You can use a coax cable to transmit radio frequency signals that need a high level of protection and great flexibility. General applications include digital audio, transmission lines, computer networking, and radio equipment. You can also use them in cable television distribution systems. Wherever you use coaxial cables, you use coaxial cable connectors too. These connectors provide a high degree of durability and versatility even in very rough environmental conditions. In this article, we will discuss them in detail.
Table of Contents
- What are Coaxial Cable Connectors?
- Difference between a 50-ohm and a 75-ohm connector
- Types of coaxial connectors
- How to choose your connector？
What are Coaxial Cable Connectors?
Coaxial cables are electrical cables capable of carrying HF multi-megahertz electrical signals. These cables have an inner central conductor and a surrounding conducting shield, and an inner dielectric insulator separates these two conducting layers. Along with these, such cables also have a protective outer jacket.
Coaxial cable connectors help you top and tail the cables to connect the cable to other devices or each other. Usually, you can also call them barrel or tip connectors. The design of these connectors helps to protect the outer interference shielding. You can use these connectors to manage a coax cable’s inner and outer conductor.
The impedance of these connectors is the same as that of the attached cable, and they maintain a coaxial form across the cable connection.
Due to high conductivity metals like silver or gold plating, the RF signal passes through the leaf only and does not enter the connector body. Silver is a poor choice among the high conductivity metals because it tarnishes quickly. As a result of tarnishing, it forms silver sulfide, a poor conductor, and affects the connector’s performance.
Image: High-quality cable with coaxial connectors
Difference between a 50-ohm and a 75-ohm connector
The value of a cable lies in the resistance that it offers against the flow of electrical signals. You can call this resistance impedance, and the unit of measurement of the impedance is ohms. Lesser ohms mean lesser resistance and thus better performance. Therefore, it means a 50-ohm connector offers less resistance than a 75-ohm connector. However, it does not mean that you should always pick a lower resistance connector. The level of resistance you need depends on the requirements of your project.
Image: connecting coaxial wires using F-connectors
Types of coaxial connectors
Coax connectors provide continuous electrical resistance across the connection point. Thus, they are a bit delicate and are prone to damage easily. Every connector’s size, style, and design are specifically designed to match the host cable’s functionality in different environmental conditions. So, you need to choose a high-quality one.
BNC or Bayonet Neill-Concelman connectors are available for significant types of coax cable. You can find them in both 50-ohms and 75-ohms options. Developed in the 1980s specifically for military use, you can use BNC connectors on radios, cable television systems, video signals, and security cameras at low frequencies (below 4GHz).
Image: fiber optic video converter with BNC connectors
TNC is a threaded connector and an advanced BNC version. The Threaded Neil-Concelman connectors minimize signal leakage to work up to 12 GHz. As these connectors are weatherproof, you can use them for outdoor applications like cell towers and antennas. You can also find a reverse polarity version in this type.
The connectors that you see at the back of your television are F-type connectors. You can use them for satellite television, cable TV systems, antenna, and cable modems. For example, you can use them on RG59, RG6, and RG11 cables.
Image: F-Type connector
Paul Neill invented these connectors and thus got their name. Initially, they were available in the 50-ohm version, but now you can get their 75-ohms version. The modern version can handle up to 18GHz. You can also get them in the reverse polarity option.
UHF Connectors (PL-259/SO-239)
UHF connectors have two options: a male connector PF-259 and a female connector SO-239. Primarily, people use them for amateur radios, and you can find a 50-ohm version in RG58 and RG8 cables. Also, there is a mini-UHF version designed for small equipment like cell phones.
SMA is a miniature thread connector that you can use on RG58 and other thin coax cables at high frequencies up to 24GHz. These include a WiFi antenna cable, walkie-talkies, or radio telescopes, and you can also get them in reverse polarity. On the other hand, you can use an SMB or Subminiature B for high-frequency equipment for transmission of 4GHz maximum with a snap-on connection.
QMA is an upgraded version of SMA, and you can connect and disconnect them easily. Developed in 2003, this is a modern type of connector that is still not very popular, and thus, it is still used for limited electrical cables only. They are suitable for communication applications, cable wiring, repair, and assembly.
FMA is also a 50-Ohm miniature connector that you can use with RG58. Due to its small size, you can run it through holes and conduits where other connectors cannot enter.
PAL stands for Phase Alternating Line, and it is a type of connection. You can see this connection where you need to connect equipment of international standards via an adaptor. You can commonly notice such links in Australia, Europe, and some parts of Africa, Asia, and South America.
Micro coaxial or Micro Coaxial Cable Connectors and Micro-Miniature Coaxial are small-sized connectors. Industries that require tiny connectors are ideal applications for these connectors. You can use MCX connectors for a TV tuner card for PCs, WiFi routers, antennas, GPS systems, and cellular applications. You can use MMCX for computer tuners to connect WiFi and GPS use.
Single-line coax connectors are available in different varieties. The first is the 1.0/2.3 version developed in the 90s for telecom systems, and it has 50-ohm and 75-ohm versions. The 50-ohm can work with high frequencies up to 10GHz, while 75 ohm supports a maximum of 4GHz. The other types are 4.1/9.5 and 4.3/10, but they are more extensive. Thus, you can use them with thick coaxial cables. Another type is 7/16 full-size DIN in the 50-ohms version. It is the same as the N-series connector and can support high power levels. It is suitable for the cable within environments exposed to high moisture.
The small size of this connector makes it suitable for use in compact devices like mobile phones, and you have to use them with fragile cables like LMR-195 and LMR-100.
You can use these removable connectors with LMR-195 and RG-58 coaxial cables. These connectors find particular use in Motorola products.
How to choose your connector？
While selecting a coaxial cable connector, you need to consider the key features of the cable you have to connect.
Most of the RF connectors you use in the telecommunication industry can operate up to 500 volts. In general, as the connector size increases, its power handling capacity also increases. For example, N-Type connectors can handle a power capacity of 2700 volts.
The durability of a connector largely depends upon environmental conditions. Mil-spec RF connectors undergo testing under high vibration and corrosion-stimulating conditions. Generally, the way of expressing testing standards is MIL-STD-XXX format.
The required frequency
Frequency means the number of times an action occurs in a second. RF connectors have groups of families and series, and every series can operate in a particular frequency range. In this regard, SMA connectors are the most suitable for many applications as they can work in a frequency range of 0-18 GHz.
Connectors must match the impedance of the cables. The maximum number of connectors operates between 50-95ohms, and RF connectors like BNC and F connectors that you use in audio and video applications work with 75-ohm cable. On the other hand, applications requiring 2400MHz frequency operate at 50 ohms.
Coaxial connector gender
All the RF connectors either have plugs or jacks. Plugs, having thread inside, are males, while jacks, having lines outside, are females. However, all RF connectors are not threaded. There are MCX connectors that use a snap-on mating process.
Coax connectors have been getting smaller since their development. Nowadays, you can get a micro-miniature IPX connector as small as 2.5mm. However, keep in mind that size affects the power handling capacity of the connector.
Several factors affect the ruggedness of RF connectors. For example, their mating cycles, outdoor or indoor use, and operating temperatures. Most of the RF connectors come with a rating of 500 mating cycles.
It is the transmitted signal power ratio to the signal loss due to device interference during transmission. The longer the signal travels, the higher the attenuation. Factors such as coax cable length and its type affect the insertion loss, and an RF connector must constantly work to reduce insertion loss.
The coupling style
The mating mechanism also affects the durability of an RF connector. For SMA connectors, the standard threaded interface is good to go, however, it is not suitable for BNC connectors.
A snap-on mating mechanism is getting popular for applications with space crunch.
Even if you find a suitable coax connector for your applications, you may get stuck on the price. SMC and SMB connectors are on the higher side of the price range, while F and BNC connectors fall at the lower end.
Coaxial connection is essential across a wide range of industries. However, you need to pick the right cables and connectors for a high-quality one. Our experts at Cloom can help you find conformable cables for your applications.