Research On Reconfigurable Holographic Metamaterial Antennas

Holographic antenna is designed by recording the interference pattern between a reference wave(the radiation pattern of the source antenna)and an object wave(the desired radiation pattern)through a fabricated holographic structure.The fidelity of the holographically reproduced far field is limited by the traditional recording method which only generates the minimum of the interference pattern,and the radiation properties of the antenna are fixed once the holographic structure is constructed.Metamaterial-based holographic structure incorporates numerous metamaterial elements,making it possible to record the hologram accurately by independently control of these micro-structures.What's more,adopting reconfigurable techniques,the antenna can reconfigure its performance by real-time adjusting of these elements.A holographic antenna design method based on the metamaterial and reconfigurable techniques is studied in this thesis and the research work is presented as follows:1.A design method of holographic antenna based on the amplitude weighted technique is researched.In order to realize the beam switch characteristic,a continuous amplitude weighted techniques is studied.The result shows that the beam can be accurately controlled once the distance between elements is small enough.Moreover,a discrete amplitude weighted technique is further discussed and a one-dimensional holographic antenna is designed based on this technique.The measured and the simulated results show that this method is certified efficient in beam manipulation.2.A reconfigurable holographic metamaterial antenna based on the PIN diodes is researched.Firstly,a coding metamaterial element loaded with PIN diodes is designed.The simulated result shows that the radiation efficiency of the element can be adjusted by changing its resonance state.Then a PIN-based holographic metamaterial antenna is designed.The simulated result shows that the main beam can be steered by adjusting the state of the elements according to the coding sequences.3.A reconfigurable holographic metamaterial antenna based on the liquid crystal is researched.A coding metamaterial element loaded with liquid crystal is designed.Then,a single-band and a dual-band holographic metamaterial antenna based on liquid crystal are designed respectively.The simulated result shows that a capability of pattern scanning can be achieved at different bands.