In this study we analyze a new vacuum microelectronics (VM) magnetic field sensor based on a simple configuration with a single-gated wedge emitter with a split anode current as detection system. The actuation of such a device has been simulated using different numerical approaches including a full determination of electrostatic potentials with an accurate description of the fields at the wedge-like emitter, the propagation of electrons inside the device, and the evaluation of the current density distributions at the anode detector screen. This device presents sensor sensitivities higher than those of conventional magnetic field sensors, and similar to other VM double-gated sensors. The dependence of the sensitivity on the geometric parameters and control voltages is discussed.