This paper presents both a comprehensive analysis of a stub loaded rectangular patch antenna and a novel method to achieve more compact sizes for the antenna. It has been found that with certain stub dimensions the operating frequency shifts about 24%-27% to the lower ranges and it is possible to design the antenna with more compact sizes at these shifted bands. The model antennas are designed to operate at sub 6 GHz 5G bands and 5.8 GHz Wi-Fi band. It has been shown that the method can also be used for any frequency between 1.3 GHz and 8 GHz. Detailed parametric analyses have been performed for the best results. With these modifications, it is attained a remarkable size reduction from nearly 0.32 lambda(2) to 0.16 lambda(2) which means a decrease of 50% for each antenna with almost the same or better radiation characteristics. Moreover, to explain the method clearer a flow chart is given for the design procedure and to gain more confidence for our simulation results a prototype for 2.4 GHz is fabricated and measured. It has been proven that experimental measurements and simulation results are in good agreement.