Spatial filtering is a useful method to suppress undesired reflection from unwanted scatters in Radar Cross Section (RCS) measurements. Actually, it is difficult to prepare an ideal field which satisfies the far-field criterion for RCS measurements of large targets. We applied the filtering method to a bistatic RCS measurement in a near field and investigated the validity of that method by varying the scanning angular span. Electromagnetic simulations show that predicted RCS profiles from near-field data with unwanted scatters closely matched far-field reference data of the test target. In conclusion, the results show that the method is effective for bistatic RCS measurements in practical field enviroments.

We propose a hierarchical multi-layer global router for Sea-Of-Gates VLSI's, which is different from the conventional global routers, in that routing and layering are executed simultaneously. The main problems to be solved in the global routing for a multi-layer VLSI are which wire segments are laid out on upper layers and how they are connected to terminals located on lower layers. The main objective is to minimize the maximum of local congestions of all layers. We solve these problems in a hierarchical manner by routing from upper layers to lower layers.