Abstract
We propose a two-way backscatter tag that uses a reflection amplifier. The reflection gain ${S_{11}}$ is used to modulate the backscatter signal while the forward gain ${S_{21}}$ is fixed. The circuit is analyzed and designed to operate at 2.45 GHz with the bandwidth of 120 MHz. Measurements show that we can have ${S_{11}\approx }20$ and −20 dB to implement ON/OFF keying (OOK) backscatter modulation scheme, while ${S_{21}\approx }15$ dB.
Highlights
A LTHOUGH, the history of backscatter communication (BSC) traces back to 1948 [1], only recently has it found many applications in communication systems
Reflection amplifiers can be used in two-way BSC systems, where two of them are added in one branch line coupler structure to build bidirectional amplifier [5], [7]
We propose a two-way BSC circuit with on/off reflection gain (OOK backscatter modulation), and a constant forward gain, Fig. 6
Summary
A LTHOUGH, the history of backscatter communication (BSC) traces back to 1948 [1], only recently has it found many applications in communication systems. Several prototypes of one-way BSC systems succeeded to increase the communication range by using reflection amplifiers. By changing the dc voltage bias of the transistor, the authors could change the reflection gain and modulate the backscatter signal. In this case, the forward gain varies by the bias voltage. One switch is used to modulate the amplified backscattered signals using On/Off Keying (OOK), while the fixed/high forward gain is always present. Compared to [8], we increased the communication range and decreased the bit error rate (BER) at the reader by maximizing the difference between reflection gain and maintaining a fixed/high forward gain
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