Design and Optimization of 5G Millimeter Wave Patch Antenna for Smart Phones

High gain microstrip patch antenna and its array are proposed to support fifth generation (5G) technology at millimeter wave band. The proposed antenna is designed on Taconic TLY substrate with dielectric constant of 2.2 and thickness of 0.8 mm. Simulations are performed with CST Microwave Studio (CST MWO). The unit antenna has two rectangular patches and tapered feed. Rectangular patches and tapered feed are placed on the upper surface of the structure. The conductor feed extends from the bottom surface through the tapered feed patch which is capacitively coupled to the rectangular patches. The bottom surface of the structure is completely covered with ground. Size of the unit antenna is $3.86 \times 3.44 \mathrm{mm}^{2}$ $\left(\lambda_{0}=11.05 \mathrm{mm}\right.$ free space wavelength at $\left.27.15 \mathrm{GHz}\right)$. The simulated results show that the unit antenna impedance bandwidth range from 25.8 to 28.5 GHz (9.95% fractional bandwidth), and has gain more than 6 dBi. Side lobe levels of the proposed unit antenna at E-and H-planes are -12.0 dB and -9.8 dB, respectively. 8-element antenna array is formed to have a compact size of $52.86 \times 3.44 \mathrm{mm}^{2}$, to fit into a smart phone. Proposed antenna array is implemented on four sides of a smart phone and simulated in CST MWS. Simulated results show that the antenna array impedance bandwidth is 26.1 to 28.7 GHz (9.50% fractional bandwidth). Broadside gain with equal excitation of antenna array is 15.7 dBi at 27.0 GHz and the side lobe level is -11.4 dB at E plane and -8.8 dB at H plane. The proposed $1 \times 8$ patch antenna provides easy implementation and fabrication for smartphones that would utilize 5G millimeter wave bands.