Cu-waveguide

Introduction:

 

MTT120 Additive Manufacturing is a Masters course in Additive Manufacturing processing which has been successfully running at Chalmers for several years now. Students are encouraged to come up with interesting and novel concepts that could showcase the applications of this technology to the industry. In this case, a group of students from 2020 AM course (comprising of David Johansson, Erik Tjärdahl, Martin Ohlsson, William Höglind, Simon Lundin, Lars Wihler) designed and developed a Copper waveguide filter for 10GHz frequency. The part was then printed by EOS, Finland in pure Cu and tested here at Chalmers by David Johansson. Now, David answers some questions for us about the components they designed.

 

Questions:

What is the application of these waveguide filters?

Waveguides are capable of transferring large amount of power at higher frequencies with little attenuation. A filter’s purpose is to extract only certain frequencies and reject the rest. It might be used in communication infrastructure, radar equipment etc.


How is this AM produced component better than conventionally produced counterparts? 

A filter like this has a very complex internal geometry and would traditionally be made from multiple parts. And one of the main contributors to losses in waveguide systems is coupling between those parts. So, you would have to have very flat surfaces and lots of fasteners to ensure a good connection. By utilizing AM technology, we can eliminate these surfaces and reduce the amount of fasteners needed. However, making such a simple component as we did is not the most exciting part. Since AM allows more 3D approach and the ability to merge multiple components into one, we can build an entire feed chain. Combining filters, splitters and antennas into one part reducing weight and improving performance.


Are there limitations to the AM design? How can it be improved according to you?

The part we printed had a very rough surface of Ra=20µm, this is too rough for frequencies higher than 10Ghz as the attenuation would be too great. This could be improved using a different AM technology designed for smaller parts or by using good post processing treatments if possible.


 Picture1

Picture1: CAD design of the component with cut section design


Picture 2



Picture 2: Simulated vs actual values for frequency showing an actual loss of -0.7 dB is observed and the frequency for lower cut is seen to be 9.977 GHz instead of 10 GHz which is close to commercially available stock part.



Picture3: Picture of actual component after printing and post processing. Printed in pure-Cu

Page manager Published: Mon 13 Sep 2021.