Research Of Co-time Co-frequency Full Duplex Antenna In Ku Band

Compared with time division duplex and frequency division duplex, the co-time co-frequency full duplex(CCFD) can make a double efficiency of spectrum in wireless communication link. Therefore, it has been widely applied in systems such as mobile communications, satellite communications, microwave relays and so on. Based on CCFD technology, this thesis gives a Ku-band miniaturized antenna structure by using the scheme of a single antenna transceiver. On this basis, a microstrip dual-fed circular polarized patch antenna and its balance feeding network are developed. Meanwhile, the isolation of the system is improved effectively. The main research work in this thesis focuses on the following:Firstly, the research on a Ku-band microstrip dual-fed circularly polarized patch antenna is presented. By using multilayer PCB technology and the way that microstrip line and stripline are orthogonal mixed feed to the slot, a Ku-band microstrip dual-fed circularly polarized patch antenna centered at 15 GHz is developed. It features a broadband and high isolation.Secondly, a broadside-coupled 3-dB directional coupler is designed by using microstrip broadside coupling. The single stage branch-line directional coupler has narrow bandwidth, while cascaded type suffers from high loss. The common coupling line directional coupler has relatively large bandwidth but not suitable for strong coupling generally. The broadside coupled line directional coupler has the advantage of good bandwidth and suitable for strong coupling. Therefore, this thesis designs a 3-dB directional coupler based on microstrip broadside coupling. In order to compensate for the unequal phase velocities between even and odd modes, a series of small stubs are loaded in the coupling region. Ultimately, it achieves good orthogonality and high isolation characteristics.Thirdly, a microstrip power splitter is designed. It has high isolation and good bandwidth by cascading two stages.Finally, the integration of antenna and balanced feed network is studied and designed. Based on the design of the antenna unit and feed network, this thesis analyzes the overall performance. It gives out the experimental verification and analysis on the basis of sufficient numerical simulations and the hardware implementation.The end of this thesis is the summary of the work and the prospect for the next step of this work as well as the development trend of related technologies.