We report the results of a volume-limited survey using the Australia Telescope Compact Array to search for transient and quiescent radio emission from 15 southern hemisphere ultracool dwarfs .
We detect radio emission from 2MASSW J0004348–404405 increasing the number of radio loud ultracool dwarfs to 22 .
We also observe radio emission from 2MASS J10481463–3956062 and 2MASSI J0339352–352544 , two sources with previous radio detections .
The radio emission from the three detected sources shows no variability or flare emission .
Modelling this quiescent emission we find that it is consistent with optically thin gyrosynchrotron emission from a magnetosphere with an emitting region radius of ( 1–2 ) R _ { * } , magnetic field inclination 20 ^ { \circ } –80 ^ { \circ } , field strength \sim 10 – 200 G , and power-law electron density \sim 10 ^ { 4 } – 10 ^ { 8 } cm ^ { -3 } .
Additionally , we place upper limits on four ultracool dwarfs with no previous radio observations .
This increases the number of ultracool dwarfs studied at radio frequencies to 222 .
Analysing general trends of the radio emission for this sample of 15 sources , we find that the radio activity increases for later spectral types and more rapidly rotating objects .
Furthermore , comparing the ratio of the radio to X-ray luminosities for these sources , we find 2MASS J10481463–3956062 and 2MASSI J0339352–352544 violate the Güdel-Benz relation by more than two orders of magnitude .