Abstract: A termination for a coaxial transmission line wherein an elongated central conductor is located in an enclosure or housing and is surrounded by a plurality of elongated resistor tubes. The central conductor is connected to the inner conductor of the transmission line and the resistor elements are connected to the outer conductor. The housing defines an inner flow chamber and a plurality of outer flow passages surrounding the inner flow chamber with the upper ends thereof communicating with the upper end of the inner flow chamber. A centrifugal blower is located at the bottom of each of the outer flow passages to generate an air flow upwardly and then through lateral ports into the upper end of the inner flow chamber, whereupon a flow proceeds downwardly in a turbulent vortex through the inner flow chamber to cool the resistor elements.

Abstract: A high power water load for microwave and millimeter wave radio frequency sources has a front wall including an input port for the application of RF power, a cylindrical dissipation cavity lined with a dissipating material having a thickness which varies with depth, and a rear wall including a rotating reflector for the reflection of wave energy inside the cylindrical cavity. The dissipation cavity includes a water jacket for removal of heat generated by the absorptive material coating the dissipation cavity, and this absorptive material has a thickness which is greater near the front wall than near the rear wall. Waves entering the cavity reflect from the rotating reflector, impinging and reflecting multiple times on the absorptive coating of the dissipation cavity, dissipating equal amounts of power on each internal reflection.

Abstract: A billet of low-density carbon-bonded carbon fiber (CBCF) composite is machined into a desired attenuator or load element shape (usually tapering). The CBCF composite is used as a free-standing load element or, preferably, brazed to the copper, brass or aluminum components of coaxial transmission lines or microwave waveguides. A novel braze method was developed for the brazing step. The resulting attenuator and/or load devices are robust, relatively inexpensive, more easily fabricated, and have improved performance over conventional graded-coating loads.

Abstract: The power loads in certain applications such as dummy antennas must have a substantially constant impedance in a wide band of frequencies. The power load is air-cooled and its resistive element is constituted by the series-connection of resistor modules made of expanded metal. Capacitors are positioned in a branching connection on the resistive element. The positioning of the capacitors along the resistive element and their value are determined to ensure frequency compensation.

Abstract: A matched or dummy load for a microwave dryer having a microwave generator and a microwave applicator. The matched load includes a waveguide having opposed broad walls, opposed narrow walls, and an end wall defining a waveguide chamber. A power absorbing body made of sintered silicon carbide, casted silicon carbide, or other materials is disposed in the waveguide chamber. One or more of the walls includes means for transferring heat from the power absorbing body. A housing or shroud having an inlet and an outlet surrounds the waveguide. The means for removing heat is disposed between the inlet and outlet of the housing so that a cooling medium passed through the housing removes heat from the power absorbing body. A tuning stub is placed in front of the power absorbing body to reduce microwave reflections.

Abstract: A quasi-optical component for microwave radiation comprises a quasi-optical element (16a) which radiates incident microwave radiation along a major axis (19) and which has a characteristic transverse dimension (D) which is smaller than 50-times one wavelength. It is distinguished by the fact that a cooled absorption device (17) is provided which is arranged closely in front of the quasi-optical element (16a) in such a manner that at least one high-power secondary peak (20) of the diffraction due to the characteristic transverse dimension is destroyed.

Abstract: A liquid cooled adjustable waveguide termination for use in high power applications is described. The liquid cooled adjustable termination includes a waveguide housing having a shorting plate disposed at an end portion of the housing and an electromagnetic energy absorbent element disposed within the waveguide. The absorbent element includes a hollow tube disposed within a bore of the element for providing the liquid coolant to an inner portion of the element. The termination further includes a flow header assembly for providing coolant to the absorbent element via the hollow tube and for directing the heated coolant out of the termination assembly, and an adjustable seal plate disposed between the flow header assembly and the shorting plate for adjusting the position of the electromagnetic energy absorbent element within the waveguide.

Abstract: The invention relates to a cooling device for circuit configurations in which high electrical energies are converted and specifically for electrical matching circuits with which the impedance of a plasma path is matched to a high frequency generator. Herein one or several coils are provided with a water cooling system in such a way that the cooling water is completely separated from the electromagnetic fields through metallic material. These coils consist of two tubes slid one into the other, wherein the cooling water is fed and drawn through the internal tube and between the two tubes so that it is completely within the field-free region.

Abstract: A dummy load for a radio frequency transmitter uses a resistive liquid within a tube of non-conducting material as the load. The tube has grounded conductors at each end, and a centrally-located terminal that provides a load, with respect to ground, across two parallel branches. The output of the radio frequency transmitter is applied between the centrally-located terminal and ground. The ends of the tube are connected into a closed liquid loop that includes a temperature controlling system with a circulating pump, a heater for raising the temperature of the resistive liquid to a given, operating level, if necessary, and a heat exchanger for lowering the temperature of the resistive liquid to the given, operating level, when necessary; whereby the heat generated by the output of the transmitter can be dissipated, and the temperature of the resistive liquid, within the tube, kept at a constant mean temperature to provide a constant resistance under all load conditions.

Abstract: A microwave oven particularly suitable for laboratory analytical use is described. The oven is designed for chemical digestion and the drying of materials to very low moisture levels. The oven utilizes a rotating platform to move the material being subjected to microwave radiation through the oven chamber to ensure uniform contact of the microwaves with the material. Radiation mixers and radiation isolators are also used to disperse radiation in the oven and absorb excess radiation.

Abstract: A waveguide device for producing absorption or attenuation includes a waveguide section which is provided with an external absorber material. For allowing a transfer of the high-frequency power into the absorber material, the wave section is provided with coupling apertures via which the absorber material is in connection with the interior of the waveguide section.

Abstract: A microwave absorber composed of dense silicon carbide having an electrical resistivity of one ohm-centimeter or more. In an electron linear accelerator, it is necessary to provide a microwave absorber to absorb excess energy used to accelerate electrons and discharge this excess energy in the form of heat in order for the accelerator to operate safely. The important characteristics are high-frequency wave absorption, good heat resistance, good thermal conductivity, and stability in a vacuum. The invention meets these requirements with a microwave absorber composed of dense silicon carbide. In an electron linear accelerator the absorber is attached to the end portion of an accelerator guide or a branch portion of a power divider to absorb unnecessary wave energy. Such a microwave absorber is found to have characteristics rendering it highly suitable for this application as well as others.

Abstract: A microwave absorber with a microwave-absorbing material, a protective hong surrounding this, and a waveguide leading into the protective housing, through which waveguide the microwaves to be absorbed can be conducted to the absorbing material, the microwave-absorbing material forming a solid body with a hollow, on one side of which the waveguide opens, a termination element being arranged on the side of the hollow opposite to the waveguide, and the housing being provided with an inlet and an outlet for a cooling fluid.

Abstract: A microwave calorimeter for very high power, with a housing, which surrou a feed chamber, into which a waveguide runs for feeding the microwaves, and an absorber-chamber which is separated from the feed chamber by a dielectric wall and contains a microwave-absorbing fluid, the fluid consisting at least in part of a compound whose capacity for the absorption of microwaves is less than that of water.

Abstract: A radio frequency coaxial vacuum feedthrough is provided which utilizes a cylindrical ceramic vacuum break formed of an alumina ceramic. The cylinder is coaxially disposed and brazed between tapered coaxial conductors to form a vacuum sealed connection between a pressurized upstream coaxial transmission line and a utilization device located within a vacuum container. The feedthrough provides 50 ohm matched impedance RF feedthrough up to about 500 MHz at power levels in the multimegawatt range.

Abstract: A microwave absorber, particularly, a microwave absorber intended for use in an electron beam accelerator, having an increased maximum power characteristic. The microwave absorber is formed of a body of dense silicon carbide having a hollow portion and a closed tip end portion. A pipe of high melting point glass or alumina is inserted into the hollow portion. Cooling water is guided through the pipe and circulated through the hollow portion of the body of the absorber.

Abstract: A modularized water load device for a microwave heat applicating unit comprising a resonator, a waveguide and a source of microwave energy. The constituent units or components of the water load device are arranged in a sandwich like manner to form a readily repairable/replaceable water load of a heat applicating device.

Abstract: A microwave power head or modular heat applicating unit comprising a resonator, a waveguide, a source of microwave energy and a water load device. The constituent units or modular components of the power head are arranged in a sandwich like manner to form a readily repairable/replaceable microwave heat applicating device.

Abstract: A calorimetric load for very high microwave power at very high frequencies is formed by a metallic, cylindrical chamber into which the wave-guide carrying the power opens. Inside the metallic cylinder is a coaxial dielectric cylinder, with a space between full of circulating wave-absorbing fluid such as water. The incoming wave may be in a higher-order mode. To make it disperse rapidly into the absorbing fluid, a conical reflector is located inside the dielectric cylinder to reflect the wave outward.

Abstract: A power absorbing termination for a waveguide transmission line comprised of a waveguide section containing a fluid carrying dielectric taper which is inclined relative to the waveguide axis so that the point end of the taper lies against the guidewall of the waveguide section. Fluid in the dielectric taper is preferably circulated around a center planar divider extended down the taper's axis; alternatively, fluid is circulated through the taper by inducing a spiral flow of fluid in the taper hollow.

Abstract: An improved system is described for cooling high power waveguides by the use of cooling ducts extending along the waveguide, which minimizes hot spots at the flanges where waveguide sections are connected together. The cooling duct (24) extends along substantially the full length of the waveguide section, and each flange (18, 20) at the end of the section has a through hole (36) with an inner end connected to the duct and an opposite end that can be aligned with a flange hole in another waveguide section. Each flange (20) is formed with a drainage groove (60) in its face, between the through hole (36) and the waveguide conduit (16) to prevent leakage of cooling fluid into the waveguide. The ducts have narrowed sections (32, 34) immediately adjacent to the flanges to provide room for the installation of fasteners closely around the waveguide channel.

Abstract: A harmonic filtering device placed in a high frequency line connecting a radio transmitter to its load with at least one cell in parallel on the line, constituted by an anti-resonant circuit (at the transmission frequency of the transmitter) in series with a resistor, whose value is approximately 1/20th of the characteristic impedance of the line. This cell is made of a coaxial line with four conductors in which inset elements (short-circuit, capacitor, load) form the inductor and the capacitor of the anti-resonant circuit and the resistor. The resistor of this cell has no effect at the transmission frequency of the transmitter and creates insulation between the load and the transmitter for harmonic frequencies.

Abstract: Liquid rheostat system especially a water rheostat, employing the principle wherein electrical energy may be dissipated in the form of heat, by passing the electrical current through a liquid resistor or electrolyte, and wherein the apparatus is reasonably portable, inexpensive, and economical to operate and maintain. The invention readily compensates in use for variations in respective resistivity of fresh and/or brackish waters in a test mixture whereby to provide sufficient initial resistance as well as an adequate range of control of resistance, while maintaining current density within the desired limits. In use the heat energy developed is absorbed and removed by the controllable water mixture which in operation of the rheostat system continuously flows out of the rheostat.

Abstract: An electromagnetic energy dissipative load or attenuator is provided having a lossy section of waveguide transmission line of sufficient length to provide substantial loss and a transition section for adaption to other waveguide configurations. The transmission line is short circuited as a terminating load, and cooling means may be circulated adjacent to the waveguide for removal of the heat energy generated in the waveguide walls. A second transition section in place of the short circuit provides for a high power attenuator. The lossy waveguide section is coiled in either a flat spiral or concentric helical configuration. A fluid coolant may be circulated adjacent to or inside the lossy section coils.

Abstract: A microwave oven particularly suitable for laboratory analytical use is described. The oven is designed for chemical digestion and the drying of materials to very low moisture levels. The oven utilizes a rotating platform to move the material being subjected to microwave radiation through the oven chamber to ensure uniform contact of the microwaves with the material. Radiation mixers and radiation isolators are also used to disperse radiation in the oven and absorb excess radiation.