Lee Yeng Seng received his Bachelor's degree in Communication Engineering (Honours) degree and Ph.D. in communication engineering from the School of Computer and Communication Engineering at UniMAP, Malaysia. He is currently being a senior lecturer at the Faculty of Engineering Technology, Universiti Malaysia Perlis (UniMAP). He also a member of IET and IEEE. His research interests include Food security, Dielectric Material Characterization, Microwave Absorber, Electromagnetic. Address: Malaysia
One of the parameters that affect the performance of microwave absorbers is the shape of the abso... more One of the parameters that affect the performance of microwave absorbers is the shape of the absorbers. This paper shows the performance (reflection loss) of truncated pyramidal and truncated wedge microwave absorbers in the range frequency between 8.2 to 12.4 GHz (X-Band) in simulation. The material used is sugarcane bagasse (SCB) which is one of the new materials that used to fabricate the microwave absorber. The complex permittivity was measured using Agilent dielectric probe technique. The designs were simulated using CST Microwave Studio Software. The reflection losses between these two shapes were compared.
This study presents the miniaturization of two-section branch microstrip lines coupler using the ... more This study presents the miniaturization of two-section branch microstrip lines coupler using the slow-wave technique. Regular and miniature branch-line couplers operating at 2.4 GHz are designed, fabricated, tested, and compared. Up to 38% reduced size of the miniature coupler is achieved compared to the conventional coupler. The miniaturized coupler is capable of operating from 1.85 to 3.2 GHz with a bandwidth of 1.35 GHz. Overall, the simulation and measurement results demonstrated a good agreement.
2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL), 2017
This study was conducted to investigate the feasibility of microwave dielectric spectroscopic tec... more This study was conducted to investigate the feasibility of microwave dielectric spectroscopic technique in characterizing commercial rice due to different level of moisture content. There are some unethical rice industry runner mixes good qualities of rice which can be sold at high price with low cost and quality of rice to maximize profit. It causes fraudulency in business and great lost in term of money to nation who take rice as staple food. It happens frequently in Asian country which is active in agricultural activities. This technique is implemented using Keysight E8362B network analyzer in conjunction with an Keysight 85070E dielectric probe ranging from 200 MHz to 10 GHz. The samples of study are commercially available at market, namely fragrant rice, white rice, and brown rice, respectively. These are the popular and favorite rice for Malaysian due its delicacy and affordable price. Nutrient level for fragrant rice, white rice, and brown rice in terms of protein, moisture, ...
The interest of the portable microwave instrument system has grown rapidly in recent years. Thus,... more The interest of the portable microwave instrument system has grown rapidly in recent years. Thus, Six-Port Reflectometer (SPR) is proposed. SPR provides a simple and inexpensive solution to industrial need of network analyzer. This paper presents the design of the multiple frequencies microstrip Five-Port ring junction which has operating frequencies of 0.37 GHz, 1.40 GHz, 2.10 GHz, 3.10 GHz and 3.80 GHz. The simulation result exhibit optimum specifications and less mismatch error.
This paper presents the new design of simple one layer ultrathin metamaterial microwave absorber ... more This paper presents the new design of simple one layer ultrathin metamaterial microwave absorber using coconut coir fibre as the substrate. The metamaterial microwave absorber is composed of a periodic array of square loops and patches with circle cut out printed on a dielectric material which is coconut coir fibre backed by PEC. CST Microwave Studio software is used for the design and simulation over frequency range of X-Band and Ku-Band (8.2–18 GHz). From the simulation result, 90% absorption was achieved in the frequency range of 8.94 – 10.0 GHz (X-Band) with highest absorption of 99.7% at 9.37 GHz. Furthermore, the metamaterial microwave absorber has a total thickness of 1.6 mm which is only approximately 0.04λ at lowest frequency. The result shows that coconut coir fibre from the agricultural waste has a great potential to be developed further in electromagnetic wave applications particularly microwave absorber.
Abstract—This paper presents the electromagnetic interference (EMI) shielding effectiveness of ri... more Abstract—This paper presents the electromagnetic interference (EMI) shielding effectiveness of rice husk and carbon nanotubes (RHCNTs) composites in the X-band region (8.2-12.4 GHz). The difference weight ratio of carbon nanotubes (CNTs) were mix with the rice husk. The rectangular waveguide technique was used to measure the complex permittivity of the RHCNTs composites materials. The complex permittivity is represented in terms of both the real and imaginary parts of permittivity in X-band frequency. The conductivity of RHCNTs shows increasing when the ratio of CNTs mixture increases. The composites materials were simulated using Computer Simulation Technology (CST) Microwave Studio simulation software. The shielding effectiveness of RHCNTs and pure rice husk was compared. The highest EMI SE of 30 dB is obtained for RHCNTs composites of 10 wt % CNTs with 10mm thickness.
In this paper, rice husk (RH) and multi-walled carbon nanotubes (MWCNTs) composite have been fabr... more In this paper, rice husk (RH) and multi-walled carbon nanotubes (MWCNTs) composite have been fabricated as single layer microwave absorber. The MWCNTs with various weight ratio composites with RH have been prepared. Three different weight ratio 3 wt% MWCNTs, 5 wt% MWCNTs, and 15 wt% MWCNTs of the RH-CNTs have been designed and fabricated. Moreover, the dielectric properties of different RH-CNTs specimens have been verified by using rectangular waveguide transmission line technique. Furthermore, the microwave absorption of these RH-CNTs has been analyzed using free space measurement and CST microwave Studio (CST-MWS). The dielectric properties and microwave absorption of different RH-CNTs were investigated in 8.2-12.4 GHz (X-band). By the measurement, the dielectric properties parameter of RH-CNTs is analyzed. Â The dielectric constant and loss factor of the RH-CNTs composite increased with increasing in MWCNTs weight ratio. However, the magnetic properties of RH-CNTs remain constant,...
This paper presents a calculation of the dielectric properties of low-loss materials using the tr... more This paper presents a calculation of the dielectric properties of low-loss materials using the transmission phase-shift method. This method can provide calibration-independent and position-insensitive features, and it was verified experimentally by measuring several well-known samples using X-band rectangular waveguides.
This paper is to study the dielectric properties, magnetic properties, and dielectric conductivit... more This paper is to study the dielectric properties, magnetic properties, and dielectric conductivity of Multi-walled carbon nanotubes (MWCNTs) and polyester (PE) composites. The composites with different amount of MWCNTs (5-15%) have been studied in the Ku-Band range (12.4-18 GHz). The rectangular waveguide (WR-62) was used to measure the dielectric properties and magnetic properties of the samples. The results show the dielectric properties and conductivity of MWCNTs/PE composites is increasing with the MWCNTs filler increases. The real part of dielectric properties values increase from 5.5 to 26.6 with increasing the MWCNTs loading from 5 % to 15 %. The increasing of MWCNTs filler in the MWCNTs/PE composites does not effects on magnetic properties, the real part and imaginary part of magnetic properties are approximate to 1 and 0. The highest conductivity of 15 % MWCNTs loading is reach to 11.02 (S/m) at 18 GHz. Keywords: composites, dielectric properties, magnetic properties, condu...
This chapter reviews the microwave complex ratio measuring (MCRM) circuits which are used for com... more This chapter reviews the microwave complex ratio measuring (MCRM) circuits which are used for complex reflection coefficient measurement. This MCRM circuit is relatively simple and cost-effective. There are various structures for the MCRM circuit, such as multi-probe transmission line circuits, five-port ring circuits, six-port hybrid coupler-based circuits, switched-reflector circuits, dual-generator circuits, and Wheatstone bridge-based circuits. Each structure of the circuits has its own advantages and disadvantages. In this chapter, the MCRM circuit calibration process has been described in detail.
One of the parameters that affect the performance of microwave absorbers is the shape of the abso... more One of the parameters that affect the performance of microwave absorbers is the shape of the absorbers. This paper shows the performance (reflection loss) of truncated pyramidal and truncated wedge microwave absorbers in the range frequency between 8.2 to 12.4 GHz (X-Band) in simulation. The material used is sugarcane bagasse (SCB) which is one of the new materials that used to fabricate the microwave absorber. The complex permittivity was measured using Agilent dielectric probe technique. The designs were simulated using CST Microwave Studio Software. The reflection losses between these two shapes were compared.
This study presents the miniaturization of two-section branch microstrip lines coupler using the ... more This study presents the miniaturization of two-section branch microstrip lines coupler using the slow-wave technique. Regular and miniature branch-line couplers operating at 2.4 GHz are designed, fabricated, tested, and compared. Up to 38% reduced size of the miniature coupler is achieved compared to the conventional coupler. The miniaturized coupler is capable of operating from 1.85 to 3.2 GHz with a bandwidth of 1.35 GHz. Overall, the simulation and measurement results demonstrated a good agreement.
2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL), 2017
This study was conducted to investigate the feasibility of microwave dielectric spectroscopic tec... more This study was conducted to investigate the feasibility of microwave dielectric spectroscopic technique in characterizing commercial rice due to different level of moisture content. There are some unethical rice industry runner mixes good qualities of rice which can be sold at high price with low cost and quality of rice to maximize profit. It causes fraudulency in business and great lost in term of money to nation who take rice as staple food. It happens frequently in Asian country which is active in agricultural activities. This technique is implemented using Keysight E8362B network analyzer in conjunction with an Keysight 85070E dielectric probe ranging from 200 MHz to 10 GHz. The samples of study are commercially available at market, namely fragrant rice, white rice, and brown rice, respectively. These are the popular and favorite rice for Malaysian due its delicacy and affordable price. Nutrient level for fragrant rice, white rice, and brown rice in terms of protein, moisture, ...
The interest of the portable microwave instrument system has grown rapidly in recent years. Thus,... more The interest of the portable microwave instrument system has grown rapidly in recent years. Thus, Six-Port Reflectometer (SPR) is proposed. SPR provides a simple and inexpensive solution to industrial need of network analyzer. This paper presents the design of the multiple frequencies microstrip Five-Port ring junction which has operating frequencies of 0.37 GHz, 1.40 GHz, 2.10 GHz, 3.10 GHz and 3.80 GHz. The simulation result exhibit optimum specifications and less mismatch error.
This paper presents the new design of simple one layer ultrathin metamaterial microwave absorber ... more This paper presents the new design of simple one layer ultrathin metamaterial microwave absorber using coconut coir fibre as the substrate. The metamaterial microwave absorber is composed of a periodic array of square loops and patches with circle cut out printed on a dielectric material which is coconut coir fibre backed by PEC. CST Microwave Studio software is used for the design and simulation over frequency range of X-Band and Ku-Band (8.2–18 GHz). From the simulation result, 90% absorption was achieved in the frequency range of 8.94 – 10.0 GHz (X-Band) with highest absorption of 99.7% at 9.37 GHz. Furthermore, the metamaterial microwave absorber has a total thickness of 1.6 mm which is only approximately 0.04λ at lowest frequency. The result shows that coconut coir fibre from the agricultural waste has a great potential to be developed further in electromagnetic wave applications particularly microwave absorber.
Abstract—This paper presents the electromagnetic interference (EMI) shielding effectiveness of ri... more Abstract—This paper presents the electromagnetic interference (EMI) shielding effectiveness of rice husk and carbon nanotubes (RHCNTs) composites in the X-band region (8.2-12.4 GHz). The difference weight ratio of carbon nanotubes (CNTs) were mix with the rice husk. The rectangular waveguide technique was used to measure the complex permittivity of the RHCNTs composites materials. The complex permittivity is represented in terms of both the real and imaginary parts of permittivity in X-band frequency. The conductivity of RHCNTs shows increasing when the ratio of CNTs mixture increases. The composites materials were simulated using Computer Simulation Technology (CST) Microwave Studio simulation software. The shielding effectiveness of RHCNTs and pure rice husk was compared. The highest EMI SE of 30 dB is obtained for RHCNTs composites of 10 wt % CNTs with 10mm thickness.
In this paper, rice husk (RH) and multi-walled carbon nanotubes (MWCNTs) composite have been fabr... more In this paper, rice husk (RH) and multi-walled carbon nanotubes (MWCNTs) composite have been fabricated as single layer microwave absorber. The MWCNTs with various weight ratio composites with RH have been prepared. Three different weight ratio 3 wt% MWCNTs, 5 wt% MWCNTs, and 15 wt% MWCNTs of the RH-CNTs have been designed and fabricated. Moreover, the dielectric properties of different RH-CNTs specimens have been verified by using rectangular waveguide transmission line technique. Furthermore, the microwave absorption of these RH-CNTs has been analyzed using free space measurement and CST microwave Studio (CST-MWS). The dielectric properties and microwave absorption of different RH-CNTs were investigated in 8.2-12.4 GHz (X-band). By the measurement, the dielectric properties parameter of RH-CNTs is analyzed. Â The dielectric constant and loss factor of the RH-CNTs composite increased with increasing in MWCNTs weight ratio. However, the magnetic properties of RH-CNTs remain constant,...
This paper presents a calculation of the dielectric properties of low-loss materials using the tr... more This paper presents a calculation of the dielectric properties of low-loss materials using the transmission phase-shift method. This method can provide calibration-independent and position-insensitive features, and it was verified experimentally by measuring several well-known samples using X-band rectangular waveguides.
This paper is to study the dielectric properties, magnetic properties, and dielectric conductivit... more This paper is to study the dielectric properties, magnetic properties, and dielectric conductivity of Multi-walled carbon nanotubes (MWCNTs) and polyester (PE) composites. The composites with different amount of MWCNTs (5-15%) have been studied in the Ku-Band range (12.4-18 GHz). The rectangular waveguide (WR-62) was used to measure the dielectric properties and magnetic properties of the samples. The results show the dielectric properties and conductivity of MWCNTs/PE composites is increasing with the MWCNTs filler increases. The real part of dielectric properties values increase from 5.5 to 26.6 with increasing the MWCNTs loading from 5 % to 15 %. The increasing of MWCNTs filler in the MWCNTs/PE composites does not effects on magnetic properties, the real part and imaginary part of magnetic properties are approximate to 1 and 0. The highest conductivity of 15 % MWCNTs loading is reach to 11.02 (S/m) at 18 GHz. Keywords: composites, dielectric properties, magnetic properties, condu...
This chapter reviews the microwave complex ratio measuring (MCRM) circuits which are used for com... more This chapter reviews the microwave complex ratio measuring (MCRM) circuits which are used for complex reflection coefficient measurement. This MCRM circuit is relatively simple and cost-effective. There are various structures for the MCRM circuit, such as multi-probe transmission line circuits, five-port ring circuits, six-port hybrid coupler-based circuits, switched-reflector circuits, dual-generator circuits, and Wheatstone bridge-based circuits. Each structure of the circuits has its own advantages and disadvantages. In this chapter, the MCRM circuit calibration process has been described in detail.
Uploads
Papers by YENG SENG LEE