Waveguide Path
Sub-terahertz signal path structures support the propagation of electromagnetic waves within the 110 GHz to 170 GHz frequency range on a printed circuit. Designing g-band transmission lines requires extreme precision in trace width and dielectric consistency to prevent excessive signal attenuation. These lines are typically implemented using grounded coplanar waveguides or microstrip geometries on specialized high-frequency substrates.
Small variations in etching or plating can cause substantial shifts in the center frequency or return loss.
Geometric Precision
Dimensional control is the most critical factor in the fabrication of these high-frequency paths. For g-band transmission lines, the tolerance on the trace width is often held to plus or minus five microns. This level of accuracy is necessary to maintain a constant 50 ohm impedance at wavelengths that are less than two millimeters.
Laser direct imaging and thin-film processing are commonly used to achieve the required resolution.
Insertion Loss
Signal power decreases as the wave travels through the dielectric and along the copper surface. The total loss in g-band transmission lines is a combination of the dissipation factor of the resin and the reactance caused by the copper surface roughness. Engineers use advanced modeling software to predict these losses and select the best material combinations.
Minimizing the length of these lines is the primary method for preserving signal strength in microwave assemblies.
