A frequency selective surface (FSS) structure based on a circular slot with 28 to 31 μm was fabricated using Electron Beam Lithography combined with wet etching technique on a 400 μm thick quartz substrate. The circular slot pattern, designed using the CST software, was transferred during the Electron Beam (EBL) exposure with 100 kV voltage acceleration, 2 nA of e-beam current, and line dosage of 1000 μC2. A 0.5 μm thick aluminium layer was deposited on a quartz substrate using the thermal evaporator technique. The aluminium thickness was confirmed by laser microscope and surface profiler measurement. The investigation shows that 20 seconds is the optimal etching time for producing the desired FSS circular slot structure compared to 40 and 60 seconds. The fabricated samples surface metrology was examined using an optical microscope, Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscope (AFM). The material compositions of the samples were confirmed by using the Energy Dispersive X-ray (EDX) measurement. Results show that, on average, there are ±1.5 μm of tolerance produced for fabricated sample size on the circular slot pattern compared to the CST simulation results. FSS performance slightly shifted in the frequency from actual 1.80 THz to 1.79 THz, whereas the transmission magnitude has increased by 0.03 from 0.91 to 0.94.
Terahertz radiation is in spectral region of 0.1THz to 10THz between microwave and infrared part of the electromagnetic spectrum. Terahertz radiation can propagate through wide range of dielectric materials [1]. This sparked many researchers' interest to further explore the potentiality of characterization, detection and sensing studies at terahertz range. Recently, Terahertz Time-Domain Spectroscopy has emerged as an attractive technique that enables the label-free detection on chemical and biological compounds [2]. It is because, the most of non-conductive materials such as chemical and biological compounds have unique molecular resonance that able to translate as transmission or absorption peak at terahertz range. Past studies show that, terahertz spectroscopy is more suitable in sensing, detection and characterization of various forms of material state, such as illicit drugs and explosive substances, alcohol and antibiotics contents, fructose
Magnetic induction tomography is an imaging
technique used to image electromagnetic properties of an object
by using the eddy current effect. (MIT) is a non-destructive
method that greatly is used in the agriculture industry. This
method provided an opportunity to improve the quality of
agricultural products. MIT simulation was used for agarwood
existence detection. This paper presented for the simulation
system contains 7 channel coils receiver and a channel transmitter
which is a sensing detector. This experiment aims to demonstrate
the reaction of induced current density and magnetic field at 10
MHz frequency. Then, it also determines the optimal solenoid coil
to be used for a better outcome for the magnetic induction system.
The simulation result shows that coil diameter, coil length, and
coil layer have a crucial role in the great performance of the
induced current and magnetic field. The more coil turns, the
greater the strength of the permanent magnetic field around the
solenoid coil. The result of the simulation is important and needs
to be considered to verify the effectiveness of the system for
developing the magnetic induction circuit design.
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