX), MMCX or MCX. The antenna connectors are generally of type N, SMA or TNC. Connectors can also be male or female (you need a matching pair) and straight or reverse polarity (you need the same polarity). All of our wireless cards have u.fl compatible connectors and our pigtails and antennas are either N-type or reverse SMA. |
| 5. Software |
| Lastly, you need software to run all of this wireless hardware. You'll need drivers for your wireless card and a network-capable operating system. You can find links to drivers for our wireless cards and various operating systems on our software resources page. |
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| The rest is up to you! |
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| What else do I need to know? |
| There are limits on the power you can output |
| The low-powered radio waves used by the 802.11 protocols are generally regulated under a class licence, which means anyone is allowed to use them. However, there are legal limits to the power you are allowed to output from a wireless device in these spectrums. In Australia, the limit is 4W (36 dBm) for 2.4 GHz and 4W (36 dBm) for 5.8 GHz. |
| To use other frequencies or output power above these limits requires a licence from the Australian Communications and Media Authority (ACMA). |
| To view the full details of the class licence from the ACMA, click here. |
To calculate the output power or Equivalent Isotropic Radiated Power (EIRP) of your system, you can try one of these calculators:
EIRP System Calculator at Benelec
Wireless Lan EIRP Calculator at Khetanna
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| You might also find this dBm to Watt conversion table useful. |
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| Power isn't everything |
| When choosing the right wireless card for your application, it's important to realise that power isn't everything. In fact, in some situations, too much power can be a problem. |
| You also need to take into account factors such as receive sensitivity and the operating frequency ranges. |
| Receive sensitivity is the capability of a wireless card to pick up weak signals, which can be more important than its power output. The lower (or more negative) the value, the more sensitive a card is. |
| For example, at 11MBps the receive sensitivity of the Ubiquiti cards is -92dbm, while the Senao 200mW's is only -86dbm. |
| To help you decide which card is right for your application, check out our handy comparison of our miniPCI wireless cards. |
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| dBm vs dBi |
| Some of the terminology used in wireless networking can be confusing. One common source of confusion is the very similar terms dBi and dBm. |
| • dBm is a measure of the output power of a system. This can also be measured in Watts. (see above) |
| • dBi is a measure of the gain of an antenna. Gain is the way in which an antenna redistributes and focuses the output power of a wireless card. |
| Although the two are related (gain affects power output) they are not the same thing and should not be used interchangeably. |
| Our glossary contains definitions of these and a number of other related terms. |
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Installation tips
Wireless cards, like all electronic equipment, are sensitive to damage from static discharge, especially the RF switch and the power amplifier. To avoid damage caused by static discharge, we strongly recommend that you do the following when installing a wireless radio card:
- Touch your hands and the bag containing the wireless card to a ground point on the board (for example one of the holes in the corner of the board). This will equalize the potential of the wireless card and board.
- Insert the radio card into the miniPCI slot on the board.
- Install the bulkhead end of the pigtail into the case. This will ground the pigtail to the case.
- Touch the u.fl end of the pigtail to a ground point on the board to discharge any static, then attach the u.fl end to the connector on the wireless card.
We also recommend that you utilise some form of lightning protection when using wireless cards and boards in outdoor locations.
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| Available products |
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| More information |
| Learn more about wireless technology at Wikipedia. |
| Check out our handy comparison of our miniPCI wireless cards. |
| Browse our range of wireless products in the catalogue. |
| If you're after pigtails and antennas we don't carry, you could try RFShop. |
| For more technical information on our miniPCI wireless cards and drivers, visit our technical information pages. |
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