RP-SMA Antenna: Why choose Reversed Polarity SMA? (2023)

Since the late 1900s, the RP-SMA connector has gained massive popularity more than SMA. As a result of this, you have a wide range of options for RP SMA antenna. Why was the RP-SMA connector easier to use in most incompatible coax cables? You first need to understand the basic terminologies of antenna connectivity to grab the whole concept.

Properties of Antenna

RP-SMA Antenna: Why choose Reversed Polarity SMA? (1)

Caption: A typical Antenna

The basic features that can define the efficiency of an antenna are as follows.


Gainis the measure of the intensity of waves that the antenna transmits in a particular region. The manufacturers design the antenna so that it can emit maximum power in the direction you want it. Thus, you also need to understand the concept of how “directivity” affects the gain.

In mathematical terms, you can define gain as

Gain= Directivity * Efficiency

(Video) SMA / Reverse-Polarity RP-SMA RF Connector Differences Explained Electronics Tutorial Banggood Parts

Directivity is the signal strength of an antenna in a specific direction. And the efficiency tells how much power loss is made due to faults and resistance in the equipment.


The frequency range on which the device can correctly operate is termed thebandwidth. Moreover, the bandwidth, measured in Hz, should be optimal so that the standing wave ratio is less than 2.1.


The electromagnetic polarity of the field that a working antenna creates in a region is known as its polarization. While communicating between two devices, you have to consider the polarity as a crucial measure, and it is because every device has a different direction of polarity.

When dealing with horizontal waves emitting equipment, you also need horizontal signal polarity on the receiver side. The same stands for the situation when you have vertically polarized radiations. Sometimes, you might need the circular polarization technique, which requires both horizontal and vertical polarity waves.

Effective Length

Effective lengthis the parameter of an antenna through which the waves can bounce back. Hence, for higher wavelengths, the more significant the effective antenna length, the higher the efficiency of the signals. Additionally, you need to measure the effective length for the sender and the receiver end as well.

The following formula measures the effective length

Effective Length = (Distribution of non-uniform area)/ (Uniform current distribution area)

(Video) What is Reverse Polarity SMA and how do we know the difference?

RP-SMA Antenna– Why are Antenna Connectors necessary?

RP-SMA Antenna: Why choose Reversed Polarity SMA? (2)

Caption: Various types of Antenna connectors

Antenna connectors are the tiny radio frequency regulator attached at the termination points on an antenna. By using connectors, signals without any significant power loss due to any factor are possible.

Although the antenna connectors may not seem like an essential part of the antenna assembling process, the reality is different. Without connectors, you cannot maintain the crucial chain of radiofrequency connections within a wireless communication system. Thus, the flow of waves across a specific area is always dependent on the use of connectors.

Higher is the quality of the connectors you choose for an antenna device; maximum is the performance. Otherwise, the system will face the loss of data due to connectivity impairment.

Moreover, the structural and mechanical properties of an antenna connector play a considerable part in better performance. So, depending on the size of the antenna connector, you will place the device in case of space problems. If not mounted properly, it may fail the antenna and consequently the failure of the whole machine.

RP-SMA Antenna– SMA Connectors

RP-SMA Antenna: Why choose Reversed Polarity SMA? (3)

Caption: A typical SMA Connector

The SMA stands for Sub-Miniature type A, designed in the late 1960s as military usage SMA equipment. It is a connector comprised of semi-precision, miniature threads. You can use an SMA connector when dealing with varying frequency systems.

(Video) Deciphering SMA vs RP-SMA WTF, Drone 101

For robust connectivity, the antennas use a Female or Male threaded SMA connector. While establishing a connection, you will connect both counterparts terminating the antenna and the cable using a hex nut. Thus, you will get more regular communication in the system.

Physical Specifications

A basic, military standard MIL-STD-348 calls for some specific product description that most manufacturers follow. The SMA connector is composed of a ¼-inch barrel with 36 conductive threads per inch.

An SMA adapter is based on two complementing coaxial connectors:

  • SMA Male connectorwith 5/16 inch hex nut to tighten up the internal thread and the center pin within the interface of the female side
  • SMA Female connectorwith external threads and a mating interface consisting of a receptacle

The antenna manufacturers usually make the body and the coupling terminal of the SMA connector with brass or stainless steel. They make the inner interface with brass or copper while insulating the whole body with aPFTEinsulator. Few SMA designs may call for the use of a silicon rubber gasket to ensure weather shielding. In proper connectivity, an SMA connector has a rating of 500 mating cycles.

Electrical Specifications

  • Frequencyof up to 18GHz
  • Theimpedanceof 50 OHMS
  • Operating Voltageup to 500 Volts
  • VSWRof 1.15+0.1f
  • Radio Frequency Leakageof up to 90dB per minute at frequency range 2-3 GHz


In recent years, SMA connectors have been a choice. Most engineers prefer establishing connections in wireless communication devices. Here are some applications we have observed over the time

  • You can find its ports on every PCB interface board since it goes well with the wireless antennas’ flexible, semi-rigid coax cables.
  • Cellular communicationprefers SMA connectors because of their smaller size and highly robust performance at the micro frequency range. Therefore, SMA connectors terminate many cellular antennas.
  • GPS antennasalso prefer using SMA over any other type of connectors as they can tolerate outdoor conditions
  • WIFI antennashave also been observed to be using the SMA connectors recently.

The RP-SMA Connector

Caption: Comparison between RP-SMA and SMA Connector

(Video) How to Install RP-SMA Connectors & Best Coax for Router, Antenna, Hotspot Helium

RP-SMA Antenna connectors are the variant of SMA connectors, identical in both electrical and mechanical performance. Many WIFI antenna systems used the standard SMA as a source of connectivity. Yet, there were non-compatible antennas for which you need a coax connector of a particular type.

Names of the connector can be the same. But, the only difference between the two is the reversal of mating interfaces between the RP-SMA male and female connector. Thus, you get a reverse polar system.

RP-SMA got popular with the rise of wireless devices. TheUS Federal Communication Commissionthought that such high usage of SMA would lead them into problems. Hence, using a look-alike connector, they wanted to prevent unauthorized connections with the antenna and raise the power supply range. However, the RP-SMA has also become available everywhere, just like its other counterpart.

RP-SMA Antenna– Physical Features

The RP-SMA is a threaded connector, just like its SMA variant, and mates using screw coupling. Similarly, RP-SMA connectors consist of 36 conductive threads per inch and use a hex nut for securing the connection. Also, the manufacturers use the same material and fabrication methods for the production of RP-SMA. Yet, it differs in polarity due to reversed mating interface.

Here, the RP-SMA is based on

  • RP-SMA male connector with internalized threading, a hex nut, and a socket instead of a center pin.
  • RP-SMA Female connectorwith external threading, but carry a center pin to insert into the socket of the male connector.

Therefore, you must be looking out for the mating interface in the RP-SMA male and female and determine the connector type. If you do not do it at the time of connection, the system may not be working like it is supposed to work.

RP-SMA Antenna– Electrical Specifications

  • Frequencyof up to 18GHz
  • Theimpedanceof 50 OHMS
  • Operation Voltage ratingup to 500 Volts
  • VSWRof 1.15+0.1f
  • Radio Frequency Leakageof up to 90dB per minute at frequency range 2-3 GHz

RP-SMA Antenna–Applications

The primary application of such connectors is to prevent the high-gain antennas from connecting the consumer equipment. It is found in

(Video) What Is A Reverse Polarity SMA Female Connector

  • WIFI devices
  • Cellular 3G, 4G LTE devices
  • WLAN devices

Although they are found on much WIFI-associated hardware, you have to take care of any SMA’s working parallel. Hence, if you disconnect the wireless antennas from the device for any reason, the RP-SMA can replace the job.


From the above, you can see RP-SMA or reverse polarity SMA is a connector found in most WIFI devices to connect different coax cables. Also, the change in polarity prevents the high gain antenna from connecting with irrelevant modules. Here at Cloom, we have special offers with a wide range of connectors and cables to support your antenna system. So, feel free tocontact usnow.


What is reverse SMA antenna? ›

Reverse polarity SMA (RP-SMA) is a variation of the SMA connector specification which reverses the gender of the interface, as shown in Figures 1-4 below. The term "reverse polarity" refers only to the gender of the connector's contact pin, not in any way to the signal polarity.

How do you choose between SMA or RP-SMA connectors? ›

If your gear has a Standard SMA-Female (SSF) connector on it, then your cable needs to have Standard-SMA-Male. If your gear has a Reverse Polarity SMA-Female (RSF) connector on it, then your cable needs to have RP-SMA-Male.

Are SMA and RP-SMA interchangeable? ›

What is the difference in these two? Reverse polarity SMA (RP-SMA or RSMA) is designed to be incompatible with standard SMA connectors to comply with U.S. FCC regulations which seek to prevent consumers from attaching non-standard aerials to wireless devices.

Is RP-SMA the same as coax? ›

SMA and RP-SMA are so-called coaxial connectors and the standard for antenna connections. With a screwable coupling mechanism, they form the minimum interfaces for coaxial cables. They are now used in many different devices and applications in the high-frequency range.

What are the different types of SMA connectors? ›

SMA Connectors have a number of different mounting configurations. The key mounting configurations include: Panel Mount (2-Hole and 4 Hold Flange) SMA Connectors, PCB Mount SMA Connectors, Edge Mount, Bulkhead Mount SMA Connectors, SMT SMA Connectors and Through Hole Mount.

How do you connect RP-SMA connectors? ›

SMA and RP-SMA connectors for RC planes - YouTube

Is SMA 50 or 75 ohm? ›

The connector has a 50 Ω impedance. SMA was originally designed for use from DC (0 Hz) to 12 GHz, however this has been extended over time and variants are available to 18 GHz and 26.5 GHz. There are also mechanically compatible connectors such as the K-connector which operate up to 40 GHz.

Is F type the same as SMA? ›

The SMA connector(SubMiniature version A) is a 50 ohm coaxial connector. It is visually similar to an F type connector that is commonly used for audio/video communication, but has different dimensions, mechanical properties and is used for different applications such as RF communications up to 18 GHz.

What does SMA stand for antenna? ›

What Does SubMiniature Version A Connector (SMA Connector) Mean? An SubMiniature version A (SMA) connector is a coaxial cable connector developed in the 1960s as a semi-precision minimal connector interface with a screw-type coupling mechanism for coaxial cables.

Why does RP-SMA exist? ›

RP-SMA stands for "reverse polarity" (sometimes also referred to as reverse SMA or for short "R-SMA"). It is designed to prevent the unauthorized connection of an external antenna to increase the range. In an RP-SMA connector, the gender has been changed.

How does an SMA antenna work? ›

SMA antennas are a diverse group of radio frequency antennas that possess an SMA connector for attachment to a coaxial extension cable or other radio frequency hardware. An SMA connector serves as the primary channel through which radio frequency signals can flow between the antenna and the device it is attached to.

How do I know what antenna connector I have? ›

A standard polarity jack (female) has a socket, whereas a reverse polarity jack (female) has a pin. A standard polarity plug (male) has a pin, whereas a reverse polarity plug (male) has a socket.

What does SMA stand for in RF? ›

SMA. The SMA (or Sub-Miniature A) connector has a 50Ω impedance and can handle frequencies up to 17 GHz. They're small enough for most consumer RF applications and they use a threaded housing to create strong mechanical connections.

How do you crimp a RP-SMA connector? ›

Reverse Polarity SMA Male Crimp Connector For RG174 - YouTube

How do you check SMA connectors? ›

HFSS Tutorial: Test-Bench for SMA Connector Verification - YouTube

What is a reverse polarity connector? ›

A reverse polarity coax connector is a variation of a standard polarized connector in which the gender of the interface has been reversed. The term “reverse polarity” refers not to the signal polarity of the connector itself, but to the gender of the center contact pin.

What are SMA antenna connectors? ›

The SMA connector is a sub-miniature coaxial cable connector and it takes its name from the words Sub-Miniature A connector. It finds many applications for providing connectivity for RF assemblies within equipments where coaxial connections are required.

What is the difference between SMA and SMB connectors? ›

SMB connectors are smaller than SMA connectors. They feature a snap-on coupling and are available in either 50 Ω or 75 Ω impedance. They offer excellent electrical performance from DC to 4 GHz. An SMB jack has a male center pin, while an SMB plug has a female basket.

What is RP TNC? ›

Reverse-polarity TNC (RP-TNC, sometimes RTNC) is a variation of the TNC specification which reverses the polarity of the interface. This is usually achieved by incorporating the female contacts normally found in jacks into the plug, and the male contacts normally found in plugs into the jack.

What is an IPEX connector? ›

I-PEX MHF connectors are miniature surface-mount coaxial connectors, that are used in applications that have limited real estate. They can be used inside smartphones, laptops and embedded systems in order to connect the Wi-Fi antenna to a Mini PCI, Mini PCIe or M. 2 WiFi card.


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