Spectrum shaping for backscatter modulation

In this letter, we demonstrate a technique for spectrum-shaping in backscatter modulation-based communication systems. With backscatter modulation, data bits are transmitted by switching the load impedance connected to the antenna. In traditional communication systems, filters are used to perform the task of shaping the pulse or the spectrum. Since most backscatter modulation radios operate on power harvested from a reader’s RF signal, filtering may not be suitable. In this letter, we show a simple spectrum shaping technique that is based on switching three loads, instead of the usual two, to transmit a bit. We demonstrate two well known shaping techniques using only load switching. The advantages of shaping the spectrum are (i) lower complexity and power consumption at the receiver and (ii) lower bit error probability for a given signal to noise ratio.