Methodology And System Design Of Antenna Radiation Efficiency Measurement

With the rapid development of wireless communication technology,the antenna is an important front-end component for transmitting and receiving electromagnetic waves in a wireless communication system,and its performance directly affects the communication quality of the whole system.Portable electronic products are usually powered by batteries with limited energy.The efficient operation of their built-in antennas is crucial for mobile electronic products.The most important performance parameter of small antennas is antenna radiation efficiency.The antenna radiation efficiency represents the efficiency of the antenna converting the high frequency current energy delivered into the antenna into the radiated electromagnetic wave.Since small antennas usually operate in a complex environment that affects their functions,the efficiency parameters of a small antenna are difficult to simulate with simulation software.Therefore,it is an important and challenging task to accurately measure the radiation efficiency of a small antenna.According to the above background,a wideband radiation efficiency measurement method based on the improved Wheeler cap method(IWC)is proposed in this paper,and a set of antenna radiation efficiency measurement system is designed.This paper focuses on the following work.1.The advantages and disadvantages of the common antenna radiation efficiency measurement methods are studied.It is found that the accuracy of radiation efficiency measurement is affected by cavity resonance.2.The effect of cavity resonance on the characteristics of the antenna in the cavity is theoretically analyzed,and the corresponding equivalent circuit model is established.The broadband radiation efficiency measurement method based on IWC is proposed.3.The correctness of theoretical analysis of cavity resonance and the feasibility of improved IWC are verified by simulation.A rectangular resonator is simulated to verify the correctness of the theoretical analysis of the cavity resonance affecting the antenna performance.A variable volumetric resonator based on improved IWC is simulated to eliminate the interference of the cavity resonance on the measurement results.A sleeve electric dipole antenna is designed to verify the accuracy of the results of the radiation efficiency measurement system.4.A fixed size rectangular cavity measurement system is set up to verify the measurement accuracy of IWC and the effect of cavity resonance on the radiation efficiency measurement.According to improved IWC proposed,a variable volumetric cavity measurement system is built to eliminate the influence of resonance,and a number of dipole antennas are measured.The measurement results are compared with the simulation results or the data provided by the antenna supplier.The final measurement results show that the proposed wideband radiation efficiency measurement method based on IWC could effectively eliminate the influence of cavity resonance on antenna radiation efficiency measurement.The variable volumetric cavity measurement system in this paper has the characteristics of rapid measurement,high accuracy,good repeatability and removing the effect of cavity resonance,and could accurately and quickly measure the radiation efficiency of broadband antenna.