Planar antenna modeling requires a constrained solution space and open boundaries and so is highly computationally intensive. One of the methods used to overcome this is by using method of moments simulation. The method of moments is a highly efficient method of solving wire antenna structures and is commonly used in antenna optimization. A method of transforming a wire antenna structure to a planar antenna structure is presented using a 4‐element Yagi‐Uda antenna designed to resonate at 905 MHz. The wire to planar transformation is based on the circular cross section wire to planar strip, a spacing adjustment based on interelement capacitance, and a length scaling to compensate for the change in effective permittivity. The planar antenna shows slightly improved impedance performance at the resonance [voltage standing wave ratio (VSWR) = 1.39]. This transformation decreased the antenna footprint by 15.11% after conversion for a wire antenna to a planar antenna in air with similar radiation characteristics and on FR4 (1.6 mm thickness), the footprint increased by 52%. The antenna simulation time was reduced from 15 min using finite element method to less than 10 s for one cycle by using the method of moments solver. All antenna properties are essentially unchanged. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:184–190, 2014.