  We consider one system in which the terminal dots of a one-dimensional
quantum-dot chain couple equally to the left and right leads and study the
influence of $\mathcal{PT}$-symmetric complex potentials on the quantum
transport process. It is found that in the case of the Hermitian Hamiltonian,
remarkable decoupling and antiresonance phenomena have an opportunity to
co-occur in the transport process. For the chains with odd(even) dots, all
their even(odd)-numbered molecular states decouple from the leads. Meanwhile,
antiresonance occurs at the positions of the even(odd)-numbered eigenenergies
of the sub-chains without terminal dots. When the $\mathcal{PT}$-symmetric
complex potentials are introduced to the terminal dots, the decoupling
phenomenon is found to transform into the Fano antiresonance. In addition, it
shows that appropriate magnetic flux can interchange the roles of the odd and
even molecular states. These results can assist to understand the quantum
transport modified by the $\mathcal{PT}$ symmetry in non-Hermitian discrete
systems.
