Metamaterial-based Electronic Scanning Antenna

In recent years, development of satellite communication system and radardetection system is rapid, so the reqirement of scanning antenna on certainfrequency is booming. Compared with mechanical scanning antennas, electricallytuned antennas are more and more popular because of its character of fast-switchingsanning angles and high accuracy scanning. Among these antennas,metamaterial-based electrically tuned leaky wave antenna plays an important roledue to its character of low-cost feeding network, low profile and high levelintegration.In this paper, liquid crystal based electrically tuned metamaterial leaky waveantenna is studied to raise the operating frequency of current scanning antennas.Firstly, microwave characters of liquid crystal are discussed and analyzed basing onthe visable light characters, and approximation method is adopted to simulate theelectromagnetic characters of liquid crystal. Secondly, a tuning method is proposedto modulate single radiation parameter of antenna. Electrically tuned mechanismsbased on this method are easy to design and fabricate, and tuning process is easy torealise at the same time. The antenna based on this method have a sanning angle of64degree in Ku band, an average gain of7.6dB and sidelobe level of-6dB. At last,another tuning method is proposed. Radiation and transmition characters can bemodulated at the same time with this method. Antnna based on this method has a50degree scanning angle at certain frequency in Ku band with an average gain of10.3dB and sidelobe level of-13.5dB.The electromagnetic charcters and application method of liquid crystaldiscussed in this paper could direct the designing of liquid crystal based microwaveand milimeter wave devices. Two tuning method can be applied for designing notonly antennas, but also other liquid crystal based devices. The antennas based onthese methods have excellent characters and could be applied in manycommunication systems.