This paper presents electrical energy measurement and monitoring for an Internet of Things (IoT) home electrical load. Energy monitoring included design, experimentation, and implementation of an IoT system for this purpose. The application used an IoT system based on an ESP8266 micro-controller and a lowcost PZEM-004T current sensor. The ESP8266 has general-purpose pins and a built-in Wi-Fi chip system. Electrical energy was displayed on a smartphone and the data was saved to a cloud system. Experimental results consisted of fixed and variable loads. The fixed loads were of three levels, 100 W, 600 W, and 1,600 with respective average errors of 0.004%, – 0.31%, and – 0.57%. The current of the variable load was higher during heating and was reduced when the device was serving to keep its sample warm. Measurements of voltage, current and total electrical power data of various loads were recorded and displayed. These values were monitored using a smartphone via a LINE application to alert the user to abnormalities. The system has the advantages of being user-friendly, simple, and inexpensive.

This research demonstrated the design technique and sensor building for liquid level measurement by applying microstrip parallel coupled lines. The design and building of the coupled line with a microstrip had coupling at -10 dB and 200 MHz of frequency. The water level for testing was 0-20 cm to check the frequency response of the coupling from 100 MHz -1.5 GHz. In accordance with the experiment, it was found that coupling with different levels of water provided the same result. This technique was easy to follow as the sensor had a small size and was inexpensive.

This paper presents a technique to improve the spurious suppression performance at the second harmonic (2f0) of a Wilkinson power divider. The technique is achieved by the insertion of bandstop filters realizing with parallel-coupled lines with the characteristic impedance of 2√Z0Ω and the electrical length of λ/8 in a conventional structure. The simulated and measured results of the conventional and the proposed divider are compared at 0.9 GHz. The insertion losses (S21, S31) are less than 3.1 dB, while the return losses (S11) are less than 34.6 dB across 100% fractional bandwidth. Moreover, the proposed Wilkinson power divider achieves more than 25.5 dB suppression at 2f0.

This research introduces the conceptualization and examination of a microwave sensor incorporated with a microstrip band stop filter. The microwave sensor’s design and assessment are based on the microstrip’s parallel coupled lines, employing a band stop filter configuration at 2.45 GHz on an FR4 substrate. This study encompasses the evaluation of soil moisture spanning from 20 to 80%. The measurement procedure involved a network analyzer, specifically the KEYSIGHT model E5063A, operating within the frequency range of 100 kHz to 4.5 GHz. This investigation centers around scrutinizing the frequency response of the insertion loss (S₂₁) across this spectrum. The outcomes of the experimentation unveiled notable disparities in frequency shifts. The resultant frequency values, labeled as (f₀-f₁), manifested at 0, 18, 60, 89, 145, and 200 MHz, sequentially. Remarkably, the correlation between the percentage representation of the frequency shift in the transmission coefficient and the frequency itself emerged distinctly, even as the range of tested samples was finetuned.