Hi, I've assembled the DIY soundplane with all the material you suggested in the paper and respected I think every aspect, measures and layers etc...The apparatus picks up signal very well on all the strips except when I put the dielectric, the red orange silicone foam rubber in between the carriers and the pick up grid. It seems to kill the signal completely. The fireface output is set to HiGain. What should I consider trying or what is it that I might have forgotten. Thanks.
rubber is almost totally transparent to the RF signals at these low frequencies. So I'm guessing it's just the distance that has caused the difference. you could try a thinner foam. Or, just try experiments with adding thicknesses of paper and measure the amount the signal drops off with distance.
A small caliper for measuring thickness is a handy tool to have.
Please keep me posted!