A magnetorheological fluid composition comprising a carrier fluid; and a plurality of high aspect ratio magnetizable particles, wherein the aspect ratio of the high aspect ratio magnetizable particles is greater than 1. In order to minimize the number of components required for matching the amplifier to different frequency bands, the circuit has a first capacitance for outputting the negative half-cycle of the transmission signal, which is rectified by a diode and is stored in a second capacitance. The first antenna is capable of transceiving a signal of a first communication mode.