1420MHz Slot-Cube Antenna
I found out about slot antennas while looking into designs for the elements in my radio telescope phased array. I most likely will be going with an array of slot antennas (waveguide-fed slots in a copper plate—not these cubic wire slots) for that setup however this antenna is more of a tangental proof-of-concept.
About slot antennas
Slot-cubes are a neat twist on slot antennas. A normal slot antenna consists of a void in a conductive plane; think a dipole but backwards. As oriented in the example image, this antenna is vertically polarized. The X axis dictates the bandwidth while the Y axis dictates the frequency. These antennas are ideally fed at the center of that slot as shown in the photo. Any offset from the center will function as a change in impedance. You can also click that example image for a link to a website that explains it much better and far more in-depth than I have.
Now for this 3D variant. a slot-cube antenna is basically a slot antenna folded three times. Think of the wires as the boundaries of the plane and void. The fact that the rest of the plane is absent is irrelevant, what matters here is that the void is fully bordered by a conductive material. The radiation pattern gets changed but the bandwidth remains the same as that's dictated by the width of the void.
Here's the tarball containing the 3D model (.stl) and FreeCAD project file.