The design of frequency tunable wıdeband axial mode helıx antennas usıng shape memory alloys

In this paper, we explore the possibility of using Shape Memory Alloy (SMA) materials for wideband millimeter-wave helix antenna applications. Nickel-titanium (NiTi) alloys are the most commonly used shape memory alloy (SMA) and have been widely used for bio-medical, electrical and mechanical applications. The proposed NiTi based antenna can be placed across the width of the handset chassis, which can be considered as part of the radiating structure. An accurate electromagnetic model of the antenna is developed using FIT for numerical analysis. Good agreement between the computed and measured results has shown for both copper-based and NiTi SMA Antennas and their performance was compared. It is shown that by keeping the length constant and varying the pitch angle (height) of the antenna, the frequency of operation can be tuned to switch between various frequency bands to cover all the standard WiFi, 3G and 4G bands required for the next generation of mobile handsets. Thus, the dispersion characteristics of the NiTi helix antenna make it very promising for wideband communication systems.