Designing tapered waveguide

Hi,

I'm new to the microwave world, I have an Electrical Engineering qualification, but never worked with microwaves. I've observed via research papers people producing microwave generated high temperature plasmas and wanted to ( very cautiously ) try and reproduce some of the results I'd seen, using a humble 2.45 Ghz magatron I have sitting on my garage work bench.

The biggest issue is that I need to develop the knowledge to producing a tapered waveguide to boost the microwave intensity at the end of the waveguide to produce a plasma.

I have done some reading, but some of the basics seem to still evade me, in reality all I wanted is a basic design and some rules of thumb ( yeah....ha ha...its RF... ) to produce a basic rectangle section waveguide to have magatron at one end, waveguide tapered to half / quarter original thickness at other end where the quartz tube and plasma will sit.

I want to learn, hence my post.

I am acutely aware of the dangers of microwaves and HV.

Can I ask for some help, as I'd like assistance in designing such a thing from the ground up and am happy to read and research but its a big and complex field.

Any help appreciated.

Thanks.

It is practical to increase the power density in a rectangular waveguide by gradually reducing the small dimension. I used that technique in conjunction with a microwave ink dryer and easily was able to burn the fabric with the ink and was thus able to reduce the input power. I have no experience with trying to produce a plasma. That might be interesting and even more dangerous.

I have often been curious about the usefulness of higher order modes, in circular waveguides in particular. This could lead to an interesting exercise with a full wave simulator looking at various structures. In circular guides some of the higher order modes do not have electric fields terminating on the walls. I wonder if that would help produce your plasma?

Regards,

Azulykit