Switch-Beam Vivaldi Array Antenna Based On 4x4 Butler Matrix for mmWave

It will be diffcult to use either omnidirectional or fixed beam antenna due to the high propagation losses caused by atmospheric absorption at mmWave for 5G mobile communication. Several studies have been conducted recently using butler matrix which is part of switchable antenna with some advantages such as simple, minimal cost, low loss, etc. Previous studies also have designed vivaldi array antenna at 28 GHz which provides a fix beam directional radiation pattern with narrow beam that requires real phase setting. However, there has been no research using vivaldi antenna with butler matrix, whereas it has some advantages such as wide bandwidth, high gain, high directivity, etc. This paper proposed 4x4 butler matrix integrated with vivaldi antenna by using phase shift of 45. The design is developed on a single layer of Rogers RT5880 with dielectric constant 2.2 and thickness 0.254 mm. Best results of simulation were picked for overall system at 28 GHz, and the results of antenna as follows: the return loss was below -10 dB, the realized antennas gain was 10.2 dB with unidirectional radiation pattern and bandwidth antenna of 6 GHz that covers from 25 GHz to 31 GHz. The butler matrix average phase di erent between output port are -44.106 degrees, 137.38 degrees, -137.66 degrees, 43.95 degrees with phase error of 0.894 degrees, 2.38 degrees, 2.66 degrees, 1.06 degrees. Antenna array that has been given di erent phase by butler matrix is able to shift radiation pattern on the input port successively with range of beam that can be achieved equal to 185 degrees.