Ultra-wideband (UWB) wireless underground sensor networks consist of wirelessly connected underground sensor nodes that communicate through the soil. Performances of buried antennas and of the communication link depend on the soil dielectric characteristics. The effects of soil moisture and depth, in the frequency band of 3.1-10.6 GHz, on an UWB antenna return loss and bandwidth are presented. The measurements are conducted in two different types of soil: sandy soil and railway pebbles. The experimental results show that burying antenna shifts down its bandwidth. This phenomenon is accentuated by the increase of soil moisture and not impacted by the burial depth variations. In a dry sandy soil, the shift of the bandwidth low-end is of 0.75 GHz, while it is 1 and 1.5 GHz at 5 and 20% soil moisture, respectively. This fact has allowed us to further miniaturise the used antenna.

This paper introduces new system concepts for an UWB transmitter architecture dedicated to 3.1-5.1GHz band. The latter is developed for an application targeting data rates up to 1Mbps, associated with localization and positioning. First, a pulse shape analysis is done in order to select the best one for our spectrum boundary mask. Then, based on a windowed cosine pulse choice, a transmitter architecture is proposed and two critical blocks, the pulse generator and the antenna, are studied more in detail. Moreover, a link budget is done in order to correlate bandwidth, ranging and localization precision.

International audienceIn this paper, we present a bandpass filter designed and implemented in 65-nm CMOS. From 0.8-2.2GHz filtering requirements are very challenging. This filter is dedicated to fully digital RF Tx cellular architectures, and is available for any Tx architecture. Our filter uses highly linear CMOS active inductors that exhibit Q factors above 1000 at cellular frequencies to reduce filter insertion losses. The highly linear characteristic of implemented active inductors drive it us to 0dBm operation while providing at least 24dB attenuation at ± 400MHz from F0. Measurement results of the filter show a central frequency (F0) of 1.8GHz with 135MHz of -3dB bandwidth (BW) with less than 0.1dB I

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