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Figure 12 – uploaded by Dr Mihai Stelian Daian

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nagnetic field parallel to the axis and hence perpendicular to the anode cathode electri

Figure 12 nagnetic field parallel to the axis and hence perpendicular to the anode cathode electri

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wave-like solutions. Maxwell knew that the wave-like solutions of the equations of gas
wave-like solutions. Maxwell knew that the wave-like solutions of the equations of gas
wave propagation. magnetic field are vectors always perpendicular to each other and to the direction of The velocity (c ) with which the wave propagates along the z -axis is given by
wave propagation. magnetic field are vectors always perpendicular to each other and to the direction of The velocity (c ) with which the wave propagates along the z -axis is given by
Depending on the dielectric properties of material, its geometry and the
Depending on the dielectric properties of material, its geometry and the
D_, does not mean that there is no heating at a depth exceeding the penetration depth. The heat dissipated in the layer bounded by the surface and the plane at depth D the power density reduces to 1/e (= 0.368) of its surface value (Metaxas and Meredith material. The penetration depth, D, is defined as the depth into the material at which grater than D, (Meredith 1998). penetration depth is one of the factors which determines the heat distribution within Besides the material properties such as thermal and heat conductivity, the
D_, does not mean that there is no heating at a depth exceeding the penetration depth. The heat dissipated in the layer bounded by the surface and the plane at depth D the power density reduces to 1/e (= 0.368) of its surface value (Metaxas and Meredith material. The penetration depth, D, is defined as the depth into the material at which grater than D, (Meredith 1998). penetration depth is one of the factors which determines the heat distribution within Besides the material properties such as thermal and heat conductivity, the
——————— Microwave processing could offer a powerful material-processing tool to wood industry Microwave processing could offer a powerful material-processing tool to wood industry
——————— Microwave processing could offer a powerful material-processing tool to wood industry Microwave processing could offer a powerful material-processing tool to wood industry
Figure 5: Physical model of microwave heating of wood (Daian 2005)
Figure 5: Physical model of microwave heating of wood (Daian 2005)
generally adopted for examinations of wood structure (Figure 6). and electrical properties are distinguished and different in the three directions which are
generally adopted for examinations of wood structure (Figure 6). and electrical properties are distinguished and different in the three directions which are
on the heels of the earlier (1938) invention of the Klystron - Figure 8. 940s with the invention, rapid development and deployment of the cavity magnetron
on the heels of the earlier (1938) invention of the Klystron - Figure 8. 940s with the invention, rapid development and deployment of the cavity magnetron
nductance (L), resistance (R) and conductance (G), is considered - Figure 13. Figure 13: Equivalent circuit of a transmission line (Laverghetta, 1988)
nductance (L), resistance (R) and conductance (G), is considered - Figure 13. Figure 13: Equivalent circuit of a transmission line (Laverghetta, 1988)
frequency range, conducting pipes have either a rectangular or a circular cross section. propagating and channelling electromagnetic energy - Figure 15. In the microwave
frequency range, conducting pipes have either a rectangular or a circular cross section. propagating and channelling electromagnetic energy - Figure 15. In the microwave
TM waves, respectively, can be expressed in terms of 4, and k,, such as:
TM waves, respectively, can be expressed in terms of 4, and k,, such as:
azimuthal component, Hy, (all fields are transverse) - Figure 19. It is an approximation
azimuthal component, Hy, (all fields are transverse) - Figure 19. It is an approximation
network, it has four S-parameters (Figure 20). The S-parameters for a two-port network are defined using the reflected or scattering or S-parameters. The number of S-parameters for a given device is equal to
network, it has four S-parameters (Figure 20). The S-parameters for a two-port network are defined using the reflected or scattering or S-parameters. The number of S-parameters for a given device is equal to
with a perfect termination placed at the output (Figure 22). Figure 22: Measuring S-parameters (Agilent Technologies 2000) termined by taking the ratio of the reflected or transmitted wave to the incident wave
with a perfect termination placed at the output (Figure 22). Figure 22: Measuring S-parameters (Agilent Technologies 2000) termined by taking the ratio of the reflected or transmitted wave to the incident wave
Figure 24: Reflection parameters (Agilent Technologies 2000) The vector and scalar expressions of the reflection waves are presented in In the same manner, the most common transmission parameters are described
Figure 24: Reflection parameters (Agilent Technologies 2000) The vector and scalar expressions of the reflection waves are presented in In the same manner, the most common transmission parameters are described
Figure 26: Reflected and transmitted electric field diagram (ScienceWorld 2006) denoted r, and f, respectively.
Figure 26: Reflected and transmitted electric field diagram (ScienceWorld 2006) denoted r, and f, respectively.
where n, and n, are the index of refraction of the original and dielectric medium. The dielectric and transmitted through a dielectric for TE radiation: The coefficients give the amount of the electromagnetic wave reflected from a
where n, and n, are the index of refraction of the original and dielectric medium. The dielectric and transmitted through a dielectric for TE radiation: The coefficients give the amount of the electromagnetic wave reflected from a
pecause their design needs to match with the proposed application.
pecause their design needs to match with the proposed application.
Figure 29: Schematic representation of a microwave conveyorised system fitted with
Figure 29: Schematic representation of a microwave conveyorised system fitted with
radiation that might be reaching you decreases dramatically. Figure 30: Australian standard AS2772.1-1990 radio frequency radiation (Standards 1S you move away from a microwave power source, the level of any leaking microwave
radiation that might be reaching you decreases dramatically. Figure 30: Australian standard AS2772.1-1990 radio frequency radiation (Standards 1S you move away from a microwave power source, the level of any leaking microwave
Figure 31: Cross section of idealised corrugated choke (Welsh and Capstick 2001) The attenuation per section of such a structure is given by the equation:
Figure 31: Cross section of idealised corrugated choke (Welsh and Capstick 2001) The attenuation per section of such a structure is given by the equation:
comprising a microwave transparent material covering the first layer. bonded to at least a portion of the inner surface of this tunnel and a second layer
comprising a microwave transparent material covering the first layer. bonded to at least a portion of the inner surface of this tunnel and a second layer
Radiata Pine, and gives even modification through the timber cross-section. This applicator is able to preheat the timber is good for producing Vintorg from
Radiata Pine, and gives even modification through the timber cross-section. This applicator is able to preheat the timber is good for producing Vintorg from
applicator surfaces is needed along with thorough cleaning after use. Careful observation and attention is required when using both of these
applicator surfaces is needed along with thorough cleaning after use. Careful observation and attention is required when using both of these
modification can be estimated with better accuracy than in the tunnel applicator.
modification can be estimated with better accuracy than in the tunnel applicator.
Electromagnetic Modelling of Microwave Equipment and Processes *Also distributed by Vector Fields, Inc. under the name Concerto,’Optimization Systems Associates, Inc. (1983-1997),°By Altair Engineering, Inc., www.altair.co ,“Engineous Software, www.engineous.com
Electromagnetic Modelling of Microwave Equipment and Processes *Also distributed by Vector Fields, Inc. under the name Concerto,’Optimization Systems Associates, Inc. (1983-1997),°By Altair Engineering, Inc., www.altair.co ,“Engineous Software, www.engineous.com
desired result of the modeling or sometimes by the designer experience. Figure 39: CST MWS solvers (Computer Simulation Technology 2005) oy the Q factor. However the lines cannot be precisely drawn and it depends on the
desired result of the modeling or sometimes by the designer experience. Figure 39: CST MWS solvers (Computer Simulation Technology 2005) oy the Q factor. However the lines cannot be precisely drawn and it depends on the
through which moisture may readily move (CRC Wood Innovation 2003).
through which moisture may readily move (CRC Wood Innovation 2003).
to the maximum power loss of each distribution.
to the maximum power loss of each distribution.
Figure 43: Dependence of the peak energy intensity on tunnel size plotted in Figure 43.
Figure 43: Dependence of the peak energy intensity on tunnel size plotted in Figure 43.
Reducing the Energy Reflection from Applicator... Figure 46: EM radiation incident to the wood surface at Brewster’s angle (Wikipedia,
Reducing the Energy Reflection from Applicator... Figure 46: EM radiation incident to the wood surface at Brewster’s angle (Wikipedia,
Figure 47: Brewster’s angle calculation (for zero reflected power from wood) basically from the engineering and manufacturing point of view.
Figure 47: Brewster’s angle calculation (for zero reflected power from wood) basically from the engineering and manufacturing point of view.
Reducing the Energy Reflection from Applicator...
Reducing the Energy Reflection from Applicator...
Reducing the Energy Reflection from Applicator...
Reducing the Energy Reflection from Applicator...
cl) One applicator (left hand side) E field parallel - One applicator (right hand side) E Reducing the Energy Reflection from Applicator...
cl) One applicator (left hand side) E field parallel - One applicator (right hand side) E Reducing the Energy Reflection from Applicator...
the water flow absorbs around 99 % percent of the input power. Figure 52 : Schematically representation of the basic water trap device In this particular case, for an applied incident power of 1 kW, it was found that
the water flow absorbs around 99 % percent of the input power. Figure 52 : Schematically representation of the basic water trap device In this particular case, for an applied incident power of 1 kW, it was found that
material within the cavities (top; bottom; left + right sides; top + bottom + left + right) n Figure 54 where 1, 2, 3 and 4 represents four different locations of the absorbing
material within the cavities (top; bottom; left + right sides; top + bottom + left + right) n Figure 54 where 1, 2, 3 and 4 represents four different locations of the absorbing
Figure 56: Experimental setup of the water trap-microwave leakage suppressor
Figure 56: Experimental setup of the water trap-microwave leakage suppressor
Figure 57: Modelling of band stop filter devices: a) 43x86 mm applicator and S11/S21
Figure 57: Modelling of band stop filter devices: a) 43x86 mm applicator and S11/S21
Figure 58 : Microwave reflective device
Figure 58 : Microwave reflective device
below.
below.
Figure 60: Graphical representation of water trap reflective device - computer modelling: a) view of water absorbing tubes, b) view of absorbing cavities
Figure 60: Graphical representation of water trap reflective device - computer modelling: a) view of water absorbing tubes, b) view of absorbing cavities
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Environmental ScienceElectromagnetic Fields and Microwave TechniquesTimber EngineeringDesign and Analysis of Microstrip FiltersAnalysis and Implementation
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