Help with reverse polarity(strange) SMA connector

Started by cogwsn 2 months ago7 replieslatest reply 2 months ago73 views


I purchased a Digikey ZigBee module and it has a very strange SMA connector(pic-a). Although they have provided an antenna with the module, which is designed only for that connector(pic-b). No other antenna or RF cable fits in that DigiKey module SMA port. 

I came to know that its called reverse polarity connector and its very common in commercial devices but not in lab devices. I don't know why they have used it. 

I only have antennas which are "normal", I mean normally used in labs(pic-c). 

Can anyone help me in finding the converter so that I can connect my antennas to the Digikey module SMA. A link for purchase will be very much helpful :) 

Thanks much








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Reply by MichaelKellettNovember 23, 2017


I just google for SMA gender changer and fllowed links from pictures.

Good luck.


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Reply by antedeluvianNovember 23, 2017

I have no knowledge of SMA connectors, but I do know that Digikey does have tech support and they are quite responsive

Also from what I have seen Pasternack has everything to do with RF

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Reply by DNadlerNovember 23, 2017

You'll find RP in USA because of bizarre FCC rules contrary to the rest of the planet.

My goto source for converters of all sorts is Pasternack:

Hope that helps!
Best Regards, Dave

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Reply by matthewbarrNovember 23, 2017

RF is not my bag, but if you search for "rp sma male to sma female adapter" or "rp sma male to sma female cable" I think you'll find what you're looking for. For example:

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Reply by rtomkinsNovember 24, 2017

This may be contrarian, but I like the design of the part that you received in comparison to the standard design.

The connector on the module has no moving parts and therefore will have reduced wear. The connector on the antennae has a moving part, an expanding ring, that probably floats inside the nylon housing. With repeated on/off cycles, this can fail, either physically or in its electrical characteristics (dielectric, capacitance, resistance, impedance). Fortunately, as a screw on antennae, getting the device back into functional specification is as simple as replacing the antennae. Were it the standard style of connector, there would be some disassembly/reassembly soldering involved with the module, and that could adversely affect the functional specifications, violating any kind of certification the module is currently conformant to.

Given that the device you purchased appears to be for learning/development purposes, I'd hazard a guess that the manufacturer was aiming for reliability. When you call them to tell them you have a problem, technical support will suggest something like, "Have you tried a new antennae?".

Zigbee is a ubiquitous network technology, they probably want to minimize the risk of an experimental device from messing up a commercial operation. All the Smart Power Meters in Ottawa use Zigbee.

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Reply by cogwsnNovember 24, 2017

Thanks, it was very much informative! 


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Reply by krell59November 28, 2017
Reverse polarity SMA (RP-SMA) is a variation of the SMA connector specification which reverses the gender of the interface. The term "reverse polarity" refers only to the gender of the connector's contact pin, not in any way to the signal polarity.

A RP-SMA(F) connector is a JACK type - has outside threads - but has an inner pin (hence reversed), and male RP-SMA connector has inside threads and a center receptacle.

RP-SMA connectors were introduced to separate professional and commercially available equipment, preventing unintentional or intentional connection of high-gain professional antennas with SMA connectors and commercial wireless equipment with RP-SMA connectors, violating federal or international laws. Today, however, both types of connectors are readily available.

The RP-SMA(F) connector has the same external housing as a standard or conventional female SMA