  Anomalous Hall effect (AHE), a protocol of various low-power dissipation
quantum phenomena and a fundamental precursor of intriguing topological phases
of matter, is usually observed in ferromagnetic materials with orthogonal
configuration between the electric field, magnetization and the Hall current.
Here, based on the symmetry analysis, we find an unconventional AHE induced by
the in-plane magnetic field (IPAHE) via spin-canting effect in $\mathcal{PT}$
symmetric antiferromagnetic (AFM) systems, featuring a linear dependence of
magnetic field and 2$\pi$ angle periodicity with a comparable magnitude as
conventional AHE. We demonstrate the key findings in the known AFM Dirac
semimetal CuMnAs and a new kind of AFM heterodimensional VS$_2$-VS superlattice
with a nodal-line Fermi surface and also briefly discuss the experimental
detection. Our work provides an efficient pathway to search and/or design
realistic materials for novel IPAHE that could greatly facilitate their
application in AFM spintronic devices.
