The highly power-efficient Backscattering communication scheme holds solid potentials to lead the Internet of Things technologies. However, the asymmetric radio frontend architectures that ensure cheap and pervasive communicating things and tags at one end of the link, overburdens the other end of the link ("reader") with complicated and expensive hardware. This turns out to prevent the integration of the technology in the wide spectrum of consumer electronic devices (e.g. RF smartphone platforms). By separating TX and RX frequency bands, harmonic backscattering scheme drastically loosens the technological constraints towards integration. We propose here the use of a single tunnel diode to build a harmonic reflection amplifier (HRA), using the non-linear behavior of the negative differential resistance region to both generate harmonics and amplify the signals. The circuit also behaves like a common backscatter, with same-frequency backscattering modulation for operation with legacy readers. Operating below 150mV, the HRA drains 144µW dc power with a measured positive conversion gain of 18dB.