ORIGINAL: Bill_Francis
DSM2 means full range. That is, as far as you can see.
The antenna is like that (short antenna and long) to mimic the placement of a remote receiver antenna as is seen with other receivers such as the AR 6200. Only the last two or so inches of the long side actually aacts as an antenna.
That long antenna looks like a "balun" antenna (balanced/unbalanced). I have an AR 500 in my Parkzone Corsair but didn't notice that cause the long wire is tucked back into the tail.
I'm very glad to see Spektrum is trying this antenna configuration and I hope they'll offer another unit with TWO of these style antennas like the FASST systems RX's have. I just bought a Futaba system chiefly cause the balun antennas are a lot easier to set up in full carbon glider/hotliner type airframes.
BTW, DSM2 does not necessarily mean "Full Range" as in getting a good long range check. The AR6100 is a DSM2 RX and that's a very short range RX. DSM2 refers to the proprietary data processing scheme Spektrum employs which yields a faster response data link than the previous DX6 and virtually all 72 MHz systems allow.
I did a thread a while back which proved the older AR6000 RX has a much better range check than the AR6100. Although DSM (DX6 and the AR6000) is considered inferior to DSM2, I still use many of the 6000 receivers in RC planes where size and weight is a concern and I want all 6 channels, and I'll keep on buying these great little RX's ($50 each) until a better 6 channel option is offered by Spektrum (hopefully with TWO balun antennae!)