Research Article
Optimization of Wavelength Selection for a Two-Color Pyrometer Based on the Flux Ratio and Planck's Law on Real Body
Issue:
Volume 14, Issue 4, August 2026
Pages:
190-195
Received:
3 July 2026
Accepted:
20 July 2026
Published:
10 August 2026
Abstract: This article examines a methodical analysis for optimizing the wavelength selection used for the two channels of a bichromatic pyrometer. Temperature measurement via pyrometry relies on analyzing the radiation emitted by a body at various wavelengths, enabling non-contact thermal assessment. Several laws mathematically characterize this thermal radiation: Lambert’s law, which states that radiance is independent of the emission direction, and Planck’s law, which allows for the calculation of the body's radiation energy density. The bichromatic pyrometer utilizes distinct wavelengths; it consists of two separate spectral filter channels and two detectors with different spectral sensitivities, each followed by its own analog processing electronics. The two signals representing the thermal radiation undergo this analog processing before being combined through digital processing. A crucial step is selecting the wavelengths for the two spectral filters. Depending on the approach, calculations for a bichromatic pyrometer can be based either on the flux ratio combined with Wien’s approximation or on the flux ratio combined with Planck’s law, with each approach offering a different level of compensation for emissivity variations. In our case, the second method, that is to say the flux ratio using Planck's law will be used. This method applies Planck’s law to a real body by modeling emissivity as a second-degree polynomial. By varying the ratio value, we can calculate pairs of wavelengths based on their difference; this difference is then evaluated against relative errors to determine how to optimize the selected wavelengths. Optimizing wavelength selection in the bispectral system, by using two wavelengths simultaneously, improves the accuracy of temperature estimation and enables more reliable modeling of the materials' spectral behavior.
Abstract: This article examines a methodical analysis for optimizing the wavelength selection used for the two channels of a bichromatic pyrometer. Temperature measurement via pyrometry relies on analyzing the radiation emitted by a body at various wavelengths, enabling non-contact thermal assessment. Several laws mathematically characterize this thermal rad...
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Research Article
Comparative Performance Analysis of RC-Coupled, Transformer-Coupled, and Direct-Coupled
Common-Emitter Transistor Amplifiers Using Multisim 11.0
Yusuf Abdullahi*
,
Ismail Garba Saidu,
Muhammad Bello Abdullahi,
Kabiru Ahmed Dabai,
Buhari Bello Sahabi,
Aisha Aminu Mode
Issue:
Volume 14, Issue 4, August 2026
Pages:
196-210
Received:
15 July 2026
Accepted:
25 July 2026
Published:
9 September 2026
Abstract: The coupling technique employed in multistage transistor amplifiers plays a fundamental role in determining voltage gain, frequency response, bandwidth, and overall amplifier performance. Although resistance-capacitance (RC), transformer, and direct coupling are widely used in analog electronic systems, their comparative performance under identical operating conditions has not been comprehensively investigated. This study aimed to compare the performance of two-stage RC-coupled, transformer-coupled, and direct-coupled common-emitter transistor amplifiers using Multisim 11.0. Three amplifier configurations were designed using identical circuit parameters, including two 2N2222A NPN transistors, a 12 V DC supply, identical voltage-divider bias networks, collector and emitter resistors, and the same input signal conditions. The only difference among the circuits was the interstage coupling technique. Simulations were carried out over a frequency range of 10 Hz to 100 MHz, and the amplifiers were evaluated in terms of voltage gain, frequency response, bandwidth, waveform characteristics, phase relationship, and signal amplification behaviors. The simulation results showed that the RC-coupled amplifier exhibited the highest and most stable mid-band voltage gain of approximately 68 dB together with the widest useful bandwidth, making it the most suitable for general-purpose voltage amplification. The transformer-coupled amplifier demonstrated moderate performance with a peak gain around 100 kHz, indicating its suitability for impedance matching and efficient power transfer. The direct-coupled amplifier produced the lowest voltage gain under the selected operating conditions but retained the capability to amplify DC and very low-frequency signals because it does not employ coupling capacitors or transformers. The study concludes that the choice of coupling technique significantly influences transistor amplifier performance. RC coupling is the preferred technique for high-gain, wide-band voltage amplification, transformer coupling is advantageous for impedance matching and power amplification, whereas direct coupling is most suitable for DC and low-frequency instrumentation applications. These findings provide practical guidance for selecting appropriate coupling techniques in the design of multistage transistor amplifiers.
Abstract: The coupling technique employed in multistage transistor amplifiers plays a fundamental role in determining voltage gain, frequency response, bandwidth, and overall amplifier performance. Although resistance-capacitance (RC), transformer, and direct coupling are widely used in analog electronic systems, their comparative performance under identical...
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