A method for the prediction of microwave properties of thick film conductors from physical measurements and d.c. conductivity

It is theoretically possible to calculate electrical losses in conductors a t high frequencies using standard microstrip equations. To do this it is ne cessary to know the length, width and surface roughness of sample tracks. T he sheet resistance at d.c. is replaced with a new term, surface resistance which is the bulk resistivity divided by the skin depth at the frequency u nder consideration. The paper looks at the relationship between these predi ctions and measured results. A wide range of commercial thick film conducto rs has had its physical properties measured and a comparison made with the figures for idealized structures. The paper contains a discussion on the di fferences between real and ideal materials. It was seen that the prediction s were close to the measured results at lower frequencies, but that there w as divergence as the frequency approached 15-20 GHz. For low-cost applicati ons it is generally considered that economically viable conductors will be unsuitable for microwave applications. However, the paper discusses whether some of the lesser used conductors, such as fritted silver, could have an application in low-cost microwave devices, for example alarm systems. (C) 2 001 Kluwer Academic Publishers.