  Investigations into the propagation characteristics, specifically loss and
wave velocity, of superconducting coplanar waveguides and microstrip lines were
conducted at a 2 mm wavelength. This was achieved through the measurement of
on-chip half-wavelength resonators, employing
superconductor-insulator-superconductor tunnel junctions as detectors. A
continuous wave millimeter wave probe signal was introduced to the chip via a
silicon membrane-based orthomode transducer. This setup not only facilitated
the injection of the probe signal but also provided a reference path essential
for differential measurements. The observed resonance frequencies aligned
closely with theoretical predictions, exhibiting a discrepancy of only several
percent. However, the measured losses significantly exceeded those anticipated
from quasi-particle loss mechanisms, suggesting the presence of additional loss
factors. Notably, the measurement results revealed that the tangential loss
attributable to the dielectric layer, specifically silicon dioxide, was
approximately $\rm{7\pm 2 \times 10^{-3}}$. This factor emerged as the dominant
contributor to overall loss at temperatures around 4 K.
