A Compact Dual-Band Dual-Polarized Loop-Slot Planar Antenna

This letter presents a compact dual-band dual-polarized loop-slot planar antenna. The antenna consists of a rectangular loop, a coplanar waveguide (CPW), and a microstrip line. The dual-band characteristic is realized using two different type resonant modes of the loop-slot antenna, namely, a loop basic mode in the lower band and a slot basic mode in the higher band. A CPW is used to excite vertical polarization modes and a microstrip line is used to excite horizontal polarization modes to achieve dual-polarized performance. The overall dimension of the prototype is only 55 ×57 mm². The proposed antenna is built and tested. It has two common -10 dB impedance bandwidths of 420 MHz (2.34-2.76 GHz) and 660 MHz (3.22-3.88 GHz) to cover 2.4 GHz WLAN band and 2.5/3.5 GHz WiMAX bands, respectively, and the isolation between the two ports is better than 21 dB in the dual-band. The antenna has stable radiation patterns and gains in both bands. The antenna also has the merits of compact dimension, low cross-polarization, and low cost.