  We demonstrate the experimental realization of a two-qubit
M{\o}lmer-S{\o}rensen gate on a magnetic field-insensitive hyperfine transition
in $^9$Be$^+$ ions using microwave-near fields emitted by a single microwave
conductor embedded in a surface-electrode ion trap. The design of the conductor
was optimized to produce a high oscillating magnetic field gradient at the ion
position. The measured gate fidelity is determined to be $98.2\pm1.2\,\%$ and
is limited by technical imperfections, as is confirmed by a comprehensive
numerical error analysis. The conductor design can potentially simplify the
implementation of multi-qubit gates and represents a self-contained, scalable
module for entangling gates within the quantum CCD architecture for an ion-trap
quantum computer.
