Design Of Antenna Array Feeder Using Microstrip Phase Shifter And Power Divider On Ferrite Substrates

With the rapid development of wireless communication, mobile terminal is becoming more and more popular. Microstrip antennas, because of its small size and easy integration, are widely used in wireless communication devices, especially in phased array applications. To realize a four patches microstrip phased arrays, an array feeder, working at 10 GHz and consisted by phase shifter and power divider, is designed as the four-patch microstrip antenna array feeder. The feed network is realized on an externally magnetized ferrite substrate and tunable phase shift is made by changing the magnetic bias, which changes the permeability of ferrite material. The varying of permeability, in turn, changes the phase velocity as well as the insertion phase of the propagating microwave signal. In this paper, the following works have been done.Firstly, with the ferrite substrate microstrip line under bias magnetic field, the transmission characteristics could be summarized as following: 1.With external magnetic field, the ferrite substrate microstrip line could transmit signal with changing phase characteristics. 2. Matching the impedance, microwave signals could be transmitted between two different substrate media. 3. Being applied in certain bias magnetic, ferrite transmission line will appear in a certain band absorption of microwave energy, resulting in the break of signal transmission.Secondly, a 10 GHz T-junction power divider is designed. With cut angles optimization, the S11 of the optimized T-junction reaches -25dB at 10GHz, and isolation between the two output ports could reaches -7dB. In addition, a 10GHz working frequency Wilkinson power divider is also designed by simulation software CST Microwave Studio. Simulation was carried out to study the transmission characteristics under influence of the external bias magnetic field.Finally, the 10GHz microstrip patch antennas are designed. Then, as the basic unit, a two way and a four way antenna array are built. Through the comparison of simulation results, we conclude that, with the increase of the antenna element, antenna gain becomes higher and main lobe pattern becomes more acute in the experimental results. Connecting the antenna arrays with the feed network, simulating and analysing the phased array radiation characteristics of the two and four-element phased array respectively. The result shows that the antenna arrays achieve beam scanning under the control of the external bias magnetic field.