Travelling Wave Applicators
Travelling-wave applicators generally consist of a length of microwave transmission line, such as a rectangular waveguide, along which the microwave energy propagates. The material to be heated is introduced directly into the transmission line via a "choked" input and output opening. The advantages of travelling wave applicators are that very good heating uniformity can be achieved and the size of the applicator can be made small relative to multi-moded cavities or ovens. Travelling wave applicators are usually used in continuous processing applications.
Examples of travelling wave applicators are meander lines (pictured) and straight sections of rectangular or circular waveguide.
Microwave New Zealand designs and builds travelling wave applicators to suit the requirements of your particular process. All of our continuous processing applicators have choked input and output "vestibules" that reduce any radiated microwave energy to well below the legally allowable levels.
Contact us to discuss your problems, ideas, or needs.
Multi-moded Cavities or Ovens
Multi-moded cavities or ovens are relatively large metallic cavities or boxes where the material to be treated is exposed to the microwaves. The microwave energy is introduced via a waveguide connection at one or more positions in the wall of the cavity. These applicators are mechanically simple and easy to operate as they usually do not require frequent re-tuning to ensure efficient heating.
Many modes can exist within the cavity and this means that there are many hot and cold heating regions or spots. The uniformity of heating within multi-moded cavities can be improved by carefully selecting where to introduce the microwave energy, by moving the material through the oven in a controlled way, or by using "mode stirrers" to stir the positions of the hot and cold spots. To optimize the cavity dimensions, it is necessary to know the dielectric properties (permittivity) of the material to be heated. Microwave New Zealand is able to measure such properties for you.
Multi-mode cavities are suited to continuous and batch processing of many materials. They are particularly suited to the processing of liquids at normal, elevated, or low pressures as the liquid material can be easily moved through any hot or cold heating regions.
Microwave New Zealand designs and builds multi-mode cavities for a range of applications. Contact us today to discuss your problems, ideas, or needs.
Other Microwave Applicators
Microwave New Zealand has designed and developed microwave applicators customised to specific industrial or scientific processes, where certain material properties make the use of travelling wave applicators or multi-moded cavities unsuitable. One of the benefits of these (normally physically small) applicators is that the low thermal mass allows rapid response and good control of, for example, the temperature of the material, or the desired melting or vaporizing.
Examples of other microwave applicator structures are:
Single mode resonant cavities
Transverse electromagnetic (TEM) applicators, such as coaxial-line applicators
Microwave New Zealand has considerable design and modelling experience of the interaction of electromagnetic waves with materials and can recommend microwave applicators for your specific need. Contact us today to discuss your problems, ideas, or needs.
Microwave New Zealand designs and builds microwave applicators to meet the specific requirements of your process or application. The tremendous range of materials and processes treated by using microwave energy means that adopting a generic applicator design may prevent you from getting good performance from your system. Many of Microwave New Zealand's applicators are tailored to the specific task. We can also often retro-fit microwave heating to existing process equipment.
Although batch microwave processing is still used, the high throughput demands of many industries means that continuous microwave processing, e.g., on conveyors or within pipes, is now being used to a greater extent.
Contact us today to discuss your requirements, thoughts, or problems.