Roig Parras, María
Tunable Metamaterial Leaky Wave Antenna based on Microwave Liquid Crystal Technology.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2015)
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|Item Type:||Ph.D. Thesis|
|Title:||Tunable Metamaterial Leaky Wave Antenna based on Microwave Liquid Crystal Technology|
In this work, a continuously electrically tunable metamaterial leaky wave antenna for Ka-band applications is designed, manufactured and investigated, which features one dimensional beam steering capabilities.
The antenna concept is developed based on the theory of leaky wave antennas and metamaterials. Leaky wave antennas provide low profile and high directivity while metamaterials offer design flexibility by means of dispersion engineering. Additionally, liquid crystal is employed as tunable material to achieve voltage tunable beam scanning. The design, implementation and characterization of the voltage tunable metamaterial unit cell that makes up the leaky wave antenna is described in detail. The design and analysis of the dispersion characteristic of the unit cell is based on equivalent circuit, analytical and full-wave models. Moreover, tunability and loss analysis as well as far field investigations are carried out.
Since technological constraints limit the feasibility of the unit cell, their influence on the design and fabrication process of the antenna is analyzed. Considering these constraints, a fabrication process that combines microwave structures with resistive voltage biasing networks and liquid crystal cavities is developed in this work. Different manufactured antenna prototypes are presented. A magnetically biased leaky wave antenna, which uses a static magnetic field to achieve a beam steering at 27 GHz is used to demonstrate and investigate the proposed unit cell concept. In addition, an electrically biased leaky wave antenna, where the orientation of liquid crystal molecules is changed by a tuning voltage that yields voltage beam scanning capability around 27 GHz is developed. Simulation, vectorial network analysis and far field measurement results of both prototypes are compared and a detailed analysis of the magnetic and electric biasing techniques is presented. Response time investigations are carried out for the manufactured voltage tunable leaky wave antenna and the liquid crystal material utilized in this work.
The presented electrically tunable metamaterial leaky wave antenna concept in combination with the fabricated prototypes demonstrates that the usage of continuously tunable metamaterials is a solid option for the realization of leaky wave antennas with a low profile at the Ka-Band. Moreover, due to the good electromagnetic properties of liquid crystal material at higher frequencies, the presented antenna concept and design methods can be applied for frequencies up to 4 THz, which is of particular importance for current and future applications in modern wireless communication systems.
|Place of Publication:||Darmstadt|
|Uncontrolled Keywords:||leaky wave antennas, metamaterials, liquid crystal, tunable antennas, tunability, Ka-Band, K-band|
|Classification DDC:||000 Allgemeines, Informatik, Informationswissenschaft > 000 Allgemeines, Wissenschaft
600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften
|Divisions:||18 Department of Electrical Engineering and Information Technology > Institute for Microwave Engineering and Photonics > Microwave Engineering
18 Department of Electrical Engineering and Information Technology > Microwave Electronics
18 Department of Electrical Engineering and Information Technology > Institute for Telecommunications > Communication Systems
|Date Deposited:||16 Nov 2015 08:11|
|Last Modified:||16 Nov 2015 08:11|
|Referees:||Jakoby, Prof. Dr. Rolf|
|Refereed:||1 October 2015|