Advantages of Additive Manufacturing for DRAs
Print Resonators in a Matter of Hours
One advantage of additive fabrication is the time it takes between finishing a design and having hardware ready to assemble. With additive technology such as Fortify’s FLUX ONE printer, a set of resonators can be printed in a few hours, then cleaned, sintered, and cooled in about two days total.
Ability to Print Complex Shapes
A more substantial advantage, though, is the ability to print complex shapes. Complex-shaped resonators can allow for efficient operation using resonators of lower dielectric constant. They can also be used for changes in polarization, beam focusing, and bandwidth. In addition to printing complex shapes, certain regions of the antenna can use latticing techniques to have different effective dielectric constant than the solid regions. Additionally, 3D printed dielectric materials are in development to push the limits of dielectric constant in additive manufacturing. If these materials can breach the 20-40 Er range, then a larger set of the DRA market will be open to additive solutions
Figure 3: DRA in a phased array configuration Integrated microstrip feed substrate is printed as one piece with the resonators.
Ability to Integrate Additive Copper
There are additive advantages to some of the feed structures that will pair with these dielectric resonators as well. In the case of the vertical edge microstrip launch, selective additive copper, as used on Fortify devices, could form the conformal copper trace that spans a plane and transitions into a vertical wall. Selective copper plating would also be favorable for a coaxial feed. The copper could be plated up the vertical side wall of the resonator or plated directly to a blind hole in the middle of the device. This would ensure that there is no air gap, as discussed above. Another option is to combine additive technologies and print metal waveguide antennas and arrays that couple to an array of dielectric resonators.
Since there isn’t a benefit to creating simpler geometries, additive manufacturing brings a higher chance to the integrated solution, where a field of dielectric resonators are printed together in a connected block of the same substrate. This substrate could then be metalized or otherwise integrated with a feed network for simpler assembly.
Figure 4: 3D printed resonator block with integrated superstrate for wide angle matching. All are printed with the same material as one part with the use of laticing for variable effective permittivity. The selective copper plating is a post process.
Ability to Integrate Latticed Devices
Due to the laticing capability of additive manufacturing, whereby a mix of air and dielectric material can be printed in different ratios for different areas of a device, there are opportunities to integrate latticed devices into the additive DRAs or arrays. Either a lensing or a gradient superstrate type solution could be integrated directly with a DRA or array of DRAs. Lensing could manipulate the beam width, affecting directivity and gain. It could also steer the boresight of an array to a new zero direction.
Impedance matching superstrates create an environment for the antennas to radiate efficiently into free space over a wider steering angle. Both classes of devices are enabled by latticed printing, which provides a way to use a varying effective εr by mixing different ratios of air to dielectric in a unit cell that is a small enough wavelength ratio to keep behavior linear.