This communication proposes an easily manufacturable multifunction multiport planar slot antenna with triorthogonal pattern diversity. Distinct radiation patterns are emitted via a common square radiative slot by exploiting three orthogonal modes. These slot modes consist of a magnetic current loop mode with an omnidirectional linearly polarized (OLP) radiation pattern, and two degenerated linear slot modes radiating broadside with orthogonal linear polarizations (LPs). The triorthogonal patterns are obtained in an overlapping frequency band, and the mutual coupling between the ports is minimized through a differential feeding arrangement. This new concept of multiport diversity slot antenna is validated experimentally at a frequency of 5.9 GHz, successfully demonstrating the operation modalities of OLP and LP radiation patterns. A minimum triorthogonal overlapping impedance bandwidth of 2.3% is measured with interport coupling below -35 dB. The proposed antenna could be used as a pattern and polarization diversity antenna, where additionally, a linear combination of the primary triorthogonal patterns can be exploited to further enhance flexibility in pattern generation.