Application Of Wideband Base- Station Antenna For Lte Communication System

With the rapid development of modern mobile communication systems, stringent requirements are imposed on base station antennas by LTE-A (Long-Term Evolution Advanced) system. According to published papers, electro-magnetic dipole and half-wavelength dipole fed by balun are suitable elements for LTE base station antenna due to wide impedance bandwidth, stable radiation pattern and gain within operating frequency. In this dissertation, extensive investigations on wideband electro-magnetic dipole, double U-slotted microstrip antenna and dual-polarization antenna fed by balun are made firstly. Secondly, two antenna arrays are formed in the E- and H-plane of the electro-magnetic antenna composed of bowtie-shaped shorted patch and dipole, which realize vertical and horizontal polarization. Since the introduced power divider network and element mutual coupling have great deterioration on the array performance, investigations are focused on the decoupling method and broadband power divider network. The dissertation is organized as follows:Firstly, a wideband antenna composed of a bowtie-shaped meander slot antenna and an electric dipole is proposed. Simulated results show that the fractional impedance bandwidth is enhanced significantly from 2.7% of the bowtie-shaped meander slot antenna to 26.2% of the proposed antenna with |S11|<-10dB. Then, an electro-magnetic dipole composed of bowtie-shaped shorted patch and dipole is simulated and fabricated. The measured results show that the impedance bandwidth is 1.7-2.7GHz (VSWR<1.4) and radiation pattern and gain are stable within operating frequency, which indicate that this antenna can be a candidate for LTE base station antenna.Secondly, investigation on wideband microstrip antenna element is implemented. A wideband microstrip antenna with double U slots is simulated. The impedance bandwidth is 0.7-1.05GHz with VSWR<2, namely fractional bandwidth is 40%. Then a dual-polarized antenna balun fed round dipole is designed and fabricated. Measured results indicate the bandwidth is 1650-2250MHz (S11<-10dB), and the isolation is better than-25dB.Finally, two kinds of antenna arrays are formed in the E- and H-plane of an electro-magnetic dipole respectively, which realize the vertical and horizontal polarization. By the use of via decoupling and multi-level wideband power-divider, the influences on antenna array performance introduced by power divider network and element mutual coupling are eliminated. The work such as PCB layout, structure layout, installation, impedance matching and measurement are finished by the author. Measured and simulated results indicate good agreement. It can be seen that the impedance bandwidth is 1710-2690MHz (VSWR<1.5), and radiation pattern satisfiy the need of base station antenna.Results show that these two arrays can be used as LTE base station antenna...