This paper presents the investigation based upon resonant circuit approach to characterize a single-, dual-and quadruple-mode microstrip patch antenna from the lowpass prototype lumped element. This theoretical method is used to determine the coupling value for quad mode antenna design in order to obtain maximum bandwidth. To validate this concept, the quad mode antenna based upon an equivalent circuit at centre frequency of 2 GHz is demonstrated and verified through simulation and measurement. Experimental results show good agreement with simulated results. This study also proposes a technique to integrate two dual-mode antennas based upon the multilayer approach. This study is useful for any microwave system design where the reduction of overall physical volume, weight and cost is very important as well as bandwidth improvement.Index Terms-resonant circuit, dual-, quadruple-mode, microstrip patch antenna.