Research And Implementation Of Ka-band Rectenna In Microwave Power Transmission

In recent years, the traditional energy is facing the crisis of depletion as growing demand for energy worldwide. With the global energy crisis intensified, unprecedented attention have been paid to the development and utilization of space solar energy, and this will become true step by step when the concept of Space Solar Power Satellite(SSPS) is presented. As the key technology in SSPS, Microwave Power Transmission(MPT) is also mainly applied to here. Furthermore, MPT can also be applied to many other fields such as aerocraft at high altitude, electric power supply in harsh environment and application at low power density. So the research about MPT is become more and more significative and tremendous application potentials.As one of the key component in MPT system, rectenna is composed of receiving antenna and rectifying circuit. In the Ka band, 35 GHz is a typical atmospheric window frequency, which has low attenuation of electromagnetic waves through the atmosphere, showed less reflection, absorption and scattering, high transmission efficiency. Moreover, compared to conventional microwave frequencies, such as the S-band, C-band, Ka-band rectenna has obvious advantages in volume.The main work of this thesis includes:1) Two different types of Ka band microstrip antenna with the resonant frequency of 35 GHz have been designed and implemented. Based on the principle of microstrip patch antenna design, T-joints and feed network simulation, by means of electromagnetic simulation software HFSS, the design of the antenna array can be completed and implemented. The measured gain of the 2×2 antenna array can reach 13.9dB with 1.45 GHz bandwidth; the measured gain of the 4×4 antenna array can reach 19.8dB with 1.85 GHz bandwidth.2) Two different types of Ka band rectifying circuit with the resonant frequency of 35 GHz have been designed and implemented. Based on the S-parameter, harmonic balance, parameter optimization, two types of efficient rectifying circuit have been designed and implemented. To be convenient for simulation and optimization of the whole rectenna system, here the receiving antenna can be equivalent to a power source, of which internal resistance is equal to the input impedance of the receiving antenna. The working emphasis of this part is analysing the conversion efficiency of the rectifying circuits at multiband frequencies and a wide span of the input power.The measured and simulated conversion efficiency are compared under different and same input power as for the two types of rectifying circuit, reasonable explains have also been given to the observations. As for series rectifying circuit with the resonant frequency of 35 GHz, it can achieve maximum conversion efficiency at 55% when the input power is 18 dBm. As for parallel rectifying circuit with the resonant frequency of 35 GHz, it can achieve maximum conversion efficiency at 53% when the input power is 18 dBm.