Design Of Shared-Aperture Antenna For Base Station Application

With the development of wireless communication technology and the opening of 5G communication frequency bands,communication system with large capacity and high quality has become a hot research direction.Base station antenna,as the transceiver equipment of various frequency bands signals in the daily needs of users,faces the issues of reducing the installation and maintenance cost and optimizing the site selection.On the premise of ensuring high-quality communication,multi-band and low interference sharedaperture antenna has become the focus of base station antenna research because of its advantage and potential for integrating communication systems in different bands.Aiming at the application of base station antenna,this paper studies the shared-aperture base station antenna on multi-band and low interference.The contents are as follows:Firstly,a low band element with a cross-shaped dipole structure is proposed,and the dualpolarization of ±45° is realized by the vector synthetic of radiation electric field through the coupling fed orthogonal dipole with Y-shaped couplers.The cross-shaped dipole can be used in shared-aperture antennas to avoid the radiation blockage of high band antennas.Compared with the traditional directly fed cross dipole,the cross-shaped dipole introduces Y-shaped couplers to feed by coupling.Adjusting the size and relative position of the coupler and dipole can control the resonance offset to broaden the bandwidth.In addition,the patch antenna with a lower profile is selected for high band antennas to reduce coupling interference.Through simulation and measurement,the proposed low band element can achieve the-10dB impedance bandwidth of 45.5%(1.70-2.70 GHz).And the low band isolation is greater than 25dB.The high band antenna can cover 3.3-3.8GHz,and the isolation is greater than 60dB.Then,based on the proposed low band element and high band antenna,two low interference and dual-band shared-aperture base station antennas are designed.Secondly,a dual-band shared-aperture base station antenna based on filtering structure is proposed.The filtering structure is introduced into the dipole arm of the low band element to reduce the high band induced current,so as to suppress the out-of-band interference between the shared-aperture antenna elements.According to the principle of equivalent circuit,the filtering structure can be equivalent to the parallel resonant circuit for high band current which is an open circuit,and equivalent to the series resonant circuit for low band current which is a short circuit,so as to ensure the operation of low band element and suppress the high band induced current to reduce interference at the same time.After simulation and measurement,the results show that the low band of the proposed sharedaperture antenna works at 1.70-2.35 GHz,the-10dB impedance bandwidth is 32.1%,and the isolation is greater than 30dB.The high band of the proposed shared-aperture antenna covers 3.3-3.8 GHz,and the isolation is greater than 30dB.Compared with the antenna with interference,the high band radiation is stable,and the radiation patterns in the operating band are restored.The proposed shared-aperture antenna can work normally.Finally,a dual-band shared-aperture base station antenna based on FSS structure is proposed.The low band element is designed as a FSS structure to achieve wave-transparent for high band signal,so as to reduce the out-of-band interference of the shared-aperture antenna.The FSS structure is of bandpass characteristics.By adjusting the width of the FSS structure and the length of the inner rectangular patch,the offset of resonance can be controlled to optimize the impedance matching.After simulation and measurement,the results show that the shared-aperture antenna works in the low band with the-10dB impedance bandwidth of 38.2%(1.79-2.69 GHz),and the low band isolation is greater than 25dB.The high band radiation covers 3.3-3.8 GHz and the isolation is greater than 30dB.The radiation patterns are restored in the high band and the whole band radiation is stable.The interference suppression between different bands is achieved in the proposed antenna and the good radiation of the sharedaperture antenna is guaranteed.