Radio frequency applicators usually comprise a pair of balanced active electrodes or an un-balanced arrangement with an active electrode above an earthed electrode. The material to be heated is placed between the two electrodes. By carefully designing the shape, orientation and dimensions of the electrodes, very good heating uniformity can be achieved. The optimal electrode dimensions also depend on the dielectric properties or permittivity of the material to be heated (workload). Microwave New Zealand has a variety of methods for measuring the dielectric properties of your material.
Choice of both frequency and RF applicator configuration can be important to reduce the maximum electrode voltages and thereby reduce the chance of arcing in the load material or on the electrode faces.
Microwave New Zealand designs and builds radio frequency applicators for a range of processes and applications. We can also often retro-fit radio frequency electrodes to existing equipment and processes. Contact us today to discuss your needs, ideas or problems.
Radio Frequency Applicators
Retro-fitting a radio frequency heating system to a freeze-drying vessel.
It is often relatively simple to retro-fit radio frequency heating components to existing processes and equipment, such as drying, vacuum drying, or pressure vessels.
When retro-fitting an electromagnetic heating system to an existing process, the choice of the best radio frequency or microwave frequency depends on particular properties of the material to be heated and the environment in which it will be heated. Since Microwave New Zealand offers both radio frequency and microwave heating systems, we can give you unbiased advice as to which technology is more appropriate.
Even for retro-fitted systems we always ensure that any radiated electromagnetic signals are kept well below the legal requirements.
Contact us to discuss your problems, needs, or ideas.
A balanced electrode configuration is where the voltages appearing on each of the electrodes are equal in magnitude and opposite in direction with respect to zero volts. The electric field set up between the electrodes is very uniform and so the heating uniformity is very good.
An un-balanced electrode configuration is where there is one active electrode whose voltage varies at the operating frequency with respect to an earthed second electrode. Un-balanced configurations are often easier to implement but do not produce heating uniformities as good as balanced configurations.
By making the height of either of the electrodes adjustable, the electrodes themselves can be used to tune the system and ensure that all the energy is delivered to the material to be heated. This can reduce the number of other tuning elements and the cost of the system.
For very thin materials (web) the electrodes can be arranged in a way that produces electric fields along the length or width of the web. This is done so that the current is not as high as if the electric field lines crossed the thin dimension of the web.
Microwave New Zealand can design and build both balanced and un-balanced electrode applicators and radio frequency tuning networks. We can also give un-biased advice as to which configuration best suits your application. Contact us to discuss your problems, needs, or ideas.