FUNcube Dongle and SMA connectors (and the Dashboard)

Folks,

I wrote a note about the SMA connectors that the FUNcube Dongle uses for its antenna connection some time ago, but I think it’s probably worth reiterating.

All FUNcube Dongles have conventional SMA female connectors, so your antenna lead needs to have a standard SMA male connector to mate with it. Standard SMA connectors have been around for decades, and are fairly ubiquitous these days in commercial RF equipment at VHF and above, but are perfectly well suited down to LF too, especially if the device is tiny (like the FUNcube Dongle!)

The problem is that as well as “standard” SMA connectors, there are also RP or Reverse Polarity SMA connectors available. The RP connectors were developed more recently as an attempt to have a physical way to make it difficult to put high gain antennas on WiFi equipment.


For the FUNcube Dongle, the SMA on the left is GOOD, but the RP-SMA on the right is BAD! (Picture linked from OscarLiang.net)

To confuse things, there is nothing physically to stop you plugging an RP SMA male into a standard SMA female, such as that on your FUNcube Dongle. You won’t break anything, but it won’t work either as there is no prong on the RP SMA male to mate with the standard SMA female on the FUNcube Dongle. This will be reflected in the apparent insensitivity of the FUNcube Dongle, which is hardly surprising either, it’s just like having a break inside you antenna cable!

So, in short, do not use RP-SMA connectors on a FUNcube Dongle, they won’t work. The correct SMA connector should have a centre pin.

Onto another subject entirely, we had a very useful meeting of the FUNcube team over the weekend, and we’ve been making some further improvements to the Dashboard software which will be released soon, increasing decoding sensitivity by about 6dB when used with the FUNcube Dongle.

Many thanks, Howard

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