Simple Microstrip Structures Calculated vs Measured

The microwave performance of simple microstrip structures such as gaps, bends, stubs, termination and Beatty lines was calculated using both standard RF analysis and EM analysis. The structures were manufactured on 10 mil alumina and the RF performance was measured to 60 GHz. The results are compared. The question of the accuracy of both models and measurements is always nagging, especially at higher frequencies and in non coax structures. Measurement capability for microstrip has improved dramatically in the past few years with improved test fixtures, microstrip calibration standards, dispersion correction and broadband time domain. Modeling has also improved and there are at least two major modeling techniques, standard circuit analysis, such as Touchstone, and Electromagnetic Simulation. EM can provide analysis of structures which are not currently covered by standard analysis. The test structures were kept simple and were mostly either broadband or were centered around 30 GHz. The structures were manufactured on 10 mil alumina which was held to a thickness tolerance of ±0.0001". The data was gathered in DOS format and plotted through Touchstone. EM simulations were provided by Sonnet Software and EESOF. Standard analysis was by EESOF Touchstone. The RF measurements and structures were provided by Wiltron. Measurements were made on a 60 GHz Model 360 network analyzer using a Model 3680V test fixture. Calibration used microstrip standards. Due to time constraints, not all structures were analyzed by all involved. The information on the data is given below.