A1. Since concrete is partly conductive and varies with mositure content and ambient conditions, the reflected path with vary substantially. The solution is to place a screen mesh over the top of the concrete. A2. The specified size is that of the elipse which is 2d by root3d. A practical size is 20m by 17m rectangle. A3. running coax on the top surface most likely will not affect the measurements but for NSA measurements, to obtain maximum repeatability ferrite cores are placed every 1m on the mast cable. It would be best to feed the cables diametrically opposed from each other so as to minimize any effects. A4. Theoretically the conrete curbs, the hedges and metal object can cause additional unwanted reflections. Those may or may not be a problem. Metal objects will have the greatest effect since most of the wave will be reflected. Hedges will most likely act as absorbers at certain frequencies, and the curb will cause reflections or absorbtion at certain microwave frequencies. Hans Mellberg EMC Consultant
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