Abstract: A method of obtaining a material property of a pavement material from a microwave field generally includes generating a microwave frequency electromagnetic field of a first mode about the pavement material. The frequency response of the pavement material in the electromagnetic field can be measured, such as by a network analyzer. The measurement of the frequency response permits correlating the frequency response to a material property of the pavement material sample, such as the density. A method of correcting for the roughness of a pavement material divides the pavement into a shallow layer and a deep layer. Two planar microwave circuits measure the permittivity of the shallow and deep layer. The permittivities are correlated to correct for roughness. An apparatus for obtaining the density of a pavement sample includes a microwave circuit and a network analyzer. The network analyzer measures the frequency response to determine the density of the pavement material.

Abstract: A method of obtaining a material property of a pavement material from a microwave field generally includes generating a microwave frequency electromagnetic field of a first mode about the pavement material. The frequency response of the pavement material in the electromagnetic field can be measured, such as by a network analyzer. The measurement of the frequency response permits correlating the frequency response to a material property of the pavement material sample, such as the density. A method of correcting for the roughness of a pavement material divides the pavement into a shallow layer and a deep layer. Two planar microwave circuits measure the permittivity of the shallow and deep layer. The permittivities are correlated to correct for roughness. An apparatus for obtaining the density of a pavement sample includes a microwave circuit and a network analyzer. The network analyzer measures the frequency response to determine the density of the pavement material.

Abstract: An elliptical exposure chamber has an extended focal region. A plurality of cylindrical reactors (25) form the extended focal region. Reducing the size of the opening (58) to each reactor (25) reduces the amount of energy reflected and increases the overall heating. In order to efficiently deliver the electromagnetic energy to the reduced opening (58), a tapered waveguide (55) has a concave end (56). A power splitter (42) divides power from a central waveguide (52) to the plurality of reactors (25). The power that is delivered to each reactor (25) can be adjusted by adjusting the impedance of each reactor (25), the width of each reactor (25) or the width of the opening (58) to each reactor (25). The width of the opening (58) to each reactor (25) can be controlled by a movable metal plate (44). A dielectric wheel can be used to shift hot spots along the focal region.

Abstract: A device for heating a material utilizes a rectangular waveguide with an elongated opening for passing a planar material through the rectangular waveguide. A source creates an electric field between a top surface and a bottom surface of the rectangular waveguide. The electric field is controlled to compensate for attenuation of the electric field. The electric field can be controlled by, for example, using a dielectric slab along the top surface of the rectangular waveguide or a tapered dielectric slab along the top surface of the rectangular waveguide. The electric field can also be controlled by, for example, making the waveguide appear electrically wider at one end. The waveguide can be made to appear electrically wider at one end by, for example, inserting one or more tapered fins. The tapered fins can be adjusted or removed to account for the lossiness of the planar material.

Abstract: An elliptical exposure chamber has an extended focal region. A plurality of cylindrical reactors (25) form the extended focal region. Reducing the size of the opening (58) to each reactor (25) reduces the amount of energy reflected and increases the overall heating. In order to efficiently deliver the electromagnetic energy to the reduced opening (58), a tapered waveguide (55) has a concave end (56). A power splitter (42) divides power from a central waveguide (52) to the plurality of reactors (25). The power that is delivered to each reactor (25) can be adjusted by adjusting the impedance of each reactor (25), the width of each reactor (25) or the width of the opening (58) to each reactor (25). The width of the opening (58) to each reactor (25) can be controlled by a movable metal plate (44). A dielectric wheel can be used to shift hot spots along the focal region.

Abstract: A passive microwave component with constant impedance and electrically adjustable phase length utilizes a microstrip or stripline transmission line geometry incorporating a composite dielectric having both ferroelectric (FE) and ferromagnetic (FM) properties. These properties can be varied with externally applied electric and magnetic fields such that the phase length (or electrical length) of the line can be varied without varying the characteristic impedance of the transmission line. Thus, the component can be electrically tuned without adversely affecting the impedance match. The component can be used in microwave devices such as phase shifters, frequency filters, directional couplers, power dividers and combiners, and impedance-matching networks.

Abstract: A source provides an electromagnetic wave that has a range of frequencies. The source sweeps the frequency of the electromagnetic wave between a cutoff frequency and double the cutoff frequency. The location, angle, or effective angle of an opening is adjusted by an opening adjuster. A path for an electromagnetic wave has a short for creating a standing wave. The path has a movable surface that can push and pull the peaks and valleys of the standing wave so as to achieve more uniform heating of the material. A dielectric wheel pushes and pulls the peaks and valleys of a standing wave so as to achieve more uniform heating of a material. A dielectric structure has a surface that has a short side and a long side. A motor rotates the dielectric structure to push and pull the peaks and valleys of a standing wave so as to achieve more uniform heating of a material. A path has a first choke flange that has a width w1 and a second choke flange that has a width w2.

Abstract: A passive microwave component with constant impedance and electrically adjustable phase length utilizes a microstrip or stripline transmission line geometry incorporating a composite dielectric having both ferroelectric (FE) and ferromagnetic (FM) properties. These properties can be varied with externally applied electric and magnetic fields such that the phase length (or electrical length) of the line can be varied without varying the characteristic impedance of the transmission line. Thus, the component can be electrically tuned without adversely affecting the impedance match. The component can be used in microwave devices such as phase shifters, frequency filters, directional couplers, power dividers and combiners, and impedance-matching networks.

Abstract: A path for a material passes through an opening and along a segment through an off-peak region of an electric field. An E-plane bend delivers an electromagnetic wave to the segment. A standing wave is used to heat the material. The peaks or valleys are pushed or pulled by a movable surface or by changing the frequency of the electromagnetic wave. A rectangular choke flange is used at the opening to the segment. A curved segment connects the segment to another segment for heating the material. According to another aspect of the invention, a segment is used to heat just the edge of a planar material.

Abstract: An electromagnetic exposure chamber has an exterior conducting surface that forms an interior cavity. The exterior conducting surface has a first substantially planar surface, a second substantially planar surface, a first end, and a second end. The first end has an opening for an electromagnetic wave. The electromagnetic wave forms an electric field. The second end has an elliptical shape that directs the electromagnetic wave to a focal region that extends from the first substantially planar surface to the second substantially planar surface. A second opening through the top surface is aligned with the electromagnetic field. It is possible to pass a material through the second opening. If the opening is aligned with the focal region, the heating is increased. If the opening is aligned with a peak of the electromagnetic wave, the heating is increased and the need for dielectric slabs is decreased. A choke prevents the escape of electromagnetic energy.

Abstract: A source provides an electromagnetic wave that has a range of frequencies. The source sweeps the frequency of the electromagnetic wave between a cutoff frequency and double the cutoff frequency. The location, angle, or effective angle of an opening is adjusted by an opening adjuster. A path for an electromagnetic wave has a short for creating a standing wave. The path has a movable surface that can push and pull the peaks and valleys of the standing wave so as to achieve more uniform heating of the material. A dielectric wheel pushes and pulls the peaks and valleys of a standing wave so as to achieve more uniform heating of a material. A dielectric structure has a surface that has a short side and a long side. A motor rotates the dielectric structure to push and pull the peaks and valleys of a standing wave so as to achieve more uniform heating of a material. A path has a first choke flange that has a width w1 and a second choke flange that has a width w2.

Abstract: A path for a material passes through an opening and along a segment through an off-peak region of an electric field. An E-plane bend delivers an electromagnetic wave to the segment. A standing wave is used to heat the material. The peaks or valleys are pushed or pulled by a movable surface or by changing the frequency of the electromagnetic wave. A rectangular choke flange is used at the opening to the segment. A curved segment connects the segment to another segment for heating the material. According to another aspect of the invention, a segment is used to heat just the edge of a planar material.

Abstract: An electromagnetic exposure chamber has an exterior conducting surface that forms an interior cavity. The exterior conducting surface has a first substantially planar surface, a second substantially planar surface, a first end, and a second end. The first end has an opening for an electromagnetic wave. The electromagnetic wave forms an electric field. The second end has an elliptical shape that directs the electromagnetic wave to a focal region that extends from the first substantially planar surface to the second substantially planar surface. A second opening through the top surface is aligned with the electromagnetic field. It is possible to pass a material through the second opening. If the opening is aligned with the focal region, the heating is increased. If the opening is aligned with a peak of the electromagnetic wave, the heating is increased and the need for dielectric slabs is decreased. A choke prevents the escape of electromagnetic energy.

Abstract: A source provides an electromagnetic wave that has a range of frequencies. The source sweeps the frequency of the electromagnetic wave between a cutoff frequency and double the cutoff frequency. The location, angle, or effective angle of an opening is adjusted by an opening adjuster. A path for an electromagnetic wave has a short for creating a standing wave. The path has a movable surface that can push and pull the peaks and valleys of the standing wave so as to achieve more uniform heating of the material. A dielectric wheel pushes and pulls the peaks and valleys of a standing wave so as to achieve more uniform heating of a material. A dielectric structure has a surface that has a short side and a long side. A motor rotates the dielectric structure to push and pull the peaks and valleys of a standing wave so as to achieve more uniform heating of a material. A path has a first choke flange that has a width w1, and a second choke flange that has a width w2.

Abstract: A path for a material passes through an opening and along a segment through an off-peak region of an electric field. An E-plane bend delivers an electromagnetic wave to the segment. A standing wave is used to heat the material. The peaks or valleys are pushed or pulled by a movable surface or by changing the frequency of the electromagnetic wave. A rectangular choke flange is used at the opening to the segment. A curved segment connects the segment to another segment for heating the material. According to another aspect of the invention, a segment is used to heat just the edge of a planar material.

Abstract: A method and apparatus for heating fluids is disclosed. One or more receptacles for holding fluids are located in an interior cavity formed by an exterior conductive surface. In one embodiment, the receptacles are spaced from a side of the exterior conductive surface a distance equal to an odd multiple of 1/4 of a wavelength. In another embodiment, bases of the receptacles are spaced a distance equal to slightly less than an odd multiple of 1/4 of a wavelength from the bottom of the exterior conductive surface. In a further embodiment, a receptacle has a pointed base for enhancing the heating of fluids. Furthermore, receptacles can be formed with bases spaced an odd multiple of 1/4 of a wavelength from at least two adjacent sides of the exterior conductive surface. Receptacles can be formed in a platform that may be made to fit into preexisting electromagnetic heating chambers.

Abstract: The present invention utilizes dielectric slabs to provide a relatively uniform electromagnetic field to a cavity between two or more dielectric slabs. Each dielectric slab is a thickness equal to or nearly equal to a quarter of a wavelength of the electromagnetic field in the dielectric slab. In a particular embodiment, sample material is introduced into the cavity between the two dielectric slabs. This sample material may be introduced through one or more openings in the dielectric slabs. In further embodiments, specialized choke flanges prevent the leakage of energy from this cavity. In a preferred embodiment, an elliptical conducting surface directs the electromagnetic field to a focal region between the two dielectric slabs. Openings to this focal region allow sample material to be passed through this region of focused heating.

Abstract: The present invention overcomes many of the problems associated with electromagnetic exposure of planar materials. A diagonal slot compensates for the effects of signal attenuation along the propagation path. Adjustably variable path lengths allow peaks and valleys of the electromagnetic field in one exposure segment to compensate for peaks and valleys in another exposure segment. Dielectric slabs may be used to extend the peak field region between top and bottom conducting surfaces to allow for more uniform exposure of planar materials that have a significant thickness. Specialized choke flanges prevent the escape of electromagnetic energy. One or more rollers between exposure segments may be enclosed by an outer surface to prevent the escape of electromagnetic energy.

Abstract: The present invention utilizes dielectric slabs to provide a relatively uniform electromagnetic field to a cavity between two or more dielectric slabs. Each dielectric slab is a thickness equal to or nearly equal to a quarter of a wavelength of the electromagnetic field in the dielectric slab. In a particular embodiment, sample material is introduced into the cavity between the two dielectric slabs. This sample material may be introduced through one or more openings in the dielectric slabs. In further embodiments, specialized choke flanges prevent the leakage of energy from this cavity. In a preferred embodiment, an elliptical conducting surface directs the electromagnetic field to a focal region between the two dielectric slabs. Openings to this focal region allow sample material to be passed through this region of focused heating.

Abstract: The present invention overcomes many of the problems associated with electromagnetic exposure of planar materials. A diagonal slot compensates for the effects of signal attenuation along the propagation path. Adjustably variable path lengths allow peaks and valleys of the electromagnetic field in one exposure segment to compensate for peaks and valleys in another exposure segment. Dielectric slabs may be used to extend the peak field region between top and bottom conducting surfaces to allow for more uniform exposure of planar materials that have a significant thickness. Specialized choke flanges prevent the escape of electromagnetic energy. One or more rollers between exposure segments may be enclosed by an outer surface to prevent the escape of electromagnetic energy.