Wireless Networking - Connectors and Adapters

Connectors allow a cable to be connected to another cable or to a component of the RF chain. There are a wide variety of fittings and connectors designed to go with various sizes and types of coaxial lines. We will describe some of the most popular ones.

BNC connectors were developed in the late 40s. BNC stands for Bayonet Neill Concelman, named after the men who invented it: Paul Neill and Carl Concelman. The BNC product line is a miniature quick connect / disconnect connector. It features two bayonet lugs on the female connector, and mating is achieved with only a quarter turn of the coupling nut. BNC's are ideally suited for cable termination for miniature to subminiature coaxial cable (RG58 to RG-179, RG-316, etc.) They have acceptable performance up to few GHz. They are most commonly found on test equipment and 10base2 coaxial Ethernet cables.

TNC connectors were also invented by Neill and Concelman, and are a threaded variation of the BNC. Due to the better interconnect provided by the threaded connector, TNC connectors work well through about 12GHz. TNC stands for Threaded Neill Concelman.

Type N (again for Neill, although sometimes attributed to “Navy”) connectors were originally developed during the Second World War. They are usable up to 18 Ghz, and very commonly used for microwave applications. They are available for almost all types of cable. Both the plug / cable and plug / socket joints are waterproof, providing an effective cable clamp.

SMA is an acronym for SubMiniature version A, and was developed in the 60s. SMA connectors are precision, subminiature units that provide excellent electrical performance up to 18 GHz. These high-performance connectors are compact in size and mechanically have outstanding durability.

The SMB name derives from SubMiniature B, and it is the second subminiature design. The SMB is a smaller version of the SMA with snap-on coupling. It provides broadband capability through 4 GHz with a snap-on connector design.

MCX connectors were introduced in the 80s. While the MCX uses identical inner contact and insulator dimensions as the SMB, the outer diameter of the plug is 30% smaller than the SMB. This series provides designers with options where weight and physical space are limited. MCX provides broadband capability though 6 GHz with a snap-on connector design.

In addition to these standard connectors, most WiFi devices use a variety of proprietary connectors. Often, these are simply standard microwave connectors with the center conductor parts reversed, or the thread cut in the opposite direction. These parts are often integrated into a microwave system using a short jumper called a pigtail that converts the non-standard connector into something more robust and commonly available. Some of these connectors include:

RP-TNC. This is a TNC connector with the genders reversed. These are most commonly found on Linksys equipment, such as the WRT54G.

U.FL (also known as MHF). The U.FL is a patented connector made by Hi-rose, while the MHF is a mechanically equivalent connector. This is possibly the smallest microwave connector currently in wide use. The U.FL / MHF is typically used to connect a mini-PCI radio card to an antenna or larger connector (such as an N or TNC).

The MMCX series, which is also called a MicroMate, is one of the smallest RF connector line and was developed in the 90s. MMCX is a micro-miniature connector series with a lock-snap mechanism allowing for 360 degrees rotation enabling flexibility. MMCX connectors are commonly found on PCMCIA radio cards, such as those manufactured by Senao and Cisco.

MC-Card connectors are even smaller and more fragile than MMCX. They have a split outer connector that breaks easily after just a few interconnects. These are commonly found on Lucent / Orinoco / Avaya equipment.

Adapters, which are also called coaxial adapters, are short, two-sided connectors which are used to join two cables or components which cannot be connected directly. Adapters can be used to interconnect devices or cables with different types. For example, an adapter can be used to connect an SMA connector to a BNC. Adapters may also be used to fit together connectors of the same type, but which cannot be directly joined because of their gender. For example a very useful adapter is the one which enables to join two Type N connectors, having socket (female) connectors on both sides.

Choosing the proper connector

“The gender question.” Virtually all connectors have a well defined gender consisting of either a pin (the “male” end) or a socket (the “female” end). Usually cables have male connectors on both ends, while RF devices (i.e. transmitters and antennas) have female connectors. Devices such as directional couplers and line-through measuring devices may have both male and female connectors. Be sure that every male connector in your system mates with a female connector.
“Less is best!” Try to minimize the number of connectors and adapters in the RF chain. Each connector introduces some additional loss (up to a few dB for each connection, depending on the connector!)
“Buy, don't build!” As mentioned earlier, buy cables that are already terminated with the connectors you need whenever possible. Soldering connectors is not an easy task, and to do this job properly is almost impossible for small connectors as U.FL and MMCX. Even terminating “Foam” cables is not an easy task.
Don't use BNC for 2.4GHz or higher. Use N type connectors (or SMA, SMB, TNC, etc.)
Microwave connectors are precision-made parts, and can be easily damaged by mistreatment. As a general rule, you should rotate the outer sleeve to tighten the connector, leaving the rest of the connector (and cable) stationary. If other parts of the connector are twisted while tightening or loosening, damage can easily occur.
Never step over connectors, or drop connectors on the floor when disconnecting cables (this happens more often than what you may imagine, especially when working on a mast over a roof).
Never use tools like pliers to tighten connectors. Always use your hands. When working outside, remember that metals expand at high temperatures and reduce their size at low temperatures: a very tightened connector in the summer can bind or even break in winter.

Home Antennas and Transmission Lines Connectors and Adapters
See also: Cables

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Connectors and Adapters Connectors allow a cable to be connected to another cable or to a component of the RF chain. There are a wide variety of fittings and connectors designed to go with various sizes and types of coaxial lines. We will describe some of the most popular ones. BNC connectors were developed in the late 40s. BNC stands for Bayonet Neill Concelman, named after the men who invented it: Paul Neill and Carl Concelman. The BNC product line is a miniature quick connect / disconnect connector. It features two bayonet lugs on the female connector, and mating is achieved with only a quarter turn of the coupling nut. BNC's are ideally suited for cable termination for miniature to subminiature coaxial cable (RG58 to RG-179, RG-316, etc.) They have acceptable performance up to few GHz. They are most commonly found on test equipment and 10base2 coaxial Ethernet cables. TNC connectors were also invented by Neill and Concelman, and are a threaded variation of the BNC. Due to the better interconnect provided by the threaded connector, TNC connectors work well through about 12GHz. TNC stands for Threaded Neill Concelman. Type N (again for Neill, although sometimes attributed to “Navy”) connectors were originally developed during the Second World War. They are usable up to 18 Ghz, and very commonly used for microwave applications. They are available for almost all types of cable. Both the plug / cable and plug / socket joints are waterproof, providing an effective cable clamp. SMA is an acronym for SubMiniature version A, and was developed in the 60s. SMA connectors are precision, subminiature units that provide excellent electrical performance up to 18 GHz. These high-performance connectors are compact in size and mechanically have outstanding durability. The SMB name derives from SubMiniature B, and it is the second subminiature design. The SMB is a smaller version of the SMA with snap-on coupling. It provides broadband capability through 4 GHz with a snap-on connector design. MCX connectors were introduced in the 80s. While the MCX uses identical inner contact and insulator dimensions as the SMB, the outer diameter of the plug is 30% smaller than the SMB. This series provides designers with options where weight and physical space are limited. MCX provides broadband capability though 6 GHz with a snap-on connector design. In addition to these standard connectors, most WiFi devices use a variety of proprietary connectors. Often, these are simply standard microwave connectors with the center conductor parts reversed, or the thread cut in the opposite direction. These parts are often integrated into a microwave system using a short jumper called a pigtail that converts the non-standard connector into something more robust and commonly available. Some of these connectors include: RP-TNC. This is a TNC connector with the genders reversed. These are most commonly found on Linksys equipment, such as the WRT54G. U.FL (also known as MHF). The U.FL is a patented connector made by Hi-rose, while the MHF is a mechanically equivalent connector. This is possibly the smallest microwave connector currently in wide use. The U.FL / MHF is typically used to connect a mini-PCI radio card to an antenna or larger connector (such as an N or TNC). The MMCX series, which is also called a MicroMate, is one of the smallest RF connector line and was developed in the 90s. MMCX is a micro-miniature connector series with a lock-snap mechanism allowing for 360 degrees rotation enabling flexibility. MMCX connectors are commonly found on PCMCIA radio cards, such as those manufactured by Senao and Cisco. MC-Card connectors are even smaller and more fragile than MMCX. They have a split outer connector that breaks easily after just a few interconnects. These are commonly found on Lucent / Orinoco / Avaya equipment. Adapters, which are also called coaxial adapters, are short, two-sided connectors which are used to join two cables or components which cannot be connected directly. Adapters can be used to interconnect devices or cables with different types. For example, an adapter can be used to connect an SMA connector to a BNC. Adapters may also be used to fit together connectors of the same type, but which cannot be directly joined because of their gender. For example a very useful adapter is the one which enables to join two Type N connectors, having socket (female) connectors on both sides. Choosing the proper connector “The gender question.” Virtually all connectors have a well defined gender consisting of either a pin (the “male” end) or a socket (the “female” end). Usually cables have male connectors on both ends, while RF devices (i.e. transmitters and antennas) have female connectors. Devices such as directional couplers and line-through measuring devices may have both male and female connectors. Be sure that every male connector in your system mates with a female connector. “Less is best!” Try to minimize the number of connectors and adapters in the RF chain. Each connector introduces some additional loss (up to a few dB for each connection, depending on the connector!) “Buy, don't build!” As mentioned earlier, buy cables that are already terminated with the connectors you need whenever possible. Soldering connectors is not an easy task, and to do this job properly is almost impossible for small connectors as U.FL and MMCX. Even terminating “Foam” cables is not an easy task. Don't use BNC for 2.4GHz or higher. Use N type connectors (or SMA, SMB, TNC, etc.) Microwave connectors are precision-made parts, and can be easily damaged by mistreatment. As a general rule, you should rotate the outer sleeve to tighten the connector, leaving the rest of the connector (and cable) stationary. If other parts of the connector are twisted while tightening or loosening, damage can easily occur. Never step over connectors, or drop connectors on the floor when disconnecting cables (this happens more often than what you may imagine, especially when working on a mast over a roof). Never use tools like pliers to tighten connectors. Always use your hands. When working outside, remember that metals expand at high temperatures and reduce their size at low temperatures: a very tightened connector in the summer can bind or even break in winter.
Home Antennas and Transmission Lines Connectors and Adapters