Renaissance has developed a new solid state programmable attenuator that can be used to perform fading simulations. The device operates from DC to 3 GHz with 5.5 dB insertion loss and can attenuate 100 dB in 1 dB steps. The attenuator can handle 20 dBm over -40 to +85 C.
Datasheet is located at http://www.rec-usa.com/Data%20Sheets/19A3BA.pdf.