3.3.2.2 The three-dimensional spacer fabrics

The silver fiber spacer fabric is prepared on the warp knitting machine, of which the silver-plated filaments with a fineness of 83dtex are used in the middle layer, and the upper and lower surfaces are all made of polyester fibers, as shown in Figure 23. The silver-plated fibers make the radar waves absorption, reflection, and multiple reflections happen in the intermediate layer.

The silver-plated fiber spacer fabric has a significant resonance peak, which should be related to the thickness of the intermediate layer of the fabric, and indicates that the shielding effect on the radar wave is not mainly due to the reflection radar wave mechanism. The reflectivity of silver-plated fiber spacer fabric is generally inferior to that of velvet fabrics, but its resonance peak can reach 30 dB, and when the reflection coefficient is below 5 dB, it has a wide bandwidth, even up to 18 GHz.
