## Appendix A
The two bands of the dual-band shared aperture are very far away from each other, enabling big and small elements to be alternately mounted, whereas the two bands of our antenna module are too close to adopt the shared aperture. When it comes to a novel structure, we can solve this problem by proposing the metamaterial lenses shown in Figure 15. A metamaterial lens for a 28 GHz single patch can be combined with the one for a 24 GHz two-by-two patch array. Each of the lenses comprises the unit cells of heights on PPS as the dielectric superstrate equivalent to the phases distributed as colors marked on the grid. They increase the antenna gains of the 28 GHz and 24 GHz primary antennas by more than 11 dB, as observed in Figure 15. Nevertheless, the reason that this new antenna is not adopted for the work of this paper is the structure becomes much bigger than the proposed antenna, resulting from the enlarged area and the gap between the metamaterial lens and its source antenna. Additionally, it requires jigs to hold the lenses, which cost more to realize. Sub-arrays have also been designed in this lab, though this is not the main focus of this paper. Figure 15 shows a 3D view of the geometry and the beam-patterns for steering at 24 GHz. Because this system is made up of multiple layers with horizontal elementsinterconnected to vertical elements, it is costly to implement. One of the reasons to use sub-arrays is to steer the beam. This necessitates the use of beamformer chips, resulting in an increased cost for connecting, debugging, and controlling. This is not suitable for developing lighter and less bulky antennas, many which will be deployed on automobiles, cube satellites, and as access points in mmW networks. When our antenna is applied to the idle nodes selected to work as relays in the cooperative network, the QoS will be enhanced by reducing the blockage error and unnecessary power consumption, as in [23]. Lastly, Figure 5 explains RS01 in more detail. Actually, there are many candidates for a reflecting surface other than the metal plane. It does not have to be a metasurface. Any arbitrary pattern is taken, because the objective of the experiments is to see whether differences occur in S\({}_{21}\) and the transmission ratio as the object changes in the sensing path. The metasurface is discussed in detail in the following figures. Figure A3: Different antennas having been designed in this lab as alternative approaches. (**a**) Metamaterial lenses for two frequencies as a new approach. (**b**) Beam directivity is improved by the use of metamaterial lenses. (**c**) Sub-array antenna requiring multiple layers to tilt the beam, when fed by the phase-set from beamformer chips expressed in from red (strongest) through green (middle) to blue (weakest). The phase distribution on the surface is needed to assure the user of a high directivity at the desired angle of reflection, as in Figure A4, and this is rooted in the unit cell given on the left of the picture. The phase of the unit cell is the function of the size of the metal part (in yellow) on the 4350 B substrate, and the size is determined to meet the phase required by the value given from the phase distribution in the middle. The reflection from all the cells will be summed to tilt the incident wave to 45 degrees as the angle of reflection here. This direction is aligned with the path from the plane to the receiver.