Electrical Delay
Phase velocity variations in planar transmission lines occur when the electrical length of the conductor changes due to environmental or geometric factors. A microstrip phase shift describes the displacement of the wave crests as the signal travels from the input to the output of a circuit. This phenomenon is critical in the design of phased array antennas and radar systems where timing is everything.
It can be intentional, such as in a tuning circuit, or parasitic, caused by temperature changes in the substrate.
Dielectric Influence
The insulating material beneath the copper trace determines the speed of the electromagnetic wave. Changes in the moisture content or temperature of the board lead to a microstrip phase shift by altering the dielectric constant. High quality laminates are selected to minimize these unplanned variations.
Vector Analysis
Measurements of the timing change are performed using a vector network analyzer. The device compares the phase of the transmitted signal against a reference signal. A microstrip phase shift is recorded in degrees or radians across the operating frequency band.
Insertion Loss
Signal attenuation often increases as the phase is manipulated. Every microstrip phase shift component introduces a small amount of resistance and dielectric loss. Engineers must balance the required delay with the signal strength.
