Dual-band circularly polarized hybrid antenna for WLAN/WiMAX applications

In this article, a dual-band circularly polarized hybrid antenna is examined and discussed. In this composition, the diagonally trimmed square shaped slot (modified slot) acts as a radiator and the feeding network of CDRA. Modified slot has been adopted to excite the orthogonal modes (HE(11 delta)(x)and HE11 delta y) in CDRA, which is responsible for the origination of circularly polarized (CP) waves in lower frequency band (2.68-3.04 GHz). Furthermore, a combination of V-shaped microstrip line with modified slot is utilized to generate CP waves in upper frequency band (5.12-5.34 GHz). The sense of polarization can be altered by taking mirror image of the modified slot. To verify the simulated outcomes, the archetype of proposed design is fabricated and tested. Experimental results show good settlement with simulated results. The proposed radiator operates over two frequency bands, i.e. 2.36-3.22 GHz and 5.0-5.34 GHz with the fractional bandwidth of 30.82 and 6.57%, respectively. Measured 3-dB axial ratio bandwidth is similar to 12.20 and 4.2% in lower and upper frequency band, respectively. The proposed antenna structure is quite appropriate for WLAN (2.4/5.2 GHz) and WiMAX (2.5 GHz) applications.