A microwave system for humidity measurements

Gulmez, Yakup; Özkan, Turgay; Gülmez, Gülay; Turhan, Enis

doi:10.1109/cpem.2012.6251098

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…In material characterization applications, enhanced sensitivity enables sensing an infinitesimal change in the dielectric constant such as the ppm levels of a gas in an environment. For one, humidity sensors essentially require ultra-high sensitivities as the effective permittivity in the air changes by 0.012% at the frequency of 5 GHz as a result of the relative humidity (RH) increase from 25% to 75% [69]. This minute change in the RH is difficult to reliably discern with regular microwave sensors due to the low sensitivity of a planar resonator to the permittivity changes of this low value.…”

Section: Immobilization Of Analytesmentioning

confidence: 99%

Techniques to Improve the Performance of Planar Microwave Sensors: A Review and Recent Developments

Abdolrazzaghi

Nayyeri

Martín

2022

Sensors

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Planar microwave sensors have become increasing developed in recent decades, especially in material characterization (solid/liquid) as they provide regions highly sensitive to the surrounding medium. However, when it comes to deciphering the content of practical biological analytes or chemical components inside a host medium, even higher sensitivities are required due to their minute concentrations. This review article presents a comprehensive outlook on various methodologies to enhance sensitivity (e.g., coupling resonators, channel embedding, analyte immobilization, resonator pattern recognition, use of phase variation, using coupled line section, and intermodulation products), resolution (active sensors, differential measurements), and robustness (using machine learning) of arbitrary sensors of interest. Some of the most practical approaches are presented with prototype examples, and the main applications of incorporating such procedures are reported. Sensors with which the proposed techniques are implemented exhibit higher performance for high-end and real-life use.

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Section: Immobilization Of Analytesmentioning

confidence: 99%

Techniques to Improve the Performance of Planar Microwave Sensors: A Review and Recent Developments

Abdolrazzaghi

Nayyeri

Martín

2022

Sensors

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“…In addition, laboratory tests have shown that this type of probe, the active part of which is surrounded mainly by air, is less exposed to changes in the properties (probe capacitance C p ) due to moisture than a disk probe. As shown in [32], the dielectric constant of air in the range of relative humidity from 25% to 75% changes only by about 0.012%. Due to the fact that its active part is filled with a solid dielectric, the disk probe significantly changes its parameters in contact with moisture.…”

Section: Capacitive Probementioning

confidence: 91%

Non-Contact High Voltage Measurement in the Online Partial Discharge Monitoring System

Walczak

Sikorski

2021

Energies

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The article presents an innovative system for non-contact high voltage (HV) measurement, which extends the measurement capabilities of a portable partial discharges (PD) monitoring system intended for diagnostics of power transformers. The proposed method and the developed measuring system are based on the use of a capacitive probe, thanks to which the high voltage measurement is safe (galvanic separation from the objects at ahigh potential). It is also flexible because the voltage ratio of this system can be configured in a wide range by changing the probe’s position. The proposed solution makes the portable PD monitoring system fully autonomous and independent of the substation systems and devices. The article presents both the concept of the non-contact HV measurement system and its practical implementation. The procedure for determining the voltage ratio and measurement uncertainty, which is at an acceptable level of 1–5% in laboratory conditions, was discussed in detail. In addition, the article discusses the digital filtering and wavelet de-noising methods implemented in the software of the monitoring system, which makes it possible to measure the voltage in the presence of strong electromagnetic disturbances occurring at the substation. Finally, the results of field tests carried out on a 250 MVA power transformer are presented, which confirmed the high accuracy of the HV measurement using a capacitive probe and the advantages of this technique.

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“…The humid air model is in a sample holder for system performance simulation. The dielectric constant is varied in the range from 1.004 to 1.014 according to a relative humidity increasing [20]. The sample holder comprises a humid air model between the first and second antennas.…”

Section: Humidity Determination Simulationmentioning

confidence: 99%

Development of Humidity Monitoring System in Greenhouse With Electromagnetic X Band and Artificial Neural Networks

Leekul¹,

Wongsiritorn²,

Chaisaeng³

2021

PIER M

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This paper presents a humidity monitoring system with X band electromagnetic transmission. The verification is performed by comparing the gain and phase difference of intermediate frequency between 10.2 GHz and 10.4 GHz. Measurement data are analyzed to classify relative humidity levels and make decisions with ANNs. The system is simulated with electromagnetic field simulation software to analyze the ability of humidity monitoring. The structure from the simulation is developed to be a prototype system, including transmitter and receiver modules. Each module consists of an antenna, a frequency synthesizer, and a frequency mixer. The different operation frequencies of the two modules are −200 MHz and +200 MHz. The obtained intermediate frequency by mixing signals from each module is introduced into the circuit to find the gain and phase difference to compare with a relative humidity level. Humidity monitoring experiment is set in a closed plastic box to control the environment. The relative humidity level is from 55% to 95%. The decrease in gain is associated with increased relative humidity. Results found that the phase difference decreases clearly at the relative humidity from 75% to 95%. Both gain and phase difference data are used to train ANNs to optimize ANNs structure. Data are divided into 50% for training and 50% for testing. The proposed ANNs structure with a learning rate of 0.05 provides 98.8% accuracy. The optimized ANNs structure is composed of two input nodes, eight hidden nodes, and four output nodes. Four output nodes represent the relative humidity in 11 levels. The simulated and experimental results show that the system is able to monitor humidity effectively for applying in the greenhouse.

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A microwave system for humidity measurements

Cited by 5 publications

References 4 publications

Techniques to Improve the Performance of Planar Microwave Sensors: A Review and Recent Developments

Techniques to Improve the Performance of Planar Microwave Sensors: A Review and Recent Developments

Non-Contact High Voltage Measurement in the Online Partial Discharge Monitoring System

Development of Humidity Monitoring System in Greenhouse With Electromagnetic X Band and Artificial Neural Networks

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