Design of Cross and Square Slot with Beamforming for Microstrip Reflectarray Antenna at 28 GHz

The improvement of wireless communication is in line with the need for data transfer speed. The requirement of high capacity, big coverage, low energy consumption, and affordable equipment is urgently need. A high gain microstrip antenna is required. One of the suitable designs is using reflectarray antenna. Reflectarray has been researched to arrange the phase distribution by adjusting the unit cell elements. Moreover, by applying beamforming technique, the focusing beam direction of the antenna can be improved. This paper aims a design of a reflectarray antenna with beamforming that for 28 GHz frequency. The reflectarray antenna unit cell model consists of a square patch with cross and square slot. A complete reflectarray consisting of $7 \times 7$ unit cells is simulated with a horn antenna feed. The simulation results show a gain of 19.33 dB with a power shift about 6 dB when compared to the measurement results. For the beamforming direction in the horizontal and vertical radiation pattern, a shift of about 6^° is seen. If the beamforming simulation results are seen at a position of 24^°, then the beamforming measurement results are at a position of 30^°.