Speaker
Mrs
Karina Hoel
(Norwegian Defence Research Establishment (FFI))
Description
Our field of work is radar electronic warfare (EW). Our research aim for the work presented here is to study the electromagnetic properties of 3D printed antennas and microwave components, with EW applications in mind. 3D printing is a very attractive technology not only due to low cost and ease of manufacturing, but also the ability to manufacture complicated 3D geometries quickly and easily.
Throughout the last decade many researches have shown that metallization of plastic, so that the plastic gains some metal characteristics, is possible. However, none of the studies we have seen did an evaluation on how different materials, 3D printing technologies and metallization methods influence the electromagnetic performance of broadband structures. Therefore, our first step was to investigate how different plastics materials, metallization processes, and thickness of the metal impacted the performance of a broadband horn antenna and waveguide structures. In our study we have investigated different 3D-printing techniques, different types of plastics and several metal thicknesses. To provide confidence in the results, all measurements were compared to measurements on standard metal antennas and waveguides.
The electrical performance of the 3D-printed antennas and waveguides was found to be comparable to standard antennas and waveguides manufactured using machining techniques. However, not all metallization methods provided equal performance and a major question to answer for our application is how would these 3D printed antennas with different metallization methods perform with high power signals. So, the next step was to test the same antennas as transmitters and the results show that the antenna with highest conductive loss does not survive high power signals.
Another area of interest to us is easy integration of these antennas and microwave structures into systems. One attractive application is to print (parts of) UAVs with (parts of) the payload integrated. One application for this could be using the UAV as a passive sensor to detect emitters of radio frequency signals – normally referred to as Electronic Surveillance Measures (ESM). ESM requires a wide band antenna, and in our case the required frequency coverage was 7.5-18GHz. Waveguides and horns have a number of desirable features for a design like this. Firstly, the structure can be considered as part of the wing structure itself – adding to the structural integrity of the aircraft. Secondly, the waveguide itself is basically an air-filled corridor, adding little weight to the wing (when the waveguide walls can be considered as part of the actual wing structure). Thirdly, waveguides and horns have low losses, making it possible to move all microwave circuitry to the main body of the aircraft. No amplifiers, filters etc. should be required close to the antenna. Finally and most importantly in this context, waveguides and horns can be fully manufactured using 3D printing. This setup showed that the wing structure is transparent to the performance of the antenna and waveguide components.
To conclude and look ahead we will briefly look at some new possibilities that 3D printing provides, specifically in terms of allowing more complex electromagnetic structures to be manufactured, providing new or unusual electromagnetic properties. This is recent and ongoing work at our establishment. Currently we are working on a 3D printed dielectric microwave lens with graded refraction index.
JUSTIFICATION FOR THE CONSIDERATION
We were invited by Peter de Maagt at ESA to present our work at the workshop on Additive manufacturing on RF/Microwave hardware.
Primary author
Mrs
Karina Hoel
(Norwegian Defence Research Establishment (FFI))
