scholarly journals Planar Phase-Variation Microwave Sensors for Material Characterization: A Review and Comparison of Various Approaches

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1542
Author(s):  
Jonathan Muñoz-Enano ◽  
Jan Coromina ◽  
Paris Vélez ◽  
Lijuan Su ◽  
Marta Gil ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Material Characterization ◽  
Low Cost ◽  
Phase Variation ◽  
Single Frequency ◽  
Dispersion Engineering ◽  
Low Profile ◽  
Planar Phase ◽  
Sensitivity Improvement ◽  
Microwave Sensors

Planar phase-variation microwave sensors have attracted increasing interest in recent years since they combine the advantages of planar technology (including low cost, low profile, and sensor integration with the associated circuitry for post-processing and communication purposes, among others) and the possibility of operation at a single frequency (thereby reducing the costs of the associated electronics). This paper reviews and compares three different strategies for sensitivity improvement in such phase-variation sensors (devoted to material characterization). The considered approaches include line elongation (through meandering), dispersion engineering (by considering slow-wave artificial transmission lines), and reflective-mode sensors based on step-impedance open-ended lines. It is shown that unprecedented sensitivities compatible with small sensing regions are achievable with the latter approach.

scholarly journals Stop Band Continuous Profile Filter in Empty Substrate Integrated Coaxial Line

2018 ◽  
Author(s):  
Darío Gómez ◽  
Héctor Esteban ◽  
Angel Belenguer ◽  
Vicente E. Boria ◽  
Alejandro L. Borja
Keyword(s):  
Transmission Lines ◽  
Low Cost ◽  
Stop Band ◽  
Coaxial Line ◽  
Design Parameters ◽  
Substrate Integrated Waveguides ◽  
Low Profile ◽  
Tem Mode ◽  
Profile Characteristics ◽  
Insertion Losses

Substrate integrated waveguides reduce the losses and increase the quality factor of resonators in communication filters when compared with traditional planar technologies, while maintaining their low cost and low profile characteristics. Empty substrate integrated waveguides go one step further, removing the dielectric of the substrate. One of these transmission lines is the empty substrate integrated coaxial line (ESICL), which adds the advantage of being a two conductor structure. Thus, it propagates a TEM mode, which reduces the dispersion and the bandwith limitation of other one conductor empty substrate integrated waveguides. Continuous profile filters, at the cost of being long structures, are very easy to manufacture and design (usually no optimization is needed), and they are highly insensitive to manufacturing tolerances. In this work a simple continuous profile filter, with a stop band response, is designed for the first time in the novel ESICL technology. The influence of the design parameters on the insertion losses and fractional bandwidth is discussed. A prototype has been successfully manufactured and measured. A sensitivity analysis shows the high tolerance of the proposed stop band filter to manufacturing errors.

scholarly journals Stop Band Continuous Profile Filter in Empty Substrate Integrated Coaxial Line

2018 ◽  
Vol 8 (11) ◽  
pp. 2176 ◽  
Author(s):  
Darío Gómez ◽  
Héctor Esteban ◽  
Angel Belenguer ◽  
Vicente Boria ◽  
Alejandro Borja
Keyword(s):  
Transmission Lines ◽  
Low Cost ◽  
Stop Band ◽  
Coaxial Line ◽  
Design Parameters ◽  
Substrate Integrated Waveguides ◽  
Low Profile ◽  
Tem Mode ◽  
Profile Characteristics ◽  
Insertion Losses

Substrate integrated waveguides reduce the losses and increase the quality factor of resonators in communication filters when compared with traditional planar technologies, while maintaining their low-cost and low-profile characteristics. Empty substrate integrated waveguides go one step further, removing the dielectric of the substrate. One of these transmission lines is the empty substrate integrated coaxial line (ESICL), which has the advantage of being a two-conductor structure. Thus, it propagates a transversal electric and magnetic (TEM) mode, which reduces the dispersion and the bandwidth limitation of other one conductor empty substrate integrated waveguides. Continuous profile filters, at the cost of being long structures, are very easy to manufacture and design (usually no optimization is needed), and they are highly insensitive to manufacturing tolerances. In this work, a simple continuous profile filter, with a stop band response, is designed for the first time using novel ESICL technology. The influence of the design parameters on the insertion losses and fractional bandwidth is discussed. A prototype has been successfully manufactured and measured. A sensitivity analysis shows the high tolerance of the proposed stop band filter to manufacturing errors.

Reducing multipath effect of low-cost GNSS receivers for monitoring by considering temporal correlations

2020 ◽  
Vol 14 (2) ◽  
pp. 167-175
Author(s):  
Li Zhang ◽  
Volker Schwieger
Keyword(s):  
Low Cost ◽  
Ground Plane ◽  
Single Frequency ◽  
Spatial Correlations ◽  
Raw Data ◽  
Multipath Effect ◽  
Temporal Correlations ◽  
Multipath Effects ◽  
Gnss Receivers ◽  
Multipath Signals

AbstractThe investigations on low-cost single frequency GNSS receivers at the Institute of Engineering Geodesy (IIGS) show that u-blox GNSS receivers combined with low-cost antennas and self-constructed L1-optimized choke rings can reach an accuracy which almost meets the requirements of geodetic applications (see Zhang and Schwieger [25]). However, the quality (accuracy and reliability) of low-cost GNSS receiver data should still be improved, particularly in environments with obstructions. The multipath effects are a major error source for the short baselines. The ground plate or the choke ring ground plane can reduce the multipath signals from the horizontal reflector (e. g. ground). However, the shieldings cannot reduce the multipath signals from the vertical reflectors (e. g. walls).Because multipath effects are spatially and temporally correlated, an algorithm is developed for reducing the multipath effect by considering the spatial correlations of the adjoined stations (see Zhang and Schwieger [24]). In this paper, an algorithm based on the temporal correlations will be introduced. The developed algorithm is based on the periodic behavior of the estimated coordinates and not on carrier phase raw data, which is easy to use. Because, for the users, coordinates are more accessible than the raw data. The multipath effect can cause periodic oscillations but the periods change over time. Besides this, the multipath effect’s influence on the coordinates is a mixture of different multipath signals from different satellites and different reflectors. These two properties will be used to reduce the multipath effect. The algorithm runs in two steps and iteratively. Test measurements were carried out in a multipath intensive environment; the accuracies of the measurements are improved by about 50 % and the results can be delivered in near-real-time (in ca. 30 minutes), therefore the algorithm is suitable for structural health monitoring applications.

scholarly journals Highly Compact Through-Wire Microstrip to Empty Substrate Integrated Coaxial Line Transition

2021 ◽  
Vol 11 (15) ◽  
pp. 6885
Author(s):  
Marcos D. Fernandez ◽  
José A. Ballesteros ◽  
Angel Belenguer
Keyword(s):  
Printed Circuit Board ◽  
Low Cost ◽  
Coaxial Line ◽  
Circuit Board ◽  
Central Layer ◽  
Printed Circuit ◽  
Integrated Technology ◽  
Low Profile ◽  
The Many ◽  
High Degree

Empty substrate integrated coaxial line (ESICL) technology preserves the many advantages of the substrate integrated technology waveguides, such as low cost, low profile, or integration in a printed circuit board (PCB); in addition, ESICL is non-dispersive and has low radiation. To date, only two transitions have been proposed in the literature that connect the ESICL to classical planar lines such as grounded coplanar and microstrip. In both transitions, the feeding planar lines and the ESICL are built in the same substrate layer and they are based on transformed structures in the planar line, which must be in the central layer of the ESICL. These transitions also combine a lot of metallized and non-metallized parts, which increases the complexity of the manufacturing process. In this work, a new through-wire microstrip-to-ESICL transition is proposed. The feeding lines and the ESICL are implemented in different layers, so that the height of the ESICL can be independently chosen. In addition, it is a highly compact transition that does not require a transformer and can be freely rotated in its plane. This simplicity provides a high degree of versatility in the design phase, where there are only four variables that control the performance of the transition.

scholarly journals A Local Oscillator Phase Compensation Technique for Ultra-Wideband Stepped-Frequency Continuous Wave Radar Based on a Low-Cost Software-Defined Radio

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 780
Author(s):  
Kazunori Takahashi ◽  
Takashi Miwa
Keyword(s):  
Software Defined Radio ◽  
Initial Phase ◽  
Continuous Wave ◽  
Low Cost ◽  
Local Oscillator ◽  
The Other ◽  
Ultra Wideband ◽  
Single Frequency ◽  
Wave Radar ◽  
Stepped Frequency

The paper discusses a way to configure a stepped-frequency continuous wave (SFCW) radar using a low-cost software-defined radio (SDR). The most of high-end SDRs offer multiple transmitter (TX) and receiver (RX) channels, one of which can be used as the reference channel for compensating the initial phases of TX and RX local oscillator (LO) signals. It is same as how commercial vector network analyzers (VNAs) compensate for the LO initial phase. These SDRs can thus acquire phase-coherent in-phase and quadrature (I/Q) data without additional components and an SFCW radar can be easily configured. On the other hand, low-cost SDRs typically have only one transmitter and receiver. Therefore, the LO initial phase has to be compensated and the phases of the received I/Q signals have to be retrieved, preferably without employing an additional receiver and components to retain the system low-cost and simple. The present paper illustrates that the difference between the phases of TX and RX LO signals varies when the LO frequency is changed because of the timing of the commencement of the mixing. The paper then proposes a technique to compensate for the LO initial phases using the internal RF loopback of the transceiver chip and to reconstruct a pulse, which requires two streaming: one for the device under test (DUT) channel and the other for the internal RF loopback channel. The effect of the LO initial phase and the proposed method for the compensation are demonstrated by experiments at a single frequency and sweeping frequency, respectively. The results show that the proposed method can compensate for the LO initial phases and ultra-wideband (UWB) pulses can be reconstructed correctly from the data sampled by a low-cost SDR.

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