Optimization of a Quasi Loss Less Air-Cavity Inverted Microstrip Line From Microwave to Millimeter-Wave Frequencies and Comparison With the Coplanar Goubau Line at 60 GHZ

Abstract

Abstract-An inverted micro-strip line (IML) is proposed at microwave and millimeter wave frequencies. This IML on high resistivity silicon (HRS) is studied from 10 to 100 GHz and presents an attenuation lower than 0.08 dB/mm on the whole frequency band. A parametric study, in order to minimize the attenuation and the dispersion of the inverted line in the 10-100 GHz bandwidth, is performed using numerical full wave calculations with HFSS (High Frequency Structural Simulator) tool. A complementary study is added: a large variety of characteristic impedances (for instance, from 38 Ω to 87 Ω at 60 GHz) is performed, the change of propagation modes is observed and the qualification and quantification of the losses allows minimizing them. A comparison with a line of the same length and width without ground plane, the Planar Goubau Line (PGL) is reported in the 10-100 GHz band and a first measure of the PGL is performed, in the 55-67 GHz band, presenting the same propagation mode as the IML at 60 GHz. The measured attenuation of 0.064 dB/mm in the 55-67 GHz obtained for the PGL promises a comparable value for the IML in the measured band.

Recessed ground microstrip line at 60 GHz and its application of band‐pass filter

“…In Reference , the conventional microstrip line is covered with micromachined silicon substrate with a ground metal filled in the shallow cavity from top, called as inverted microstrip line. The inverted microstrip line, in Reference , on silicon is covered with an air‐cavity glass substrate with ground plane filled in the shallow cavity from top.…”

Coplanar-PGL Transitions on High Resistivity Silicon Substrate in the 57-64 GHZ Band and Influence of the Probe Station on the Performances

“…This line, because of its possible integrated circuit fabrication processes [12][13][14][15], can be used to realize functions without the necessity to report a ground plane: the width of the strip, the thickness and the relative permittivity of the substrate can be selected to favor the confinement of the field to reduce the attenuation or, in inverse, to favor the radiation of the PGL to couple the lines together (the lines must be curved to optimize the coupling) and realized couplers for instance [14]. It has been compared recently with a Inverted Microstrip Line (IML), that offers a natural mechanical encapsulation, protecting the device from any electromagnetic radiation [17] with the same characteristics of propagation mode, but with a more complex technological process: the PGL can be replaced by IML to offer a ground plane, or to prevent from the sensibility to the electromagnetic radiation. The characterization of PGL structures requires coplanar waveguide probe pads.…”