Broadband circularly polarized printed monopole antenna with protruded L‐shaped and inverted L‐shaped strips

A novel approach in the design of broadband circularly polarized antennas is presented in this article. The design uses a simple monopole structure with a triangular tapered feed. Right‐/left‐hand circular polarization (CP) is achieved by protruding L‐shaped strip and inverted L‐shaped strip along the left/right radiating edge of the monopole. It is proposed that the 3‐dB axial ratio bandwidth (AR‐BW) can be enhanced when the length of these strips is equal to λ g /4 at the center frequency of their respective CP bands. This principle is verified by fabricating the prototype on 1 mm thick FR4 substrate occupying a compact area of 0.19 λ 0 × 0.19 λ 0 . From the measurement results, it is observed that the overlapped bandwidth ( S 11  ≤ −10 dB and AR ≤ 3 dB) of the antenna is 129.04% (1.38–6.4 GHz) which covers all the major WLAN bands including the WiMAX. The proposed antenna has bi‐directional radiation characteristics with a broadside gain of 3.49 dBic in the CP band.