Coax RF connectors: a critical component of antenna design

Coax RF connectors are an important component in designing new antennas.

You may also have to consider the connector while choosing products for an existing antenna to avoid communication issues and troubleshooting later.

Whether an RF connector is the right choice for particular products depends on several factors, including size, gender, weight, finish, and quality.

This article details different types of RF connectors and their use in various applications. 

Coax RF connector basics:

Radio communication uses coaxial cables; thus, you can call them RF coaxial cables, where RF stands for radio frequency.

These cables transfer radio signals from one spot to another with the help of connectors, which also provide shielding to the cables.

50-ohms vs. 75-ohms RF connectors:

In the radio frequency and microwave market, antennas use RF connectors with 50-ohms impedance.

At the beginning of the 20th century, it was the main industrial requirement because it balanced voltage, attenuation, and power.

Most applications use 50-ohm connectors that can handle high power and voltage requirements with little attenuation.

On the other hand, applications associated with video transmissions use 75-ohm Radio frequency connectors, as video applications use less wattage but have long cables.

A 75 ohms connector offers less attenuation, which is desirable for long-distance transmissions. 

If you want to use a connector in any system, you must match the impedance, saving you from expenses and complexities in the future.

If you fail, you will notice RF energy returning to the Radio Frequency transmitter after reflection.

It is termed standing waves, which tend to dwindle system efficiency. It may also reduce the system range and the loss of the Radio Frequency link budget.

Also, if too much RF energy gets reflected, it may damage the transmitter components like power amplifiers.

Comparison of Rotating and non-rotating RF connectors:

Non-rotating Radio Frequency connectors

In omnidirectional antennas, you can use Non-rotating Radio Frequency connectors with a fixed/non-rotating outer shell.

When you use it in an antenna, you have to rotate the whole antenna to tighten the female and male connectors correctly.

Now, as the omnidirectional antenna radiates energy all around (covering 360 degrees) the antenna, it does not matter where you keep the final antenna position while tightening the connector.

Several considerations that make use of non-rotating Radio Frequency connectors essential for omnidirectional antennas are:

  • There are no rotating parts, so sand and dust intrusion are impossible between the collar and the connector.
  • There is no noise as there are no rotating parts.
  • Antenna installation is easy and may not require any specific tools.
  • Improved performance in terms of insertion loss over frequency and VSWR over frequency compared to rotating connectors.
  • Ideal for outer environments as the connection is weatherproof and waterproof.

You will find non-rotating RF connectors (female) on sector antennas and directional panels, while the corresponding RF cable has male rotating RF connectors. In other words, all types of female connectors are opposite, i.e., non-rotating.

 Rotating connectors

As the name clears, rotating connectors have an outer shell that rotates independently without involving the remaining connector assembly.

You can tighten the mated RF connector to the antenna with the help of the threads inside the shell.

These connectors are suitable for applications where you cannot rotate the entire system to mate the two RF connectors.

Due to the rotating nature of the shell, they may not be completely waterproof after connection unless you use special waterproof options.

Generally, you will find rotating connectors as male connectors.

Sometimes, you may need torque to fix a rotating connector, and it becomes more important for high-frequency functions ranging from 18 GHz to 24 GHz and sometimes higher.

If the connector remains untightened in such applications, it can lead to bad performance or system failure.

The torque wrench fixes the connector tightly to its specific torque rating without damaging it.

Also, it is advisable to use a torque wrench even for low-frequency purposes, as without tools; you may apply too much pressure, breaking the shell, center pin, or other components.

Right-angle Radio Frequency connectors and adapters:

You may require right-angled radio frequency connectors and adapters for applications when you need the cable or antenna perpendicular to the mated connector.

These connectors are available in 45 degrees and 90 degrees angles.

Generally, it is advisable to avoid these connectors, but if you need to use them, pick high-quality designs to prevent insertion loss.

Low-quality RF adapters with poor designs result in high VSWR and substandard insertion loss, leading to the excessive reflection of power in the adapters.

Using radius bend adapters, you can ensure better performance and minimize insertion loss and VSWR (voltage standing wave ratio) in the Radio Frequency system with the right-angle adapter.

The cost of high-quality right-angle RF adapters is too high; you must plan first if you want to use these adapters.

Articulating RF connectors:

Radio Frequency connectors capable of bending to 90 degrees are articulating connectors, and they are used on a few antennas, mostly on commercial equipment like Wi-Fi modems.

The equipment’s mechanical weakness and signal degradation would not affect the antenna performance.

Also, you need to align the antenna vertically to the horizontally installed RF connector.

Apart from this, you can also find articulating connectors in cellular antennas.

These connectors have a mechanical knuckle through which you can select two to three angle positions.

The RF coax cable passes through the knuckle, which is not weather sealed.

These connectors are unsuitable for harsh and rugged environments as cables pass through non-weatherproof knuckles, and moving parts weaken the connector.

Gender and polarity of RF connectors:

There are two common gender classifications of RF connectors; male and female.

In large RF connectors like Type-N, SMA, and TNC, threading secures the connections in male/ female versions.

On the contrary, small Radio Frequency connectors such as MMCX and U.FL use locking rings/ detents to secure themselves.

Apart from the gender classification, you can also classify these connectors based on their polarity.

Most applications use standard polarity, while others use RF connectors with reverse polarity (RP), which is majorly done to limit the usage of non-approved radio antennas based on FCC (Federal Communications Commission) rules and regulations.

One of RP RF connectors’ most common uses is Wi-Fi with outer antennas.

According to CFR 47 part 15 (regulated unlicensed transmitters), Wi-Fi internet radio and antennas must have combined certification not to use aftermarket antennas.

Using such antennas may affect the emission of RF energy in transmitters leading to undesirable interference with medical and other devices.

Manufacturers supply routers with reverse polarity RF connectors so consumers do not use aftermarket antennas.

Identifying the gender and polarity of RF connectors:

Several attributes decide the gender or polarity of the RF connectors.

Let’s understand this through male vs. female TNC RF connectors.

  • A male version of the TNC connector with standard polarity has an outer shell having threads on its internal surface. The dielectric insulating material (white Teflon) surrounds the center pin.
  • A female RF connector with standard polarity has a jack with threads on the shell’s outer surface to match the threads on the internal surface of the male plug. Inside, the connector has a hole that mates with the male’s center pin.

Sometimes, RP RF connectors can be confusing as they are similar to the corresponding standard polarity connectors of the opposite gender.

However, you can spot the difference with these tips:

  • RP male connectors have threads on the inner side of the shell but will have a central hole like female connectors. 
  • RP female version will have threads on the shell’s outer surface but with a center pin as comes in male connectors.

The main difference between the standard and reverse polarity connectors is that of the middle pin.

In standard polarity, the male is a plug, and the female is a jack, while the male is a jack and the female is a plug in the reverse polarity.

Right-angle connectors

Right-angle connectors

Common types of RF connectors and their applications:

In the antenna market, different variants of RF connectors are used to create a rigid connection,  including rotating, non-rotating, reverse polarity, and male/female connectors.

SMA, TNC, and Type-N connector:

SMA (male) RF connectorTNC (male) RF connectorType-n connectors
Advantages: Can handle 11 GHz max frequency suitable for rugged applicationsWeatherproof on proper matingMore than 500 mating cyclesDisadvantages: Not as robust as large RF connectors.Disadvantages: More weight and large size than SMA connectors
Disadvantages:Not as robust as large RF connectors.Disadvantages: More weight and large size than  SMA and TNC connectorsAdvantages: Can operate at 11 GHz max frequency suitable for rugged applicationsWeatherproof on proper mating 500 and more mating cycles

UHF, IPEX, MMCX, and SMP connectors

For applications that require antennas to be installed in tight spaces, such as vehicles, drones, or other tight spaces that are not visible or easily detectable, very small RF connectors, such as MMCX, U.FL, SMP, and IPEX and connectors, are compulsory.

These connectors have a locking snap ring inside to keep them mated.

These Radio Frequency connectors rotate freely on mating to allow flexible routing of radio frequency cables. 

Due to their miniature size, these connectors have lesser durabilityThese RF connectors cannot withstand nearly as many mating cycles as their full-size counterparts, typically 30 to 100 (part-specific).

These RF connectors are not waterproof and must be used within an enclosure that protects them from outdoor elements.

Coax cables


Cloom advises you to consider all the factors of RF connectors while dealing with antenna systems.

One wrong decision can lead to several problems and even system failure.

Our professionals have deep knowledge of these connectors and can guide you to make the right decision in RF connectors to get the best performance from the system.

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