A novel printed stub-loaded square helical antenna

A novel planar printed stub-loaded square helical (PSLSH) antenna is presented for 2.4GHz WLAN applications. Unlike conventional stub loaded helical (SLH) antennas, the input impedance of the proposed antenna is real. Therefore, a simple quarter-wave transformer can be used to match this antenna. Simulation results show that the antenna has a maximum gain of 10 dBi, a front-to-back ratio of 12dbi, a 70° half-power beam width and a good axial ratio. The volume of PSLSH antenna is 75% less than conventional axial mode helical antennas and 17% less than SLH antennas. Furthermore, the usable bandwidth of PSLSH antenna (46%) is significantly higher compared to SLH antenna (10%).