W-Band Radar Altimeter for Drones

Abstract

In this study, we propose a W-band frequency modulated continuous wave(FMCW) radar altimeter that can measure the altitude based on the frequency differences of transmitted and received signals. This W-band FMCW system is powered by an altitude control algorithm, which we propose to help prevent collisions of drones with obstacles in real deployment by measuring the relative altitude. It is shown that this algorithm enables the drone to be positioned within a 3 % error of altitude from the desired input height. The chip used in the W-band transmitter and receiver was fabricated using a 65-nm CMOS process, and a horn antenna was directly fed by incorporating an embedded waveguide feeder into the chip [1]. The clutter spectra observed in terrains including soil, grass, and calm lake water were measured and compared, confirming the reflectivity characteristics of various surfaces of different water contents.

Considering cell volume in dopant screening for improving Li-ion mobility in an amorphous LiPON solid-state electrolyte: an ab initio study

“…Lee et al reported that, in their experiments, doping Ti into amorphous LiPON enhanced Li + ionic conductivity, 17 quite consistent with our theoretical calculations on the effect of Ti-doping on the ionic conductivity. However, due to the poor energetic stability of Ti-doped LiPON, compared to that of undoped LiPON, more rapid formation of secondary phases and worse cyclability (shorter lifetime) were expected.…”

“…However, all the doping elements considered in this study were indicated to reduce the LiPON crystal unit cell volume-but, interestingly, to increase the amorphous LiPON cell volume, indicating the ability of the dopants to enhance the Li ion conductivity. Lee et al reported that, in their experiments, doping Ti into amorphous LiPON enhanced Li + ionic conductivity, 17 quite consistent with our theoretical calculations on the effect of Tidoping on the ionic conductivity. However, due to the poor energetic stability of Ti-doped LiPON, compared to that of undoped LiPON, more rapid formation of secondary phases and worse cyclability (shorter lifetime) were expected.…”

“…Ti-doping was calculated to slightly narrow the band gap of LiPON, consistent with the experimental results of reduced impedance. 17 …”

“…Ti-doping was calculated to slightly narrow the band gap of LiPON, consistent with the experimental results of reduced impedance. 17 In Fig. 4, we present the results of AIMD simulations performed to demonstrate the validity of cell-volume-based dopant screening.…”

“…However, there are only a few reports on doping strategies for LiPON. 17,18 In order to have LiPON achieve electrochemical performance measures comparable to those of other SEs, an in-depth investigation of appropriate dopants for LiPON needs to be conducted.…”