A planar antenna that uses surface waves (SWs) for leaky wave (LW) excitation is presented. Specifically, a surface-wave launcher (SWL) is employed to excite SWs for bound, guided-wave propagation along the utilized dielectric slab. By introducing simple techniques to route excited fields, guided waves can be confined for increased directivities and radiation performances. Concepts are first examined in simple test circuits and extended to the proposed LWA design. Simulations and measurements demonstrate one-sided beam scanning from back- to forward-fire with directive beam patterns in the far field from 17 to 25 GHz. Reported gain values are greater than 10 dBi. Such a low-cost and low-profile LWA may be advantageous for radar systems and satellite communications. Presented routing techniques are also applicable to other antennas and printed circuits operating at microwave and milliliter-wave frequencies.