Compact broadband circularly polarized slot-patch antenna array

A simple design of circularly polarized slot-patch antenna array with broadband operation and compact size is presented in this article. The antenna element consists of a circular slot and a semicircular patch, which are etched on both sides of a substrate. For the gain and axial ratio (AR) bandwidth enhancement, its array antennas are implemented in a 2 x 2 arrangement and fed by a sequential-phase feeding network. The final 2 x 2 antenna array prototype with compact lateral dimension of 0.8(L) x 0.8(L) ((L) is the lowest frequency within AR bandwidth) yielded a measured impedance bandwidth of 103.83% (2.76-8.72 GHz) and a measured AR bandwidth of 94.62% (2.45-6.85 GHz). The peak gain values within the AR bandwidth are from 2.85 to 8.71 dBi. A good agreement between the simulated and measured results is achieved. This antenna array is suitable for multiservice wireless systems covering WiMAX, WLAN and C-band applications such as satellite communications.