  We investigate rectification of a low-frequency ac bias in Y-junctions of
one-channel Luttinger liquid wires with repulsive electron interaction.
Rectification emerges due to three scatterers in the wires. We find that it is
possible to achieve a higher rectification current in a Y-junction than in a
single wire with an asymmetric scatterer at the same interaction strength and
voltage bias. The rectification effect is the strongest in the absence of the
time-reversal symmetry. In that case, the maximal rectification current can be
comparable with the total current $\sim e^2V/h$ even for low voltages, weak
scatterers and modest interaction strength. In a certain range of low voltages,
the rectification current can grow as the voltage decreases. This leads to a
bump in the $I$-$V$ curve.
