The five of FBG were embedded in the PE sheath of a tether optical cable, which has about 18mm diameter and 7000mm length. The temperature and tension characteristics of the FBGs embedded in the polythene (PE) sheath had been demonstrated quantitatively. The Bragg wavelength of the embedded FBG shift linearly with the change of pulling force loaded on the tether optical cable and its tension sensitivity is about 3.75 pm/kg. The results of temperature experiment suggest the embedded FBG have been sensitized by PE material, so that its temperature sensitivity increase from 9.37pm/°C to about 12.51pm/°C.
The conventional phase coded lidar systems require the collection of every returned laser pulse and are restricted in
range resolution by sampling frequency and subpulse width. A phase coded lidar system with high range resolution is
proposed with the accumulated m-sequence acquisition method by utilizing detector characteristics for signal detection.
The detector accumulates kN-1 or kN+1 bits of the emitted laser sequence to deduce the a single bit of the sequence. The
indoor experiment achieved 2 us resolution with the sampling period of 28 and 32 us by employing a 15-bit m-sequence.
This method achieves the acquisition of m-sequence with narrow subpulse width whereas the sampling frequency is kept
low. The experiment results showed an approach to implement the phase coded imaging lidar into practical application.
90° and 180°-switched-line phase shifters using composite right/left handed transmission line (CRLH TL) are presented.
To achieve a relatively constant phase shift over a large bandwidth, CRLH TLs implemented using lumped elements and
right-handed transmission lines (RH TLs) are used as the reference and delay arms, respectively, of the phase shifters.
Computer simulation is used to study and design the phase shifters. The phase shifters are also fabricated and measured
to verify the simulation results. For comparison, traditional 90° and 180°-switched-line phase shifters are also designed
and simulated. Simulation and measurement results show that, the proposed phase shifters have a constant phase shift, a
high return loss and a low insertion loss across the operating frequency band.
This paper presents the design of a circular-shaped ultra-wideband (UWB) time-delay lines inspired by the use of
composite right/left-handed transmission line (CRLH TL) unit cells. A rotated version of a conventional CRLH TL unit
cell is used as the basic element to achieve UWB operation. For comparison, time-delay lines using the right-handed
transmission line (RH TL) and CRLH TL unit cells are also studied, fabricated and tested. Simulation and measurement
results show that our proposed time-delay lines have high return loss, low insertion loss, UWB operation and much
longer time delays than that of the time-delay line based on RH TL.
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