Siretta delta direct connect antennae siretta delta5xtncmss4 the delta 5 from siretta is a direct connect stubby antenna measuring 100mm in length it is a frac14 wave helically wound omni directional antenna with a centre frequency of 868mhz it is far more focused than wide band antennas such as quad band gsm providing far superior performance this does however mean that the delta 5 is limited to 868mhz only applications 868mhz resides within the industrial scientific and medi