A low‐loss planar goubau line and a coplanar‐PGL transition on high‐resistivity silicon substrate in the 57–64 GHz band

Abstract

Planar Goubau line (PGL) structures on high-resistivity silicon are adapted to the 57-64 GHz frequency band. Simulations and measurements show a lower attenuation than with the coplanar line is obtained. Very low losses are attained with a measured average attenuation of 0.064 dB/mm on the whole band. To allow this measurement, coplanar-PGL transitions have been optimized.

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

“…This phenomenon could be attenuated by the addition of a length of constant coplanar line in order to position the probes. Nevertheless, the de-embedded insertion loss per transition is approximately 1.36 dB from 57 to 64 GHz; this low-loss transition allows accurate measurement of PGL attenuation and phase constant: the measured loss for the PGL with w = 100 µm is 0.064 dB/mm [16].…”

“…The energy conservation that is equal to 91.2% for the 8 mm length PGL line without the transitions is reduced to 80.9% with the transitions, and breaks down to 70.5% in presence of the chuck and with the transitions. The difference could be due essentially to the excitation by the coplanar line to other modes [16] or to the confinement of the field along the edge of the tapered transition ( Figure 5). Nevertheless, the metalized chuck, that decreases the energy conservation of the PGL with the transitions down to 55.3% for a 350 µm thick of silicon, can be minimized by placing glass substrate between the silicon substrate and the metalized chuck: then, the energy conservation is equal to 70.5%.…”

“…We have recently developed a low loss PGL structure on high resistivity silicon with a measured average attenuation of 0.064 dB/mm on the whole 57-64 GHz band [16]. The low losses and the low dispersion of the PGL, combined with a simple fabrication process, make it a good candidate for UWB applications.…”

“…The transition is actually operating as an impedance and field matching transformer between coplanar probes and PGL and has been designed to measure electrical characteristics of the PGL. The PGL can be compared to a high frequency band line, so in order to decrease the cut-off frequency of the PGL; we have to increase the substrate thickness and the relative permittivity [16].…”

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

“…We already extensively studied and characterized this structure, called a Planar Goubau Line (PGL), in the 57-64 GHz band in a previous paper [9].…”