Described herein are a magnetic resonance probe and a NMR, MRI, or EPR apparatus including the same. The magnetic resonance probe includes a conductor electrically coupled to the resonator and configured to transmit and receive electromagnetic radiation to and from a sample, wherein the conductor includes one or more cascaded narrowed regions along its longitudinal dimension and a slot within one of the one or more cascaded narrowed regions; and an electrical circuit coupled to the conductor and the resonator.