This letter presents a novel broadband planar antenna, the modified aperture bowtie. The design is based upon a bowtie-shaped aperture antenna fed with coplanar waveguide. The antenna and feed occupy a single plane, making the structure ideal for low-profile and conformal applications. The impedance bandwidth of the planar antenna is increased by altering the edge of the bowtie-shaped aperture. The radiation structure was numerically modeled using FEKO and HFSS electromagnetic solvers. The aperture was constructed and measured for comparison to the numerical solution. The fabricated antenna has a 54% bandwidth, an increase of 1.75 GHz at a center frequency of 6.4 GHz due to the modifications.