5G Millimeter Wave Array Antenna

As antennas are indispensable devices in the process of electromagnetic wave propagation,antennas with expected radiation properties are of great value to ensure high quality transmission in communication systems.The low frequency band of microwave has been overused and there are little bands available,while millimeter wave becomes a good option for 5G communication in the future due to its high-speed communications and low latency.How to improve the gain of the antenna as well as a wider bandwidth have been the main concern when designing millimeter wave antennas.Low loss and easy to integrate in the millimeter wave band are significant advantages of SIW,so it is widely used in millimeter wave antennas.A 5G millimeter wave antenna array using substrate integrated waveguide technology is proposed in this thesis,which includes 2×2 elements.The array operates in the n257 band（28 GHz）with a relative bandwidth of 4.3%and a gain greater than 11d B.The way to widen the bandwidth of the cell antenna and the feeding method of the array antenna are studied in detail.The millimeter wave broadband substrate integrated waveguide back cavity radiating slit antenna adopts coplanar waveguide feeding structure,and a pair of short-circuiting metal vias are added in the cavity,which can bring the resonant frequency of TE₁₁₀ mode and TE₁₂₀ mode closer,then the multi-mode resonance appears in an expected frequency band range.By this way,the antenna bandwidth can be effectively expanded.As the simulation result shows,the antenna has a relative bandwidth of 17.8%and the corresponding frequency ranges from 25.1GHz to 30GHz.Besides,the antenna has a maximum in-band gain of 4.9d B,and a maximum radiation efficiency of 97%.A substrate integrated waveguide slit antenna with two layers of SIW adopts slit-coupled feed structure.The energy enters the lower SIW cavity through the SIW-microstrip feed structure and is transferred to the upper SIW cavity through the coupling gap etched on the metal contact surface between the two layers,and the energy is radiated outward through the butterfly-shaped radiation gap etched on the upper SIW surface.The antenna has a bandwidth of 27.5-28.5 GHz,a maximum in-band gain of3.7 d B and a maximum radiation efficiency of 94.5%.Based on the previously designed gap-coupled fed substrate integrated waveguide back cavity radiating slit antenna,a substrate integrated waveguide T-type power splitter that can cover the cell antenna’s operating band is designed,and further obtaining a planar array antenna containing 2×2 units.The array antenna has a bandwidth of27.3-28.5 GHz,a maximum in-band peak gain of 11.2 d B,and a maximum radiation efficiency of 93.7%.It is obvious that the bandwidth and gain of the array are better than the cell antenna.The designed antennas all work at 28GHz,the first antenna fully meets the broadband requirements and can cover most of the 5G millimeter wave n257 and n258frequency bands;the array and its element both have moderate bandwidth and gain.All the antennas designed above have high radiation efficiency that is above 90%and are suitable for 5G millimeter wave system.