A microstrip antenna array consisting of two elements combined with a stripline hybrid (rat-race) ring coupler is used to implement a zero-sum antenna. Numerical optimization of individual antenna elements in terms of feed location and patch size was achieved using IE3D (Zeland Software Inc., Fremont, CA), a fullwave 3-D planar electromagnetic simulation software. Further, design of a hybrid (rat-race) ring coupler in a stripline environment was carried out, yielding the sum and difference functions as 0.5 dB and 40 dB, respectively. A combination of a two-element antenna array and a hybrid (rat-race) ring coupler as a zero sum antenna has been studied numerically revealing that 40 dB differences can be expected between the sum and difference patterns in the forward direction at the operating frequency. Experimental results using MC5 material (ε_r=3.26 and thickness t=60 mils) (Glasteel Industrial Laminates, Colliervile, TN) have shown that satisfactory performance can be achieved at the chosen operating frequency f=2.254 GHz.