Study And Design Of Broadband Multimode Base Station Antenna

People's increasing communication demands have greatly promoted the upgrading of mobile communication systems.The accelerated deployment of 5G around the world can be divided into two major categories:FR1 Sub-6 GHz and FR2 millimeter wave.The millimeter-wave frequency band is temporarily shelved for key technical research due to its propagation characteristics and technical bottlenecks.Therefore,the Sub-6 GHz frequency band has become the preferred frequency band for 5G deployment in various mainstream countries.The selection of Sub-6 GHz as the initial construction frequency band for 5G can effectively reduce the cost of base station deployment,accelerate the speed of 5G network deployment,and also trade off signal coverage and communication transmission rate.A base station antenna with large bandwidth and stable gain is crucial for a new generation of the communication system.This dissertation will study and design the broadband antenna covering the three major domestic operators in the sub-6 GHz frequency band.The primary workings of this dissertation are as follows:1.A multi-mode broadband base station antenna suitable for the Sub-6 GHz frequency band is developed,and the design method of the multi-mode antenna is explored at the same time.Based on four elliptical slot from four rectangular patches separately,four T-shaped dipoles and balun feeding structure,four operating modes were excited together,which expands the bandwidth and gain while maintaining the antenna radiation pattern stable.This dissertation evolves the structure of the antenna for mode analysis,and systematically studies the four operating modes of the antenna and the influence of each parameters.The measured results show that the-15 d B relative bandwidth of the antenna can achieve 53.1%,the impedance bandwidth can covers 2.28 GHz to 3.92 GHz,and the radiation pattern and gain are stable.The proposed antenna is suitable for the application of Sub-6 GHz communication systems.2.A cross dipole antenna loaded with double loops is designed.The antenna is loaded with two parasitic rings upon a crossed dipoles to achieve the purpose of exciting two new resonance modes at high and low frequencies to expand the antenna bandwidth.The dissertation analyzes the key parameters of the antenna's cross dipole and two parasitic rings to achieve mode matching,and analyzes the operating mode of each resonant point to reveal the method of loading the parasitic ring to expand the antenna bandwidth.The final designed antenna size is 0.327?₀×0.327?₀×0.143?₀.The simulated results show The antenna-10d B impedance can achieve 43.97%and operating over 3.30?5.16 GHz with the gain of8.55±0.72 d Bi,and it can effectively cover communication frequency bands such as N77 and N78.3.A dual-band base station antenna design that can effectively cover Sub-6 GHz is proposed.The antenna expands the antenna bandwidth by loading Y-shaped dipoles,coupling excitation ring dipoles,and changing the shape of the balun patch.At last,the prototype antenna was fabricated and measured.The measured results show that under the standard of VSWR<1.5,the antenna's low frequency impedance bandwidth can cover 2040 MHz to 3800MHz,and the high frequency can cover 4800 MHz to 5040 MHz,and the gain in the operating frequency band is 9.17±0.90 d Bi.Meanwhile,the radiation pattern in the low frequency band is relatively stable,but the side-lobe level of the high frequency pattern is relatively larger.The proposed antenna provides a multi-band design idea for the antenna field,and it can cover three communication bands of 2515 MHz to 2675 MHz,3300 MHz to 3600 MHz and 4800MHz to 5000 MHz divided by the three major operators.