An electrical interface on a circuit board is disclosed for electrically connecting the circuit board to a connector to reduce reflections and impedance mismatch and increase power transfer from the connector to the signal path of the circuit board. The signal interface includes a signal conductor including a signal pad configured to connect to a connector pin and a waveguide section extending from the signal pad. The waveguide narrows from a signal pad width to connect to a microstrip conductor. A first ground section is spaced rightward from the signal conductor such that the inner edge of the first ground section, angles in correspondence with the narrowing of the waveguide to generally track an outer right edge of the waveguide. A second ground section is spaced leftward from the signal conductor and configured generally similarly to the first ground section.