Four arms spiral ground of MPA with different feed techniques for size reduction and multi-band operation

Novel electromagnetic band-gap (EBG) structure as a four arms spiral shape is presented to replace the conventional ground plane of MPA. MPA with different feed techniques (inset, offset and center line feed) are presented. The structure investigated and illustrated some merits to design multi-band EBG structure by adjusting the capacitance and changing the inductance through varying width and length of the spiral ground plane. Four arms spiral artificial magnetic conductor (SAMC) as a ground plane of microstrip patch antenna creates multi resonant frequencies, improves antenna gain and reduces antenna size compared to a conventional microstrip patch antenna element at same size. From investigation we obtained that four spiral arms ground plane with offset feed MPA and equal spiral width with air gap = 0.017λ_o gives 72% reduction of electrical antenna size with multi-resonating frequencies at GSM, Bluetooth, WLAN, and other wireless applications bands.