Ultrawide Bandwidth 2 $\,\times\,$2 Microstrip Patch Array Antenna Using Electromagnetic Band-Gap Structure (EBG)

Four types of EBG structures are proposed and used in the design of a patch antenna array to improve the bandwidth, gain and reduce the overall array size. The four ground plane designs for the 2
$\,\times\,$
2 microstrip patch antenna array (MPAA) are; spiral artificial magnetic conductor (SAMC) ground plane, an SAMC embedded with a large spiral artificial magnetic conductor (LSAMC), an SAMC embedded with small spiral patch cells (SSAMC), and an SAMC embedded with small spiral mushroom-type electromagnetic band-gap patches (ESEBG). Simulation results show that each configuration has its advantages and limitations. For example while LSAMC provides better response in the array size reduction and improved bandwidth, SSAMC provides better response in reflection phase and hence higher gain. The ESEBG design provides better antenna gain and bandwidth. The achieved bandwidth of the 2
$\,\times\,$
2 array antenna extends from 0.5 GHz to 20 GHz with 85% reduction in array size compared with conventional array with normal ground plane. The array gain increased from 6.5 to 10.5 dBi and the radiation patterns are all improved when using EBG structures.