  We detect radio emission in an additional two epochs of the ultracool dwarf
binary LP 349- 25, finding that the observed emission is broadband and steady
on timescales between 10s and 10.7 hours, as well as on timescales of 0.6 and
1.6 years. This system is unusual for ultracool dwarfs with detectable radio
emission, in exhibiting a lack of any large scale variability, particularly the
bursting (periodic or aperiodic) behavior exhibited by the other objects with
detectable levels of radio emission. We explore the constraints that the lack
of variability on long and short timescales, and flat spectral index, imply
about the radio-emitting structures and mechanism. The temporal constraints
argue for a high latitude emitting region with a large inclination so that it
is always in view, and survives for at least 0.6 year. Temporal constraints
also limit the plasma conditions, implying that the electron density be n_e
<4x10^5 cm-3 and B < 130 G in order not to see time variations due to
collisional or radiative losses from high energy particles. The observations
and constraints provided by them are most compatible with a nonthermal radio
emission mechanism, likely gyrosynchrotron emission from a spatially
homogeneous or inhomogeneous source. This indicates that, similar to behaviors
noted for chromospheric, transition region, and coronal plasmas in ultracool
dwarfs, the magnetic activity patterns observed in active higher mass stars can
survive to the substellar boundary. We also present new epochs of
multi-frequency radio observations for the the ultracool dwarfs 2MASS
05233822-140322 and 2MASS14563831-2809473(=LHS 3003); each has been detected in
at least one previous epoch but are not detected in the epochs reported here.
