Dielectric constant, loss tangent, and surface resistance of PCB materials at K-band frequencies

This paper develops the theoretical approach and describes the design of a practical test rig for measuring the microwave parameters of unclad and laminated dielectric substrates. The test rig is based on a sapphire whispering-gallery resonator and allows the measurement of the following parameters: dielectric constant (/spl epsiv/) of the dielectric substrate in the range from 2 to 10, loss tangent (tan/spl delta/) of the dielectric substrate in the range from 10/sup -4/ to 10/sup -2/, and microwave losses of copper coating of the substrate in the range from 0.03 to 0.3 /spl Omega/. Measurements of numerous commonly used microwave printed-circuit-board materials were performed at frequencies between 30-40 GHz and over a temperature range of -50/spl deg/C to +70/spl deg/C.