Sharif Digital Repository

An important issue in High-Frequency circuits is the transmission of electrical signals in Integrated Circuits and Printed Circuit Boards (PCBs). At high frequencies, however, the often used transmission lines suffer from high conductor and substrate loss as well as unwanted electromagnetic coupling to other circuit elements caused by parasitic substrate surface. One method through which both of the above problems may be solved is utilizing waveguide structures on PCBs and ICs. In this way, due to the reduction of conductor loss, a large proportion of signal passes easily. Moreover, and because of closed nature of cavity waveguides, neighboring circuits are protected against electromagnetic... 

In this study some experiments were performed to investigate the effect of sweep angle on the transition location of laminar flow to turbulent flow. Three half wing models were used, each having a different sweep angle but with the same aspect ratio in various angles of attack. Two flat plates were used at the ends of the swept wing models to prevent the flow from rolling up over the wing. By simulating flow over infinity swept wing by eliminating tip vertices, the effect of sweep angle on flow transition phenomenon was investigated.
The experiments included the study of transition flow via hot-film sensors, which were glued on the wing surface. We found that the small leading-edge...