Showing papers by "Saibun Tjuatja published in 2016"
TL;DR: Temperature sensing without electronics is demonstrated through wireless interrogation of passive antenna-sensors using an ultra-wide-band microstrip antenna as the transmitting/receiving antenna and a microstrip patch antenna serving as the temperature-sensing element.
Abstract: Temperature sensing without electronics is demonstrated through wireless interrogation of passive antenna-sensors. The sensor node is equipped with an ultra-wide-band microstrip antenna as the transmitting/receiving (Tx/Rx) antenna and a microstrip patch antenna serving as the temperature-sensing element. A microstrip transmission line connecting the Tx/Rx antenna and the antenna-sensor delays the signal reflected from the sensing element and thus separated it from the background clutter. The operation principle of the wireless sensing scheme is first discussed, followed by the design and simulations of the sensor node circuitry. A digital signal processing algorithm that extracts the antenna resonant frequency from the wirelessly received signal is also described. Temperature tests were conducted to validate the performance of the wireless antenna sensor inside an oven.
53 citations
01 Aug 2016
TL;DR: The design, simulation and validation of the FMCW generator, developed to detect antenna-sensor's resonant frequency, which encodes the pressure information, are described and compared with those from Network Analyzer measurements to demonstrate its accuracy.
Abstract: This paper presents a compact antenna-sensor interrogator for pressure sensing. A Frequency Modulated Continue Wave (FMCW) generator was developed to detect antenna-sensor's resonant frequency, which encodes the pressure information. The power consumption of this generator is less than 160mW and can be powered by a 3.7V portable lithium battery. In the paper, the operation principle of this FMCW interrogator is firstly explained. Subsequently, the design, simulation and validation of the FMCW generator are described. Finally, static pressure tests were performed to validate the performance of the proposed FMCW interrogator. The results were compared with those from Network Analyzer (VNA) measurements to demonstrate its accuracy.
7 citations
10 Jul 2016
TL;DR: System simulation based on the stationary (frequency modulation continuous wave) FMCW is developed and implemented for both point target and extended target and good agreement between the simulated by extend target model and real measured SAR images is obtained.
Abstract: SAR is a complex system that integrates two major parts: data collector and image formatter [1–2]. In the phase of data collection, radar transmits electromagnetic waves toward the target and receives the scattered waves. The transmitted signal can be modulated into certain types, commonly linearly frequency modulated with pulse or continuous waveform. The process involves signal transmission from generator, through various types of guided device, to antenna, by which the signal is radiated into free space, and then undergoes propagation. The measured scattered signal been made in bistatic or monostatic configurations is essentially in time-frequency (delay time - Doppler frequency) domain. The role of image formatter is then to map the time-frequency data into spatial domain where the targets are located. The mapping from the data domain to image domain, and eventually, into target or object domain must minimize both geometric and radiometric distortions. Essentially, two models that define the SAR operational process: physical model and system model. This paper concentrates on the physical process of a SAR system from wave scattering to imaging. System simulation based on the stationary (frequency modulation continuous wave) FMCW is developed and implemented for both point target and extended target. To further validate the simulation and thus our physical understanding of the imaging chain, measurements at aniconic chamber with two mental spheres and two dielectric spheres displaced with varying spacing were conducted. Good agreement between the simulated by extend target model and real measured SAR images is obtained.
1 citations
10 Jul 2016
TL;DR: Two methods are presented which can compensate for the defocusing of targets in subspace-based images due to physical scattering phenomena.
Abstract: Traditional subspace-based image processing treats the target as a collection of scattering points whose phase component is dependent only on phase change due to target motion. Physical scattering mechanisms can result in magnitude and phase components outside this model and defocusing of scatterers in the resulting image. Two methods are presented which can compensate for the defocusing of targets in subspace-based images due to physical scattering phenomena. The focusing effectiveness of these two methods are demonstrated and compared.
10 Jul 2016
TL;DR: A numerical study of microwave brightness temperature of residual foam cover on ocean surface using Kelvin's Tetrakaidecahedron structure to determine total emission from the foam layer is presented.
Abstract: This paper presents a numerical study of microwave brightness temperature of residual foam cover on ocean surface. The foam layer is modeled using Kelvin's Tetrakaidecahedron structure. Absorption and scattering of the foam layer, i.e. the layer phase matrix, are calculated using a multilevel UV method to accelerate method of moment (MoM) solution of Maxwell's equations. Matrix doubling method, which accounts for interactions between the foam volume and interfaces, is then utilized to determine the total emission from the foam layer. The calculated foam layer absorption rates at a frequency range of 1.5GHz to 36.5GHz are presented and analyzed for both H and V polarizations. Brightness temperatures at 1.5GHz for both planar and rough interface with different water fractions in the foam layer are simulated and analyzed. Effects of foamboundary interactions on foam layer emission are discussed.