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Interest of Micro-Electromechanical System (MEMS) antennas in Terahertz (THz) applications has rapidly expanded in recent years due to the advent of accurate Computer Aided Design (CAD) tools. The very special needs of newly proposed MEMS antennas, especially with a wide bandwidth range, require advanced optimization procedures of enhancing already established designs. This paper provides a compact design of a wideband MEMS helix antenna optimized using tree-dimensional High Frequency Structure Simulator (3D-HFSS) based on Quasi-Newton (Q-N) and Sequential Non Linear Programming (SNLP) techniques to modify the antenna structure with a high accuracy for the selective band of frequencies by training the samples and minimizing the error from Finite Element Method- (FEM) based simulation tool. The helix antenna is presented using MEMS technology and shows high performance demonstrated by very low return losses of less than -20 to -65 dB for a wide range of frequencies from 2.5 to 5 THz. High antenna geometry precision and efficient performance are finally achieved by rectifying and synthesizing various tunable parameters embedded in silicon substrate including both helix form and feeding line parameters.

This paper investigates for the first time concepts of W-band dielectric-core helix antennas which are fabricated by three-dimensional micromachining into the volume of a semiconductor (high-resistivity silicon) wafer substrate. The maximum antenna gain is achieved by free-etching the antenna but loading the core of the helical antenna with a dielectric-rod tailor-made out of the substrate, and by properly modifying the geometry of the substrate-integrated ground plane. The simulation results show that an optimized antenna concept has a return loss S11 of -22.3 dB at the nominal frequency of 75 GHz, and a 3dB-bandwidth of 2.5 GHz. For the whole band from 69 to84 GHz, the reflection coefficient is better than -10 dB. A maximum gain of 13.2 dB and a half-power beamwidth (HPBW) of smaller than 40° are obtained for a single antenna. The front to-back (F/B) ratio is better than 23.5 dB with an axial ratio of 0.94. An eight-element helix line array is demonstrated and has a maximum gain of 22.3 dB with a HPBW of 7° in the y-z plane and an F/B ratio of 23.71 dB. QC 20120730. Honorable Mention in Student Paper Competition