Comparison of Near Electrically Small Helical Antennas for WLAN Applications

We compare near electrically small helical antennas with and without an electrically-connected central support for wireless local area network (WLAN) carrier frequency bands. The simulation results show that the helical antenna without the electrically connected central support offers a good directivity and gain performance as compared to its dipole and monopole counterparts of a similar dimension for frequencies slightly higher than their natural frequency. The helical antenna with an electrically connected central support, on the other hand, offers a significant improvement over the other three types of antennas for some frequencies that are below their natural frequency, making it near-electrically small. This study shows that the performance of helical antennas is sensitive to details of the design and adding an electrically-connected central conductor changes its radiation pattern significantly, making it more suitable for near-electrically small antenna applications.