V-Band End-Fire Radiating Planar Micromachined Helical Antenna Using Through-Glass Silicon Via (TGSV) Technology

Abstract

In this paper, we demonstrate a V-band planar micromachined helical antenna (PHA) with end-fire radiation on the glass substrate. The planar rectangular helical configuration is realized using the novel through-glass silicon via (TGSV) technology. The proposed micromachined antenna is designed and fabricated on a borosilicate glass substrate of thickness 350~\mu \text{m} , which has a very low-dielectric loss compared to silicon at millimeter-wave bands. The proposed PHA is fed by a microstrip line, and the planar helical configuration with 3.25 turns with a truncated ground plane is designed for achieving wideband end-fire radiation with seven tungsten-coated silicon vias and six connected gold arm patterns, which are fabricated using the TGSV technology. The electrical length of the proposed antenna is ( 3\,\,\lambda -{\text{o}} \times 1.4\,\,\lambda -{\text{o}} ). The designed antenna operates at the center frequency of 58 GHz. A prototype of the proposed antenna is fabricated by micromachining technology and tested. The simulated and measured results show that the proposed antenna has a wide operational bandwidth of 50.3 to 65 GHz for \vert \text{S}-{ {11}} \vert < -10 dB with a fractional bandwidth (FBW) of 25.5%. The measured peak gain is 6.3 dBi, and measured efficiency is 62% at the center frequency of 58 GHz. All measurements are in close agreement with simulated results. The proposed planar helical antenna with end-fire radiation is useful for applications in traveling-wave-tubes operating in millimeter-wave and higher frequencies, millimeter-wave on-board wireless communication, radar imaging, and tracking applications.